Guys. I intended to stay out of this discussion, but as it is right now, I might add my experience.
I bought my Coupe with an old style single fork nose gear. While I did not experience many problems with that installation, I was shocked about the price of one 5.00-4 tire and since my by then wrongly rigged nose gear did drag the tire a bit , I needed a tire ones every annual. Too expensive I thought and invested in a single fork nose gear that would allow for a 5.00X5 installation. (Yes they do exist) While changing the gear and tires I noticed that both were extending the nose gear by 1 inch each - the 5.00x4 tire is just a smaller tire, despite the number. Now the nose was up, the tail down and the plane did exactly what the "tribal knowledge" predicted. It kept flying longer, means when on the ground it kept developing more lift than usual. That lead to some wild landings in cross winds and I decided that the spacers needed to go in. Also an Ercoupe with a drooping tail looks like a sad bird. The spacers lifted the tail enough that it did not look like a tail dragger anymore and the landing characteristics had been partially restored. What I need though is the shorter taxi spring. But one needs a part number for that and I am also having an Electrol gear. According to Univair, there are almost no parts available for that gear. However. I know that one can land the coupe even with a drooping tail successfully when you apply forward pressure to the yoke . That way the tail will be lifted and the nose tire be pressed firmly to the ground. Makes for some extra abrasion, but better this than veering off runway. It lands much easier with a tail high attitude in a strong cross wind though. Hartmut ----- Original Message ----- From: WILLIAM BIGGS To: [EMAIL PROTECTED] ; [email protected] Sent: Wednesday, May 02, 2007 7:12 PM Subject: RE: [ercoupe-tech] Re: Landing gear spacers approval Here is another thought. The "optimum tail height" is achieved with the plane empty. The plane rarely flies empty. The minute you add a pilot the tail "droops". What if there are two large occupants? Where is the gain? Is there an acceptable "window" for the static tail height? Does load effect the landing characteristics? This is why I wonder about the "tribal knowledge" thing Bill ---------------------------------------------------------------------------- From: "Ed Burkhead" <[EMAIL PROTECTED]> Reply-To: <[EMAIL PROTECTED]> To: "'WILLIAM BIGGS'" <[EMAIL PROTECTED]>,"et" <[email protected]> Subject: RE: [ercoupe-tech] Re: Landing gear spacers approval Date: Wed, 2 May 2007 11:16:04 -0500 Bill Biggs wrote: > Am I missing something? > > The spacers have no effect on the EXTENDED length of the gear. > The plane first touches with the gear extended and the "castoring > effect" takes place immediately. Then (unless you greased it on) > the donut-belvilles compress. At best the plane (oleo-donut) is in > the "level position" for only an instant somewhere in there. Bill, Yep, you did miss something. We so often concentrate on the moment of touchdown - but the bad behavior that comes from a droopy tail mostly occurs after the castoring is done. When a Coupe is rolling along the runway, near touchdown speed (or even above "stall" or minimum flying speed), the plane should roll along nicely and stably on the ground. Coupes can do this, even at speeds well above minimum flying speed because the on-the-ground attitude is level and the wings are at a very low angle of attack. But, when the tail is low on the ground, the wings are at an excessive angle of attack. Thus, there's excessive lift for a plane rolling on the ground. Worse, because of dihedral, the upwind wing is at an even higher angle of attack. The result of a low on-the-ground tail is that the on-the-ground behavior is not stable, not acceptable and can even be dangerous. As I said yesterday, I used to hear stories about Coupes landing in strong crosswinds that had the upwind wing lift so high people were afraid they'd flip or they'd fear the other wingtip would touch (almost impossible) and their upwind main gear would lift and it'd be almost impossible to steer and they'd veer off the runway, maybe into other planes or runway lights or ditches or fences! These are things that occur after the touchdown, during the rollout (and sometimes, to a lesser extent, during the takeoff roll) in strong crosswind conditions. Coupes with the tail at the correct height, which thus have the plane level in pitch and thus have the wings at the designed low angle of attack behave well on the ground even in crosswinds that have grounded most other planes. I hope this is a better explanation. Does it seem clear, now? Ed Burkhead http://edburkhead.com ed -at- edburkhead???.com (change -at- to @ and remove "???") ------------------------------------------------------------------------------ Download Messenger. Join the i'm Initiative. Help make a difference today.
