How's the economy?

Question:

I fly less now than I did in the booming economy of late 90’s.  I own residential rentals in Dallas and housing is soft now.  Less money in my pocket means less hours in the sky.  Plus, I squirrel away more money now. I know of a couple CFI’s who had to find other jobs.  A couple lowered rates and practically begged for students.  A lot of tech geeks gave up their expensive hobby when their jobs disappeared. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive. Some say yes, some say no.

Consumer confidence.  Plain and simple consumer confidence. Sad situation. -RM

– Hide quoted text — Show quoted text – Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive. Some say yes, some say no. How ’bout it — you folks flying any less because of bad times? — Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination"

Response:

How ’bout it — you folks flying any less because of bad times?

I started flying in bad times (post 2001-09-11), so I have nothing to compare to, but when I have to pay so much for insurance, tie-down, maintenance, and annual, I want to make damned sure that I get my money’s worth by flying a lot of hours. Even at Canadian prices, avgas for my Warrior costs up to only CAD 35/hour (USD 25/hour) at 75% power and 8.5 gph, and less if I’m flying slower.  Flying the same trip (say, Ottawa to Toronto), the cost of gas for the Warrior II or for our 1999 Toyota minivan comes up to about the same, even though mogas is cheaper per liter.  In downtown in big cities, parking is sometimes a little cheaper for the Warrior than it would be for our minivan.  The main extra cost of taking a family trip by air is having to rent a car at the other end. All the best, David

Response:

Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on.

Considering they market products that are TOTALLY optional, I don’t think you can use them as a good example of the overall industry.  Laminar Flow, and they’re chief competition Knots2U, have been around for a pretty long time (probably close to 20 years).  They have to realize that their market is low volume.  The Powerflow exhaust is a great idea (I have one), but it’s priced pretty high if you consider the cost of a replacement stock exhaust. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive.  Some say yes, some say no. How ’bout it — you folks flying any less because of bad times?

Significantly less than I ever have before,  but mostly because of the Fed’s silly airspace restrictions.  I would bet that gas isn’t that much higher, if at all, than it’s ever been if you compensate for inflation. Maintenance costs don’t seem any higher,  and avionics upgrades are, most of the time, optional. — Jay                                   __!__ Jay and Teresa Masino           ___(_)___ http://www2.ari.net/jmasino/     !  !  ! Checkout http://www.oc-adolfos.com/    for the best Italian food in Ocean City, MD    and…    Checkout http://www.brolow.com/ for authentic Blues music on Delmarva

Response:

"acquiring my ATP in a couple hundred hours" I thought you needed something like 1400 hours for your ATP? – Hide quoted text — Show quoted text – How ’bout it — you folks flying any less because of bad times? I’m in the internet test gear market.  Last year was the company’s best year of the last four.  So far we’re down compared to those (perhaps unrealistic) numbers, but in the last two weeks we’ve received quite a few orders, several of which were unexpected.  If the 4th quarter is nearly as good as last year, we should wind up doing about 75% of last year’s gross, which is more than enough to stay in the black, and really not bad when one considers how many companies have imploded in my area in recent memory. Another data point … all of my friends who were out of work, including one who was on semi-permanent vacation for 18 months, are now gainfully employed.  Overall, I’d say the economy is (finally) picking up. Employees don’t have the pricing power they did in the late 90’s, but we have to walk before we run, no? As for flying, I recently exceeded my annualized record for flight time, but not without personal sacrifice.  My justification and motivation for continued spending in aviation is hinged on acquiring my ATP in a couple hundred hours. -Doug — Doug Vetter, CFIMEIA http://www.dvcfi.com

Response:

My freelance work has picked up very noticeably this past month. I’m getting more requests from startup businesses and quite a number of my current clients are repeats.

So when are you gonna quit your day job, Jeffro? — Jim Fisher

Response:

How ’bout it — you folks flying any less because of bad times?

I’m in the internet test gear market.  Last year was the company’s best year of the last four.  So far we’re down compared to those (perhaps unrealistic) numbers, but in the last two weeks we’ve received quite a few orders, several of which were unexpected.  If the 4th quarter is nearly as good as last year, we should wind up doing about 75% of last year’s gross, which is more than enough to stay in the black, and really not bad when one considers how many companies have imploded in my area in recent memory. Another data point … all of my friends who were out of work, including one who was on semi-permanent vacation for 18 months, are now gainfully employed.  Overall, I’d say the economy is (finally) picking up. Employees don’t have the pricing power they did in the late 90’s, but we have to walk before we run, no? As for flying, I recently exceeded my annualized record for flight time, but not without personal sacrifice.  My justification and motivation for continued spending in aviation is hinged on acquiring my ATP in a couple hundred hours. -Doug — Doug Vetter, CFIMEIA http://www.dvcfi.com

Response:

Being as your in the hotel business, on an airport, I bet you can see the trend easier then most of us.

Our hotel business is so bizarre, it’s hard to gauge how things are really doing in the economy.  This is partially due to our location in a University town, which tends to insulate us from the "real" economic world.   One thing’s for sure, though:  If we had to depend on pilots for our core business, we would have closed the doors by now. We’ve really had our ups and downs this first year.  We had a catastrophic late winter/spring, when the war in Iraq literally stopped everyone from making travel plans.  The country took a collective breath, held it, and we literally had weeks with almost no guests, virtually no income — and plenty of expenses that never stopped… With the cessation of hostilities, and a big increase in fly-in guests, we had an absolutely incredible summer.  We were so busy with both fly-in and "regular" guests that we fell four months behind in our remodeling schedule. We made up everything we lost in the spring, and then some… Now, since Labor Day, it’s been pretty dead again, with nights (like tonight) at just 30% occupancy.   However, these nights are separated by our incredible "College Football Weekends", thanks to the University of Iowa Hawkeye home games, when we can almost literally charge ANYTHING for any room, and command a two-night minimum stay.  And we have a long waiting list of folks praying for cancellations, at any price.  (We’ve even started renting out vacant rooms in our dorm — a 3-story rooming house.  I’ve got people absolutely thrilled to pay fifty bucks a night to stay in a 12 by 12 foot room, with shared bath facilities!) This is all fine, but our goal — and reason for opening the hotel — is to provide an outstanding destination for fly-in pilots, so that folks like us have a place to spend a getaway weekend among friends who "speak aviation", in a city with lots of neat things to do.   To this end, we’ve attracted many pilots from all over the world, and it’s been great — but it’s still just a smattering percentage of our overall business. As a whole I’d say that General Aviation has been way down around here for at least the past 6 months, and it doesn’t look like it’s getting better any time soon — although our local FBO just told me that they have recently seen a HUGE increase in their number of student pilots, which bodes well for the future. While this is great news, it’s not going to impact my business anytime soon. It would sure be good to see G.A. booming again, because we’d MUCH rather hang out with you guys than just a bunch of "normal" guests!  ;) Oh well — I hope Laminar Flow and Power Flow Exhaust can hang in there. They seem like good people, trapped in a very bad segment of the economy. — Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination"

Response:

How ’bout it — you folks flying any less because of bad times?

No.  Less flying because of TFR nonsense (a small contributer), but mostly work commitments are interfering with my ability to just take a few hours of vacation and fly.   I keep telling them that if I don’t have time to fly then there isn’t any point to having the job… :-/ — Bob Noel

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How ’bout it — you folks flying any less because of bad times?

Yeah, by at least half. RE: the overpriced exhaust system…. A new (rebuilt) stock system runs about $1000 including all new heat shrouds and brackets, for a Cherokee 140. I know… did that last year’s annual. The Powerflow system is $3675.00. http://www.powerflowsystems.com/products/PA28150_web.htm That’s absolutely *NUTS* !

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How ’bout it — you folks flying any less because of bad times?

Personally, no – our business is great. But the Mobile Bates Field Aero Club is in the worst financial condition it’s been in for 20 years because the members just aren’t flying. I don’t use the club planes anymore, but I glanced at the reservation book last month and found weeks with NO hours flown by any of the three airplanes. — Dan C172RG at BFM

Response:

I try to fly somewhere (XC – I dont consider local zooming around flying) at least once a week. We have an internet business, even tho its down by about half since 2000, its still doing ok enough for me to take my wife to her horse shows. Being as your in the hotel business, on an airport, I bet you can see the trend easier then most of us. I have several friends who are CFI’s, they said business has recently picked up alittle, but for awhile, was horrible. This weekend, its off to the Prescott, Az.  Airfair… – Hide quoted text — Show quoted text – Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive.  Some say yes, some say no. How ’bout it — you folks flying any less because of bad times? — Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination"

Response:

… sounds like a good time for a paint job?

Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business.

I feel for those guys. But it is not only the economy that is hitting them, I believe there are side effects from the security situation and the unnecessary choking of GA post 9-11. It would be GREAT if we actually had an economic plan besides tax cuts for the guys with jets. How ’bout it — you folks flying any less because of bad times?

The same. It just hits my pocket book harder.

Response:

How ’bout it — you folks flying any less because of bad times?

Lost my job last November. Since then, I’ve run through quite a bit of unemployment insurance and finally opened up a home repair service to get a little money coming in. On the other hand, I’ve done my best to attend every Young Eagles flight in New Jersey (made it to about half). So it’s probably about the same total time. No long trips, though, and I skipped Osh. George Patterson       God grant me the senility to forget the people I never liked anyway, the       good fortune to run into the ones I like, and the eyesight to tell the       difference.

Response:

The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive. Some say yes, some say no. How ’bout it — you folks flying any less because of bad times?

Since all my flying currently is business related, we’re flying more and making inroads with new customers since we do business face-to-face, whereas our competition is merely doing phone calls and e-mails.

Response:

– Hide quoted text — Show quoted text – Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive. Some say yes, some say no. How ’bout it — you folks flying any less because of bad times?

Here in the UK fuel is $6.50 a US gallon and with landing fees at every airstrip, Minimum this year has been $12 for a simple grass strip and $100 for a provincial airport when I had to divert you have no idea of cost.  An initial issue of a pilots licence is  $240 after paying the test fees. you can be sure I fly all the hours I can. Don’t land anywhere though. Dave

Response:

I haven’t flown in over a year.  A big reason is saving cash.  I suspect that I’m not the only one.  A couple of years ago, on a typical summer Sunday, the Mpls Star Tribune used to have about 30+ classified listings under aviation.  For the last year or so, it’s been averaging 6 listings on a Sunday. The good news is that in my business, things are coming back to life. Another couple of months of decent sales, and I’ll start getting more interested in getting back into the cockpit. Mike Schumann

– Hide quoted text — Show quoted text – Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive. Some say yes, some say no. How ’bout it — you folks flying any less because of bad times? — Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination"

Response:

– Hide quoted text — Show quoted text – Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive. Some say yes, some say no. How ’bout it — you folks flying any less because of bad times? — Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination"

Am flying the same if not more.  I don’t think one company can be considered a trend.  The people I know that have bought Power Flow exhaust say the plane has improved performance not because of the Power Flow exhaust but because their wallet is so much lighter.  Might have something to do with the current financial condition of the company.

Response:

I’m flying a tad less these days but it’s due to conflicting schedules and not lack of funding.  I try to fly once every 7-10 days or so and sometimes it goes two weeks between flights.  Fortunately, I’m able to fit the costs of flying into the budget. — Jack Allison PP-ASEL "When once you have tasted flight, you will forever walk the Earth with your eyes turned skyward, for there you have been, and there you will always long to return"  - Leonardo Da Vinci

Response:

The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive.  Some say yes, some say no. How ’bout it — you folks flying any less because of bad times?

If it’s worth anything at all, the industry we sell to (cast-metal foundries, that is. Have a look in your cowling to see where my work intersects your flying) usually leads the rest of the economy. When things are about to go badly, we’re some of the first to be hit. When they begin to get better, we know it first. So it might be instrumental for everyone to know that our orders for software to this industry are up, our consulting contracts are swamping our engineer, and people are paying the bills. We’re getting this in spite of an industry full of engineering consultants and also full of remarkably reticent customers. So I think the economy is on the mend and has been for about five months. I’m sure it won’t get as white-hot as it was in the mid-nineties overnight, but my own out-of-work relatives are now back to work and making ends meet. And I was one of the lucky ones, having never lost work to the colossal executive sophistry and stock market driven fear pervading my own specialty. By the time the election rolls around I’d guess people will be quite apathetic about the economy. Rob — [You] don’t make your kids P.C.-proof by keeping them ignorant, you do it by helping them learn how to educate themselves. — Orson Scott Card

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How ’bout it — you folks flying any less because of bad times?

Not me personally, but I know others that are not flying as much. Rental and fuel costs have increased steadily over the last five years. Given that the majority of pilots are renters, that is significant. We had a leaseback 1999 C172S in our club for three months before the owner pulled it due to lack of income generation. Of course, it didn’t help that he priced it out of the market at $96/hr. The older C172N’s are still renting for $72/hr. Then there is the recent lease back of a 1982 Piper Archer that is renting for $96/hr, it isn’t flying much either. There are basically two groups of renters in our club, the high performance/complex group and the low power types. The HP/CPLX are relatively small in number, perhaps 15-20 people renting (wet) a C182R ($112/hr), PA28T-201T ($112.50/hr), and PA32-300 ($115/hr). The remainder of the 700+ members split the three C172’s, two C152’s, a Katana, and a PA28-181. The majority of the club’s membership only fly between Memorial Day and Labor Day. The C172’s are used pretty steadily for Student Pilot training and weekend outings. How do I determine that flying is down? Aircraft availability. Until two years ago, I would have to reserve an aircraft months in advance. Now, I walk into the office, look at the schedule book and block an aircraft for the dates and times I want.

Response:

How ’bout it — you folks flying any less because of bad times?

Absolutely.  Positively. For a while I thought this stupid economy was gonna kick my ass.  I started kicking back, though, and have survived with only a few scars.  I learnt my lesson, though.  I ain’t gonna get back into the air regularly until I have more solid footing on the ground. — Jim Fisher

Response:

Not flying as much. Don’t have the income that I had 2 years ago. We have a residential interior design firm. When the economy is down, people put off up-grades on their houses and their planes! — Kevin McCue KRYN ‘47 Luscombe 8E Rans S-17 (for sale) —–= Posted via Newsfeeds.Com, Uncensored Usenet News =—– http://www.newsfeeds.com – The #1 Newsgroup Service in the World! —–==  Over 100,000 Newsgroups – 19 Different Servers! =—–

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Last year was my biggest year ever, but it had nothing to do with the economy.  This year I’m back to about normal. — Gene Seibel Hangar 131 – http://pad39a.com/gene/plane.html Because I fly, I envy no one. – Hide quoted text — Show quoted text – Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive.  Some say yes, some say no. How ’bout it — you folks flying any less because of bad times?

