By Tommy H. Thomason

Monday, October 12, 2009

The Knee Bone Connected to the Thigh Bone

There was relatively little innovation in the basic tail hook design. Whether it was a V-frame or a single "stinger" appears to have been based on whether the aircraft structure had a single keel or two heavy stringers on the bottom of the aft fuselage because the tail hook attach point had to tie in to a main structural load path.

For example, the FR-1 Fireball, which was an early attempt to take the jet engine to sea by combining a piston engine in the nose with a jet engine in the tail, provided for removal of the jet engine by making the aft fuselage a separate bolted on structure. To avoid loading that joint and inexperienced with the dynamics of an arrested landing, Ryan engineers attached the tail hook to the aft end of the forward section of the fuselage. When the hook snagged a cross-deck pendant, the result was a nose-down pitching moment. This was really hard on the nose gear and there were failures.

Douglas, somewhat more savvy about carrier operations, initially chose to integrate the tail bumper and the tail hook on the F4D, as shown here on the mock up with the hook in the "stinger" position for taxi over the remaining wires and barriers.

At least one of the two XF4Ds were built with this design, but by the time the XF4D went to sea for initial carrier trials, this arrangement had been replaced with a more conventional V-frame hook that was attached directly to the airframe.

No comments: