Soup, All Flavors

Last week the U.S. felt that it could afford to turn down an opportunity to make the best aircraft engine that Britain has yet devised. This did not mean that the U.S. already has the best air craft engines in the world-- far from it. But it meant that, rightly or wrongly, responsible officials thought the U.S. engines now coming up were so promising that it would be foolish to try experimenting in new fields.

This belief of U.S. officials made a sad man, a man with cool heels, of an engineer named Alex Taub. A British-American, a Chevrolet man who went to work for Vauxhall Motors Ltd. (the General Motors in Britain), Mr. Taub returned to the U.S. last December with a mission and three specimens of a whang-dinging good British aircraft engine. The mission: to persuade the U.S. to manufacture the engines in quantity. The engine: Napier's 24-cylinder, 50-horsepower, inline, liquid-cooled Sabre (TIME, May 5).

By this week, wispy, earnest Engineer Taub was ready to give up. Best the U.S. could do was offer to manufacture a few Sabres for experience. For the rest, Britain would have to lean on its own productive plant for its supply of the sensational new engine. One reported reason for this cold shoulder was that British bigwigs in the U.S. did not want to complicate their purchasing with a new item. Another was that the services and OPM thought they had good enough engines now, better ones being made, still better ones in the works.

U.S. engine builders and aircraft design ers were up to their hips in a great war of horsepower-- a technical war that may well win or lose World War II. Pinched for machine tools, already well along on designs for tomorrow's engines, they had no time for a new engine that would also call for new/plane designs.

Whatever the merits of Alex Taub's quest, the Sabre, already flying in the formidable Hawker Typhoon fighter, was a fair symbol of the horsepower race. Well knowing that there is no substitute for "soup," British designers had gone all out after horsepower. The Sabre turns up nearly twice the horsepower of the old British pursuit engine, the 1,200 horsepower Rolls-Royce Merlin (which Packard is still tooling up to make for Britain and the U.S., under a $187,500,000 order). But the U.S. is hot after horsepower too: it already has 2,000-to-2,200 h.p. engines flying. And last month in London, Pan American Airways President Juan Terry Trippe let it be known that U.S. engine manufacturers, now going into production in the 2,000-2,200 h.p. range, are developing aircraft engines of 3,000 h.p.

Radial or In-Line? While the fundamental problem in the engine-design race is to get more horsepower, the race is being run with two kinds of mounts. One of them, best known to U.S. citizens, is the air-cooled radial, an engine with one or two (and next year, more) banks of cylinders ranged spokelike around a central crankcase. The other is the liquid-cooled, with the cylinders ranged in rows of six along a longer crankcase in two banks (like the Merlin or a V-type auto engine), or four (like the Sabre). Basic virtue of the air-cooled engine is that it is simpler (therefore easier to maintain), less vulnerable to gunfire (no bullet can drain the cooling system), tends to be lighter. Basic virtue of the liquid-cooled is that, where the radial is broad-on to the wind, it noses into it, is therefore easier to streamline.

Thus, for the practical fighting purposes of World War II (as defined by the British) the No. 1 function of U.S. radials is to power bombers. As far as Britain is concerned, stepping up radial horsepower has meant constantly lengthening ranges, constantly increased speeds for U.S. light, medium and heavy bombers, which Britons admit are the best in the world. Except for some last year's U.S. pursuits, Britain has stuck to liquid-cooled engines for first-line pursuit planes. Latest British pursuit is the Sabre-powered Hawker Typhoon, which can easily outrun 400 miles an hour, carrying plenty of cannon and machine guns into the bargain.

F4U v. P-40. One outfit that does not string along with the British doctrine on fighters is the U.S. Navy. The Navy sticks to air-cooled engines for fighters as well as for bombers. And soon after Pratt & Whitney came out with its 2,000-h.p. engine, the Navy too could point with pride. Its pride was the Vought-Sikorsky F4U, a plus-400 m.p.h. speedster (now being worked over for "bugs" before being put into production). The Vought-Sikorsky fighter may well be a milestone in air-cooled manufacture. Its big radial engine is cowled to cut its head resistance to the irreducible minimum. The plane's speed and fighting ceiling (around 37,000 feet) showed that its design had overcome most, perhaps all, of the air-cooled's fundamental disadvantage.

