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Wheel alignment verification tecnique

PostPosted: Mon Nov 30, 2015 6:27 pm
by The Flying Hare
In the build manual it states "The gear legs must be squared to each other and the fuselage"
The Boys at the factory said that this was no longer the way they do it. I was told by them that the only thing needed was to measure from the end of the main axles to the rudder post, and make sure that these are equal, and to adjust the Hiem joints as needed. As I am building, I wanted to verify that the axles were aligned with each other and found a $6.00 solution. With the Fuselage suspended on the forward rotisserie, the gear legs attached (no air shock) and holding the gear legs up (so the axles are level) with a nylon strap. I got 2 perfectly straight (and do carefully check them) 1" wood dowels from Home "D", and shoved them into the axle tubes, (Might take some light sanding) with the majority of the dowel under the Fuselage. Then I stretched a string line between the L/H and the R/H brake backing plates, then further tighten it with tape, wrapping the tape around the dowel and the string. With this setup you can see the toe in/out by looking at the clearance between the string and the dowels where the 2 dowels meet. At the end of the dowel, using basic math, 1 degree of axle deflection will be about 3/8 of an inch (between the string and the dowel)
dowel1.JPG

dowel2.JPG

dowel3.JPG

This method gives a simple, accurate way to check the toe in/out. Also, I used AN960-616"L" washers to shim the Heim, as they are 1/2 the thickness of the regular washers supplied.

Chris Hare
SS #340
Conroe TX

Re: Wheel alignment verification tecnique

PostPosted: Thu Dec 03, 2015 6:16 pm
by R Rinker
Brilliant Chris...looks like yours are pretty well aligned...
I have a friend that built an RV and has had a horrible time with steering issues. He never checked his wheel alignment, just learned to live with it.
I definitely think it's worth it to find out what the actual alignment is...

Re: Wheel alignment verification tecnique

PostPosted: Tue Dec 08, 2015 9:42 pm
by User GDS
If you are using regular airplane tires with grooves, you can put them on and with your tape measure halfway up the back of the tire, measure from a groove on the left to the same groove on the right. Then repeat the measurement halfway up the front of the tire. They should be the same. If they are slightly toe-in it will probably be fine, if they are toe-out, it makes landings more exciting than they need to be.

Re: Wheel alignment verification tecnique

PostPosted: Tue Dec 08, 2015 11:44 pm
by alan
I've got to disagree with you G. Toe in bad, toe out good. In moderation of course. On a tailwheel airplane, when the airplane starts to turn, the outside tire, if toed in, bites harder and encourages the turn. If toed out, the outside tire is less inclined to make the turn worse.

A two degree toe out is far more stable than the inverse.

Alan

Re: Wheel alignment verification tecnique

PostPosted: Wed Dec 09, 2015 10:52 am
by User GDS
Honestly, I don't know which is more stable, toe-in or toe-out, but too much of either is not good. My friend had a Kitfox with poor wheel alignment and it was always trying to dart off the runway when landing on pavement.

I'll amend my statement to "You'll be better off if both wheels have zero toe-in/toe-out."

Re: Wheel alignment verification tecnique

PostPosted: Thu Feb 11, 2016 11:52 am
by Augustus
I did something like The Flying Hare. When building at the factory, I inserted aluminum tubing in each axle tube (perfect fit) extending 12" outward (with the aircraft level - tires off).
I then measured 12" ahead and 12" behind the each tubing. Put tape on the floor parallel to the tubing 12" ahead and 12" behind each tube.
Adjusted the heim fittings so that the distance from the end of each tube to the upper tail wheel shock mounting bolt was equal and the distance 12" behind the aluminum tubing and 12" ahead of the tubing was equal perpendicular to the fuselage.
This method is not factory-endorsed.