Science: Out of Thin Air

• Share

The plummeting shriek of bombs was the first warning the Germans had that there was something new over the western front. Thirty thousand feet above the battleship Gneisenau, lying camouflaged at Brest, flew U.S.-built Flying Fortresses manned by the R.A.F. They had arrived through the substratosphere, unheard and unseen in the broad daylight; they had done so because behind each of the Fortresses' four engines were turbo-superchargers, feeding them fat air to breathe in the thin heights. Though the coast below was warm and summery, the planes were frosted over with rime. They cruised serenely above the effective range of ground fire and were on the way home long before German pursuit planes could struggle up to have a go at them.

Thus, literally out of thin air, the turbosupercharger emerged last week as a menace to Hitler's power. It emerged, too, from 22 years of dusty neglect as a belated triumph for its inventor, Dr. Sanford Alexander Moss, 68, who developed the turbo long ago to help beat the Kaiser. As flyers in World War I reached for higher & higher altitudes, they found their engines losing power dangerously. Reason: atmospheric oxygen is as vital an aviation fuel as gasoline. At 20,000 feet, air is only half as dense as at sea level, at 35,000 feet one-fourth as dense. Hence a 1,000-h.p. motor seven miles up will deliver only a puttering 250 h.p. without artificial respiration.

Planes were first supercharged by devices geared to their crankshafts. This saps the engine's driving power. Whimsical, fox-bearded Dr. Moss had a better idea: to harness energy which would otherwise be wasted—the engine's flaming exhaust gases. Drawing on his youthful attempts to devise a practical gas turbine for General Electric, Moss developed a thin-bladed turbine which the exhaust drove at about 20,000 r.p.m., geared this to a blower which shot compressed air into the carburetors at sea-level pressures.

When Moss turned up at Dayton's McCook Field with his turbo in 1918, he met the traditional experience of all inventors: the "glassy eye," as he recalls, of skeptical industrialists and Army brass hats. He took them to the top of Pike's Peak, where a 350-h.p. Liberty motor gave only 230 h.p. in the thin air at 14,000 feet. When Moss cut in his supercharger, the motor roared away at 356 h.p.

Then came the Armistice. Moss's supercharger was forgotten by everyone except a handful of G.E. and Army and Navy air service enthusiasts. The geared supercharger became standard equipment on planes, and in 1938, aged 65, Dr. Moss sadly retired from General Electric. But World War II set flyers again to striving for altitudes incredible in 1917, brought the turbosupercharger and its inventor off the shelf. Today Moss is further improving the turbo (details are military secrets). Last week G.E. was completing a windowless, $5,000,000 supercharger plant at Everett, Mass., and announced plans for a similar $20,000,000 plant at Fort Wayne, Ind. Even if a turbo fell intact into the Nazis' hands today, Dr. Moss thinks it would take them at least a year to begin production of its intricate mechanisms.