Millin Factory Shimmy Damper

From Velocity Aircraft Wiki
Jump to: navigation, search

Prior to the development and installation of the Scotts Performance Damper, the primary means of preventing shimmy was a compressed stack of Bellville washers. This solution has been around for decades. It is a simple, elegant solution that works well within limits. The Bellville Washer Solution (BWS) creates a resistance to turning. An increase in the compression of the washers creates an increase in the breakout and turning force of the nose gear fork. BWs are not a shimmy damper; they are a shimmy preventer. By keeping a high enough breakout force, movement that could initiate a shimmy event is essentially locked out.

There are downsides to the BWS solution. If the stack looses compression, there will not be enough resistance to stop shimmy. In the Velocity installation this means checking the big nyloc nut on the nose gear is tight before each flight. Even if the nut is tight in the pre-flight, it may work itself loose during taxi or takeoff.



Andy Millin worked with the factory to prove out this design, with some input from Velocity motorcycle racer Bill Mulrooney. It's a damper from Scotts Performance mounted on the nose fork.

First you must drill the gear leg and insert a roll pin, or ship your gear leg back to the factory and have them do it. The only thing I don't like is not being able to rotate the gearleg 180 degrees, an issue that apparently was resolved somehow on the retract.

Andy Shimmy 1.jpg Andy Shimmy 2.jpg
Installing Roll pin Mount damper

Rene Dugas

Just got my Damper back and mounted. Looks real cute. Easy taxi now. Thought some might wish to zoom in on the tire to see how violent a shimmy can be. All the cross hatching is result of recent mild shimmy. 35# pressure in tire and 15 # of tension measured with a fish gage just before flight. Solo flight, 3/4 fuel, smooth runway. Slight cross wind crab corrected well I thought. 600 hrs in Velocity.

Those who have not had a bad one beware it is violent. Not like a Cessna.

Rene

Scott Brochure

Retract version installed on Rene' Dugas' N129RD Scott Dampener.jpg