John Savot wrote:
> Hello All, Let's try to put tail height to rest. If the landing > gear is maintained properly, the aircraft has not been bent > and all modifications and alterations were properly approved it > don't matter how tall the tail is. Any opposition? John, Heres where maintenance imperfections slip in. As you say, the landing gear is maintained properly, the aircraft has not been bent and all modifications and alterations were properly approved. The trouble is, that mechanic Joe at County Airport usually doesnt know the importance of level on-the-ground attitude for Coupes. He doesnt know that Coupes dump their lift as they settle to the ground. He doesnt know that dumping the lift is important to a high dihedral aircraft in a strong crosswind where the ailerons are not available to be turned into the wind to dump upwind-wing lift. He doesnt know that its a key part of the Coupes abnormally good crosswind capability. So, Joe looks at the Coupe on the ramp and in the shop and its at the same pitch angle as the Cherokee on the ramp with a drooping tail. Joe may know that when the Cherokee touches down in a strong crosswind, the pilot turns the yoke into the wind so the aileron is up and pins the wing to level. And, Joe doesnt know that the Coupe pilot cant do that. (When my Alon-kit-rudder-pedal Coupe had a drooping tail, I could still do strong cross-wind landings with no problem because I could turn my barn-door aileron way up and dump lift from the upwind wing after touchdown.) No problem for a correctly maintained Coupe, you say. Thats true. A Coupe, correctly maintained so its on-the-ground attitude is level, will have a very small angle of attack and, essentially zero lift. Even the up-wind wing will have such small lift (from the dihedral) that it wont rise up. But Joe, not knowing this, will not think twice about the drooping tail. If the Coupes owner doesnt know either, nothing is ever done. Its not easy to diagnose old rubber donuts from crawling under a Coupe or even taking the gear legs apart. I certainly dont know how. But its a matter of seconds to measure a Coupes tail and see that its below 75 (or 76½ for a double-fork nose gear plane). (A couple of inches divergence from ideal seems to be no big deal. But the more droop, the more effect.) How about if there are mods that were installed by a mechanic who knows airplanes well and signed off by an FAA wienie who knows airplanes well? How about if the owner changes from the single fork nose gear (perfectly good if maintained right) to a double fork because s/he was told thats better or to get rid of shimmy. Or something else is done to the landing gear thats perfectly reasonable for any airplane. But those things change the on-the-ground attitude of the Coupe, hence the tail droops. The mechanic, the AI and the FAA inspector havent got a clue that theyve degraded the crosswind landing characteristics of the Coupe. That was the situation up to about 25 years ago. All the landing gears were maintained properly and all the mods were properly approved. But it did matter how tall the tail was. Lots of Coupes (maybe most) had drooping tails back then. I used to hear stories about Coupes landing in strong crosswinds that had the upwind wing lift so high people were afraid theyd flip or theyd fear the other wingtip would touch (almost impossible) and their upwind main gear would lift and itd be almost impossible to steer and theyd veer off the runway, maybe into other planes or runway lights or ditches or fences! Get the picture? No matter how great the maintenance and mods that are done by ignorant (as-yet-uneducated) people, it does matter how high a Coupes tail is on the ground! Really, John, your comments do have face validity but we have positive experience that its not the case for this situation. This is a special case. Ed Burkhead http://edburkhead.com ed -at- edburkhead???.com (change -at- to @ and remove "???")