Response:

Jay, care to cross-post the thread here or will that be a no-no by CPA standards? Marco

– Hide quoted text — Show quoted text – Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive. Some say yes, some say no. How ’bout it — you folks flying any less because of bad times? — Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination"

 Posted Via Usenet.com Premium Usenet Newsgroup Services     ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY **                 http://www.usenet.com

Response:

Just read an amazing — and depressing — post over on Cherokee Chat (the Cherokee Pilots Association’s chat page) from the makers of Laminar Flow products, and the Power Flow exhaust system, almost literally *begging* CPA members for some business. I’ve never read a more honest post from a business person — it was obviously written from the heart, probably in a weak moment, by someone who has invested their life’s time and money into a business that is not doing well.  It sounds like they’re barely keeping the lights on. The discussion that ensued swirled around whether pilots are being squeezed harder than average by the current economic situation, with gas at $3 bucks a gallon, maintenance costs high, and avionics outrageously expensive.  Some say yes, some say no. How ’bout it — you folks flying any less because of bad times? — Jay Honeck Iowa City, IA Pathfinder N56993 www.AlexisParkInn.com "Your Aviation Destination"

Response:

ethylene glycol vs. propylene glycol

Question:

I am a staunch promoter of protecting the environment and I don’t change my stance depending on what I’m doing or who I am affiliated with.  The beauty of the natural world is too important to my sanity to do otherwise.  I was reading an article about the SR-22 (nice plane) and realized that we still use ethylene glycol in icing systems. This stuff is really very toxic.  It kills plants and animals.  It even has an enticing smell and flavor.  Does anyone know why proplyene glycol cannot be used instead?  Here is the current recipe for icing systems: 85 parts of ethylene glycol, 5 parts of iso-propyl alcohol and 10 parts water. I can’t believe the performance is much different since propylene glycol is used in automotive applications.

Response:

Does anyone know why proplyene glycol cannot be used instead?

I asked a chemical engineer friend of mine about the difference between ethylene and propylene glycol.  What I can remember of his explanation indicated that propylene glycol wasn’t really that much better. For what it’s worth, though, the stuff we carry on board in our deice cans is propylene glycol. — Larry Fransson Seattle, WA

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What do you use for deice cans? Mike MU-2

– Hide quoted text — Show quoted text – Does anyone know why proplyene glycol cannot be used instead? I asked a chemical engineer friend of mine about the difference between ethylene and propylene glycol.  What I can remember of his explanation indicated that propylene glycol wasn’t really that much better. For what it’s worth, though, the stuff we carry on board in our deice cans is propylene glycol. — Larry Fransson Seattle, WA

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Propylene glycol is used in ice cream, don’t try that with ethylene glycol! Mike MU-2

– Hide quoted text — Show quoted text – Does anyone know why proplyene glycol cannot be used instead? I asked a chemical engineer friend of mine about the difference between ethylene and propylene glycol.  What I can remember of his explanation indicated that propylene glycol wasn’t really that much better. For what it’s worth, though, the stuff we carry on board in our deice cans is propylene glycol. — Larry Fransson Seattle, WA

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Isopropyl alcohol isn’t all that good for you either. There’s a reason it’s used as an antiseptic.

| Propylene glycol is used in ice cream, don’t try that with ethylene glycol! | | Mike | MU-2 |

| | Does anyone know why proplyene glycol | cannot be used instead? | | I asked a chemical engineer friend of mine about the difference between | ethylene and propylene glycol.  What I can remember of his explanation | indicated that propylene glycol wasn’t really that much better. | | For what it’s worth, though, the stuff we carry on board in our deice | cans is propylene glycol. | | — | Larry Fransson | Seattle, WA | |

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This stuff is really very toxic.  It kills plants and animals.

Really?  At what dose?  Oral, subcutaneous, inhaled, topical…  ? Any data to back this up?  Define ‘toxic’ in this sense? Before you go off on something this silly, think it through.  Glycol is quite poisonous *if you drink it*.  The amount used for deice is completely harmless after it’s stirred into the slipstream and spread out over a gazillion miles. If you wanna equate ‘toxic’ with ‘dangerous’, then quit drinking water.  People die from an overdose of water all the time… ‘toxic’ stuff, right? The avgas you carry around is significantly more dangerous than glycol in several different respects. -Dave Russell Uninformed fear, be it ecology or aviation, leads to less-than-good ideas.  Don’t be a Daley.

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Does anyone know why proplyene glycol cannot be used instead? I asked a chemical engineer friend of mine about the difference between ethylene and propylene glycol.  What I can remember of his explanation indicated that propylene glycol wasn’t really that much better.

Better in what regard? Better for de-icing? Or better as in "not that much less toxic than ethylene glycol"? If it’s the first one then then there’s no reason to use ethylene glycol.  If it’s the second then you’re wrong.  There are huge differences in the toxicity.  Ethylene glycol is very nasty stuff. – Hide quoted text — Show quoted text – For what it’s worth, though, the stuff we carry on board in our deice cans is propylene glycol.

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This stuff is really very toxic.  It kills plants and animals. Really?  At what dose?  Oral, subcutaneous, inhaled, topical…  ? Any data to back this up?  Define ‘toxic’ in this sense?

There’s a lot of data on ethylene glycol. Toxic is a good word that doesn’t change meaning with context. Since you’re from AOL you may be internet challenged so here’s a link for you: www.atsdr.cdc.gov Before you go off on something this silly, think it through.  Glycol is quite poisonous *if you drink it*.  The amount used for deice is

Get your self some data yourself.  You’re wrong. completely harmless after it’s stirred into the slipstream and spread out over a gazillion miles.

Don’t forget about de-icing on the ground.   If you wanna equate ‘toxic’ with ‘dangerous’, then quit drinking water.  People die from an overdose of water all the time… ‘toxic’ stuff, right?

Really happens all the time?  Now this is something silly.  You’re starting to sound like part of the problem. The avgas you carry around is significantly more dangerous than glycol in several different respects.

Just to let you know, this is not an argument.  This is a "straw man". – Hide quoted text — Show quoted text – -Dave Russell Uninformed fear, be it ecology or aviation, leads to less-than-good ideas.  Don’t be a Daley.

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Well, you see, ethylene glycol is better because it is also useful for getting rid of those damn cats that hang around the airport and insist on climbing on cars and airplanes and scratching the paint… So much quieter than shooting them with a .45 or 12-gauge… <evil-grin

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Isopropyl alcohol isn’t all that good for you either. There’s a reason it’s used as an antiseptic.

Well, it’s "denatured" — which is to say, it contains a poison. Other than that deliberate toxicity, it’s pretty much the same as vodka. By the way, my daughter used to use Popov vodka as anti-freeze in the water lines of her boat. It was cheaper than the commercial anti-freeze and didn’t leave an aftertaste when it was flush out. all the best — Dan Ford (email: web AT danford.net) see the Warbird’s Forum at http://www.danford.net/index.htm Vietnam | Flying Tigers | Pacific War | Brewster Buffalo | Piper Cub

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Propylene glycol is used in ice cream, don’t try that with ethylene glycol!

It’s also used in some soaps, shampoos, and is known to cause skin irritation in some people. Many products humans use contain this substance and for the most part it’s considered safe for our usage.

Response:

| | | completely harmless after it’s stirred into the slipstream and spread | out over a gazillion miles. | | Don’t forget about de-icing on the ground. | A small nit: you don’t run your de-icing system on the ground. The de-icing system only works for a few minutes as it is. If you have ice on the ground you need to find some other way to remove it, or you won’t have the de-icing system in the air where you really need it.

Response:

What do you use for deice cans?

One of our former pilots put ours together.  He started with a 2 gallon metal spray can.  He put an electric heater (I think it came from an auto parts store) on the bottom of the can.  He got rid of the hose that came with the can and put on a heavier coiled hose with a quick disconnect fitting at the discharge end.  It looks like he used the spray wand that came with the can, but he threaded a quick disconnect fitting into it and put a different nozzle on it.  Then he packaged the whole thing up in a custom made nylon bag.  It’s pretty slick – certainly better than the plastic cans we had been using.  The bag is designed to hold the wand and if you clear the hose and then disconnect it, you don’t get glycol running everywhere.  The whole thing is also a lot smaller and easier to wrangle in and out of the back of the aiplane.  We fill the whole thing with 100% glycol, use about half of it, then fill it with water before continuing.   One important lesson we have learned recently:  We’ll probably have to put a temperature switch on the can to limit the maximum temperature.  We’ve messed up a couple of the cans due to pumps that got stuck in the can.   From what we can determine, the glycol got too hot for the pump (made of poly-somethingorother) and the pressure in the tank caused the pump to collapse and get stuck.  The guy who built the tanks said that full of glycol, they’d heat up to 140 F in about 45 minutes.  We’re thinking that even 100 degrees should be plenty, and should prevent similar problems. — Larry Fransson Seattle, WA

Response:

Uh, you are thinking of ethyl alcohol as drinkable.  Isopropyl is sometimes used to "denature " ethyl alcohol.  Vodka is pretty much ethyl alcohol. Isopropyl alcohol will kill you, as will methyl alcohol and most of the others.  Leo

– Hide quoted text — Show quoted text – Isopropyl alcohol isn’t all that good for you either. There’s a reason it’s used as an antiseptic. Well, it’s "denatured" — which is to say, it contains a poison. Other than that deliberate toxicity, it’s pretty much the same as vodka. By the way, my daughter used to use Popov vodka as anti-freeze in the water lines of her boat. It was cheaper than the commercial anti-freeze and didn’t leave an aftertaste when it was flush out. all the best — Dan Ford (email: web AT danford.net) see the Warbird’s Forum at http://www.danford.net/index.htm Vietnam | Flying Tigers | Pacific War | Brewster Buffalo | Piper Cub

Response:

Thanks.  My problem is usually falling snow at temperatures around freezing. By the time the plane is pulled out of the hanger, engines started and clearance recieved , there is some question as to whether the accumulated snom will blow off by rotation speed.  I was thinking about spraying non-heated propylene glycol on the lifting surfaces. Mike MU-2

– Hide quoted text — Show quoted text – What do you use for deice cans? One of our former pilots put ours together.  He started with a 2 gallon metal spray can.  He put an electric heater (I think it came from an auto parts store) on the bottom of the can.  He got rid of the hose that came with the can and put on a heavier coiled hose with a quick disconnect fitting at the discharge end.  It looks like he used the spray wand that came with the can, but he threaded a quick disconnect fitting into it and put a different nozzle on it.  Then he packaged the whole thing up in a custom made nylon bag.  It’s pretty slick – certainly better than the plastic cans we had been using.  The bag is designed to hold the wand and if you clear the hose and then disconnect it, you don’t get glycol running everywhere.  The whole thing is also a lot smaller and easier to wrangle in and out of the back of the aiplane.  We fill the whole thing with 100% glycol, use about half of it, then fill it with water before continuing. One important lesson we have learned recently:  We’ll probably have to put a temperature switch on the can to limit the maximum temperature.  We’ve messed up a couple of the cans due to pumps that got stuck in the can. From what we can determine, the glycol got too hot for the pump (made of poly-somethingorother) and the pressure in the tank caused the pump to collapse and get stuck.  The guy who built the tanks said that full of glycol, they’d heat up to 140 F in about 45 minutes.  We’re thinking that even 100 degrees should be plenty, and should prevent similar problems. — Larry Fransson Seattle, WA

Response:

– Hide quoted text — Show quoted text – | | | completely harmless after it’s stirred into the slipstream and spread | out over a gazillion miles. | | Don’t forget about de-icing on the ground. | A small nit: you don’t run your de-icing system on the ground. The de-icing system only works for a few minutes as it is. If you have ice on the ground you need to find some other way to remove it, or you won’t have the de-icing system in the air where you really need it.

And since we’re nitting, alcohol/glycol is used as an anti-ice.  Your de-icing on the ground is usually accomplished with heat and the alcohol/glycol is to keep the melted ice (water) from refreezing.

Response:

Doesn’t vodka help lean out the mix? And provide extra warmth of you have to do a forced landing in the winter? And help start a signal fire? And help make friends with the various large (and usually carnivorous) wildlife? Come to think of it, vodka probably belongs on the equipment list for a winter survival pack.

| | Isopropyl alcohol isn’t all that good for you either. There’s a reason it’s | used as an antiseptic. | | Well, it’s "denatured" — which is to say, it contains a poison. Other | than that deliberate toxicity, it’s pretty much the same as vodka. | | By the way, my daughter used to use Popov vodka as anti-freeze in the | water lines of her boat. It was cheaper than the commercial | anti-freeze and didn’t leave an aftertaste when it was flush out. | | all the best — Dan Ford (email: web AT danford.net) | | see the Warbird’s Forum at http://www.danford.net/index.htm | Vietnam | Flying Tigers | Pacific War | Brewster Buffalo | Piper Cub

Response:

Isopropyl alcohol isn’t all that good for you either. There’s a reason it’s used as an antiseptic.

Yeh, but it doesn’t taste good. Ethylene glycol does. This doesn’t matter if you don’t mind poisoning the local animal life, I suppose. George Patterson "Cuius testiculos habes, habeas cardia et cerebellum." – When you have  their full attention in your grip, their hearts and minds will follow.

Response:

If you wanna equate ‘toxic’ with ‘dangerous’, ….

Nobody wants to do that. "Toxic" has a very rigorous definition – it is poisonous. Water is not toxic. George Patterson "Cuius testiculos habes, habeas cardia et cerebellum." – When you have  their full attention in your grip, their hearts and minds will follow.

Response:

Well, you see, ethylene glycol is better because it is also useful for getting rid of those damn cats that hang around the airport and insist on climbing on cars and airplanes and scratching the paint… So much quieter than shooting them with a .45 or 12-gauge… <evil-grin

Works on deer, too. George Patterson "Cuius testiculos habes, habeas cardia et cerebellum." – When you have  their full attention in your grip, their hearts and minds will follow.

Response:

- Hide quoted text — Show quoted text – | | | completely harmless after it’s stirred into the slipstream and spread | out over a gazillion miles. | | Don’t forget about de-icing on the ground. | A small nit: you don’t run your de-icing system on the ground. The de-icing system only works for a few minutes as it is. If you have ice on the ground you need to find some other way to remove it, or you won’t have the de-icing system in the air where you really need it. And since we’re nitting, alcohol/glycol is used as an anti-ice.  Your de-icing on the ground is usually accomplished with heat and the alcohol/glycol is to keep the melted ice (water) from refreezing.

Large transports are de-iced with glycol based products Lots of airports even use glycol based products on runways.  Ethylene glycol is being replaced, but not everywhere, yet.

Response:

Isopropyl alcohol isn’t all that good for you either. There’s a reason it’s used as an antiseptic. Well, it’s "denatured" — which is to say, it contains a poison. Other than that deliberate toxicity, it’s pretty much the same as vodka.

You’ve been drinking it lately, have you?  Sounds like you’re getting some really cheap vodka. – Hide quoted text — Show quoted text – By the way, my daughter used to use Popov vodka as anti-freeze in the water lines of her boat. It was cheaper than the commercial anti-freeze and didn’t leave an aftertaste when it was flush out. all the best — Dan Ford (email: web AT danford.net) see the Warbird’s Forum at http://www.danford.net/index.htm Vietnam | Flying Tigers | Pacific War | Brewster Buffalo | Piper Cub

Response:

" And since we’re nitting, alcohol/glycol is used as an anti-ice.  Your de-icing on the ground is usually accomplished with heat and the alcohol/glycol is to keep the melted ice (water) from refreezing. Large transports are de-iced with glycol based products

HEATED glycol based products – Hide quoted text — Show quoted text – Lots of airports even use glycol based products on runways.  Ethylene glycol is being replaced, but not everywhere, yet.

