Hi Jim: I have used the "toy" altimeters, watch altimeters, and the new very reliable Telario talk and Sky melody units. The margin of error on the very good 300-400 dollar Variometer /altimeters is only a few feet, if that. If you calibrate these units daily from your field, the error is not very much. We have on numerous occasions over the years, at Elmira and other sites, confirmed altitude with full scale aircraft. We have also checked one type against another. The 30 dollar cheap ones are really worthless, I agree. There are units available today that you can use with an auto pilot and actually auto land your aircraft. Get out your wallet. But for $1400.00 you get the auto pilot too, plus GPS. 14 oz and it will fit in a 40 size trainer!
There have been all sorts of wild claims about visibility at extreme altitudes. The bottom line, or lines as the case may be, is that atmospheric conditions, relative contrast(what part of the sky you are flying in), are the biggest variables. Some days you can see a 5 meter scale ship easily at 3500 agl, other days and times of the day you are lucky to see it at 2000 agl. The slant effect is very applicable as you indicate. Any plane unless you are flying a 1/2 scale Fox or Swift (wide chord, huge area) will be on average, difficult to see over 2000. Your son has great eyes to see a two meter at even 1800'. Remember it is the chord that makes a plane most visible, not the span. Do the 8'long 2" wide strip vs a 4' wide x 8'long sheet of plywood test at 600 feet. The highest (confirmed by full scale aircraft) altitude with a model that I have personally witnessed was Theo Arnold flying at Elmira. He was flying a 5.3 meter Duo Discus (>10" root chord). A full scale glider pilot reported him at over 4200' AGL. Theo does have Chuck Yeager vision I might add, and conditions were perfect. I looked up where he was gazing and could not acquire the model with my 20/20 eyes. Finally I saw it glinting every so often in the sun, only the fuselage was visible to my eyes. The wings would appear and disappear as he circled. I asked Theo how he could control his model at such extreme altitude. He dryly said, the plane is either going left, or it is going right. You have to know Theo to appreciate his comment... John Derstine Endless Mountain Models http://www.scalesoaring.net email: [EMAIL PROTECTED] -----Original Message----- From: JIM EALY [mailto:[EMAIL PROTECTED] Sent: Monday, October 06, 2003 8:58 AM Cc: [EMAIL PROTECTED] Subject: Re: [RCSE] How High? Hello guys: During the early 80's I was involved with AMA altitude attempts. My son did set a AMA 2-M record (about 1800 ft) which held up for about 10 years - and then was only broken by a very small margin. We used triangulation with high quality serveying instuments. ***The only way that I will believe has any merit!*** RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
