Kitfox 4 left turning tendencies.

[THRC12]

I have a 92 model Kitfox 4 that I'm currently flying every day possible. It has 80 horse 912 and 3 blade Warp, taper tip. No bad habits at all except for the dreaded left turning tendencies. No issues out of the ordinary anywhere but cruise. 80-85 mph and if you let go of the pedals it will seriously yaw to the left. Wind direction will obviously make it better or worse. I do have a bendable trim tab and it's bent pretty good. Worst yawing is with a quartering tailwind from the left. I have played with it in different wind directions and for the most part it's always there. Should I maybe do a bigger tab, or maybe consider a tick of right thrust in the engine? Tab is about 3x5 and bent probably 35-45 degrees now. Headwind from the right and it's pretty good. Thanks!

[jiott]

That much yaw sounds pretty excessive to me. Have you checked the vertical fin for being out of alignment or bent? If everything else is OK, possibly a bigger bendable trim tab will help; I have a 2x6 tab on my SS7 bent about 30 degrees and it flies straight with feet off pedals.

[THRC12]

It's actually only excessive in the left quartering tailwind. Definitely, absolutely nothing bent. All other conditions it's mainly just a moderate nuisance having to keep a bit on the right rudder. No wind at all and it is just a faint turn. Only in cruise I think I mentioned. Power on stall and it's only a tick of right rudder when slow and pitched up. Never drops a wing in any stall conditions power on or power off.

[aviator79]

The wind direction should not have any affect on this. Steady winds only affect how your airplane moves relative to the ground. Have you checked flaperon rigging?

The few Kitfoxes I have flown are not as statically stable in yaw as a garden-variety Cessna. They require that the pilot use the pedals to keep it coordinated. I understand early models had pretty much neutral yaw stability. This has been improved, but the airplane still has short coupling to the vertical stab and rudder.

[PapuaPilot]

The wind direction should not have any affect on this. Steady winds only affect how your airplane moves relative to the ground.

Have you checked flaperon rigging?


I totally agree with the first statement. Wind doesn't have any affect on this.

Also, you might want to check that the wing's angle of incidence and washout are the same on both sides (as well as flaperon rigging). One thing you can do to check this is fly the plane, center the ball with the wings level. The plane should not turn if it isn't disturbed by gusts or bumps. If it turns then you probably have a wing or flaperon rigging problem.

One more thing, make sure your ball is centered when the plane is level. Otherwise you are chasing the wrong problem. Check this first.

[THRC12]

Not saying it will not fly hands off. Wing rigging and flaoerons are perfectly the same both sides. If wind direction doesn't have any effect on your course, then why course correction? Just asking, because it is Only prominent in specific wind directions. I'm talking in the 10-30 kt range. It's earlier model 4 with smaller rudder. Straight headwind and and it's hands off to very slight. I can put a bigger trim tab no problem, I'm just thinking that by holding right rudder or having a tab do it for me, I'm inducing drag unnecessarily. Thanks!

[THRC12]

I'm going to test a different size trim tab and probably play with the location some.

[PapuaPilot]

I guess I'm not totally sure what you are trying to describe here. It might be best to get an experienced Kitfox pilot or CFI to go along with you and help you work this out.

If you are in straight and level cruise flight the required rudder trim will be the same regardless of heading and wind direction.

If your plane requires excessive trim input then there is probably a problem with rigging or the ball not being level.

[THRC12]

Adjusted more tab. All fine. Flying now. For now I just bent more angle as it wasn't quite the angle I described in any case. Tab is 2"x6.5. I have come to the conclusion that it isn't really effective where it is located. Midways up the rudder roughly 5" above the stab. Maybe any suggestions as to position? Maybe the airflow isn't as great where it is?

[jonstark]

With the ball carefully centered how does it stall? Thats the first thing I’d want to check.

Jon

[THRC12]

Kitfoxs don't stall! 😁😂

[THRC12]

Seriously, you can stall it power on, or power off and I will not drop a wing. Power on the tork and p factor will have you on the right rudder as most any other plane. Power off it stays centered without any effort. Only issue has ever been in light cruise flight. More angle on the tab has pretty much gotten it just fine. I still believe there might be a better location for the trim tab to be more effective though.

[Wheels]

I have the same plane with a 912UL. I drift a little left as well and just deal with it. that said, I put a couple degrees of angle on the engine mount with spacers when I first got it. No effect at all. Wast of time and effort. Do the trim tab, check for alignment, eat your veggies.
Jay

[THRC12]

Kinda what I'm thinking. Thanks. I'm going to maybe make a trim tab I can clamp to different places on the back of the rudder to find the sweet spot. I don't want to be drilling holes up and down the rudder for nothing. As far as making changes and finding out whether it likes it or not, I can fly it with or without the trim tab, flip it around, whatever doesn't matter, just would like have it a little better. Lol By that I mean it isn't a problem if I have to hang my leg out the door, I can fly it.

[Wheels]

Awhile back I asked about the trim tab and one of the guys on the forum had used double sided sticky tape and a piece of aluminum to attach a trim tab. He said it was still on the plane after 2 years. I need to resurrect that thread and do the trim tab install as well. I"m tired of the drift like you. My right foot gets tired.
Lets collaborate and find out where the best placement is for the trim tab. I"ll start playing with it in the next couple of days. I just need to be home so I can fly.

[jiott]

It could have been me that said I used a piece of aluminum and double sided automotive trim tape. It is now 5 years and 700 hours and that trim tab is still there with no sign of coming loose.