Response:

  Don’t forget about de-icing on the ground.   The only good point you made. My doctorate is in organic chemistry; my day job is pharmaceutical research.  Please don’t tell me to go read some web page for tox data… we worry about things like this every day. Again, fear of something you don’t understand leads to *poor* choices in action and policy.  There are many examples of ignorant fear, often fanned by the ignorant news media, pushing for a solution to a problem that sounds good to the lay person but, in reality, makes things worse. Aviation is often a victim of this type of nonsense, with Mayor Daley’s bulldozers being the most recent and obvious example.  History is replete with the same, sorry type of story in many fields.  Power lines, paper fast food wrappers, magnetic fields… there’s a long list. Rational risk assessment would indicate that there are more important things to worry about than the ethylene glycol used for anti-ice systems.  If you feel strongly about it, fine, then don’t use it. But please don’t try to tell me why I shouldn’t. -Dave Russell 8KCAB (obviously a huge glycol user

Response:

  Don’t forget about de-icing on the ground. The only good point you made.

And you missed it the first time around…. My doctorate is in organic chemistry; my day job is pharmaceutical

Having a doctorate in OChem is meaningless, you no doubt spent years studying some excruciating detail that no one cares much about. You still haven’t provided any facts toward your argument. research.  Please don’t tell me to go read some web page for tox data… we worry about things like this every day.

Maybe you should follow that link.  Did you study ethylene glycol toxicity? Again, fear of something you don’t understand leads to *poor* choices in action and policy.  There are many examples of ignorant fear, often fanned by the ignorant news media, pushing for a solution to a problem that sounds good to the lay person but, in reality, makes things worse.

Don’t look now but your ignorant fear is showing. Aviation is often a victim of this type of nonsense, with Mayor Daley’s bulldozers being the most recent and obvious example.  History is replete with the same, sorry type of story in many fields.  Power lines, paper fast food wrappers, magnetic fields… there’s a long list. Rational risk assessment would indicate that there are more important things to worry about than the ethylene glycol used for anti-ice

Again your ignorance is blinding you.  You don’t know anything about this topic you just feel you should respond because you have a PhD in ochem. systems.  If you feel strongly about it, fine, then don’t use it. But please don’t try to tell me why I shouldn’t.

Never told anyone what they should or shouldn’t use.  You’re having a hard time staying on track and on topic.  I’ll give you the benefit of a doubt though since your handle shows you from AOL. Use whatever you want and do what ever you want to your environment. – Hide quoted text — Show quoted text – -Dave Russell 8KCAB (obviously a huge glycol user

Response:

Rookie in the house

Question:

Hello people. I would like to learn to fly ultralights.  I have finally stopped listening to my worried-loving, landlubber friends and family.  However, when I called the number for a school in my area the (&^^$#! number was out of service.  I hope that this is not an omen. My question is:  does anyone know of a school in or around the Ottawa (Canada) area?  If so please let me know. John — the Wright brother that no one talks about

Response:

Hello people. I would like to learn to fly ultralights.  I have finally stopped listening to my worried-loving, landlubber friends and family.  However, when I called the number for a school in my area the (&^^$#! number was out of service.  I hope that this is not an omen. My question is:  does anyone know of a school in or around the Ottawa (Canada) area?  If so please let me know. John — the Wright brother that no one talks about

John… Get in contact with Bright Aviation…Kathy should be able to help you. Good luck and happy flying… Rejean — I invite you to visit my homepage at… http://www.angelfire.com/ca/flylite "Ultralights in Northwestern Ontario"

Response:

Ultrasport 496 question

Question:

Hi to all. I would like to know what are the latest news on Ultrasport 496 helicopters. Hoped to see it at Oshkosh – failed. What is the situation with these bird and its manufacturer? I would also like to contact any ‘496 builders/owners. Any information will be greatly appreciated. Cheers, Alex Lameko http://www.rusavia.ru – General Aviation in Russia

Response:

Hi Alex  In this months PRA magazine is a large article on the Ultrasport. The government has made an Unmanned Remote Piloted vehicle from the Ultrasport.  It is a great article.  Looks like Ultrasport will be doing business with the gov.  There is also an article on a friend of mine that owns and flies his Ultrasport.  His name is Tom Hoffman.  He has made several modifications to the Ultrasport with great success. Fred Stewart Hi to all. I would like to know what are the latest news on Ultrasport 496 helicopters. Hoped to see it at Oshkosh – failed. What is the situation with these bird and its manufacturer? I would also like to contact any ‘496 builders/owners. Any information will be greatly appreciated. Cheers, Alex Lameko http://www.rusavia.ru – General Aviation in Russia

Response:

rec.aviation OSHKOSH 1996 update

Question:

I have heard that there is an air conditioning unit that is not driven directly by the engine.  There is an electric motor that drives the compressor.  Does anyone know about this and if so please post and e-mail me the information.  This will be greatly appreciated. Calvin

Response:

I have heard that there is an air conditioning unit that is not driven directly by the engine.  There is an electric motor that drives the compressor.  Does anyone know about this and if so please post and e-mail me the information.  This will be greatly appreciated.

Enviro systems makes one for certified aircraft.  Big Bucks!! It also eats lots of power.  about 50 amps at 28 volts.  I heard that the plymoth neon also uses one but I am not sure.  It may even have been a different car but it was a small one.  Regardless it will take lots of power to run it. Mark

Response:

I’ve put a bunch of information up on the web for rec.aviators who may be interested in attending the EAA Convention and Fly-in at Oshkosh, Wisconsin 8/1 through 8/7.  Key pages are:     Information:        http://reality.sgi.com/geoff/osh_info.html     Registration:       http://reality.sgi.com/geoff/osh_reg.html     Who’s coming:       http://reality.sgi.com/geoff/osh_list.html For those who don’t have web access, an ASCII version of the information page is attached. This information will be continuously updated through the beginning of the Oshkosh airshow. –Geoff                       Experimental Aircraft Association                             Convention and Fly-In                              Oshkosh, Wisconsin                           Rec.aviation Information                                 1996 Edition                                  Geoff Peck   These pages are developed by individual EAA members and do not represent                        official EAA policy or opinion. Well, folks, it’s about a month away from the 44th annual EAA Fly-In and Convention which will, as usual, be held at Wittman Field, Oshkosh, Wisconsin. This year, the convention starts on Thursday, August 1st and ends Wednesday, August 7th. The EAA has an official web site which contains a great deal of information on the convention:                    http://www.eaa.org/oshkosh/index.html Over the past years, we’ve found that over 100 rec.aviators typically come to Oshkosh and meet one another face-to-face (horrors! non-electronic communication! ). In order to help rec.aviators have a better idea of who’s coming from this diverse group, we’ve had a sign-up system in place for the last N years. This year, an automated web-based signup is available at                  http://reality.sgi.com/geoff/osh_reg.html If at all possible, please use this form to register. If you are reading will send you a "fill-in-the-blanks" form which you can then e-mail back to me. If you’d like to see who’s already registered, see                  http://reality.sgi.com/geoff/osh_list.html What’s Oshkosh? Oshkosh is loads of fun for everyone and is a truly unique gathering – over 12,000 airplanes will be "in residence" at Oshkosh, including (literally) thousands of antique, classic, homebuilt and warbird aircraft. In 1995, more than 830,000 people and 12,000 airplanes – including a record 2,719 showplanes – attended the event. Each afternoon, there’s a formal airshow, with top-notch aerobatics, warbirds, parachuting, wing-walking and so on, but throughout the day, interesting aircraft are busy flying by! When the airshow isn’t occupying the skies, there are still plenty of aircraft, from ultralights to B747-400’s to blimps to keep your eyes fixed in the sky. If watching all the airplanes isn’t enough to keep you busy (and it is!), there are *10* or more parallel technical sessions throughout most of the convention, totalling nearly 500 forums, seminars and workshops. There are five warehouse-sized buildings with aviation shops and manufacturers of all types hawking their wares. There’s the EAA Adventure Museum, with its ever-expanding collection. There are aircraft displays by most of the aircraft manufacturers (those that are left – sigh!) and kitmakers. There’s the "fly market", with its vast array of aviation bargains and curios. ("You want a grommet for a what? A 1943 GazeboLifter Mark IV? Turbocharged? Oh, no problem, we have a bag of those grommets over there…") Rec.aviation activities                  Tentative information; subject to change.    * Meet each day at the northwest corner of the control tower:         o between 12:15 noon and 12:30 p.m.         o after the conclusion of the day’s airshow (T +0:15 to T +0:30)      The lunch-time meeting has been by far the most popular, although we      have had great success in spontaneously gathering 20-30 people for      dinner! **NEW**      Meet each day between 8:30 and 8:45 a.m. at the picnic tables in front      of the Steakhouse Cafe, which is where you can buy wonderful home-made      doughnuts (see below); the Steakhouse Cafe is located near the NASA      building and the South Exhibits building.    * There will be a rec.aviation "sign-in" list at the message center      booth. The message center folks know about this folder; just ask for      it. Please do not leave it unattended, and please do not give away the      handouts to non-rec.aviators, as only a limited number of them are      printed.      When you arrive at OSH please obtain the list and write down where you      are tied down (or camping, or what motel you are staying at, etc.) next      to your name. This is incredibly useful if another netter wants to find      you – he/she can stop by your plane but only if you’ve written down      where it is!      If you arrive before the "official" list does, please start a temporary      list. When the "official" list arrives, there will also be a supply of      printed rosters of expected rec.aviation attendees garnered from the      on-line registration process. Even if you don’t fly in (or you’ve flown      into an airport other than OSH), please do sign in so others can tell      whether you’re around.    * Ham-radio frequency: 2 meter, 145.750 simplex, call rec.aviation. (One      of these years we’re going to want to set up our own repeater…) Since 1991, we’ve had a growing group dinner at a restaurant in downtown Oshkosh on Friday or Saturday night. Several years ago, over sixty netters were there! Coordinating this event is rather complex, and this year we may try some experiments like bar-b-queues and/or planned dinners on more than one night. Please fill out the rec.aviation registration form to let the organizers (conspirators?) know what your preferences are; we’ll keep everyone up-to-date on what’s being set up. **NEW** We will be organizing a rec.aviation bar-b-queue on Sunday, August 3rd. Tentative plans call for having a relatively informal gathering at a to-be-selected rec.aviator’s aircraft tiedown in the North 40. We expect to have several small charcoal grilles and to provide food to cook (so not everyone has to run across the road to go to the grocery store), with reimbursement from those who attend. You can expect non-scheduled food-related get-togethers, both at lunch and dinner, and perhaps even breakfast, throughout the airshow and probably even before it starts! General Information Flying in Flying in is actually relatively easy. Make sure you have a copy of the FAA NOTAM for Oshkosh, which describes the VFR arrival procedures. Do what they say, listen up (don’t talk!) on the radio, and you’ll find that it’s no harder than landing at Reid-Hillview on a busy Saturday. While it is possible to fly in IFR, I personally cannot recommend it. Several netters have successfully filed IFR to a nearby airport/VOR (Sheboygan if arriving from the east), then canceling IFR and making a VFR intercept for Fisk/Ripon/etc, as published for VFR arrivals. If you want to park at OSH, be aware that tiedown space is limited, and when it fills up, you will be directed to an outlying airport (Fond du Lac or Appleton), from which shuttle bus service should be available. Sometimes these airports fill up too… In general, if you arrive before noon on Tuesday July 30th, or after noon on Monday August 5th you should be able to park at Oshkosh. Also, note that you must have a tiedown kit; three ropes with big screw-in thyngies is the usual arrangement. You can buy or rent them right at your parking spot but this is relatively expensive. (If you need to get tie-down gear when you arrive, go over to the Fly Market, and you should be able to put together a kit on your own for about $10.) There are several types of aircraft parking available at Oshkosh. Those who get to park in one of the "special" categories (homebuilt, warbird, classic, antique, …) should already know what to do. Otherwise, there are two choices: "camping" spaces and "parking" spaces. The camping spaces are closer to the showers and to the activities on the field, but they cost money; the "parking" spaces are free, and you can camp there, but there’s quite a hike to the showers and there are many fewer port-a-potties… EAA Fees (1996)                                  Existing    EAA Members        Non                                EAA Members joining at show  EAA Members     Adult (19 or older)           $13/day      $16/day        $21/day     Flight Line Admission        $75/week      $83/week      $143/week     Spouse/Student (14-18)        $10/day      $16/day        $21/day     Flight Line Admission        $31/week      $83/week      $143/week     Youth (8-13)                  $7/day        $7/day        $11/day     Flight Line Admission        $23/week      $39/week       $73/week     Child (7 and under)     Flight Line Admission          Free          Free           Free     Aircraft Camping     Auto / RV Camping             $14/day      $14/day     not available     Day Automobile Parking        $3/day                       $6/day     Day Parking (over 20′ long)   $5/day                       $7/day     Adult General Admission     No Flight Line Access         $5/day        $5/day        $15/day Admission to the flight line is $21/day for non-EAA members, $16/day if you join EAA at the show, and $13/day if you join beforehand. A pass which works throughout the show is $75 for EAA members, $83 if you join EAA at the show, and $143 for non-EAAers. There is no rebate on the week-long admissions if you arrive late or leave early. Lower prices are available for additional family members; kids 7 and under are free. Note that access to the flightline is permitted only for qualified aviation visitors – certificated pilots, members of qualified aviation … read more »

Response:

