Hi,
I've got about 75 hours on the standard C152/PA28 nosedraggers, but I'm hoping to do a tailwheel conversion over the summer, in anticipation of which I've been reading up on the peculiarities of the ground dynamics etc. I was interested in some of the technical fixes that have been used to make taildraggers more user-friendly, in particular castoring main gear (!), which seems to cause as many problems as it solves.
This got me thinking about an alternative solution, which I thought I'd post up here to see if it's been tried before and/or if it would work! My idea would be to allow each main wheel to castor
out by a few degrees (maybe 5-10), probably against spring pressure, but to not allow it to castor
in at all. By "out" and "in", I mean that the left main wheel would be allowed to "steer" anywhere from straight ahead to 5-10 degrees to the right, and vice versa for the right main wheel.
The reasoning is this: during a normal ground roll, any crab angle developed results in both main wheels crabbing at the same angle relative to the direction of movement, and hence developing the same frictional force. However, considering a crab to the left, the left wheel has a greater lever arm from the CoG, thus causing a further yaw to the left, and so on until you hit the nearest hedge. If the left wheel is allowed to castor to the right, but the right wheel is forced to remain pointing straight ahead wrt the aircraft, the left wheel would then develop a much smaller frictional force that the right, leading to a net restoring yaw torque to the right.
(Did I explain that well enough??
)
Sounds reasonable to me? Does anyone know if this has ever been tried, and (assuming it has, which seems likely) why doesn't it work?
Cheers,
cbl.