[aviator79]

If wind direction doesn't have any effect on your course, then why course correction?

It sounds like you're getting it sorted, but I wanted to address this just so that nobody else barks up the wrong tree. The wind does affect your course, that is true. But how your airplane flies through stable air has nothing to do with your course.

Assuming a nice, steady, constant wind, your airplane is flying through a moving air mass, and moves right along with it. The airflow around your plane is the same as it would be with zero wind. Your track over the ground will not be the same direction that your nose is pointed, but your track through the air will be (assuming you're coordinated). If you find that your rigging is different depending on your heading, you are subconsciously doing something with the controls that is different.

[Wheels]

It could have been me that said I used a piece of aluminum and double sided automotive trim tape. It is now 5 years and 700 hours and that trim tab is still there with no sign of coming loose.

Can you resend the pic and if not through the forum, due to technical difficulties, could you send them to my email. jayandpamela@yahoo.com
Awesome!! Thanks for responding to that thread.

[avidflyer]

Here is something else to look at. Are your rudder pedals even when the rudder is straight. I had a Kifox 1 that had a little twist in one set of rudder pedals. I would naturally try to keep my feet even, and that was actually giving a slight bit of rudder. Adjusted the cable length, and then all was well. Now the passenger would have had to deal with it if he was doing the flying.... JImChuk

[THRC12]

Pedals are good. They originally had never been gusseted and the right side pedal had bent on the cross tube. I removed both assemblies and replaced the right side cross tube with 3/4 .058 tube instead of the thin mess. Gusseted all the pedals with Tig welded gussets instead of the rivet/ epoxy AD. Super strong and they are all even. That was a while ago. Going extra on the trim tab got it to quit yawing so much. I am going to move trim tab down below the stab centerline on the rudder and see if I can get more effect from the airstream. I think where it's at it has dead airflow. Same thing on the wings for down force on the drag cars I build. If the wing is under or before the airflow, you get little to no effect. Teddy

[jiott]

My rudder trim tab is a piece of thin aluminum 4x6. It is bent at 2", so 2" sticks to the fabric with double sided 3M foam auto trim tape, leaving 2"x 6" bent in the wind. I also put a piece of contoured wood over the part stuck to the fabric to make it look better, but I'm not sure that was successful. The vertical center of the trim tab is located 29" up from the bottom of the rudder (SS7).

[Wheels]

Thank you Jim. Did you move it from top to bottom during testing or did you put it on and leave it?

[JimS]

Did you try tightening up the spring on the right rudder pedal. Just a little bit might get you the right yaw your looking for.

[PapuaPilot]

Did you try tightening up the spring on the right rudder pedal. Just a little bit might get you the right yaw your looking for.

I don't think that is true because the rudder on a Kitfox is just going to streamline itself with the airflow. The end result will be your rudder pedals will be offset.

This suggestion will work only if there is a centering mechanism to hold the rudder pedals centered. This is how the tricycle Cessna single engine planes do it, the nose gear extends and centers holds the rudder pedals in the neutral position. Rigging of the rudder system is done with it in this centered position.

[avidflyer]

I think Jim S may have a point though. It may offset the pedals just a tad, but maybe not enough to notice. Obviously, if you put a strong enough spring on, it would pull the pedal to the floor, a weaker one, a lesser amount. Maybe it just needs a little bit. I'm thinking of an elevator trim system I've used on Avids for nose up trim. Tie a light duty bungee cord around the seat truss, loop around the joystick, and back to the seat truss. If the bungee is at the right tauntness, it will stay where you put it on the stick. The higher up you go on the stick, the more nose up trim you get. Basicly making something else do some of the work for you. I think it's worth a try, as I don't think it can hurt anything, and it's easy to go back to the way it was. JImChuk

[jiott]

I had seen other trim tabs in roughly the same location, so I just put mine there and it has worked fine. No need for further experimentation. Way easier than messing with spring or bungee adjustment.

[rosslr]

And I followed Jim's design and it has worked perfectly for 400hrs.

cheers

r

[av8rps]

I once saw an Avid Flyer that the owner had made a trim tab that was attached to the fuselage through the trailer hitch attachment holes. Basically a bent piece of aluminum with a hole in it that a very long threaded rod went through with nuts on either side of fuselage to hold it in place.

Taylorcraft at one time had done something similar on their aircraft, with the idea of moving the entire fuselage over rather than just the rudder. Technically it should be aerodynamically cleaner, as the fuselage is what is yawed going through the air, so if you could move it into place where it belongs with a fuselage tab it might be a better way to do it?

I don't know if it worked well or not, but it would be simple to try.

[JimS]

I don't think that is true because the rudder on a Kitfox is just going to streamline itself with the airflow. The end result will be your rudder pedals will be offset.

This suggestion will work only if there is a centering mechanism to hold the rudder pedals centered. This is how the tricycle Cessna single engine planes do it, the nose gear extends and centers holds the rudder pedals in the neutral position. Rigging of the rudder system is done with it in this centered position.

Actually my suggestion would not work if the rudder pedals were locked in their centered position. They have to be free to move to whatever position results in straight flight. Bottom line is you need more right rudder in cruise for coordinated flight, right? Multiple ways to get it. One other suggestion is to unhook your rudder right rudder cable at either end and add a few twists to it. That will shorten it a bit and the pedal return spring in front of the pedal will pull a bit more on it.

[efwd]

Thanks for that tid bit Jim. That can save a guy a bunch of work shortening a cable. Bet it would come out too short also if I cut it down.