We now have almost **60** netters registered as coming to Oshkosh! Now’s your last chance to sign in and let others know you’ll be there, so please hurry and do it before Friday 7/26!!! I’ve put a bunch of information up on the web for rec.aviators who may be interested in attending the EAA Convention and Fly-in at Oshkosh, Wisconsin 8/1 through 8/7.  Key pages are:     Information:        http://reality.sgi.com/geoff/osh_info.html     Registration:       http://reality.sgi.com/geoff/osh_reg.html     Who’s coming:       http://reality.sgi.com/geoff/osh_list.html For those who don’t have web access, an ASCII version of the information page is attached. This information will be continuously updated through the beginning of the Oshkosh airshow.  Please note that the information page is changing almost on a daily basis! –Geoff                       Experimental Aircraft Association                             Convention and Fly-In                              Oshkosh, Wisconsin                           Rec.aviation Information                                 1996 Edition                                  Geoff Peck                       Experimental Aircraft Association                             Convention and Fly-In                              Oshkosh, Wisconsin                           Rec.aviation Information                                 1996 Edition   These pages are developed by individual EAA members and do not represent                        official EAA policy or opinion. Well, folks, it’s about a month away from the 44th annual EAA Fly-In and Convention which will, as usual, be held at Wittman Field, Oshkosh, Wisconsin. This year, the convention starts on Thursday, August 1st and ends Wednesday, August 7th. The EAA has an official web site which contains a great deal of information on the convention:                    http://www.eaa.org/oshkosh/index.html An additional and very good source of information about Oshkosh is the Air & Space magazine (of the National Air & Space Museum) web page for Oshkosh:                        http://www.airspacemag.com/EAA Over the past years, we’ve found that over 100 rec.aviators typically come to Oshkosh and meet one another face-to-face (horrors! non-electronic communication! ). In order to help rec.aviators have a better idea of who’s coming from this diverse group, we’ve had a sign-up system in place for the last N years. This year, an automated web-based signup is available at                  http://reality.sgi.com/geoff/osh_reg.html If at all possible, please use this form to register. If you are reading send you a "fill-in-the-blanks" form which you can then e-mail back to me. If you’d like to see who’s already registered, see                  http://reality.sgi.com/geoff/osh_list.html What’s Oshkosh? Oshkosh is loads of fun for everyone and is a truly unique gathering – over 12,000 airplanes will be "in residence" at Oshkosh, including (literally) thousands of antique, classic, homebuilt and warbird aircraft. In 1995, more than 830,000 people and 12,000 airplanes – including a record 2,719 showplanes – attended the event. Each afternoon, there’s a formal airshow, with top-notch aerobatics, warbirds, parachuting, wing-walking and so on, but throughout the day, interesting aircraft are busy flying by! When the airshow isn’t occupying the skies, there are still plenty of aircraft, from ultralights to B747-400’s to blimps to keep your eyes fixed in the sky. If watching all the airplanes isn’t enough to keep you busy (and it is!), there are *10* or more parallel technical sessions throughout most of the convention, totalling nearly 500 forums, seminars and workshops. There are five warehouse-sized buildings with aviation shops and manufacturers of all types hawking their wares. There’s the EAA Adventure Museum, with its ever-expanding collection. There are aircraft displays by most of the aircraft manufacturers (those that are left – sigh!) and kitmakers. There’s the "fly market", with its vast array of aviation bargains and curios. ("You want a grommet for a what? A 1943 GazeboLifter Mark IV? Turbocharged? Oh, no problem, we have a bag of those grommets over there…" However, if you find someone who has a supply of transparent aluminum, please let me know – I’ve been looking for some for years…) Rec.aviation activities                  Tentative information; subject to change.    * Meet each day at the northwest corner of the control tower:         o between 12:15 and 12:30 p.m.         o after the conclusion of the day’s airshow (T +0:15 to T +0:30)      The lunch-time meeting has been by far the most popular, although we      have had great success in spontaneously gathering 20-30 people for      dinner! **NEW**      Meet each day between 8:30 and 8:45 a.m. at the picnic tables in front      of the Steakhouse Cafe, which is where you can buy wonderful home-made      doughnuts (see below); the Steakhouse Cafe is located near the NASA      building and the South Exhibits building.    * There will be a rec.aviation "sign-in" list at the message center      booth. The message center folks know about this folder; just ask for      it. Please do not leave it unattended, and please do not give away the      handouts to non-rec.aviators, as only a limited number of them are      printed. When you get the list, write down where you are tied down (or      camping, or what motel you are staying at, etc.) next to your name.      This is incredibly useful if another netter wants to find you – he/she      can stop by your plane but only if you’ve written down where it is!      If you arrive before the "official" list does, please start a temporary      list. When the "official" list arrives, there will also be a supply of      printed rosters of expected rec.aviation attendees garnered from the      on-line registration process. Even if you don’t fly in (or you’ve flown      into an airport other than OSH), please do sign in so others can tell      whether you’re around.    * Ham-radio frequency: 2 meter, 145.750 simplex, call rec.aviation. Jim      repeater on 146.56, PL 107.2. (Anyone up to contributing a duplex      repeater one of these years?) Since 1991, we’ve had a growing group dinner at a restaurant in downtown Oshkosh on Friday or Saturday night. Several years ago, over sixty netters were there! Coordinating this event is rather complex, and this year we may try some experiments like bar-b-queues and/or planned dinners on more than one night. Please fill out the rec.aviation registration form to let the organizers (conspirators?) know what your preferences are; we’ll keep everyone up-to-date on what’s being set up. **NEW** We will be organizing a rec.aviation bar-b-queue on Sunday, August 3rd. Tentative plans call for having a relatively informal gathering at a to-be-selected rec.aviator’s aircraft tiedown in the North 40. We expect to have several small charcoal grilles and to provide food to cook (so not everyone has to run across the road to go to the grocery store), with reimbursement from those who attend. You can expect non-scheduled food-related get-togethers, both at lunch and dinner, and perhaps even breakfast, throughout the airshow and probably even before it starts! General Information Flying in Flying in is actually relatively easy. Make sure you have a copy of the FAA NOTAM for Oshkosh, which describes the VFR arrival procedures. Do what they say, listen up (don’t talk!) on the radio, and you’ll find that it’s no harder than landing at Reid-Hillview on a busy Saturday. While it is possible to fly in IFR, I personally cannot recommend it. Several netters have successfully filed IFR to a nearby airport/VOR (Sheboygan if arriving from the east), then canceling IFR and making a VFR intercept for Fisk/Ripon/etc, as published for VFR arrivals. If you want to park at OSH, be aware that tiedown space is limited, and when it fills up, you will be directed to an outlying airport (Fond du Lac or Appleton), from which shuttle bus service should be available. Sometimes these airports fill up too… In general, if you arrive before noon on Wednesday July 31st, or after noon on Monday August 5th you should be able to park at Oshkosh. Also, note that you must have a tiedown kit; three ropes with big screw-in thyngies is the usual arrangement. You can buy or rent them right at your parking spot but this is relatively expensive. (If you need to get tie-down gear when you arrive, go over to the Fly Market, and you should be able to put together a kit on your own for about $10.) There are several types of aircraft parking available at Oshkosh. Those who get to park in one of the "special" categories (homebuilt, warbird, classic, antique, …) should already know what to do. Otherwise, there are two choices: "camping" spaces and "parking" spaces. The camping spaces are closer to the showers and to the activities on the field, but they cost money; the "parking" spaces are free, and you can camp there, but there’s quite a hike to the showers and there are many fewer port-a-potties… If you’re seeking ride-sharing information for Oshkosh 1996, Air & Space magazine (of the National Air & Space Museum) has a web page for this:           http://www.airspacemag.com/EAA/RideLink/OSKRidelink.html EAA Fees (1996)                                  Existing    EAA Members        Non                                 EAA Membersjoining at show  EAA Members     Adult (19 or older)           $13/day      $16/day        $21/day     Flight Line Admission        $75/week      $83/week      $143/week     Spouse/Student (14-18)        $10/day    

… read more »

Response:

We now have almost **60** netters registered as coming to Oshkosh! Now’s your last chance to sign in and let others know you’ll be there, so please hurry and do it before Friday 7/24!!! I’ve put a bunch of information up on the web for rec.aviators who may be interested in attending the EAA Convention and Fly-in at Oshkosh, Wisconsin 8/1 through 8/7.  Key pages are:     Information:        http://reality.sgi.com/geoff/osh_info.html     Registration:       http://reality.sgi.com/geoff/osh_reg.html     Who’s coming:       http://reality.sgi.com/geoff/osh_list.html For those who don’t have web access, an ASCII version of the information page is attached. This information will be continuously updated through the beginning of the Oshkosh airshow.  Please note that the information page is changing almost on a daily basis! –Geoff                       Experimental Aircraft Association                             Convention and Fly-In                              Oshkosh, Wisconsin                           Rec.aviation Information                                 1996 Edition                                  Geoff Peck                       Experimental Aircraft Association                             Convention and Fly-In                              Oshkosh, Wisconsin                           Rec.aviation Information                                 1996 Edition   These pages are developed by individual EAA members and do not represent                        official EAA policy or opinion. Well, folks, it’s about a month away from the 44th annual EAA Fly-In and Convention which will, as usual, be held at Wittman Field, Oshkosh, Wisconsin. This year, the convention starts on Thursday, August 1st and ends Wednesday, August 7th. The EAA has an official web site which contains a great deal of information on the convention:                    http://www.eaa.org/oshkosh/index.html An additional and very good source of information about Oshkosh is the Air & Space magazine (of the National Air & Space Museum) web page for Oshkosh:                        http://www.airspacemag.com/EAA Over the past years, we’ve found that over 100 rec.aviators typically come to Oshkosh and meet one another face-to-face (horrors! non-electronic communication! ). In order to help rec.aviators have a better idea of who’s coming from this diverse group, we’ve had a sign-up system in place for the last N years. This year, an automated web-based signup is available at                  http://reality.sgi.com/geoff/osh_reg.html If at all possible, please use this form to register. If you are reading send you a "fill-in-the-blanks" form which you can then e-mail back to me. If you’d like to see who’s already registered, see                  http://reality.sgi.com/geoff/osh_list.html What’s Oshkosh? Oshkosh is loads of fun for everyone and is a truly unique gathering – over 12,000 airplanes will be "in residence" at Oshkosh, including (literally) thousands of antique, classic, homebuilt and warbird aircraft. In 1995, more than 830,000 people and 12,000 airplanes – including a record 2,719 showplanes – attended the event. Each afternoon, there’s a formal airshow, with top-notch aerobatics, warbirds, parachuting, wing-walking and so on, but throughout the day, interesting aircraft are busy flying by! When the airshow isn’t occupying the skies, there are still plenty of aircraft, from ultralights to B747-400’s to blimps to keep your eyes fixed in the sky. If watching all the airplanes isn’t enough to keep you busy (and it is!), there are *10* or more parallel technical sessions throughout most of the convention, totalling nearly 500 forums, seminars and workshops. There are five warehouse-sized buildings with aviation shops and manufacturers of all types hawking their wares. There’s the EAA Adventure Museum, with its ever-expanding collection. There are aircraft displays by most of the aircraft manufacturers (those that are left – sigh!) and kitmakers. There’s the "fly market", with its vast array of aviation bargains and curios. ("You want a grommet for a what? A 1943 GazeboLifter Mark IV? Turbocharged? Oh, no problem, we have a bag of those grommets over there…" However, if you find someone who has a supply of transparent aluminum, please let me know – I’ve been looking for some for years…) Rec.aviation activities                  Tentative information; subject to change.    * Meet each day at the northwest corner of the control tower:         o between 12:15 and 12:30 p.m.         o after the conclusion of the day’s airshow (T +0:15 to T +0:30)      The lunch-time meeting has been by far the most popular, although we      have had great success in spontaneously gathering 20-30 people for      dinner! **NEW**      Meet each day between 8:30 and 8:45 a.m. at the picnic tables in front      of the Steakhouse Cafe, which is where you can buy wonderful home-made      doughnuts (see below); the Steakhouse Cafe is located near the NASA      building and the South Exhibits building.    * There will be a rec.aviation "sign-in" list at the message center      booth. The message center folks know about this folder; just ask for      it. Please do not leave it unattended, and please do not give away the      handouts to non-rec.aviators, as only a limited number of them are      printed. When you get the list, write down where you are tied down (or      camping, or what motel you are staying at, etc.) next to your name.      This is incredibly useful if another netter wants to find you – he/she      can stop by your plane but only if you’ve written down where it is!      If you arrive before the "official" list does, please start a temporary      list. When the "official" list arrives, there will also be a supply of      printed rosters of expected rec.aviation attendees garnered from the      on-line registration process. Even if you don’t fly in (or you’ve flown      into an airport other than OSH), please do sign in so others can tell      whether you’re around.    * Ham-radio frequency: 2 meter, 145.750 simplex, call rec.aviation. Jim      repeater on 146.56, PL 107.2. (Anyone up to contributing a duplex      repeater one of these years?) Since 1991, we’ve had a growing group dinner at a restaurant in downtown Oshkosh on Friday or Saturday night. Several years ago, over sixty netters were there! Coordinating this event is rather complex, and this year we may try some experiments like bar-b-queues and/or planned dinners on more than one night. Please fill out the rec.aviation registration form to let the organizers (conspirators?) know what your preferences are; we’ll keep everyone up-to-date on what’s being set up. **NEW** We will be organizing a rec.aviation bar-b-queue on Sunday, August 3rd. Tentative plans call for having a relatively informal gathering at a to-be-selected rec.aviator’s aircraft tiedown in the North 40. We expect to have several small charcoal grilles and to provide food to cook (so not everyone has to run across the road to go to the grocery store), with reimbursement from those who attend. You can expect non-scheduled food-related get-togethers, both at lunch and dinner, and perhaps even breakfast, throughout the airshow and probably even before it starts! General Information Flying in Flying in is actually relatively easy. Make sure you have a copy of the FAA NOTAM for Oshkosh, which describes the VFR arrival procedures. Do what they say, listen up (don’t talk!) on the radio, and you’ll find that it’s no harder than landing at Reid-Hillview on a busy Saturday. While it is possible to fly in IFR, I personally cannot recommend it. Several netters have successfully filed IFR to a nearby airport/VOR (Sheboygan if arriving from the east), then canceling IFR and making a VFR intercept for Fisk/Ripon/etc, as published for VFR arrivals. If you want to park at OSH, be aware that tiedown space is limited, and when it fills up, you will be directed to an outlying airport (Fond du Lac or Appleton), from which shuttle bus service should be available. Sometimes these airports fill up too… In general, if you arrive before noon on Wednesday July 31st, or after noon on Monday August 5th you should be able to park at Oshkosh. Also, note that you must have a tiedown kit; three ropes with big screw-in thyngies is the usual arrangement. You can buy or rent them right at your parking spot but this is relatively expensive. (If you need to get tie-down gear when you arrive, go over to the Fly Market, and you should be able to put together a kit on your own for about $10.) There are several types of aircraft parking available at Oshkosh. Those who get to park in one of the "special" categories (homebuilt, warbird, classic, antique, …) should already know what to do. Otherwise, there are two choices: "camping" spaces and "parking" spaces. The camping spaces are closer to the showers and to the activities on the field, but they cost money; the "parking" spaces are free, and you can camp there, but there’s quite a hike to the showers and there are many fewer port-a-potties… If you’re seeking ride-sharing information for Oshkosh 1996, Air & Space magazine (of the National Air & Space Museum) has a web page for this:           http://www.airspacemag.com/EAA/RideLink/OSKRidelink.html EAA Fees (1996)                                  Existing    EAA Members        Non                                 EAA Membersjoining at show  EAA Members     Adult (19 or older)           $13/day      $16/day        $21/day     Flight Line Admission        $75/week      $83/week      $143/week     Spouse/Student (14-18)        $10/day    

… read more »

Response:

Quick Questions from Math Class

Question:

My 12 year old son is in 7th grade, learning about slope (y = mx + b).   A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL).

