Vertijet

A favorite dream of airplane designers is a VTOL (vertical take-off and landing) that will leap into the air like a helicopter, fly as fast as a jet interceptor, and land vertically. Helicopters cannot be upgraded to do this job: they are inherently too slow. The Navy's "Pogo" (Convair XFY-I) takes off and lands vertically, but it has propellers and therefore can never fly as fast as a jet. Many other types have been tried (movable wings, swiveled engines, folding rotors), but none of them show promise of matching the designers' dream.

Rising Ratio. The ideal VTOL may come into being through the continuous improvement of jet engines. Research Engineer Earl R. Hinz of Ryan Aeronautical Co. points out that when the static thrust of an airplane's engines exceeds the airplane's weight, a vertical take-off is possible--at least in theory. Apparently no operational jet plane has such thrust at present, but the ratio of thrust to weight--even with the low-power figures still published by the security-morbid U.S. Department of Defense--is climbing rapidly. For the F-86 Sabre jet the ratio is four to ten. For the British Gloster Javelin it is six to ten. For the newest U.S. interceptor, the Lockheed F-104A, it is about eight to ten. Only 25% more thrust (or less weight) would theoretically free the F-104A from take-off runs. This is so close, says Hinz, that a true jet VTOL should not be far away.

Hinz has reason to know, because Ryan has built the only serious jet plane designed for vertical takeoff. Financed by the Air Force, Ryan started by testing an almost bare jet engine in a concrete cell, where it rose and fell like a captive balloon. Gradually Ryan added the wings and other makings of a real airplane, and shipped the result last summer to Edwards Air Force Base in the Mojave Desert for flight testing.

Secret VTOL. Nothing has been released about Ryan's X-13 "Vertijet" which is still a highly classified project. But the technical public got a quick look at it when it was shipped to Edwards, carefully wrapped (see cut). Airplane-industry gossip has been swapping bits of information about it ever since.

The X-13 is a small delta wing with a fuselage about 30 ft. long. It now has conventional landing gear for test purposes, but is designed as a "tail sitter" (sitting on its tail on take-off). When rising or hovering in the vertical position, it probably depends for control on outboard thrust outlets taking power from the engine or supplied with gas by small rockets. Some of the gossips believe that the X-13 will never try to land on its tail --a stunt that is still not easy for the less critical, propeller-driven Pogo. Instead, they think, it will hover near the ground, nose upward, and then slowly move under an overhead framework, from which it will suspend itself like a bat landing on a roof of a cave.

Up to the beginning of this month, the X-13 had not taken off or landed vertically. It has taken off many times, however, in the old-fashioned way, and Test Pilot Pete Girard is feeling out, at safe altitudes, its ability to hover nose up and to rise and descend vertically.

A successful vertical takeoff, transition to horizontal flight, and vertical landing may be kept secret for a considerable time after it has been accomplished. It would be of considerable military importance. Modern high-performance jet interceptors need so much runway for takeoff and landing that they cannot be used from temporary or improvised fields. So an enemy knows just where to expect them. Vertijets, which could take off from almost any lot. from inside a high-walled enclosure, or perhaps from a bombproof underground tank, would break air power's dependence on old-fashioned bases, and put jet interceptors where they are not expected.

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