Hot Tornados

Talk among engineers this spring is rife with rockets, jet-propulsion planes and gas turbines. These three devices, all harnessing the hot, violent blast of burning oil flames, are already in development for postwar purposes. Last week Allis-Chalmers advertised "How to Cut a Locomotive in Half," by using the compact gas turbine with no boiler, no cylinders. FORTUNE for June discusses the whole subject at length.

All three of the new devices dispense with heavy construction, cylinders, most moving parts and much lubrication. But each is unique.

Rockets. The rocket -- an efficient light projectile--burns either gasoline or an explosive powder and does not depend on the outside air for combustion. It carries its own oxygen, compressed or liquid, or combined in the explosive. The gases spurt out the tail and drive the rocket forward, purely by recoil.* The rocket flies best in the thin air of the stratosphere, should fly even better in airless interstellar space. It needs no wings. The bazooka shell is a true rocket; but there is no such thing as a practical "rocket plane"--the rocket principle has so far proved unpractical for man-carriers. Possible peacetime use for the rocket: collecting weather data.

Jet-Propulsion. The jet-propelled plane is pushed forward, without a propeller, by a roaring backward blast of hot gases. The air for combustion is sucked into the engine from outside and compressed. Such planes cannot operate at very high altitudes (about 67,000 ft.) for lack of enough air for combustion or to support the wings. At speeds above 500 m.p.h.,.where propellers lose efficiency, jet propulsion works best.

Turbines. In the gas turbine a bladed wheel, like a multiple propeller, is whirled by the hot blast. The gas turbine has great possibilities for electric power plants, locomotives, marine engines and even airplane engines.

J. Kenneth Salisbury, General Electric turbine engineer, predicted at Tulsa fortnight ago that postwar cargo and transport planes would need engines up to 8,000 h.p. The most powerful gasoline aviation engine yet announced is 2,200; the most powerful now built is a military secret. Turbine men who hope to build aircraft engines see no reason why the output of their power plants cannot be stepped up eventually to 10,000 h.p.

The major obstacle to getting this much power is the need for metals that keep their strength at bright red heat. But metallurgical advance has recently been rapid; much of it has been made in perfecting the turbosupercharger, already in use on some high-altitude combat planes. It is, in effect, a small gas turbine mounted in the white-hot (1,700DEGF.) exhaust of the engines, which is used to compress thin, high-altitude air into the plane cylinders.

The 5,000-h.p. gas-turbine locomotive (promised by Allis-Chalmers, General Electric and Westinghouse) will be about 75 feet long as against 150 for Diesel and 100 for steam engines of the same power. The gas turbine's advantage over steam is the same as that of the Diesel: one-third the fuel consumption, fast acceleration, no stops for water, no pounding on the tracks. But the gas turbine is superior to the Diesel in compactness, first cost, maintenance and lubrication costs.

Gas turbines for ships are already under construction by Allis-Chalmers, Elliott, and De Laval. The ships will have no boilers, heavy condensers or feed-water problem, can thus probably carry about 10% more cargo than steamships can.

*The rearward thrust of high-speed gases drives the vehicle forward. This is in accord with Newton's law that every action has an equal and opposite reaction or recoil.

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