The answer is still 20 mins even in pilot world.  If you have 30,000 ft on the altimeter and you nail a 1500 ft/min descent rate on the altimeter and the VSI, then the altimeter will read zero exactly 20 minutes later (or never, if the ground intervenes). If you’re going to bring in non-linearities in the altimeter setting, then you’ll have to use those same ones in the descent rate. But aren’t we clever to have made a 7th grade problem really complex:-) Peter Cassidy Pilot and Pedant

Response:

My 12 year old son is in 7th grade, learning about slope (y = mx + b).   A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL). (1) is easy and obvious, but for (2) I don’t have a copy of the FARs handy, so I need some cites… If you are above 18,000 MSL, you use 29.92" on your altimeter according to what reg? Thanks Sandy

A perfect example of why teachers should be paid more… JP

Response:

- A question in his math book was, "How long will it take a plane to – descend from 30,000 feet at 1500 ft/min?"  I told him that the – question could not be answered because (1) you don’t know how high – the plane is, and (2) you don’t know where the ground is (MSL). While you are correct, do you REALLY what to piss off the math teacher with pressures, FARS, and MSL?  Remember most people think the ground is zero and 30,000 would be 30,000 feet above the ground. And if you son is anything like mine, they would NEVER quote FARs to the teacher.  After all you are the PARENT…and everybody knows parents are the STUPIDEST creatures on earth —                                     ——-    Virginia Beach, Virginia                                          —–      (804) 471 6776

Response:

- Hide quoted text — Show quoted text – My 12 year old son is in 7th grade, learning about slope (y = mx + b). A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL). (1) is easy and obvious, but for (2) I don’t have a copy of the FARs handy, so I need some cites… If you are above 18,000 MSL, you use 29.92" on your altimeter according to what reg? Thanks Sandy

Thanks to you all (and to those who sent me private e-mail, as requested) for spending the time to read my post.  The correct answer to the only question which was raised, i.e., "What is the cite to the FAR?", was provided by James Knox.  The answer being Section 91.121. I was quite surprised by the number of people who felt the need to answer the question raised by the math problem — 20 minutes. I was somewhat less surprised by the number of responses which I got for even raising the question…  Yes, I agree that the intent of the problem was to have the student divide 30,000 ft by 1500 ft/min to obtain 20 minutes.  Unmentioned in my posting was the fact that the teacher had already made it a point to "teach" the class that all aircraft altitudes are always measured AGL.  While that was true on the radar altimeter in my Piper Lance, it ain’t true in general. So to all, I say, "Thank you" for your time.  To Jim Knox, a special "Thanks."  To those who I may have (privately) responded to in a manner found to be objectionable (by pointing out that they were answering a question which was not raised and not answering the one which was raised), I apologize; and in general, I suggest that since this particular news group is intended to be used by people with knowledge of IFR, I think that the questions raised here should be responded to in that manner. By the way, I just saw a photo of the crashed "Cessna 117" in a Time Magazine cover article.  If those of us with some knowledge of aviation don’t make any effort to educate those who are writing about aviation, and otherwise teaching others, who will?  Remember, often history is little more than lies recorded — Bryant Gumble, NBC Today Show. Sandy

Response:

As everyone has said, the authors of the math textbook almost certainly did not want the problem to include the pressure/altitude issues. They just want to see if he can conceptually relate a simple equation to a solution space and plot a straight-line curve. Once you’re sure your son really really understands that, and the homework is done, and if he seems interested, maybe you could make up some extra-credit work with him. Don’t do it unless he thinks it’s fun. But sometimes word problems are more fun if they’re more real, and teaching him how to make one up might teach him how to do them better.  Also bear in mind that a common trick of word problems is to include irrelevant information, and the general trick of doing word problems is to figure out what the person writing the question was really trying to ask. But make sure he understands y=mx+b before bringing up any other jazz. Personally, I hated math, and was consistently terrible at it.

Response:

: My 12 year old son is in 7th grade, learning about slope (y = mx + b).   : A question in his math book was, "How long will it take a plane to : descend from 30,000 feet at 1500 ft/min?"  I told him that the question : could not be answered because (1) you don’t know how high the plane is, : and (2) you don’t know where the ground is (MSL). : (1) is easy and obvious, but for (2) I don’t have a copy of the FARs : handy, so I need some cites… If you are above 18,000 MSL, you use : 29.92" on your altimeter according to what reg? SANDY!   What are you doing!?!  Your confusing your son about stupid airplane issues when you should be helping him with his math!  I’m sure the authors of his math book had no concept of MSL vs. AGL and standard pressure, etc.  Just help him with his damn math!  – Jay       _/ Jay Masino      and      Teresa Larson          `67 Piper Cherokee _/      _/ digital H/W design       Database Design               N4269J      _/     _/ systems engineering       Sybase and Oracle RDBMS       __!__      _/    _/ UNIX and network admin     UNIX and VAX              _____(_)_____ _/   _/ C programming               C programming                !  !  !   _/  _/    Visit our homepage…  http://www2.ari.net:80/home3/jmasino/    _/

Response:

: My 12 year old son is in 7th grade, learning about slope (y = mx + b).   : A question in his math book was, "How long will it take a plane to : descend from 30,000 feet at 1500 ft/min?"  I told him that the question : could not be answered because (1) you don’t know how high the plane is, : and (2) you don’t know where the ground is (MSL). … Poor kid… -Ade

Response:

My 12 year old son is in 7th grade, learning about slope (y = mx + b).   A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL).

With all due respect, I think #1 is a really stupid answer.  The plane is at 30,000 feet.  Those of us who make a study of flying might ask "Is that MSL, AGL, or PA?", but the point of the exercise is to learn math, not to argue FARs.  The kid is trying to learn a fundamental mathematical concept, and the question applies that concept to a real-life problem.  To clutter up the answer with trivial details such as the difference between MSL and Pressure Altitude is absurd. The correct answer, in the context of a 12 year old kid learning how y=mx+b applies to the real world, is "30000 ft / (1500 ft/min) = 20 min". You could even take advantage of the problem to work in a short discussion of dimensional analysis (i.e. why "ft/(ft/min)" gives you units of "min"), which will give him a head start for when he takes physics in a couple of years. If you want to suggest that the landing airport might not be at 0 altitude, that’s fine, you now have a non-zero "b" term in the equation; "How long will it take a plane to descend from 30,000 feet to Denver International Airport, which is at an altitude of 5000 feet, at 1500 ft/min?" is a reasonable question.  Wait until he’s taking his PP-ASEL ground school to introduce the concept of altimeter settings. — Hippocrates Project, Department of Microbiology, Coles 202 NYU School of Medicine, 550 First Avenue, New York, NY 10016 "This never happened to Bart Simpson."

Response:

: My 12 year old son is in 7th grade, learning about slope (y = mx + b).   : A question in his math book was, "How long will it take a plane to : descend from 30,000 feet at 1500 ft/min?"  I told him that the question : could not be answered because (1) you don’t know how high the plane is, : and (2) you don’t know where the ground is (MSL).         come on!  this is a seven grade math book!  they assume the ground is 0 M.S.L and that 30,000 feet is in M.S.L also.  lets not drive the kids nuts, just cause we want to be cool as pilots!  ;-) Certified Flight Instructor – Airplane, Instrument Ground Instructor – Advanced, Instrument Commercial Pilot – Single Engine Land, Instrument       what good is it to fly … eh, a quoi bon l’enfant qui vient de naitre?

Response:

My 12 year old son is in 7th grade, learning about slope (y = mx + b).   A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL). (1) is easy and obvious, but for (2) I don’t have a copy of the FARs handy, so I need some cites… If you are above 18,000 MSL, you use 29.92" on your altimeter according to what reg?

You could answer it if you assume the author of the problem is a non- pilot.  Most difficulties in working story problems come from making the problem more difficult than it is by introducing "real-world" factors such as the already mentioned pressure vs real altitude dichotomy and the elevation of ground relative to sea level.  No 7th grader is expected to know these things so there’s no reason why they should be factored into the solution. It’s like the classic case of a physics story problem which sets a box of given dimension and weight into the back of a moving vehicle (pickup truck in the one I’ve seen), moves the vehicle at a given speed and then stops it and asks at which speed the vehicle had to be moving to make the box tip over.  Asking whether the bed of the truck was rusty and therefore flexible thus affecting the answer was neither expected nor desired…  8^) — Mike My opinions, not Argonne’s…

Response:

My 12 year old son is in 7th grade, learning about slope (y = mx + b).   A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL). (1) is easy and obvious, but for (2) I don’t have a copy of the FARs handy, so I need some cites… If you are above 18,000 MSL, you use 29.92" on your altimeter according to what reg? Thanks Sandy

actually, sandy, the problem doesn’t state whether the 30,000 feet is pressure altitude, msl, or agl.  you are making the _assumption_ that it is p. a. based on your piloting knowledge.  however, if you switch to the _assumption_ that it is agl, the problem is easily solvable (soluble?).  that is the assumption _i_ would make, given the problem, supported by two further assumptions:  1) the writers of the textbook would probably not give a seventh grader a ‘trick’ unsolvable problem, and 2) the writers of the textbooks are most likely non-pilots.  (even if they were pilots, they were writing to assumed non-pilots, seventh graders.  if they added ‘agl’ to the end of the 30,000 feet without explanation, it would confuse more people than it would to leave it off, and the explanation is beyond the scope of the lesson — they are teaching math, not piloting).  put the problem in the proper context. mho, john — ‘this place is full of yahoos’ — jonathon swift

Response:

My 12 year old son is in 7th grade, learning about slope (y = mx + b).   A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL). (1) is easy and obvious, but for (2) I don’t have a copy of the FARs handy, so I need some cites… If you are above 18,000 MSL, you use 29.92" on your altimeter according to what reg? Thanks Sandy

Response:

My 12 year old son is in 7th grade, learning about slope (y = mx + b).   A question in his math book was, "How long will it take a plane to descend from 30,000 feet at 1500 ft/min?"  I told him that the question could not be answered because (1) you don’t know how high the plane is, and (2) you don’t know where the ground is (MSL).

  {:) I suspect you already know a **LOT** more about it than did the person who wrote the problem, which means that they were probably just looking for "20 minutes." As you point out, the first BIG question is "descent to what?"  20 minutes of descent over Denver CO will produce a lot of noise during the last couple of minutes! <G   The question you raise about 29.92 is correct, but we have to assume it is not relevant.  Below 18,000 the altimeter is set to a correction pressure so that it will indicate MSL (altitude relative to mean sea level).  Obviously all it *really* reads is atmospheric pressure.  As you fly along the local pressure changes and you keep getting (and setting) new correction numbers (in the Kollsman window).   Above 18000 the planes are assumed flying so fast and far that the corrections would come too fast to be practical.  Accuracy is not important relative to the ground (no ground up that high <G), but relative to the other aircraft accuracy *is* important.  So everyone sets their altimeter to 29.92 and reads altitude based on the same "assumed" pressure.  [And hopefully remembers to set to local when descending below 18,000.] The point is, I doubt whoever wrote the book knew about this.  A plane above 18,000 *indicating* 30,000 might be at 30,000 — or might not.  So we have to assume they mean the plane is REALLY at 30,000 feet MSL, no matter what is indicated. Some typical city elevations in the US:         Austin, TX      AUS     632 feet         Dallas-Ft Worth DFW     603 feet         Denver CO       DEN    5431 feet         Houston Int     IAH      98 feet         Los Angeles     LAX     126 feet         Cheyanne WY     CYS    6156 feet                                                 James Knox

Response:

Calculating wind vectors

Question:

Does anybody know how to calculate wind vectors mathematicaly.  It seems that I cannot remember by high-school trigonometry well enough to do so.  I am trying to incorporate the calculations into a spreadsheet so I don’t have to use my E6-B every time.   Specifically, given  4 out of 6 of TH, TAS, WD, WS, TR, GS, what is the formula for calculating the other 2?

Response:

Does anybody know how to calculate wind vectors mathematicaly.  It seems that I cannot remember by high-school trigonometry well enough to do so.  I am trying to incorporate the calculations into a spreadsheet so I don’t have to use my E6-B every time.   Specifically, given  4 out of 6 of TH, TAS, WD, WS, TR, GS, what is the formula for calculating the other 2?

Given: TC, TAS, WD, WS Find: TH, GS    WCA (wind correction angle) = arcsin( (WS/TAS) * sin(WD-TC) )    TH = TC + WCA   (limit between 0-360 degrees)    GS = sqrt( TAS**2 + WS**2 – 2*TAS*WS*cos(TH-WD) )     Watch your trig functions; make sure you keep radians and degrees straight.    –Tom Turton

Response:

Hi.   For ordinary, garden-variety flying in a light a/c, you can do well enough by remembering two things:   (1)  The hypotenuse of a 45 degree right triangle is 1.4 times the length of a side. (2) A "60-30" triangle (one with angles of 90, 60 and 30 degrees) has a hypotenuse that is twice the length of the short side. Draw some "wind triangles" on paper and you’ll soon get a feel for how your track and ground speed are affected by a wind that is 30, 45, 60 or 90 degrees from your heading.  Then you can just interpolate for winds that are between those directions. Yes, it’s inexact.  But so are forecast winds, and who holds a heading within two degrees on a cross country, while enjoying the scenery? I find that above works just fine for a two- or -three hour flight in a Cherokee.  If after an hour I find that I’m drifting off ocurse, I can adjust the heading.   However, the wind changes, too, by the time I’ve flown a hundred miles. I’m not recommending this for transatlantic flights, but as I said at the outset, it works fine for vfr cross-country flying in small a/c. There’s a 40-year-old E6B in my bag, that I carry "just in case."  But it hasn’t been out of that bag for a long time.     vince norris writes:Path: news.cac.psu.edu!news.ems.psu.edu!news.math.psu.edu!chi-news.cic.net!newsxf er2. – Hide quoted text — Show quoted text -Organization: InfoRamp Inc., Toronto, Ontario (416) 363-9100 Lines: 7 NNTP-Posting-Host: ts16-14.tor.inforamp.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.0 (Macintosh; I; PPC) Does anybody know how to calculate wind vectors mathematicaly.  It seems that I cannot remember by high-school trigonometry well enough to do so.  I am trying to incorporate the calculations into a spreadsheet so I don’t have to use my E6-B every time.   Specifically, given  4 out of 6 of TH, TAS, WD, WS, TR, GS, what is the formula for calculating the other 2?

Response:

Does anybody know how to calculate wind vectors mathematicaly.  It seems that I cannot remember by high-school trigonometry well enough to do so.  I am trying to incorporate the calculations into a spreadsheet so I don’t have to use my E6-B every time.  

Quick course in trig.  Draw a triangle, with sides of length A, B, and C. Label the three angles a, b, and c, with an angle’s name matching the side opposite it.                a          C               b                                    /                                     /                          B          /   A                                 /                                       *                                           c Two basic laws of triangles.                sin(a)     sin(b)     sin(c) Law of Sines:  —–   =  ——  =  —–                  A          B          C   Law of Cosines:  A^2 + B^2 – 2*A*B*cos(c) = C^2 Notice that if you make C a right angle, cos(90)=0 so the last term on the left side drops out and you’re left with A^2 + B^2 = C^2, which is the famous Pythagorean Theorm which every high school student learns, and which the Scarecrow in The Wizard Of Oz recited upon getting his brain. Specifically, given  4 out of 6 of TH, TAS, WD, WS, TR, GS, what is the formula for calculating the other 2?

Starting with the two laws above, you should be able to work out the rest. If unsure you’ve got the right answer, confirm with pencil and paper drawings, or use a whiz-wheel. — Hippocrates Project, Department of Microbiology, Coles 202 NYU School of Medicine, 550 First Avenue, New York, NY 10016 "This never happened to Bart Simpson."

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Does anybody know how to calculate wind vectors mathematicaly.  It seems that I cannot remember by high-school trigonometry well enough to do so.  I am trying to incorporate the calculations into a spreadsheet so I don’t have to use my E6-B every time. Specifically, given  4 out of 6 of TH, TAS, WD, WS, TR, GS, what is the formula for calculating the other 2?

Attached is a 123 spreadsheet "wca.wk4" Hope this helps Contact me if you have any questions. Miro

  WCA.WK4

8K Download

Response:

writes: Does anybody know how to calculate wind vectors mathematicaly.  It seems that I cannot remember by high-school trigonometry well enough to do so.  I am trying to incorporate the calculations into a spreadsheet so I don’t have to use my E6-B every time.   Specifically, given  4 out of 6 of TH, TAS, WD, WS, TR, GS, what is the formula for calculating the other 2?

