AFCS and Slingloads
Some background on an aspect of your subject.
The CH-54 community had noticed that the AFCS could, sometimes, be de-stabilizing. Pilot out of the loop ( i.e., hands off the cyclic )
I think it was about the time the CH-54B arrived that two of our very sharp AFCS engineers conceived the idea of a dynamic AFCS " Load Stabilization and Precision Hover System. The Program Office proposed it to the Army and they funded the design and flight tests, all of which were quite successful. Loads that went unstable above 35-40 kts could now be flown to 80. May not sound like much, but now, one had an IFR capable machine with that load. Principle behind the load stabilization system was sensing cable angle at the Cargo hoist and timing the corrective signal. Precision hover was based on a ground contrast electronic signal. Remote control of the helicopter was provided thru a hand held model airplane type device, so that a ground controller could put the load exactly where he/she wanted it.
The Army decided not to incorporate, but lo and behold, when the Boeing HLH model was designed, the SA tested system was provided to Boeing ( The Army owned it, after all ).
As I recall, there had been one horror story from Vietnam about a night CH-54 sling load of a D-8. The weather was lousy and the load got to swinging. Attempts to pickle the load via the electrical hook release failed. The cable cutter charge did not fire. The Crewchief attempted to use his M-16 to break the cable as it swung ( shooting out the door of the " back porch ", as it was called. No joy there. Eventually the pilots got down close enough to land the load in a situation where the issue of whether they were flying the load or the load was flying them was open to argument. They rolled it up in the landing, but all survived.
One of the engineers, Don Fowler, may still be working at SA and you might try chasing him down.
Good luck in your endeavor,
John
Last edited by JohnDixson; 26th Jul 2014 at 21:57.
Reason: typo/additional info