Originally Posted by RV8JD
I installed the Condor2 fork, hub, and pneumatic tire onto my existing JDAir bearing tailwheel yoke several days ago on my RV-8. I am using chains. Today, on the fourth-ever landing with it, it shimmied for several seconds during the rollout. The landing was smooth and the tailwheel gently touched the runway. And it was lightly loaded during the rollout (i.e., neutral stick). On many gear setups, that is a pro-shimmy combination if the setup is prone to shimmy. On the next landing of the day, with more load on the TW, it did not. After I got to the hangar I checked the tire pressure and it was down to 45 psi, from the recommended 50 psi. I raised it back to 50 psi.
I plan to do some experimentation with TW load on the rollout. If it shimmies again, I'll play with tire pressure, and I may put the steering arm back on (adds a little damping). The JDAir bearing yoke, with its zero yawing friction, may also play a part. I really do not want to give up the JDAir bearing yoke, with its smooth and easy steering. The Condor pneumatic tire also has a small contact patch which doesn't help to prevent shimmy.
Or ... the event may have been a fluke. I'm thinking about calling Blake on Monday and see if he has any thoughts.
I like the pneumatic tire so far, it's much smoother, quieter, and rolls over larger cracks in the pavement more gracefully than the smaller, solid tire. But if it is prone to shimmy, it's history.
I'm throwing this out there to see if anyone else has encountered shimmy with the Condor2 assembly. And hopefully, as more units get installed and if there are shimmy events, they'll get reported.
In the 2500+ hours I've flown RV-8s I don't recall ever having a TW shimmy event. And that included many hours on the Van's TW assembly, a modified Van's TW assembly, the Bell TW fork, and the full-up JDAir bearing TW assembly. These were with the standard Van's TW tire and the lightweight TW tire. And they included a steering arm on some of them and chains on most of them. And I don't recall hearing of anyone else having one either.
I have a fair amount of TW time in various airplanes and have experienced TW shimmy on several occasions with other airplanes, and I'm familiar with the parameters that affect shimmy and how severe it can be.