> The "Stall Speed" given on p. 10 of the 415-E & G Manual > is 60 mph (power off, with "up" elevator limited to 20º). > This is verified as being at 1400 lbs. gross weight on p. 11.
Bill, The term “stall speed” seems to get used with some fluidity in Ercoupe discussions and documents as minimum flying speed (with a particular elevator limit) is not quite the same as the wing’s real stall speed. Heck, even the wing’s stall speed is spread out over a range as it stalls at the root and the stalled zone moves progressively outward, developing more and more turbulence which causes burble (and stall warning) over the tail and interferes with your ability to push the tail further downward. I think you’ll find that the 60-65 mph “stall speed” on an E or later model is what you get when the elevator hits the pre-loaded-spring low- speed warning cushion. (Query: did all split elevator Coupes have the low speed warning cushion or, if not, when was it introduced and/or dropped?) When you pull through, against the resistance of that spring, you pull the elevator up to 20˚ and the touchdown speed goes down to about the same as the 415-C and 415-CD. Hartmut reports seeing airspeed numbers in the 30-38 mph range when he’s pulled through the cushion to the elevator 20˚ up travel position. I suspect those extreme numbers reflect airspeed indicator deviations due to pitot static tube installation location. That deviation is designed to be zero at 100 mph but increases slowly the farther you get from 100 mph. I’d bet a penny, maybe even a dime, that doing a triangular GPS vs. airspeed calibration at that speed would show true speeds closer to 48-50 or so. I don’t think the wing, airframe and weight are even theoretically consistent with a stall speed below about 48 mph. As an example, with a new ASI, in a plane with 9˚ elevator up travel, my ASI reported an airspeed of about 50 at touchdown. That airspeed calibrated within .25 mph at 100 mph. Having said that, the ASI numbers for minimum flying speed, stall, etc., should be consistent in that plane from day to day and, once known, should be a reliable indicator of your aerodynamic condition. I’ve only got about 10 hours in a split elevator E model but my observations (and I was experimenting with it quite deliberately) matched this. Any further data or observations are welcome. Ed
