REFLECTOR: Nosewheel shimmy

[Dave Philipsen]

Hmmm,

A couple of ideas on that.  My first guess would be that the wheel isn't 
spinning fast enough to be an effective gyro and my second guess is that 
the gyro would be more effective if the axis were at a right angle to 
the axle.  Just an uneducated guess though.

I am a new owner and I have not yet experienced any shimmy in the 
nosewheel.  But, I believe my washer must be pretty snug.  One thing I 
have done is this:  while pulling the plane back into my hangar, 
sometimes I need to get the nosewheel turned a bit.  So, I pick up the 
nose of the plane (only weighs maybe 20 pounds or so) and move the nose 
in the direction I want it to go.  Then I drop the wheel back to the 
ground as the nose is swinging around and the tire kind of scuffs the 
asphalt and forces the caster around a bit.  By doing this, I believe I 
can get a good 'feel' for how tight the contraption should be and I'll 
know if it starts to get loose.



Hiroo Umeno wrote:
> The thing about the gyro idea, though, the shimmy only happens when the
> wheel is spinning, right?  Why wouldn't the wheel itself act as a gyro
> and self-dampen the inclination to caster?
>
> Something I am not clear on, as someone who hasn't taxied his plane...
>
> The Belleville Washer somewhat works as long as you keep it torqued to
> factory specifications, right?  Once it is torqued to spec, how often
> does it need to be re-torqued?  I have a fixed gear with wheel pants.
> In order to re-torque or check the washers, the pants needs to come off.
> Clearly, this is not an item for every pre-flight.  Clearly, it will be
> a part of my annual condition inspection.  But that seems pretty
> infrequent if this is something that loosens up readily.
>
> So, how often do y'all check and torque these little thingmabobs?
>
> Hiroo 
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Douglas Holub
> Sent: Wednesday, June 28, 2006 7:49 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Nosewheel shimmy
>
> I don't know how practical it is either, but you definitely get points
> for creative thinking.
>
> Doug Holub
> ----- Original Message -----
> From: "Dave Philipsen" <velocity at davebiz.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Wednesday, June 28, 2006 9:34 PM
> Subject: Re: REFLECTOR: Nosewheel shimmy
>
>
> Here is another idea (perhaps it's a little outrageous). How about
> putting a gyro on the landing gear? Wouldn't that effectively resist any
> forces causing shimmy? I don't know. It may not be very practical as far
> as size goes.
>
>
> Al Gietzen wrote:
>   
>> Has anyone tried a flatter profile tire such as the Goodyear? The
>> Condors are quite round. The greater rubber in contact with the ground
>> might help keep the tire aligned with the onrushing pavement. Only had
>> one shimmy but keep my Bellvilles very tight.
>>
>> Just a thought..
>>
>> Rene'
>>
>> Rene'
>>
>> The SE comes with a squared profile tire. Some years ago another
>> Velocity driver told me that he solved the shimmy problem by changing
>> to a rounded profile tire. Apparently it can happen with either.
>>
>> Al
>>
>>
>>     
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-- 
Dave Philipsen
STDFG
N171SP

soon-to-be N83DP