I always draw a little picture in the margin.  It shows my intended course with a vector labeled with my TAS.  The wind speed vector gets added to the picture with the "right" relative angle, the WCA.  Then resolve the WS vector into a component along the heading and a component perpendicular to it.  The one that affects your ground speed is |WS| cos(WCA)  and the crosswind component is |WS| sin(WCA). If you figure out how an E6-B works, this is it.  You are creating the wind vector and then rotating it graphically!  But be careful about the angles: Written wind directions are usually True, but controllers convert them to Magnetic.  Then you have to worry about magnetic variation in your area and compass deviation in your airplane.  Good stuff to know if you can’t use VOR navigation some day and don’t own a GPS!  –Bill Wm W. Plummer, 7 Country Club D., Chelmsford MA  01824  508-256-9570 PP-ASEL,G

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Path:

dodo.global.co.za!hermes.is.co.za!news.uoregon.edu!usenet.eel.ufl.edu!newsf eed.inte rnetmci.com!swrinde!hookup!news.nstn.ca!inforamp.net!usenet – Hide quoted text — Show quoted text – Newsgroups: rec.aviation.piloting Organization: InfoRamp Inc., Toronto, Ontario (416) 363-9100 Lines: 7 NNTP-Posting-Host: ts16-14.tor.inforamp.net Mime-Version: 1.0 X-Mailer: Mozilla 2.0 (Macintosh; I; PPC) Status: N Does anybody know how to calculate wind vectors mathematicaly.  It seems that I cannot remember by high-school trigonometry well enough to do so.  I am trying to incorporate the calculations into a spreadsheet so I don’t have to use my E6-B every time.   Specifically, given  4 out of 6 of TH, TAS, WD, WS, TR, GS, what is the formula for calculating the other 2?

When you have 4 out of the 6 variables, you should be able to use either the sine rule or cosine rule which apply to any triangle. sin A / a = sin B / b = sin C / c a2 = b2 + c2 – 2*b*c*cos A where a, b, c are the lengths of the sides of the triangle, and A, B C are the angles opposite the side of teh same name (e.g. A is included between sides b and c).  a2 means a squared, etc You should be able to identify which of the two formulae applies to the problem by checking which contains only one unknown.  In a spreadsheet, the calculation should be trivial. Neil A Fraser TEL: 27 (11) 468 2892 FAX: 27 (11) 468 2895 ** There’s more fun in getting there    than being there **

Response:

Gyroplane Info

Question:

Since I don’t have a lot of room I thought a gyroplane would be a good choice.  Are they easy to build? What are the costs, and how long will it take? I want to keep it as simple as possible. Are there any homebuilt type gyroplanes for sale? Is that a good path to choice?

Don, A gyro is a very good choice for the above reasons,  if you like rotorwing aircraft. Might I suggest that you attend one of the various rotorcraft fly-ins around the country and take an introductory flight to confirm your desire to fly this type aircraft. There are various Instructors and flight schools that could also accomplish this, as well, listed on one of the two Gyro Web pages (http://www.iag.net/~norman/gyro.html and http://osf1.gmu.edu/~pbarber/welcome.html). Ease of building is revelant to your skills and the equipment you have, should you construct from plans only. A middle of the road approach might be for you to construct the basic airframe, as with the Brock KB series or the Martin Hollman Bumble Bee and buy the more complicated components, such as the rotor head, prerotor and blades. Airframe construction consist of mostly  cutting the tubing and angle material and drilling attachment bolt holes. If you have access to a machine shop you could also make the head, although I seriously doubt that you will save much, based on the price of a finished head from Ken Brock. Cost and construction time will vary depending on what avenue you take. For a kit from Brock you could possibly assemble it in a week of part time construction. Of course the price of admission is going to be somewhere in the neighborhood of $10-$12K for this practically turn-key gyro. On the other hand, The Bumble Bee, utilizing the Ralph Taggart updates can be built for about $5-$6K in about 3-6 mos. utilizing the off ther shelf components, Ralph suggest you buy. Used gyros are always available at the many gyro fly-ins around the country and are also advertised in the classified section of PRA Magazine as well as Sport Aviation (EAA Pub),  Kit Planes and Trade-A-Plane. There is also a classified section on the Gyro Web Page that you might want to check. Caution is advised when buying used. Enlist someone knowledgeable in the construction of gyros before you lay your money down. A good deal may not be so good,  if it’s not safe and poorly constructed. The basic simplicity of these crafts opens the door to a wide range of construction levels. Do your home work before you make a costly mistake. I would also encourage you to purchase the several books published on gyros by the likes of Abbott and Hollman, both advertised in the pages of the PRA Mag or detailed in the Web pages previously mentioned. Whether this is a good path to take is relevant to whether you are interested in rotorwinged aircraft. I’m fairly new at the sport but once I had my first instruction, was hooked. If you like it, you will love it. Others think we have a death wish. You just need to educate yourself through a relation with PRA, read everything you can on the subject, talk with builders and flyers at the various gyro fly-ins and get a demo ride to convince yourself that this is indeed the type of aviation you want to comit. Feel free to contact me or any of those listed in the Web pages if you need additional info.

Response:

I am interested in a aircraft for sport flying. Considering a homebuilt project.  Since I don’t have a lot of room I thought a gyroplane would be a good choice.  Are they easy to build? What are the costs, and how long will it take? I want to keep it as simple as possible. Are there any homebuilt type gyroplanes for sale? Is that a good path to choice? Don Kyle

Response:

Attitude indicator – How does it work?

Question:

 The position it should try to erect to would be to indicate zero bank in this constant turn. Does it do this? Anyone tried sitting in a 30 degree turn for ten minutes to find out?

 But the correction is in an absolute sense, relative to the earth (an inertial frame). So if the plane’s say, going north and turning to the right, the errection mechanism thinks that gravity is over to the west. But after 180 of turn,it will try to correct the other way, to the east — so it all tends ot balance out if you go in a circle. The true test is to do the 30 degree bank in a very high speed aircraft, so that after several minutes the plane hasn’t really turned that much — in which case you’d see the gyro trying to show wings level. Light aircraft just turn to fast to see the effect.

Response:

Roll-erection cut-out, set at 7 degrees roll in most AIs. RTFM.

Trouble is, most used aircraft tend to be sold without the FMs for instruments like the AI.  So I’d guess few pilots actually have access to such a document.  Will King etc. send them out on request? Julian Scarfe

Response:

a sustained shallow turn will cause the AH / AI to read erroneously (acquire a false vertical).  I don’t know the physics behind it, but this is a basic instrument error that was taugh to me in flight school.

True. Other errors: 1)  application of `G" loading during a turn will cause the turn indicator    to record an error. ie.  If you pull up HARD when doing a rate 1    turn, the indicator will show a higher rate of turn.. and vice versa

Is this really an error?  If you are in a turn and pull up hard, two things will happen: 1) you will climb, and 2) your turn will tighten and, therefore, the turn rate will increase.  I believe the rate of turn shown by the instrument will still be accurate. 2)  The VSI is a great TREND instrument.. very useful for catching slight    climbs / descents b4 the altimeter shows anything.   However, it    lags pretty badly. ie when you level off, it will initially show    a climb even though the altimeter has stopped.

It will show a descent if, prior to leveling off, you were descending. 3)  DG also has a turning error associated with it.  For a constant    rate turn, it tends to speed up passing through E/W and slow down    passing N/S (or the other way round.. but there is an error)

I believe you are mistaken here.  I know of no such error.  This sounds like compass error, sorta.  See below. 4)  Compass also has turning and acceleration errors (Could someone    plse elaborate to them?  I can’t recall what the exact errors are

In the northern hemisphere, turns in the northern half of the compass will cause the indicated heading to lag the turn.  In the southern half of the compass, the compass indication will lead the turn.  On headings of east or west, the compass will indicate correctly. Accelerations to the east (or deccelerations when facing west) will cause the compass to indicate a turn to the left.  Opposite accelerating to the west.  No acceleration effects north or south. Bill Levenson PP-ASEL-IA

Response:

indicate zero bank in this constant turn. Does it do this? Yes, but it doesn’t do this as rapidly as it does on startup. Apparently the erection mechanism is only fully functional when the gyros aren’t spinning rapidly.

No, No.  The gyro should *never* erect to indicate zero bank when in a turn.  In a 360 degree turn, the first part of the turn will cause the gyro to erect in one direction and the last part of the turn will cancel this out and cause it to erect in the opposite direction (remember, we’re talking inertially here, that is, the gyro is tilting relative to it’s proper orientation relative to the horizon).  There is an error that is greatest for a 180 degree turn. And the erection mechanism *is* fully functional when the gyro’s are spun up. Anyone tried sitting in a 30 degree turn for ten minutes to find out? A friend of mine did. He reported that the AI had a distinct tilt after he resumed level flight. The instrument in question was about 15 years old.

In a sustained turn, the error should be greatest when turning through the heading that is 180 degrees from where you started the turn.  Ideally, this is true no matter how many times you go around and the amplitude of the error is the same no matter how many times or how long you sustain the turn.  The error will also be zero at the heading that you started the turn from no matter how many times you go around. Bill Levenson PP-ASEL-IA

Response:

    I don’t think I can ever remember climbing into a "rent-a-wreck" and     not seeing the HI tilted at a crazy angle – albeit still with brown     generally down and blue generally up.  If the center of gravity is     below the mounting gimbals, given the quality of the bearings required     to prevent significant precession errors due to friction, why doesn’t     the gyro right itself after it has spun down?    Aw rats!  You’ve got me.  OK, we need ten volunteers to rip apart their    AIs please… The c of g isn’t necessarily below the mounting gimbals, in fact I’d guess it’s at a very similar level. The auto-erecting depends only on small free swinging plates which allow air to blow out from a hole which they uncover when they swing to point down. There are four of these, one for each cardinal direction if you like, and each can only swing one side of straight down. If the AI is not erect according to gravity, one or at most two of these little plates will swing, exposing a hole through which air blows, applying a couple to the AI which helps erect it to the position where all four plates cover their respective holes. The original question still remains though. Dave and I had a chat about it last Saturday whilst failing to go flying due to bad weather. In a prolonged constant turn, with apparent gravity through the floor of the plane (we’re talking about a coordinated turn here), one of the aforementioned plates should swing open, thus allowing the air to blow and created the couple which starts to re-erect the AI. The position it should try to erect to would be to indicate zero bank in this constant turn. Does it do this? Anyone tried sitting in a 30 degree turn for ten minutes to find out? — Harlequin Ltd.                                          44 1223 872519 (fax) Barrington Hall Barrington Cambridge CB2 5RG England

Response:

- Hide quoted text — Show quoted text – DM Any instrument technical gurus out there? I’m not an instrument guru, but I may be able to field some of the many good questions that Dave asks.  Can I change the order a little? DM I read somewhere that it is impossible to distiguish DM between the force of accelleration and the force of gravity without any DM external reference. That is true enough — you can’t tell the difference between a uniform gravitational field and an acceleration.  The classic example is that it’s impossible to distinguish the following situations: a) being in a lift (elevator) car in interstellar space with no gravity b) being in a lift car in a lift shaft on Earth just after the cable has been cut.

One small nit-pick….. in a real situation in b) you could tell that you were in the vicinity of the earth because the force at the bottom of the car would be slightly higher than at the top, so a free falling collection of bits would gradually be separated in the vertical direction.   This would not occur in free space (if this were even possible !)  The situation in b) is a tidal gravity force. Unfortunately you cannot get a "uniform" gravitational field ! Only a "small" point… but just to keep the record straight ! Mike

Response:

indicate zero bank in this constant turn. Does it do this?

Yes, but it doesn’t do this as rapidly as it does on startup. Apparently the erection mechanism is only fully functional when the gyros aren’t spinning rapidly. Anyone tried sitting in a 30 degree turn for ten minutes to find out?

A friend of mine did. He reported that the AI had a distinct tilt after he resumed level flight. The instrument in question was about 15 years old.                     |                     | Convenience stores are named that because they’re George Patterson –  | open all night. It saves the robbers the trouble                     | of breaking in.                     |

Response:

Well, some really good replies so far, but still no "absolute" on whether a sustained turn will cause the AI to start falsely "erect".

I will give you my humble absolute: An AI will "falsely erect" in a sustained coordinated turn of any degree. (It will take longer in a steeper turn.) Does it matter? Not really- my main wings level instrument is the TC/inclinometer anyway, not the AI. However, my CFII, knowing this (since I told him last weekend that I never use the AI except for a few moments during transitions) decided that having my TC was a bad idea and he failed it for the whole flight. Bummer. At least it has a little red flag indicating OTS! I think that’s a great idea. Spend a whole day flying w/o the TC, then a whole day flying w/o the AI. You’ll learn the strengths and weakness of each really quickly, and when you have them both you’ll be that much better. I just wish my AI had an inclinometer on it now. (BTW, my "whole day" is about three hours under the hood.) Cheers, Doug —    _   Doug   / | Fields     http://www.311wc.com /    N311WC

Response:

: Any instrument technical gurus out there? : I would like to know how a modern AI compensates for the actual : vs the gyroscopic horizen.  Any limitation in the instrument would be : very usefull indeed.  Does it use any form of pendulum to adjust its gyros : to the aircraft attitude? Pendulous vanes.  You need it even in an nose dragger to initially errect a non-caging gyro. : Is there some sort of slow-acting pendulum in a modern AI?  If so, : is it possible to "fool" the instrument by a sustained co-ordinated turn? Yes it is. Also, they are subject to accelleration effects as well. -Ron

Response:

[a valiant attempt at describing gyro operations without pictures deleted... nice job] The gyro is calibrated so that the top of the rotor housing is leaned (slanted) forward about 2 1/2 degrees. It is also bottom heavy by a couple of ounces. This aids in the erection as well as the vanes. If my memory serves me right, the slant is to allow for some acceleration/precession errors.

Hmmm.  I’ve never heard of this before.  Is it possible you are mixing up the directional gyro with the artificial horizon?  I have found reference to balance weights and "tilt" to compensate the directional gyro for earth rotation. The gyro in the DG is, of course, fixed in space. Once you set the DG to point to North, it stays pointed that way.  But the earth rotates under it such that at some time later, the DG (let’s assume it’s perfect will no longer be pointed North.  This effect is dependent on the latitude at which you are located.  At the equator, this effect is zero if you are pointing to true north because true north remains in the same inertial direction relative to the equator as the earth rotates. The effect is greatest very near the pole.  If you point the DG to true north when you are very near the pole, the error will build at roughly 3.75 degrees every 15 minutes. To compensate for earth’s rotation, a "balance weight" is added to the DG and the DG is tilted a few degrees.  With the tilt, the balance weight applies a restoring moment which acts in the plane of the tilt.  Since gyroscopes respond 90 degrees out of phase from the applied torque, the result is a precession of the gyro.  The text I have that describes this states that the gyro’s in the U.S. are designed to be accurate between 25 and 48 degrees latitude. This seems like a small effect to me but that’s the only thing I could come up with that would explain a "tilt" and a "balance weight" as you describe It seems to me that if such a mechanism were employed on an AI, it would cause a nasty wobbling effect due to precession. One calibration test was to turn the indicator (while stabilezed) 180 degrees from front to back as if an airplane could make a flat turn instantaneously. Because of the slant, the indicator will be off by 5 degrees. The gyro was required to erect itself withing certain amount of time.

Or perhaps the tilt is some mechanism for compesating for the errors induced by a 180 coordinated turn?  Just guessing.  I still don’t see how a balance weight would work. Also tested was the erection speed by tilting the gyros 30 degrees and timing it to 0 degrees. This was down for roll left, roll right, pitch up, and pitch down. In all cases, it would have to erect itself to 0 (visually) withing a certain amount of time.

Can you tell us what the time constant for this was (i.e.  how long did it take for the error to reduce by a factor of 2)? Well I wish I could draw some pictures, but that’s all I have.

Nice job! I’m also not 100% sure my memory is serving me right, so take everthing with a grain of salt. It was alot of fun fixing gyros, it was almost an art form (the fact that they were so delicate).  It required alot of feel and hearing to repair them correctly and took a while to master. What a limited skill to have.

