REFLECTOR: Nose wheel shimmy

[Al Gietzen]

Kirk,

 

Every time I hear about an "incurable" nose gear shimmy I wonder, what 

is different.  There are too many flying V's with no problem, like my 

airplane for this to be a design flaw. 

 

I’ll propose 4 factors that could influence whether nose wheels shimmy or
not:

 

1.     Assembly of the wheel hub.  The two halves of the wheel hub are not
indexed (at least mine were not), and with the three bolts, it can be
assembled in three positions.  I found the only one position that aligned
properly so there was no wobble or run-out.

2.     Wheel balance.

3.     Vertical alignment – side to side.

4.     Negative caster angle (Kurt referred to as king pin angle). I think
it is supposed to be about 2 ½ degrees – forward of vertical.  Wayne (IIRC)
has written about getting it right on his.

 

Of course there could be others.

 

I set the ‘drag’ on my nose wheel at 10-12# with the fish scale on the back
edge of the tire.  Not much experience yet, but some high speed taxis, nose
wheel lift, crow hop, and a 100 kt touchdown from first flight; and no signs
of shimmy yet.  Perhaps I got lucky and had the factors come out OK.

 

I have some ideas about rotational balance around the vertical axis that
could allow lower drag force.  I’ll test something after I get through Phase
I, or close to it.

 

FWIW,

 

Al

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.tvbf.org/mailman/private/reflector/attachments/20060811/e7f84a8e/attachment.htm