On Thu, 30 Jul 2015 16:06:08 -0700, Captain Obvious
wrote:

On Thu, 30 Jul 2015 11:36:15 -0400, Ed Huntress
wrote:


Ok, since we've now run into two people with the temerity to talk
about the factors involved in front-wheel oscillation, where does
precession come into it? Or doesn't it?

I don't see how. On bikes the culprits tend to be loose steering
heads, unbalanced fork springing or damping, dogtracking, bad tires,
etc. On the model of plane I know had the issue, it was probably
rooted in zero rake, negligible trail, rigid lamb tire, and tiny
contact patch.

That sounds a lot like my old BSA Victor. g No caster to speak of.
Let go, and crash.

Those are not good memories.

And set off by poor elevator leverage at slow speed
allowing the nose to smack down. A friction damper cured it so long as
its tune was maintained, which was unreliable in the usually oily
environment. A secondary hydraulic damper was added, but there were a
number of incidents of wheel oscillating violently from stop to stop
followed about 1 second later by the nose wheel making a run for it. I
experienced a minor case of it myself and from then on became
religious about checking both dampers.

Ok, precession is magic, anyway.

--
Ed Huntress