K48 might have helped us uncover another myth! The distinction that someone told him about a mysterious hydraulic lock condition that runs around waiting to infect your servos, and that somehow explains the cases where "straight and level" aircraft lose control (because someone thinks you can't get jack stall in an aircraft that is not at weird attitudes).
For the record, you can make an aircraft that is prone to jack stall get the condition in every flight attitude known to man. The stall of the rotor is the key. Rotor stall causes the servos to be loaded up by the changing pitching moment from the blades. In a helo that gets jack stall, the servos are too weak to fight this condition, and the forces overwhelm the servo, which then can lock the controls or even cause them to whip around the cockpit. Jack stall is a euphemism for "out of control because the servos are too small for the rotor". Jack stall is preventable by designing proper controls for the helicopter (servos big enough to always tell the blades to keep their forces out of the cockpit.)
The new item that K48 throws out (he calls it hydraulic lock) has nothing to do with a maneuvering helo, it is a condition that old worn out servos might get, or servos with worn seals, and it is rare enough indeed. When it does show up, it can be seen during the controls check during runup, when each servo is felt while the other is turned off, and weak servos usually tell themselves by producing jumps as the systems are switched, and odd forces when the bad servo is manipulated.
Last edited by NickLappos; 26th Oct 2007 at 16:08.