High & Fast

The airlines of the future, most aeronautical engineers agree, will fly swiftly and serenely far above turbulent weather in the rarefied air of the substratosphere. Already air transports are being built with cabins in which, by supercharging, interior atmospheric pressure approximating that aground can be maintained at substratosphere levels. Mainly responsible for development of a supercharged cabin was the U. S. Army Air Corps. Last week the Air Corps received from President Roosevelt this year's Collier Trophy for "the greatest achievement in aviation whose value has been demonstrated in actual use." Meantime, aeronautical science has its sleeves rolled up to attack the problem of full utilization of substratosphere speed potentials.

P: One difficulty of substratosphere flying is that in the thin upper air a propeller blade has to take bigger or more frequent bites of air to maintain the ship's speed and altitude. By increasing the pitch of propeller blades bigger bites are possible, but wind-tunnel experiments have indicated that any propeller's effectiveness reaches a limit when the speed of its blade tips surpasses the speed of sound (at sea level, 780 m.p.h.; at 20,000 ft., 500 m.p.h.). When propeller tips reach the speed of sound, they find themselves in a sort of dead heat with the sound waves they are generating. These waves, unable to get away from a source traveling just as fast, jam up around the propeller tips in clusters sometimes referred to as "compressible burbles," creating as much of a drag as if the propeller had suddenly been transformed into a twirling dumbbell. Since sound waves travel more slowly in thin air than at normal atmospheric pressure, propellers in the substratosphere have a lower effective top speed than at sea level. Last week scientists attending the Fifth International Congress for Applied Mechanics at the Massachusetts Institute of Technology suggested a way to improve propeller performance in the substratosphere: bigger propellers, designed to take bigger bites of air to make up for slower turning speed. For a starter they suggested 20-foot propellers, nearly twice the size of the largest now in use.

P: To turn such blades efficiently, airplanes must have lustier power plants. Last week Vega Airplane Co., a Lockheed subsidiary, announced specifications for a plane with two motors in one unit, geared with overrunning clutches to a single propeller. Overrunning clutches, similar in effect to a bicycle coaster brake or to the overdrive principle in some modern automobiles, permit a failing motor automatically to disengage itself, saving the still-functioning motor the strain of working against the inertia and compression of the dead one.

P: With aviation seemingly crowding the barriers of physical possibility, few aeronautical visionaries are prepared to admit the feasibility of a 900 m.p.h. airplane, 120 m.p.h. faster than the speed of sound, twice as fast as man has ever flown, nearly thrice as fast as man has traveled on land (see p. 47). But Russian-born Inventor Ivan Eremeef, Philadelphia protege of Orchestra-man Leopold Stokowski, was last week tinkering with a model for just such a craft. Inventor Eremeef's wingless, finned, torpedo-like conception, carrying two small cannon and four hours' fuel supply, would zip 1,000 miles or more to bombard an enemy, could then retreat at a speed faster than some enemy bullets could chase it.

This file is automatically generated by a robot program, so reader's discretion is required.