There was a good article on landing gear I read once that described the caster angle in relation to the distance from the axel to the pivot point. When I made my nose wheel fork I used those dimensions. I didn't have any shimmy problems however on landings I would bend the spindle back a few degrees. It was cheap though, made out of 3/4" cold rolled steel. I had too much distance from the axel to the spindle and to solve the problem I reduced that distance by rebuilding the fork. No more bent spindles (except for that time I landed hard and buckled the nose strut) but it did tend to shimmy from time to time. The most recent problem I had with it I added enough spring washers to stiffen up the rotation. Now it's a little harder to steer on the ground. That Diehl nose wheel in the video looked like a shoping cart caster in the super market.
-Joe Scappoose Ore. > Maybe I should have emphasized caster angle a little more... > caster angle (the angle from the vertical pivot point to the > contact patch of the tire on the pavement, similar to the > trail on a motorcycle) can improve the stability and natural > tendency of the tire to track true. I agree with all of the > points that Mark L has made, but the video I saw showed the > shimmy continuing all the way down the runway... if the > caster angle and balance had been properly done, the shimmy > would tend to cancel out as the plane went down the runway. > Granted, I know more about motorcycles and cars than I do > about planes, but once the bird is on the ground, I would > think similar rules would apply. Yes damping is important, > but if the geometry of the set-up is off, it won't help the > shimmy unless the gear is "locked in" (too > stiff) which kind of defeats the purpose of a castering nose > wheel doesn't it? > > JMHO > > Mark W > N952MW
