[Ben Hecks]

I think the Army also dropped some of these in Vietnam using the CH-54 Skycrane. The CH-54 was designed for external loads and had an interesting system for disengaging from the load if it started to sway out of control (bad).

[Mr. Lucky]

My guess would be the sound is made by huge quantities of gas escaping from where the sphincter use to be when somebody's ass just got bombed off.