William.
I read in my FAA approved flight Manual 56 miles true air speed as the lowest power off speed for 415-E and G models. This is meant for a gross weight of 1400 pounds. A 13 degree up elevator should get you down to 60 Miles in any Coupe. Maybe less even. But not much. At least this is what the books are saying. My split elevator stop holds the elevator 13 degrees up and when I let the plane settle to the speed it gives me then, I fly 60 -65 indicated. That is the published approach speed for a Coupe. So all would be good on final, but I would not be able to flare if I would not be able to pull over the spring stop into a region where I can get still the nose up. This is what the 20 degree up elevator gives you. You can pull wayy beyond the limitations of the earlier models. Makes for better, shorter landings. Now imagine what a 9 degree elevator stop leaves you when you sail engine off with 60 Miles or less to the runway. Little or nothing. Now you need to add power to get the prop wash push down the tail. That seems not natural and requires planning. Airmanship. Not everyone is able to do so. These folks will have a rather hard landing and learn to come in fast. Coming in fast is mostly ok, but when you have a short runway or other not so favorable conditions, you may want to come in slower. With the split elevator, you can do that. It is not about the stall speed. The stall speed is determined by wing load. It is about being able to have elevator travel left beyond the slow speed cushion. When I pull the elevator full back, power off, the speed go down to 38, then the plane breaks. With power on and just me in the plane and almost empty tanks, I see speeds around 30 until the stall breaks. You can not get into these low speeds with a 9 degree elevator limitation. The spring stop that comes with the split elevator is there so you don't get that low in speed inadvertently. The split elevator makes the Ercoupe more like the other airplanes that you can stall if you want to, thus flare nicely in ground effect at low speed, but it still follows the safe design philosophy that you shall not be able to stall the plane in a normal flight regime. So you keep having an elevator stop at 13 degrees, and then not. Your choice how to fly it. Hartmut To: [email protected] From: [email protected] Date: Wed, 17 Mar 2010 16:48:48 -0500 Subject: Re: [ercoupe-tech] Re: split elevator Ed, The "Stall Speed" given as Item #1, p. 10 of the 415-D Manual is 58 mph (power off, with "up" elevator limited to 9º). This is presumed as being at 1400 lbs. gross weight because data in Items 2, 3 and 4 are "at 1400 lbs., gross weight". on this and p. 11. 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. Since the 415-D does not have the "split elevator" and later models do, I would presume that substitution of the "split elevator" reduces "minimum speed" (or touchdown speed) at any given weight on comparable airframes by (a mere) 2 mph. Two strictly personal observations: 1. I prefer the "look" of the earlier elevator (with a trim tab) 2. I HATE change in yoke "feel" with the "low speed warning cushion" spring (and associated mental adjustment in the flare) Any "cost to benefit" ratio calculated on above 2 mph difference would make the "goodness" of this conversion all but impossible to justify. What am I missing, here? Regards, William R. Bayne .____|-(o)-|____. (Copyright 2010) -- On Mar 17, 2010, at 06:21, Ed Burkhead wrote: I don’t think there are enough no-longer-needed split elevators available to meet the demand. Now, if someone were to set up an Ercoupe elevator conversion “factory” with PMA authorization and convert a bunch of elevators, we could improve the entire fleet. Or, would it be (under current regulations) that each owner would “fabricate” a replacement part him/herself, using a skilled mechanic as his/her assistant? But, then, demand also depends on cost. Back before you all caught on to the goodness of the split elevator idea, I wanted one but couldn’t justify the cost to benefit ratio. Ed _________________________________________________________________ Hotmail: Powerful Free email with security by Microsoft. https://signup.live.com/signup.aspx?id=60969
