By Tommy H. Thomason

Wednesday, May 27, 2009

Before Steam Catapults

In the early 1950s, the weight and end speed requirements of new jet airplanes were at the upper limits of the capability of existing hydraulic catapults. One technique explored to get the maximum benefit out of what was available was the tail-down launch at maximum angle of attack.

The F7U Cutlass was already positioned at an exaggerated nose-up attitude when on its wheels but this catapult lash-up made it more so. The holdback fitting, main gear strut extension and position (it was angled forward for takeoff), and the little "grocery-cart" wheels added under the vertical fins allowed the catapult crew to tension the airplane at the steepest possible angle. You'll note that the tires are notably flattened by the forces involved.

However, the shore-based trials at Patuxent River demonstrated that there was no benefit relative to a more conventional hookup to the catapult: The angle of attack off the bow was greater but the end speed less, so the lift attained at the end of the catapult stroke was about the same. The extra time required to force the airplane into this position for launch was also a drawback. In any event and fortunately for Naval aviation,  Colin Campbell Mitchell's timely development of the steam catapult allowed a significant increase in the upper weight and end speed limits.

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