Deflected Thrust

Latest entry in the VTOL (Vertical take-off and landing) competition is the Bell X-14, which achieves vertical flight in a horizontal flying attitude by means of a Venetian blind. The X-14 has two Armstrong Siddeley jet engines that give more than 3,500 lbs. of thrust, their hot gas shooting out horizontally under the fuselage. When the X-14 is rigged to take off vertically, a system of vanes like a Venetian blind deflects the gas downward. The thrust, acting upward, lifts the craft off the ground.

During this maneuver, the normal control surfaces do not work because there is no flow of air over them, so their job is done by rotating compressed air nozzles. One of them in the tail controls pitch. Two more, one on each wing tip, take care of roll and yaw. The X-14 can hover indefinitely at any level, supported by the deflected thrust of its engines and balanced by its nozzles. When the pilot wants to fly horizontally, he merely adjusts the Venetian blind so that the gas stream from the engines shoots directly astern. Then the X-14 flies like an ordinary jet plane, supported by the lift of its wings and controlled by its conventional ailerons and tail surfaces.

The first complete transition from vertical to horizontal flight and back again was accomplished by Bell Aircraft Corp. at Niagara Falls on May 24, when Test Pilot David W. Howe lifted the X-14 vertically off the runway. He hovered for a few seconds, then flew horizontally at 160 m.p.h. Returning to the airport, he came to a full stop ten feet off the ground, made a 180DEG hovering turn, and settled down on the surface.

Many details of the X-14, which was developed for the Air Force, are still secret. Bell will not say how much weight the deflected thrust will lift off the ground, but the company is confident that in the reasonably near future large aircraft, both civil and military, will be equipped with vanes and nozzles for vertical operation from small airports.

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