"Heavy" wing....rigging

With the recent discussion about rigging regarding how to correct for a roll tendency I spent some time thinking about how often this comes up with phase 1 testing.

There is no empirical data that I am aware of; but, it seems that more often than not the roll tendency is to the left (left wing heavy).

If any normal distribution of builder measurement/rigging variation would occur, it would seem that we could expect half the time left roll off and half time right rolloff, while most would experience no tendency to roll one side or the other.

I'd like to initiate a survey to see if there is a bias towards one side or the other. For the purpose of the survey, it would probably be good to stick with similar design Kitfoxes......including the SS, series 7, 6 and 5.

Sincerely,

Dave S
KF 7 Trigear
912ULS Warp Drive

our ss7 was left wing heavy, adjusted on the right wing to take lift out without a lot of effect. went to the left wing and added 1 turn of lift and that fixed it. each airplane is different so what works on one may not work on another. if you do need to make some adjustments it helps if you write down each adjustment you make so you will know if you are going the right way or you need to take out the last adjustment and add more going that way. saves a lot of time:o

My vintage 1993 Model IV had a heavy left wing. My vintage 1992 (newly completed) Model IV has a heavy left wing. I have also tried a couple of adjustments to the right wing with little effect.

When I was researching the design of my engine mount, I discovered that the Kitfox Rotax mount doesn't have thrust offset. It is Zero vertically and Zero horizontally. I suspect this might be the issue. Since the two stroke propellers turn the other way, it would be confirmation of that if they in fact report a heavy right wing.

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I suspect this might be the issue. Since the two stroke propellers turn the other way, it would be confirmation of that if they in fact report a heavy right wing.

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Yes. My model 4 two stroke left hand prop has a slight roll to the right hands and feet off. The ball is out to the left about a 1/4 ball. I checked and rechecked rigging of wings and horizontal and can find nothing needing adjusting. It takes an oh so light pressure of left rudder to center the ball and fly straight hands off.

I also checked engine thrust line and near as can tell it is straight ahead. Cub guys always tell me I should bend the vertical fin to correct it.

I suspect the roll is caused by spiraling slip stream of the prop hitting the right side of the vertical tail. I'm pretty sure either one of the common fixes, ie. a half turn or so on a wing strut or a rudder trim tab would fix it but I guess it doesn't bother me enough to do it.

With my HKS the prop turns opposite the 912's, to the left. However, my heavy wing is on the left as well. :confused: Ball is slightly swung to the right.

It's the same whether I have a passenger or not too.

All bets are off until you get that ball centered with wings level. First things first then on to hands-off and whether you still have a heavy wing.

jon

Sorry, should have elaborated. This was noted on my first few flights before any significant adjustments. I totally agree, and even with the ball centered and rudder trimmed I had a heavy left wing... Another thing is this was on my first few flights. Heaviness is more or less taken out now by adjustment of strut end ball links.

my best way to describe the fix for the heavy wing. That is why there is an adjustment.