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Bill, This has nothing to do with getting the angle of incidence of the wing, as controlled by the elevator, correct for takeoff. The Coupe was very thoughtfully designed to have as few bad behaviors as possible. One of the choices was that when rolling on the ground, the wing should be at such a low angle of attack it as nearly zero lift. It is not quite zero angle of attack but it should have a very low angle of attack. When on the ground, this is governed by the geometry of the landing gear. The original design, with the single fork nose gear, has the tail at 75” above the tarmac and that gives the wing angle of attack Fred Weick decided was best on the ground. This dumps lift so the plane doesn’t raise an up-wind wing upon touch-town or get skittish (trying to blow sideways) on liftoff. This makes Coupes very well behaved in a crosswind. If you install the double-fork nose gear, that raises the nose about 1.5 inches. In theory, you need to raise the plane at the main gear by 1.5 inches to bring the plane back to the same on-the-ground angle of attack. This would bring the tail, I’d compute, to 76.5 inches. (Sorry I can’t quote the exact leveling from the service manual – my books are buried in a box and I’ve got an appointment to fix a friend’s computer in less than an hour.) I kind of remember the spec as being level as measured on the windowsills. Leveling fore and aft is normally specified by tail height but when you change the length of the nose gear that measurement would logically change. In practice, if your tail is within a couple of inches of designed height, the take-off / touché-down behavior is pretty good. On a single fork nose gear plane, if my tail were 73 inches or higher, I’d be satisfied. On a double-fork nose gear plane, I’d want my tail to be 74.5 – 76.5 inches and I’d probably settle for 75” quite happily. Ed Burkhead http://edburkhead.home.insightbb.com/ [EMAIL PROTECTED] -----Original Message----- From: WILLIAM BIGGS [mailto:[EMAIL PROTECTED] Sent: Saturday, August 17, 2002 12:54 PM To: [EMAIL PROTECTED] Cc: floridaecoup Subject: Re: [COUPERS-FLYIN] Take off I am new to Ercoupes but I keep hearing the 72 to 75 inches mentioned. What is trying to be accomplished is to get the angle of incidence of the wing, as controlled by the elevator, correct for takeoff is that right? I am in the process of changing my nosegear to the 500-5, double fork. I have heard that this raises the nose, thus lowers the tail, so we put spacers in the mains. Does anyone know the actual angle desired in relationship to the leveling point? (the window reinforcing rails) Bill Biggs ----- Original Message ----- From: Ed Burkhead Sent: Saturday, August 17, 2002 10:31 AM To: [EMAIL PROTECTED] Cc: Coupe-List (E-mail) Subject: RE: [COUPERS-FLYIN] Take off ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- Bless you, Bill. What you’ve done by getting the spacers approved brought tail height on the ground to everyone’s attention. Now-days, the only Coupes I see with a drooping tail are non-EOC members who are also non-list members or people who recently bought their plane from someone in those categories. Though the droopy-tail accidents were mostly fender-benders, over the years and all the planes, I bet you’ve saved a life or three. Thanks for continuing to follow-through on the formula so people can get more precise adjustment of the tail-height and handle non-standard situations and gear configurations. Ed Burkhead http://edburkhead.home.insightbb.com/ [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Saturday, August 17, 2002 10:04 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Cc: [email protected] Subject: Re: [COUPERS-FLYIN] Take off Ed A while back we talked about a formula to raise the tail. It will give you the exact size of the spacer to correct any deviation in tail height. I have passed it around to many FAA guys and they can find no problem with it. Coupe Capers should come out with my article on it soon. Everything should be detailed. Of course, I did not dwell on all of the aspects of aerodamics involved because you have covered that very well in your articles. I said just enough to want you to give it a try if you have a drooping tail. I do have copies available for anyone for an sase. Bill Coons FAA Safety Counselor Gt. Lakes Region. DuPage FSDO ================================================================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm ====================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm ====================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm
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