For thus smoothing the drag of what liquid-cooled men scornfully call a "waffle-iron" engine, top credit went to the engineers of National Advisory Committee for Aeronautics at Langley Field, Va. Dr. Jerome Clarke Hunsaker, famed aeronautical engineer and head of M.I.T.'s aviation department, seeing what had been done, had a broad conclusion to draw, which "waffle-iron" men heard with joy. Said he: "Recent research has shown how to streamline installation of air-cooled motors so that their resistance to forward motion is no greater than that of a liquid-cooled engine of the same output." Since Dr. Hunsaker is a member of NACA and privy to its secret research work, plane designers listened with respect.

While the Navy held to air-cooled for its pursuit ships, the Army Air Corps (now The Army Air Forces) in 1939 turned to liquid-cooled, subsequently laid down $190,000,000 in contracts for the 1,090 h.p. 12-cylinder Allison, manufactured by General Motors. Among the planes it got for its Allison money were a couple of notable dandies: the Bell Airacobra and the twin-engined Lockheed. Airacobra, with 1,090 h.p., ticked off close to 400 miles an hour, is a pilot's airplane to boot --handy and maneuverable. The Lockheed, driven by two Allisons, topped 400. Allison has since twice stepped up the horsepower of its 12-cylinder engine, once to 1,150, then to 1,325. Today, at Allison's Indianapolis plant, where 400 engines were produced in May, the production is being turned into 1,325 h.p. jobs. What they will do to step up the performance of the Bells, Lockheed and Curtiss P-40s is a secret The Army Air Forces keeps religiously.

Even with all the improvement in Allison's output, however, it is still far short of the air-cooled horsepower top. Few weeks ago the Army hedged its liquid-cooled bet, put down $56,500,000, the biggest pursuit plane order in its history, for a brand-new plane, the Republic P-47, built around Pratt & Whitney's 2,000-horsepower air-cooled engine. Souped up by a brand-new and secret supercharger, P47 may well be the fastest, highest-riding pursuit plane in the world, with a fighting ceiling above 35,000 feet, a top speed well above 400 m.p.h.

3,000 Horsepower? Where design will go next is anybody's guess. Because the engine design comes first, the plane next, this year's engine must go into next year's plane. Thus this year's 2,000-h.p. radials will not power Republic and Vought-Sikorsky airplanes in production quantities until 1942. And for 1941, British and U.S. pilots flying the latest U.S.-made fighter planes will shove the throttle on last year's engines--power plants ranging from 1,000 to 1,350 horsepower.

Next year's air-cooled engine (for 1943's planes) seems likely to be the 3,000 horsepower radial. Among liquid-cooled makers, Lycoming and Continental are working hard on engines that some airmen hope will be good for pursuit. Henry Ford is plugging at two different high-powered, liquid-cooled engines (besides air-cooled Pratt & Whitneys, which he is making on contract). Allison has been long at work on a 24-cylinder, liquid-cooled engine that should develop around 2,400 h.p. The experimental Allison's cylinders are grouped in a W over two-geared crankshafts. Napier's Sabre is built into an H over geared shafts, is thus narrow for its power.

Today U.S. aircraft manufacturers are getting air-cooled engines about as fast as they can put them into planes. Combined output of Pratt & Whitney and Wright is about 2,900 engines (2,850,000 horsepower) a month. The supply will be stepped up more than 2 for 1 after Ford, Buick and Studebaker come into production late this fall with their air-cooled engine plants, will jump again when Chevrolet starts producing radials by the fall of 1942. Allison, with production-slowing difficulties now apparently licked, has big production in sight, hopes to catch up with plane production by fall.

To the average U.S. citizen, this engine competition spells good enough news. Interested in the air-cooled v. liquid-cooled controversy only as a healthy contest, all he wants to see is U.S. planes that will fly faster, higher and farther than anything anyone else can make. In the bomber field, the U.S. is already there. Among the fighters, its P47 may be there, or nearly. At the great horsepower training table, in short, U.S. plane designers are getting plenty of soup, whatever the flavor.

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