REFLECTOR: Damper

[Andy Millin]

All,

 

I spoke with Duane Swing about shimmy at Osh in 2010.  This was shortly
after a couple shimmy incidents.  He said they would love to have a
solution.  They have been waiting for a builder to find one.  I took up the
cause.

 

The credit for this damper starts with Bill Mulrooney.  He had seen this
type of damper used on performance motorcycles.

 

There were two possible options that might have worked for us.  I called
both companies and Scotts Performance seemed the better company to work
with.  Their damper has been used in many applications.  Among other things
their dampers are used on the overhead cameras in football games that fly
over the players.  They analyzed our needs and thought their damper would be
an excellent match.

 

The damper provides separate adjustment for response to "high speed" and
"low speed" movement.  So it will not respond during taxi, but give it a
jarring motion and it will kill it.

 

Scott Swing devised the mounting bracketry.  It went through several
evolutions on the Velocity trainer.  It was finalized shortly before Oshkosh
this year.

 

Scott said he knew it was done after they trained the last five students
with the system.  The gear nut was loose so the damper was the only
prevention from shimmy.  There was none.

 

There are two advantages:

                No shimmy

                With the nut loose, the plane handles very well on the
ground.

 

Items of Note:

                The damper is hydraulic.  It is an arm that sweeps inside of
a pie shaped chamber.  There is enough range to do a single wheel locked
turn.  It will not spin 360 degrees.

                It will fit inside the nose gear pant of an FG without
modification to the pant.

                The unit with brackets weighs about 1.5 lbs.

 

The pictures are as it was setup for the FG.  Scott has worked out the
install for the RG as well.

 

Thanks very much to Scott Swing for working out the install and John Abraham
for testing it out.

 

I'll send a couple of pictures.

 

damper_1.jpg

 

Andy

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