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All these observations are of course only true for a nicely rigged plane to factory specs. Hartmut ----- Original Message ----- From: "Ed Burkhead" <[EMAIL PROTECTED]> To: "Larry Snyder" <[EMAIL PROTECTED]>; "Coupe-Tech" <[email protected]> Sent: Friday, March 04, 2005 9:42 AM Subject: RE: [COUPERS-TECH] Unusual stall behavior > ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- > > > Larry, > > I waited a while to respond to see what other answers were given (and > because I was fairly busy when I first saw your question). > > As designed, the Coupe's wing is designed to stall from the wing root > outward in a fan-shape (hugging the fuselage at the wing-front and > fanning out at the trailing edge). As you get slower yet, there will > bee some stalling of the wing root. area. This burbling of the air-flow > will cause turbulence at the tail, reducing the tail's lift (downward > vector pushing the tail down). The downward pressure on the tail is > limited by elevator up-travel limitations AND will be further limited by > this burbling/turbulent airflow over the tail. > > Here are my observations, based on a 415-D. > > Within certificated gross weight and CG, a no-power stall is a > non-event. It bobbles a bit and keeps on gliding straight ahead. > > AT gross weight and near rearward CG, the more power I added, the more > the slipstream pushed down the tail and the slower became the stall > speed. Similarly, the more power, the less polite became the "stall" > behavior. > > As I neared full power, I got results similar to yours. The stall break > got more pronounced (though it was NEVER a fully developed stall - like > most well-designed planes, I was able to maintain aileron control > throughout the procedure). > > The worst case condition I tried was about 100 rpm below full power, > full up elevator (9?) and FULLY CROSSED CONTROLLS - left-full-rudder and > enough right aileron to keep it going straight! In this condition, I > got a distinct break, loss of climb and it circled slowly to the left. > AS SOON AS I relaxed the controls a bit OR reduced power, I was back in > full control (no left turn). > > I'd bet that a Coupe at 1260 lb. would also do as well with fully > crossed controls. I seem to recall Fred Weick telling me at an Iowa > regional fly-in that the Coupe was certificated as spinproof WITH and > WITHOUT rudder pedals. > > I would not want to predict behavior with 13? of up-travel, 1400 lb. > gross weight and fully crossed controls except that I want to wear a > parachute when flight-testing it. (Some unusual altitude aerobatics can > get you nose-down and picking up speed very fast.) Doing this same test > in a Coupe with rudder interlink and no pedals, I'll go for the ride and > won't worry about the parachute. > > I'd ask you to get out your weight and balance paperwork and do a full > weight and balance calculation for the flight you had the unpleasant > full-power stall test. Please let us know the model, elevator up > travel, gross weight and CG. Considering that you were testing at full > power (maximum down-push of the tail from the slipstream), I'd say your > resulting flight behavior was not out of line. > > Ed Burkhead > http://edburkhead.com/ > ed -at- edburkheadQQQ.com (change -at- and remove the QQQ) > > I know you believe you understand what you think I said, but I am not > sure if you realize that what you heard is not what I meant. (Jim, AKA > Midnight Plowboy) > > > -----Original Message----- > From: Larry Snyder [mailto:[EMAIL PROTECTED] > Sent: Sunday, February 27, 2005 6:50 AM > To: [email protected] > Subject: [COUPERS-TECH] Unusual stall behavior > > ----[Please read http://ercoupers.com/disclaimer.htm before following > any advice in this forum.]---- > > > All, > > I have read in many places that an Ercoupe doesn't stall, it just loses > altitude. I was out with my instructor yesterday and my 415-C had some > odd behavior at slow speeds. > > Under full power, at about 60 mph indicated (or a bit under) the left > wing would just drop, along with the nose. It would quickly recover, > since as soon as the nose dropped it would pick up speed. I had to give > it right aileron to try to level the wings. > > At idle, the behavior was kind of scary - at 50 or 55 the left wing > would drop again, sharply, along with the nose. I was pretty quickly > looking at the ground! I could push the nose down and quickly recover > in about 50 feet, and if I gave it full throttle I could recover with > almost no altitude loss. > > I know now how to handle these situations, but they don't seem like > typical Ercoupe behavior. Could the rudders not be adjusted correctly, > causing the plane to be uncoordinated? I always received a warning > before the stall - my left wing would start to drop off. > > Thanks for any information on why it might behave this way. > > Larry > N99430 > > ======================================================================== > ====== > To leave this forum go to: http://ercoupers.com/lists.htm > Search the archives on http://escribe.com/aviation/coupers-tech/ > > > > > > ========================================================================== == == > To leave this forum go to: http://ercoupers.com/lists.htm > Search the archives on http://escribe.com/aviation/coupers-tech/ > > > > ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers-tech/
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