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Old Oct 12, 2003, 10:38 PM
JIMJAM is offline
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Ideas Needed so I can Double Check Plane before 2nd Attempt "crash"


I have a Kavan High wing Fokker WW1 Plane. One its first maiden,as soon as it broke ground it wanted to roll over to the right something bad. I fought it but when I cut power to abort,she rolled over. The motor mount was prebuilt so Im assuming the thrust angle is correct. I had some right rudder added in as all my planes do. Any IDEAS on what would cause a hard roll and uncontrollabilty? CG within range,throws dialed down and everything appears to be straight.
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Old Oct 12, 2003, 10:41 PM
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Maybe there is a warp in your wing. With aileron you could correct it but with rudder...no, you can't. I'd check for warps, and if that isn't it, im outta ideas.
Old Oct 12, 2003, 10:47 PM
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Staring at the wing and nothing really jumps out as being obviously wrong. There is a small landing gear wing but I cant see with its size and slow speed being able to upset the plane that badly. I considered the elevators being at different pitches but they appear to be equal.
Old Oct 12, 2003, 10:51 PM
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Is it possible, that one wing tip could be higher than the other? With how it's set up, it looks kind of easy to offset it. That might contribute to your rolling tendancies.
Old Oct 12, 2003, 11:20 PM
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Also check your lateral balance. A lot of pilots neglect this and trim it out with aileron only to have a plane that rolls at high speeds.
Old Oct 12, 2003, 11:42 PM
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Suspended by a string tapped dead center the rec CG, the plane hangs level. Im going to attempt again with the rudder centered. But what bothers me is that it was less of a yaw problem than a roll. I ruled a stall out cause I let the plane lift off on her own and power is no problem. Then again the entire event probably took less than 2 seconds....
Old Oct 12, 2003, 11:50 PM
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To my bad eyes, it looks like the leading edge at the last third of the left wing is higher that the right wing. If this is the case, it would tend to push the left wing up, causing the right wing to dip. I may be wrong, but it would be worth checking. Of course if the picture shown is a mirrow image then you can forget that.

Peace, and good luck,
LcJ
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Old Oct 13, 2003, 12:06 AM
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PIC ONE
Old Oct 13, 2003, 12:07 AM
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from my past experience with this same problem I did have a warped wing... very tough to see as it was not much, but had a drastic effect never the less....
Old Oct 13, 2003, 12:08 AM
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Pic 2.
Old Oct 13, 2003, 12:18 AM
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Outboard the wing struts, its easy to twist and pull up and flex the wing.
Old Oct 13, 2003, 07:47 AM
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From the frontal view it looks just the opposite, but only very slightly. You probably do have some warp in the wing, but from these picture, it is hard to tell. Have you made any adjustments yet? I hate to say this, but be sure your contols are set correctly. Right stick, rudder move to the right, left stick, rudder moves to the left. From you earlier post, I would think that is correct, but it doesn't hurt to check. Also verify that the back of the tip of the trailing edges are an equal distance for the back middle of the fuselage.

Good Luck,
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Old Oct 13, 2003, 08:28 AM
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Trying erring on a bit nose heavy. If you hit the stall angle of attack and it's tail heavy, it will want to wallow.

Either way, dang handsome little Fokker!
Old Oct 13, 2003, 08:40 AM
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Assuming everything is correct,wing warp, controls,motor mount etc. The only thing I can think of is that even if the plane lifted off, it still could have snap rolled on you.Have you tried a hand launch to see what it does? If two much up elevator is used on take-off it can get airborne before it has sufficent flying speed to substain flight, followed by a snap roll.Just one more thought.Try a hand launch next time with a gentle climb out and see what it does.
Finally, you may still need a little more nose weight , balance level may still be tail heavy for this plane, some of the manufacturers are a little off on there recommended balance point.If you read any of the GWS P-51 threads, we had a learning curve on that airplane to find the best balance point.It really sounds to me that the airplane lifted off to early and snap rolled in.Classic symtoms.
Good Luck, and let us know what you find.
Old Oct 13, 2003, 09:15 AM
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Boy that is a sweet looking plane. The snaproll theory sounds pretty logical to me. I had a similiar problem on one of my scratcho's and it was a result of a very slight wing warp. The one thing I noticed by your picture is that I couldn,t visualy draw a straight line down the center. It could just be a slight angle in the photo, but I figured I'd roughly grid it out to better explain what I was seeing.

Good luck

Kenny..


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