Thank-you for the meal. : )
Couplet at C is gen'd by the weight x arm length to wheel. Couplet at B
is gen'd by weight x same arm length. Couplets diminish progressively to
zero as the arm goes to zero moving toward A and D.
I now must attribute the damage I suffered (which was a very big job to
fix properly) was caused by the twist resulting from the wheel being at
a turn angle, the tire being solid, and the tire having to jump a
pavement edge of nearly half the diameter of the solid tire. That
coupled with the fact that the Fuse30 doubler was not in place (it was
set up as a floatplane but on wheels temporarily) and the internal side
extensions Fuse83? did not exist in this vintage (068). It looks like
with all those reasons, labelling the tailwheel structural design as a
cause was erroneous and unfair to the designer.
Anyone who has a similar situation to what I described would be well
advised to taxi carefully.
Garry
Ken wrote:
With a reference plane of the center of the wheel, you correctly did not
show a moment at the center of the wheel which I will call point D.
After all a thin wheel would fall over if it had to depend on ground
contact to resist a moment. There would be shear in the axle at that
point but not a moment.
Similarly you should not expect a moment at A. I assure you that there
is no twist on my spring no matter how much I bounce the tail up and
down. So remove the statement "then at A, then at the moment point above
A." and your description then makes sense to me.
Alternately try working it from the perspective of moments acting on the
vertical part of the fork ie the solid section B-C There is a moment at
point B and C which cancel. No moment at A or D.
Or turn your diagram upside down and see if it makes sense. The forces
and moments will be the same. The fact that the weight vector passes
vertically through the mountpoint is what causes the magnitude of the
moments to exactly cancel. If it did not pass through the center there
would indeed be a moment and a resultant twist on the tailspring.
|
A|__ B
|
__|C
D|
|
Ken
Garry Wright wrote:
The concept seems rather simple actually. Looking at the tailwheel from
the rear in ascii form below we see various points of reference
|
|
A |______ B
|
| | One armed tail wheel assembly.
|_____ | C
|
|
The wheel is just a line - sorry my ascii art leaves a lot to be
desired. : )
The wheel creates a cw moment at C of weight x distanceAB in inch lbs or
whatever units you like. This must be countered by a moment provided in
an anti-cw direction at C by the member BC. This in turn is countered by
a moment at B, then at A, then at the mount point above A. If anyone can
adjust my understanding of the statics involved here I would appreciate
being un-misconceived. The fact that the weight vector does indeed pass
vertically thru the mountpoint is not relevant to the resolution of moments.
Garry
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