Sound great! -ds

Bill Levenson PP-ASEL-IA

Response:

A friend insists that an attitude indicator is what a drill sergeant points at his platoon so that he knows who to march up to and shout "You’ve got a bad attitude, mister!"  Probably an old joke, but I liked it!

Response:

Roll-erection cut-out, set at 7 degrees roll in most AIs. RTFM.

Response:

- Hide quoted text — Show quoted text – Well, some really good replies so far, but still no "absolute" on whether a sustained turn will cause the AI to start falsely "erect".  My guess based on the thread so far is that it will.  A pendulum will be fooled by centripetal force (it will behave the same as the ball in the turn & slip), and if this is the *only* "earth" reference that the AI has …. It’s not quite the same.  Don’t forget that as the aircraft turns, the centrifugal force also rotates in the inertial frame, and it’s the inertial frame that the gyro knows about. So unless the correction is *very* rapid, the effect of that force will average out to zero. I was fully intending to test this out this weekend by holding a 30deg banked turn for, say, 10 minutes, but the weather was not on my side during the times I had to do it.  If there is anyone who can afford to burn 10 minutes or so of flying to check this out, I think that it would be a worthwhile exercise. I’ll wager you your ten minutes fuel that there will be no error due to the centrifugal force! If you’re still dubious, try imagining what the gyro’s doing.  Remember that in the turn, the aircraft (and AI mount) banks while the gyro stays vertical.  So, say your error were introduced, and the gyro axis tilts 5 degrees towards the North.  On the other side of the turn, the correction mechanism would tilt it 5 degrees South…  It *must* cancel out over the turn. So the error can’t build up, it can only be (almost) instantaneous.  And if you’re going to make the AI correct itself to the apparent vertical almost instantaneously, there’s no point in spending all that money on a gyro, just buy a plumb line (or look at the slip ball!). Julian Scarfe

Hello again Julian!  :-) In my IFR training, the precession error we expect due to turns was for a 180 deg coordinated turn.  When rolling out level on the reciprocal heading you expect were to expect an error of a few degrees in pitch and bank (I forget which way).   Hmmm, didn’t I say this before?  :-) However, in a 360 deg turn, you didn’t expect any error, because, just as you said, the errors of the second half of the turn cancel out the errors of the first half. Bruce Bateman

Response:

a sustained shallow turn will cause the AH / AI to read erroneously (acquire a false vertical).  I don’t know the physics behind it, but this is a basic instrument error that was taugh to me in flight school. Other errors: 1)      application of `G" loading during a turn will cause the turn indicator         to record an error. ie.  If you pull up HARD when doing a rate 1         turn, the indicator will show a higher rate of turn.. and vice versa 2)      The VSI is a great TREND instrument.. very useful for catching slight         climbs / descents b4 the altimeter shows anything.   However, it         lags pretty badly. ie when you level off, it will initially show         a climb even though the altimeter has stopped. 3)      DG also has a turning error associated with it.  For a constant         rate turn, it tends to speed up passing through E/W and slow down         passing N/S (or the other way round.. but there is an error) 4)      Compass also has turning and acceleration errors (Could someone         plse elaborate to them?  I can’t recall what the exact errors are I have actually witnessed the AH/AI error, as well as 1-3 in flight.  Was deliberate attempt to demonstrate the errors and prove them. Anyone care to add to the list? Song

Response:

Well, some really good replies so far, but still no "absolute" on whether a sustained turn will cause the AI to start falsely "erect".  My guess based on the thread so far is that it will.  A pendulum will be fooled by centripetal force (it will behave the same as the ball in the turn & slip), and if this is the *only* "earth" reference that the AI has ….  The question wil then be how long before a significant false reading results.  An e-mail respodent mentioned a rate of 3 deg per minute.  If so, this would be significant. I would figure that in order to take turning forces into account, the AI would need to be very "clever", because ISTM that the rate of turn would need to be referenced to *speed* to figure bank angle (and an AI has no speed input). I was fully intending to test this out this weekend by holding a 30deg banked turn for, say, 10 minutes, but the weather was not on my side during the times I had to do it.  If there is anyone who can afford to burn 10 minutes or so of flying to check this out, I think that it would be a worthwhile exercise. The consequences of such an instrument error are quite big.  In a sustained turn in IMC, such instrument error would tend to make the pilot increase bank.  If the turn indicator is not taken into account during the pilot’s instrument scan, a spiral dive could result – not a trivial error then! This is the main reason that I don’t believe that such an error could exist – surely it would be a *major* caution taught in an instrument course if it were.  I can appreciate that normally sustained turns would not be done IFR, and a racecourse hold would maybe give enough time during the straight legs to get the AI correctly earth-referenced.  I have never felt the need *yet* to do a sustained turn in IMC, but I can imagine real situations where I might want to.  E.G., holding a position whilst taking cross-bearings on several VOR’s or ADF’s etc, or making an ad-hoc hold along a route whilst IMC, but not under IFR rules (as is a normal condition with a UK IMC rating). I will try again next weekend as I can’t fly during the week Dave Mould Ordinary PPL

Response:

DM Any instrument technical gurus out there? I’m not an instrument guru, but I may be able to field some of the many good questions that Dave asks.  Can I change the order a little? DM I read somewhere that it is impossible to distiguish DM between the force of accelleration and the force of gravity without any DM external reference. That is true enough — you can’t tell the difference between a uniform gravitational field and an acceleration.  The classic example is that it’s impossible to distinguish the following situations: a) being in a lift (elevator) car in interstellar space with no gravity b) being in a lift car in a lift shaft on Earth just after the cable has been cut. Both a and b look like freely falling inertial frames.  If you release something it obeys Newton’s first law (uniform velocity or no motion at all). [Another way of looking at it is that gravity *is* a manifestation of the failure to use an appropriate freely falling frame!] However, you *can* tell the difference between a rotating frame and a non-rotating frame (pace Ernst Mach, who explored some very interesting alternatives). Give something a velocity in a rotating frame and watch it curve (coriolis force)! That’s in essence *why* a gyro works.  It remembers which direction was which in a rotating frame. But there’s no perfect gyro, so gyros need to be referenced to something on a regular basis to avoid errors due to precession.  With the DG that’s easy: you set it against the compass from time to time, but the AI is different.  What you want to know is which way is "down", "down" being the direction in which gravity is acting, and *any* AI worth having must have a mechanism for sensing "down". DM If I fly several hours on a N/S heading, the earth has rotated many DM degrees.  I would expect a free-floating gyroscope to precess DM and indicate an increasing amount of bank.  But the modern AI does not. DM How is this achieved? Even an old gyro does not, because it’s not (as Dave has deduced) free gyro. The name (almost confined to books on aircraft!) given is "Earth gyro". DM I would like to know how a modern AI compensates for the actual vs the DM gyroscopic horizen.  Any limitation in the instrument would be very DM usefull indeed.  Does it use any form of pendulum to adjust its gyros DM to the aircraft attitude? …So how does a gyro detect down so that it can reorient itself? Well how would *you* do it?  Drop a plumb line, right?  Older vacuum-driven gyros worked on a very similar principle, using hanging "pendulous vanes" to open up or cut off a a current of air that applied an appropriate correcting force on the gyro. A don’t know if modern vacuum-driven gyros still use exactly that principle. An electric gyro can use mercury switches to the same effect. But like any such self correction mechanism (just like an autopilot), the designer has a choice about how fast the device tries to make the correction.  Too slow and the instrument may become inaccurate before the correction can compensate.  Too fast and any temporary or transient influences on the sensing mechanism could cause it to correct itself constantly.  This has some interesting consequences. DM  For instance:  If I start up in a DM taildragger, I am obviously in a very nose-up attitude.  Modern AIs DM have no manual erection knob, but nevertheless seem to indicate the DM correct attitude. The old AI’s need to be manually erected after DM establishing straight & level. How do modern AI’s do this DM automagically? When you say "old AI’s need to be manually erected after establishing straight & level", that’s true, but it’s not a *calibration* that you’re performing, it’s getting the thing close so that the automagic mechanism has an easier job.  A bit like "helping" the autopilot by putting the aircraft in a close to level-flight attitude before pressing the altitude hold.  It’s not essential, but it helps to sort things out quicker. I believe many modern gyros have a "fast erect" button for this.  That substantially increases the rate at which the automagic seeks the apparent vertical.  So you can press it when you’re stationary on the ground and you know that there are no inertial forces messing up what it thinks is vertical. DM Is there some sort of slow-acting pendulum in a modern AI? I think I covered that… DM  If so, is it DM possible to "fool" the instrument by a sustained co-ordinated turn? My DM suspicion is that it might begin to "erect" itself to align with the DM new apparent "gravitational" direction. You might have thought so, but remember that the gyro *does* know what’s a rotating frame and what’s not.  So in a sustained co-ordinated turn, the gyro "knows" that the apparent vertical is revolving in space, and the average correction that it makes is towards the average Earth vertical. If you could sustain a *linear* acceleration for long enough, you could, in theory, fool it. However, that depends on the timescale over which the correction is applied being much longer than the period of the turn.  If you were to use a fast erect mechanism in coordinated turn, you might get it confused enough for long enough to think that the vertical had moved, which is why that’s only for unaccelerated conditions. DM If I do aerobatics, including loops and rolls, my modern AI still DM appears to read correctly afterwards.  Are there any limitations?  Is DM it possible to "topple" a modern AI? Well, the need for gimbals on which to mount the gyro restricts the orientations somewhat.  My hat off to the person who designed the gyro that continues to read through the vertical into inverted flight!  As I understand it the sort of AI used in most modern fighters is vastly more expensive for just that reason. (Maybe it’s all done with laser gyros now?). DM If left uncaged, an old-fashioned DM AI also fitted in my aircraft is performing rapid gyrations after the DM same manoevours untill I manually erect it.  Is there then an essential DM design difference between the two? I doubt it.  Perhaps the stops are in a different orientation? DM If I accidentally entered a spin in DM IMC, but recovered OK (whew!) can I still use my AI afterwards, or DM should I fly on limited panel in case the AI is fouled up? (Particularly) good question.  That depends very much on the construction of the AI.  There’s no reason in principle why the gyro shouldn’t cope, but the practicalities of engineering the thing might intervene to cause problems. DM How about an extended "hold"? No problem. As described above, as long as the erection mechanism is slow enough it should average out the centrifugal force. Julian Scarfe

Response:

I don’t think I can ever remember climbing into a "rent-a-wreck" and not seeing the HI tilted at a crazy angle – albeit still with brown generally down and blue generally up.  If the center of gravity is below the mounting gimbals, given the quality of the bearings required to prevent significant precession errors due to friction, why doesn’t the gyro right itself after it has spun down?

Aw rats!  You’ve got me.  OK, we need ten volunteers to rip apart their AIs please… Julian Scarfe

Response:

: Yes, there’s a sort of pendulum in there. I’ve not seen one disassembled, : but there’s a description in the Jepessen manual. So far I have read a bunch of good information on this subject in this thread, especially Julian’s article. I used to repair AI (or artificial horizons – AH), from Edo’s to Kings. Primarily for general aviation airplanes. They all worked essestially the same, even electric ones. And to the best of my knowledge, they’ve haven’t change much in operation for decades. But what has advanced is the electronics (autopilot, flight directors, etc.) and the bearings. If anything fails in an AH, it will be the bearings. But I’ll try to describe what I remember. The gyro is a spinning mass (rotor) about 2 inches in diameter and about 2 inches tall and spins about a vertical axis (10-20,000 RPM?). It has groves along the perimeter that air (suction) is forced over to spin the rotor. It is contained in a housing that has four vents in the bottom: fore, aft, left, and right.  The housing contains bearings so that it pivots fore and aft about a horizontal axis that runs from left to right. Housing pivots translate into pitch indication. Air is forced into the housing through one of it’s pivot points and exits the vents.  There are two pendulums (vanes) that cover the vents, one for the fore and aft, the other for the left and right. As one vent is covered, the opposite is opened. The vanes are set up so when the gyro is erected, there is an equal amount of opening on both sides. There is a u-shape part (name?) the supports the rotor housing. The rotor housing is limited by spring stops from spinning all the way around.  This u-shaped part is hollow on one side for air to flow into the rotor housing. The u-shape has it’s own axis that it spins that is horizontal and fore and aft via a hollow shaft in the back part of the U. This shaft is also hallow for air to flow. The U-shaped part is allowed to rotate freely 360 degrees within the housing of the instrument casing and translate to roll in the indicator. It is through this shaft that air originates as it is open to the outside of the indicator (in the back). The instruments’s chamber represents where air is let out through the vents and then eventually through another hole in the back of the unit. On most (if not all) AI’s, air is sucked (vacuum) from here and not forced through the shaft. The gyro is calibrated so that the top of the rotor housing is leaned (slanted) forward about 2 1/2 degrees. It is also bottom heavy by a couple of ounces. This aids in the erection as well as the vanes. If my memory serves me right, the slant is to allow for some acceleration/precession errors. One calibration test was to turn the indicator (while stabilezed) 180 degrees from front to back as if an airplane could make a flat turn instantaneously. Because of the slant, the indicator will be off by 5 degrees. The gyro was required to erect itself withing certain amount of time. Also tested was the erection speed by tilting the gyros 30 degrees and timing it to 0 degrees. This was down for roll left, roll right, pitch up, and pitch down. In all cases, it would have to erect itself to 0 (visually) withing a certain amount of time. Well I wish I could draw some pictures, but that’s all I have. I’m also not 100% sure my memory is serving me right, so take everthing with a grain of salt. It was alot of fun fixing gyros, it was almost an art form (the fact that they were so delicate).  It required alot of feel and hearing to repair them correctly and took a while to master. What a limited skill to have. -ds

Response:

BB I was taught in my instrument training that when rolling out of a BB 180deg standard rate co-ordinated turn, that I should expect to see BB an error in the HI of several degrees in both pitch and bank.  I BB though this was supposed to be due this exact effect – the gyro trying BB to correct itself to an "incorrect" down. An excellent point. In the light of Bruce’s comment, the notes for the PPL/IR that I just consulted, and a comment from Ken Sykes, the more I think about it, the more I think that I have underplayed the effects of acceleration error in my original article. To look at acceleration error in more detail, take the classic textbook example of an aircraft accelerating along the runway: its antiquated AI shows a nose-up right-wing down attitude, from two independent sources: 1) The erection mechanism feels the inertial force of the acceleration (acting towards the rear of the aircraft), which it can’t differentiate from gravity and tries to "right" the AI, so it tips to indicate nose-up. 2) The erection chamber is a big lump of iron on the bottom of the gyro. That means that the CG of the gyro is below the pivot on the gimbal. As a result, the inertial force of the acceleration causes a couple on the gyro, and, since gyros display this perverse habit of *precession*, the couple results in a right-wing down indication for an AI rotating couterclockwise when viewed from the top (which apparently is the de facto standard for vacuum AIs). Have you ever seen either of these happen on a modern AI?  Have you seen the error that Bruce describes when rolling out of a standard rate turn? I’m not sure that I have, and I will make some speculative deductions about the development of AIs from that. Please bear in mind that I’m not in the aircraft instruments business and I’d welcome any corrections. a) From the absence of (1) I infer that the normal erection mechanism in a modern gyro is probably designed to work more slowly than in an old brick-sized AH. After all, if gyro mechanisms are getting better, the precession because of mechanical instrument imperfections is likely to require less rapid correction. No technology can eliminate part (1) of acceleration error (unless it cheats by time-averaging the acceleration, and even then there will be some error) because of the equivalence principle (elevators in space ‘n all that) I described before. b) If you think about (2) for a minute, you might see a logical flaw. Why on Earth do we *allow* the CG of the gyro to be below the pivot? Why not put a balance weight on the top so that CG is exactly in line with the pivot? Ken Sykes described to me by email a cunning way of eliminating this effect altogether using a pair of counterrotating gyros. The only deduction I can make is that the designers *wanted* it this way so that the gyro is self-righting when it’s not spinning. After all, when you’ve started the engine, before the gyro has got up to speed, wouldn’t it be better if a straightforward pendulum effect put it in almost the correct attitude to start with? Evidently modern gyros have a better mechanism for doing this (the fast-erect mechanism?), even on vacuum driven gyros and can be perfectly balanced so that an acceleration fore or aft need not cause a bank indication on the AI. So I’d like to correct what I said to in reply to Dave: DM If left uncaged, an old-fashioned DM AI also fitted in my aircraft is performing rapid gyrations after the DM same manoevours untill I manually erect it.  Is there then an essential DM design difference between the two? JS Not really.  Perhaps the stops are in a different orientation? I think there *is* good reason to suspect that the older gyro will be much less reliable after accelerations than modern ones, for the reasons I describe above. There may well be an essential design difference between the two. I hope that clarifies things a little. Julian Scarfe

Response:

I would like to know how a modern AI compensates for the actual vs the gyroscopic horizen.  Any limitation in the instrument would be very usefull indeed.  Does it use any form of pendulum to adjust its gyros to the aircraft attitude?  

