Model 2 adverse yaw?

[herman pahls]

I have hundreds of hours on my model 2 Kitfox.
The first 14 years with a Rotax 532 (C.G. was near the rear of envelope).
The last 2 years with a Jabiru 2200 (C.G is near the front of the envelope).
I like flying behind the Jabiru engine but find that in windy and gusty conditions coordinated turns are almost impossible and therefore dangerous. The 532 seemed to have much less adverse yaw (much easier to keep the ball centered). I am tempted to reinstall the 532 to determine if this is all in my head.
I added 4 pounds to the tail to move the CG more to the middle and still do not like how it flys.
I started flying a Piper Pacer 3 years ago and coodinated turns are a non issue.
When I found this model 2 kit in a barn 17 years ago I was advised to hold out for a model 4 because of differential aileron action on the improved model 4 controls.
I would like opinions from the undercambered Avid and kitfox flyers about what I am experienceing and is there a fix.
Are the model 4's handling vastly improved?
Thanks Herman Pahls Oregon 541 404 6464

[SkySteve]

Herman,
I fly a model I with a 912, 80 HP. I cut the vertical off, replaced it with a model IV vertical & rudder. Huge difference in a good way.

[rogerh12]

My model 2 with a 582 engine had horrible adverse yaw. People seem surpised when I say that, but I'm glad someone agrees with me. Maybe it was because of the heavier engine, I don't know. All I know is it was bad.
Now I have a model 4, for the reasons you mentioned before (but it's now flying yet)

Roger

[jiott]

I believe the Model 2 did not have aileron/flaperon differential. The differential (less down than up travel) makes a big difference in reducing adverse yaw because the drag on the outside wing is reduced in comparison to the inside wing. I don't know, but maybe the Model 2 flaperon linkage could be modified to provide differential.

Jim

[Av8r3400]

I believe the I-III flapperon mixer is virtually a direct copy of the Avid Flyer units. There is a modified part offered by Airdale that adds an amount of 'differential' to the aileron control. The part is something like F-7a or similar. Brett would know off the top of his head. This may help your situation.

Additionally, is there built in vertical stabilizer offset in the early Kitfoxes? If so, wouldn't this be in the opposite direction when going from a two stroke to a four stroke Jabaru (Prop rotation direction). Could this be part of your problem?

[toekh]

I have about 100 hours in my Kitfox 2 behind Jabiru. There is no weight added when they did the conversion from Rotax 532 to the Jabiru engine. The start battery is placed about 3 feet behind the seat. I have wing tanks.
I have very little adverse yaw, almost none. When some of my buddies try to fly my plane, almost everyone of them overdo the rudder movement. In the other hand I have to push right rudder a little bit constant to fly in a straight course.
One of my friends formerly owned an Avid Flyer, similar to my plane. He also had a Jabiru engine in his plane. He was able to trim his aircraft flying hands off in every plan and his method was changing the engine angel with some shims in the engine mount.
Must say that I love the Jabiru engine, even if it takes a few more feet’s to go off the ground compared to a Rotax 532/582. In the other hand it sounds like a real airplane and burn 2-2,5 gph at 55 kt. And it looks like a jewel

[dholly]

I believe the I-III flapperon mixer is virtually a direct copy of the Avid Flyer units. There is a modified part offered by Airdale that adds an amount of 'differential' to the aileron control. The part is something like F-7a or similar. Brett would know off the top of his head. This may help your situation.

Looking at my KF-III mixer, I do not believe these parts are directly interchangeable. The Avid mixer differential mod consisted of:

- replacing (2) existing p/n F7 bellcranks with (2) new p/n F7a bellcranks (the new bellcranks have noticeably more curve, as seen in the attached comparison).

- replacing (2) p/n F37 straight ~2-1/2" long threaded-end rods with (2) new p/n F37a bent ~5" long threaded-end tube rods.

I've also attached a pic of the (unpainted) F7a and F37a modification parts installed in my old Mk-IV mixer.