Alignment or What??

[vetdrem]

I have a problem that I hope someone can help me with.

I have a model III with a bungee gear and FOXKING tires that I "hanger" in an enclosed trailer.

I placed blocks in the ground to help position the mains while the tailwheel is put in a track centered in the trailer. I put the mains on the blocks, tailwheel in the track and winch the plane into the trailer.

It seems that the plane tends to move to the right as it enters the trailer. When I winch the plane back out, it moves to the right even more. It will move 10-12 inches. Picture 1 shows how I position it before winching it into the trailer, picture 2 shows how far to the right it moves when winching it in and back out.

I did a quick check of the alignment and I think that it is toed-in a little, but both seem to be about equal. The distance from the main axel to the tailwheel is equal for both wheels. We just changed the bungees and there seems to be quite a bit of camber with it sitting empty but I think that is to be expected.

I just don't understand why it acts like the mains are turning to the left when winching it into the trailer, and like the mains are turning (a lot) to the right when winching it out of the trailer.

ANY IDEAS?????

Louie

[jrevens]

Louie,
The wheels may be aligned perfectly with each other but are not aligned with the center-line of the aircraft, or the gear is not aligned with the center-line. They should be aligned with reference to the center-line of the fuselage, as well as with each other. The only other thing I can think of right now is some possible excess friction (i.e. - a dragging brake) on one of the wheels.

[KFfan]

Here is a good tutorial on alignment

http://www.teamkitfox.com/Forums/sho...ighlight=align

[t j]

That is strange. Does the main gear spread when rolled backwards and close back in when rolled forward...due to the toe in? Maybe that has something to do with it but I can't figure out why it doesn't come back to the same spot.

[PapuaPilot]

That is correct. If you have toe in the wheels will tend to come when going forward and spread if you back the plane up.

BTW I am going to add a couple more suggestions to the thread on wheel alignment.

[beeryboats]

Does it have a tendency to try and ground loop? My dad had a Baby Great Lakes that was a little touchy on landing. He found it had excessive toe-in.

[Paul Z]

Here is a good tutorial on alignment

http://www.teamkitfox.com/Forums/sho...ighlight=align

Excellent Posting on how to do the alignments. Even if you know what you are doing this is a great refresher.

[KFfan]

This is from a posting relevant to automobiles but is applicable to the situation at hand. IMHO


"Caster is the tilting of the uppermost point of the steering axis either forward or backward (when viewed from the side of the vehicle). A backward tilt is positive (+) and a forward tilt is negative (-). Caster influences directional control of the steering but does not affect the tire wear. Caster is affected by the vehicle height, therefore it is important to keep the body at its designed height. Overloading the vehicle or a weak or sagging rear spring will affect caster. When the rear of the vehicle is lower than its designated trim height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than its designated trim height, the front suspension moves to a less positive caster. With too little positive caster. If one wheel has more positive caster than the other, that wheel will pull toward the center of the vehicle. This condition will cause the vehicle to pull or lead to the side with the least amount of positive caster."


The picture in my brain indicates the mains moving one direction, moving backwards, and the opposite direction, moving forward.


My wife would probably have said, "You're wrong".

[mr bill]

You are making my head hurt.

[cgruby]

Louie, From your description, it appears the gear is twisting to arrive at one spot going backward and another going forward.
Loose axle?
Broken gear strut?
Excessive wheel friction causing gear to twist?

Jack it up and check for any twisting movement.

And BTW, having been there and done that, I prefer to align the gear straight ahead, i. e., no toe in or out.

Good luck,