Yes, there’s a sort of pendulum in there. I’ve not seen one disassembled, but there’s a description in the Jepessen manual. The old AI’s need to be manually erected after establishing straight & level. How do modern AI’s do this automagically?

They have a quick erection air bleed system. My understanding is that this only operates for a short time after the unit starts up. Some units have a "non-locking caging knob" which can be used to engage this system at any time. These are popular for use in aerobatic aircraft. Is there some sort of slow-acting pendulum in a modern AI?  If so, is it possible to "fool" the instrument by a sustained co-ordinated turn? My suspicion is that it might begin to "erect" itself to align with the new apparent "gravitational" direction.

You are correct. If you stay in a coordinated turn long enough, the thing will gradually erect itself. ….impossible to distinguish between the force of accelleration and the force of gravity without any external reference.  But the AI is (apparently) able to achieve this??

Not really. The gyroscope is simply resistent to any change in attitude, so it stays nice and level while the aircraft moves around it. If I do aerobatics, including loops and rolls, my modern AI still appears to read correctly afterwards.  Are there any limitations?  Is it possible to "topple" a modern AI?  

According to Sigma-Tek, their basic models are accurate through 360 degrees. If I accidentally entered a spin in IMC, but recovered OK (whew!) can I still use my AI afterwards, or should I fly on limited panel in case the AI is fouled up?

I would simply double check the AI against the turn coordinator or T&B and use it if they agree. I don’t have much instrument training, and I’ve no spin training, however, so that opinion isn’t worth much. How about an extended "hold"?

The holding procedure which I was taught involves standard-rate procedure turns separated by two minute legs of straight & level flight. Since it requires at least five 360 degree turns before the unit starts to tilt, holding turns are no problem.                     | The Swordfish relies on her "peggy" George Patterson –  | The modified Taurus ain’t sound                     | So the Swordfish flies off on her missions                     | And the Albacore stays on the ground.

Response:

Ahhh Julian, you continue to impress me with your astute analysis. But…..  :-) – Hide quoted text — Show quoted text – ….<snip… To look at acceleration error in more detail, take the classic textbook example of an aircraft accelerating along the runway: its antiquated AI shows a nose-up right-wing down attitude, from two independent sources: 1) The erection mechanism feels the inertial force of the acceleration (acting towards the rear of the aircraft), which it can’t differentiate from gravity and tries to "right" the AI, so it tips to indicate nose-up. 2) The erection chamber is a big lump of iron on the bottom of the gyro. That means that the CG of the gyro is below the pivot on the gimbal. As a result, the inertial force of the acceleration causes a couple on the gyro, and, since gyros display this perverse habit of *precession*, the couple results in a right-wing down indication for an AI rotating couterclockwise when viewed from the top (which apparently is the de facto standard for vacuum AIs). Have you ever seen either of these happen on a modern AI?  Have you seen the error that Bruce describes when rolling out of a standard rate

I’ve never noticed, but then, I’m still at a point where if I end up within a couple of degress of ANYTHING when I finish a maneuver (take-off roll, 180deg turn, etc) I’m pretty happy.  :-) a) From the absence of (1) I infer that the normal erection mechanism in a modern gyro is probably designed to work more slowly than in an old brick-sized AH. After all, if gyro mechanisms are getting better, the precession because of mechanical instrument imperfections is likely to require less rapid correction. No technology can eliminate part (1) of acceleration error (unless it cheats by time-averaging the acceleration, and even then there will be some error) because of the equivalence principle (elevators in space ‘n all that) I described before.

The only comment I’d add here is that in all the descriptions I’ve ever read about vacuum gyros, they’ve all indicated the use of "pendulous vanes" as an erecting mechanism.  I suspect that improvements have come in the form of lighter materials, more accurate tolerances, better bearings, etc. – Hide quoted text — Show quoted text -b) If you think about (2) for a minute, you might see a logical flaw. Why on Earth do we *allow* the CG of the gyro to be below the pivot? Why not put a balance weight on the top so that CG is exactly in line with the pivot?  Ken Sykes described to me by email a cunning way of eliminating this effect altogether using a pair of counterrotating gyros. The only deduction I can make is that the designers *wanted* it this way so that the gyro is self-righting when it’s not spinning. After all, when you’ve started the engine, before the gyro has got up to speed, wouldn’t it be better if a straightforward pendulum effect put it in almost the correct attitude to start with? Evidently modern gyros have a better mechanism for doing this (the fast-erect mechanism?), even on vacuum driven gyros and can be perfectly balanced so that an acceleration fore or aft need not cause a bank indication on the AI.

I don’t think I can ever remember climbing into a "rent-a-wreck" and not seeing the HI tilted at a crazy angle – albeit still with brown generally down and blue generally up.  If the center of gravity is below the mounting gimbals, given the quality of the bearings required to prevent significant precession errors due to friction, why doesn’t the gyro right itself after it has spun down? ….<snip….. I hope that clarifies things a little. Julian Scarfe

Back in your court!  :-) Bruce Bateman

Response:

 Julian Scarfe covered most everything very well, but may I add that 2  counter-rotating gyros on the gimbaled platform will cancel any acceler-  ation precessions. The Earths rotational precession is 15deg/hr times the  sine of the latitude. Therefore, the vertical sensor corrector need work  at no more than 15deg/hr. Actually that’s a pretty slow rate, 1/2 the rate  of a clock’s hourhand.  Tallyho !  Alpha Kilo

Response:

Excellent (as usual) analysis, Julian.  I have only one comment….. – Hide quoted text — Show quoted text – DM Any instrument technical gurus out there? I’m not an instrument guru, but I may be able to field some of the many good questions that Dave asks.  Can I change the order a little? ….<snip……. DM  If so, is it DM possible to "fool" the instrument by a sustained co-ordinated turn? My DM suspicion is that it might begin to "erect" itself to align with the DM new apparent "gravitational" direction. You might have thought so, but remember that the gyro *does* know what’s a rotating frame and what’s not.  So in a sustained co-ordinated turn, the gyro "knows" that the apparent vertical is revolving in space, and the average correction that it makes is towards the average Earth vertical. If you could sustain a *linear* acceleration for long enough, you could, in theory, fool it. However, that depends on the timescale over which the correction is applied being much longer than the period of the turn.  If you were to use a fast erect mechanism in coordinated turn, you might get it confused enough for long enough to think that the vertical had moved, which is why that’s only for unaccelerated conditions. ….<snip……

I was taught in my instrument training that when rolling out of a 180deg standard rate co-ordinated turn, that I should expect to see an error in the HI of several degrees in both pitch and bank.  I though this was supposed to be due this exact effect – the gyro trying to correct itself to an "incorrect" down. ???? Bruce Bateman

Response:

Any instrument technical gurus out there? I would like to know how a modern AI compensates for the actual vs the gyroscopic horizen.  Any limitation in the instrument would be very usefull indeed.  Does it use any form of pendulum to adjust its gyros to the aircraft attitude?  For instance:  If I start up in a taildragger, I am obviously in a very nose-up attitude.  Modern AIs have no manual erection knob, but nevertheless seem to indicate the correct attitude. The old AI’s need to be manually erected after establishing straight & level. How do modern AI’s do this automagically? If I fly several hours on a N/S heading, the earth has rotated many degrees.  I would expect a free-floating gyroscope to precess and indicate an increasing amount of bank.  But the modern AI does not. How is this achieved? Is there some sort of slow-acting pendulum in a modern AI?  If so, is it possible to "fool" the instrument by a sustained co-ordinated turn? My suspicion is that it might begin to "erect" itself to align with the new apparent "gravitational" direction.  I have not conducted any extensive tests, ‘cos I’m hoping that someone already knows all the answers  I read somewhere that it is impossible to distiguish between the force of accelleration and the force of gravity without any external reference.  But the AI is (apparently) able to achieve this?? If I do aerobatics, including loops and rolls, my modern AI still appears to read correctly afterwards.  Are there any limitations?  Is it possible to "topple" a modern AI?  If left uncaged, an old-fashioned AI also fitted in my aircraft is performing rapid gyrations after the same manoevours untill I manually erect it.  Is there then an essential design difference between the two?  If I accidentally entered a spin in IMC, but recovered OK (whew!) can I still use my AI afterwards, or should I fly on limited panel in case the AI is fouled up?  How about an extended "hold"? I have questioned CFIs and qualified mechanics on the above, but have received contradictory advice, and nothing that sounds authorotative. Dave Mould Ordinary PPL

Response:

I think it has to do with the limits of motion of the gyro cage.  The older gyros had stops that limited the travel of the gimbels.  If you hit the stops, it forced the gyro to a new position in space.  This caused the gyro to tumble and then it had to be erected or caged and restarted in the new position.  The new gyros do not have these stops. The gimbals are completely free and the gyro is "non tumbling" and does not require the caging and manual erection to straighted it out after it tumbles.  Many of the new non tumbling gyros can get pretty confused after some aerobatic maneuvers though.  It can take them awhile to damp out and stop their oscillation after you roll them over. John – Hide quoted text — Show quoted text – Any instrument technical gurus out there? I would like to know how a modern AI compensates for the actual vs the gyroscopic horizen.  Any limitation in the instrument would be very usefull indeed.  Does it use any form of pendulum to adjust its gyros to the aircraft attitude?  For instance:  If I start up in a taildragger, I am obviously in a very nose-up attitude.  Modern AIs have no manual erection knob, but nevertheless seem to indicate the correct attitude. The old AI’s need to be manually erected after establishing straight & level. How do modern AI’s do this automagically? If I fly several hours on a N/S heading, the earth has rotated many degrees.  I would expect a free-floating gyroscope to precess and indicate an increasing amount of bank.  But the modern AI does not. How is this achieved? Is there some sort of slow-acting pendulum in a modern AI?  If so, is it possible to "fool" the instrument by a sustained co-ordinated turn? My suspicion is that it might begin to "erect" itself to align with the new apparent "gravitational" direction.  I have not conducted any extensive tests, ‘cos I’m hoping that someone already knows all the answers  I read somewhere that it is impossible to distiguish between the force of accelleration and the force of gravity without any external reference.  But the AI is (apparently) able to achieve this?? If I do aerobatics, including loops and rolls, my modern AI still appears to read correctly afterwards.  Are there any limitations?  Is it possible to "topple" a modern AI?  If left uncaged, an old-fashioned AI also fitted in my aircraft is performing rapid gyrations after the same manoevours untill I manually erect it.     Is there then an essential design difference between the two?  If I accidentally entered a spin in IMC, but recovered OK (whew!) can I still use my AI afterwards, or should I fly on limited panel in case the AI is fouled up?  How about an extended "hold"? I have questioned CFIs and qualified mechanics on the above, but have received contradictory advice, and nothing that sounds authorotative. Dave Mould Ordinary PPL

Response:

Help save NH airstrip

Question:

Walt, I’m very sympathetic to your issues, as I am also the operator of an aircraft facility within New Hampshire (NH71), that, and we "Walt"s have to stick together! First, you neglect to indicate the absence or presence of commercial activity at your air-strip.  If you are totally non-commercial, the issue shouldn’t be a lot different than a tennis court in the back yard. My seaplane base, for example, is on the sectional as (PVT), and the applications clearly states "…no commercial service of any kind…".  Was your airport clearly registered with the FAA, with an identifier, and on the sectional…then you may well have issue with the local authorities on the ability to shut it down.  The AOPA should be able to provide references to a good aviation issues atty. Much as we aviation types abhor litigation, may I suggest you file suit against the offending pilot for "loss of value" to your property.  These funds may well be the support for your legal redress. Talk to me by E-mail…at least keep me posted.

Response:

I’ve posted this to both rec.aviation.homebuilt and rec.aviation.owning- my apologies to those who read both. I’m looking for some help and advice to get my private strip in Brentwood, NH reopened.  All was fine until an uninvited pilot dropped his Warrior in my neighbor’s yard during an aborted landing 2 years ago.  For the full story, drop me a line and I’ll e-mail the saga.           The short version is that the neighbor hired a lawyer and complained to the town and I received a cease and desist on a zoning technicality.  We tried to change the zoning twice- and lost both times, first by 27 votes and then by 90+ (they had much more money and time than we did).  I will mention they rode in my plane prior to the accident and thought it was great.         Despite their victory at the polls, they have put their house on the market, but at $525K, it hasn’t seen much action.  I’ve waited a year for it to sell, but it looks like they aren’t in a big hurry to leave.  I’m now looking for a new tact, or a revision of the old to reclaim my right to fly off my own land. This is what I have done: 1) Contact AOPA: "We’re sorry but we can’t get involved in individual problems.         We have to concentrate on the large airport closings." 2) AOPA Legal Services Plan Attorney: "You had better notify your homeowner’s         insurance carrier in case the pilot sues you." 3) Attempt to change town Zoning ordinance:         a) The first attempt was not well written, and lost by 27 votes.         b) The second attempt was met with a well-organized and well-funded         opposition, who used several mailings with effective scare tactics and         misinformation.  Despite the RECOMMENDATION by the town Planning Board,         the ordinance was more soundly defeated, even though we received more         votes than the first time. 4) Contact the State Aeronautics Board: "There’s not much we can do to help-         we need some way, possibly through State legislation, to end this         discrimination against aircraft" Unfortunately, we’re at a loss as to what to do.  We lost the use of our dream airstrip because of the bad judgement of another pilot.  I’m looking for other owners or pilots from NH interested in a campaign to protect the rights of landowners- can we lobby the legislature to permit private, non-commercial airstrips?  Does someone know a GOOD zoning and aviation attorney?  (I am reluctant, however, to spend my children’s college tuition on a such a risky attempt.) We pilots need to get more active in protecting our priviledge to fly.  Public hysteria, fed by the media, is constantly restricting our hobby (and profession for some).  Help!    /      Walt Porter       /         *             | | (Obviously not the opinion of H-P!)

Response: