Model 2 adverse yaw?

[C5Engineer]

Herman try Pulling on some flap at cruise speed. You will get a nose down moment but see if your roll forces lighten up. The more positive ( trailing edge up) on your dlapweons the stiffer your roll rate will be. This is what I do when I am yanking and banking down low. It's out of trim but when your maneuvering you won't really notice it.

[herman pahls]

Joey
My prop is off getting repitched so I will have to wait to experiment with the roll pressure on my Kitfox.
Dave (FOXDB) from Idaho reported to me that by pulling part way up on the flap handle on his model 1 the aileron control pressure became very light in comparison to when the lever is all the way to the floor.
Joey, I am curious how you knew this was the problem.
I assume having the flapperons up too high on the trailing edge would act like a spoiler and decrease lift and increase stall speed.

I have room to move the leading edge of the horizontal stab down another 1/2 inch.
Hopefully that will be enough trim so the flaperons can return to the position that has minimal stick pressure in roll.
Hopefully repostioning the flapperons will make ball centered -coodinated turns like they were with the 532.

Does anyone know if these early Avids or Kitfoxes have offset vertical stabs that would counter act for P-factor?
All those years with the 532 I never considered a rudder trim tab.
The Jabiru prop rotates opposite from the 532 and I have a 6" high by 2" long rudder trim tab bent at 40 degrees to reduce right rudder pedal pressure.

I want to thank those who offered suggestions and shared experiences.
Herman

[C5Engineer]

Herman I learned this theory by experimenting. I found that if I rigged my flaperons to where I had nose up trim using flaps the roll was far too stiff. I experimented until it would just maintain level flight in cruise. The roll is still a little stiff but in cruise it's no big deal. Like I said if I want to go play I just pull like 1/4" on the handle and it greatly lightens the roll forces but then it wants to pitch nose down. I'm in the process of adding some VGs to my tail which is suppose to help this dilemma. My Avid manual states that with some positive relflex it will increase cruise speed. I think I ended up with right around 5 degrees. This is with the mixer mod like what is posted in this thread..max in the directions with that mod was 6. Without the mod the manual stated to rig them at 2-3 degrees I think.

I don't' know about the Kitfox but the early AVIDS did have a tail offset to compensate for the Right turning Rotax 2 stroke. Your not the first person to have issues going from a two stroke to a 4 stroke. You can probably fix this with some shims on the motor mount. If not I made a tab with a scrap piece of aluminum and I stuck it to the rudder with some 3M double sided tape and rattle canned it to match my paint. Took me all of 30 minutes to make and works great.

[skelly]

Hi,

I know that this is an old thread but I wondered if anyone had a solution for making a differential flapperon action for the Mk2 Kitfox.

Any ideas ?

Cheers,
Skelly.

[avidflyer]

A few guys have changed out the mixer controls to the Kitfox 4 style. But it's a lot easier to have your slip skid ball in a good spot to see it and use it till your butt tells you what you need to do. Adverse yaw isn't that bad if you use your feet. JImChuk

[av8rps]

The early Avids for sure had the vertical fin offset. When they originally had the Cuyuna engine in them, and then later changed to the Rotax 2 stroke you were told to remove the offset and reweld it centered on the fuselage. I've flown a lot of Avids and Kitfoxes in my life and have to say that flying the early ones taught me how to use my feet better than any airplane I've ever been in (I learned how to fly in a J3 Cub).

As the models changed and improved / evolved they became a bit more stable in yaw, but overall might still appear a bit "twitchy" and unstable for your average Cessna or Piper pilot. Few will be able to keep the ball centered until they get a few hours in it (with someone that can teach them what to do and not do). Unfortunately, many will walk away in the first hour thinking these planes fly badly and aren't worth owning. But the ones that stick with it and learn how to adapt their skills to fly the plane correctly will really enjoy the airplane, recognizing its nimble flying qualities and the off the charts fun factor. But that is common with many airplanes that do some things other planes can't. Examples of that I have experience with, a Pitts Special and a Lake amphibian. Both can be demanding to learn, but awesome airplanes once you get past the difficult learning curve.

So I learned to love the adverse yaw as foolish as that may sound. Overall I felt the early Avids and Kitfoxes were more maneuverable because of it, but that is just my opinion. I flew Avids with and without the F7 differential kit and overall didn't think it did much. But again, I had learned to offset the shortcomings of the design by adapting my pilot skills to the airplane, more than thinking I would ever be able to get the airplane to fly more like a Piper or Cessna.

Avids and Kitfoxes are short fuselaged, long winged airplanes (aka High Aspect Ratio). Adverse yaw is inherent in those designs. Over the years Kitfox has improved it some, but it is still there. I own a couple early Avids yet, and a Model 4 Kitfox. Yes, the Kitfox is a bit tamed down compared to the early airplanes, but it is my opinion that if they got rid of all of the things some pilots don't like about the design, they would kill much of the fun that we love about these airplanes. I own a Highlander also, and it is a great flying airplane that feels more like a cross between a Kitfox and a Cub. A bit more conventional feeling you might say. But the Kitfox has a much sportier feeling to me that makes it a bit more fun to fly. So you have to choose your battles...

I personally love all of the various offshoots of the original Avid Flyer design. They all have their pluses or minuses, but in the same family they are all GREAT airplanes that I have never gotten bored with (unlike my experiences with most all the "trainer-like feeling" Cessnas and Pipers).

With that said, the earlier parts of this thread indicated some issues associated with other issues that indicated some flapperon, rigging, W&B, or engine offset issues. That would only make things worse to the point of making some of the known idiosyncrasies of the design potentially intolerable for even the best of pilots. So my comments above are based on airplanes not having any of those issues.