John Bouyea wrote: > >>During my entire flight today, I had to hold forward pressure on the > stick. ...That leaves the trim tab "neutral position" is set > incorrectly or it's just too darn small...Can anyone comment on facing > & curing the same problem in their KR?<< The first time I flew N891JF, the plane pulled down and right. The elevator trim tab cable housing had broken so I had "fixed" it inline with the elevator with a pair of #2 screws and four large-diameter washers. Once I got to altitude I let go of the stick and it nose dived down and to the right, in a pretty dramatic fashion. Previously, it had been flown with "full up" trim on the tab, and once I fixed it straight, the plane behaved as it would without the tab. Before I flew it again, I added a trim tab to both elevator and rudder. I took a piece of .020" 2024 aluminum and cut out a 6" x 2.5" piece and bent it so that I would have a 1.5" trim tab, leaving an inch to fasten it to the elevator. I then drilled two holes through the trailing edge of the elevator (on the other side from the movable tab) and secured the tab to the bottom with two #4 screws and large-diameter washers.
My tab is bent at about 35 degrees, but once fastened to the bottom, it is effectively a 25 degree tab. It now flies hands off straight ahead and level, and now that I've replaced the nyrod cable from servo to elevator, the trim works great and is only used in a narrow band around "stick neutral". In your case, you would probably want to mount it on top of the elevator instead so the forces aren't trying to rip the screws out so badly, and it wouldn't need quite so much angle on it. See http://www.n56ml.com/n891jf/trim_tab.jpg for details. This can be done in twenty minutes...nothing like reworking the horizontal stabilizer angle, and the difference in speed would be unmeasurable, in my guesstimation. Having said all this, rechecking weight and balance calculations might be prudent! I flew to Corvair College in Barnwell S.C. Friday and returned today. It was good to see Joe, Dan, Chris, and other KR builders there, and lots of folks building and testing their Corvair engines under the eye of William Wynne and other experienced engine builders. And it's nice to have a time machine that allows me to fly 320 miles in 2 hours and 15 minutes! I burned 3.3 gph @145 mph at 11,500' in the cruise phase on the way there, and the same on the way back at 10,500'...44 mpg. 145 mph is about all it'll do at those altitudes...it was wide open, although I didn't have a spinner on it...I'm using it as a mold to make a fiberglass one. I've really got to hook a heater up in that thing... Mark Langford ML at N56ML.com http://www.n56ml.com
