The Vertijet

A long-term dream of airplane designers, the jet-powered vertical take-off plane, became an official reality last week. The Air Force announced that Ryan Aeronautical Co. has test-flown successfully its jet X-13 VTOL (vertical take-off and landing), putting it through all its paces after 18 months of partial tests.

The X-13, named the Vertijet. is a small, delta-winged job that takes off from a suspended position, hanging from a framework like a bat. Last week Test Pilot Peter F. Girard, sitting on his back with his face to the sky. started its powerful jet engines. As the roaring exhaust hit the pavement below, a spray of dirt and melted tar boiled into the air. When the X-13 became airborne, Pilot Girard maneuvered it off its suspension rig and free of the framework. Then he flew it upward like a deliberate rocket and made a gradual pushover to normal level flight.

Coming back to his take-off point at Edwards Air Force Base in the Mojave Desert, he pulled up the nose of the X-13 until it was hovering noisily like a rotor-less helicopter. Then he descended under the framework and maneuvered the batlike plane into take-off position. After two such demonstrations, the X-13 was tipped onto its belly and wheeled into the hangar like any other jet plane.

The basic fact that makes jet VTOLs possible: jet engines can lift much more than their own weight. The X-13, presumably, has a high-thrust power plant whose weight is as low as possible, but it must have many other novelties too. At the moment of takeoff, while it is still moving at negligible speed, its tail surfaces are useless. Some other system, such as secondary gas jets, is presumably provided to keep it under control until it has gained enough speed for the conventional control surfaces to go into operation.

Another difficult moment is the approach to the ground in tail-down attitude. The pilot has to watch the ground in some way. He may look over his shoulder with mirrors or other optical aids, but it is more likely that electronic instruments tell him his distance from the ground and the speed with which he is approaching it. An "automatic landing pilot'' may even control the whole operation.

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