Science: Fuel in Flight

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Every airminded schoolboy has wondered why airliners do not refuel from flying tankers. The advantages (longer range, lighter takeoff, bigger payload) are obvious. Today an airliner labors off the ground carrying fuel for the whole flight, though it will not need most of it for the first thousand miles or so.

Last week, Flight Refuelling Ltd., a British company, was about to test flying tankers on the air's toughest main line: the stormy, midwinter North Atlantic. If the trials (scheduled for this month) are successful, refueling may eventually come into general use on long-distance airlines.

Flight Refuelling Ltd. has ten specially trained pilots, four Lancaster bombers converted into tankers, and a set of gadgets which Managing Director Sir Alan Cobham, 53, pioneer refueling fan, believes have eliminated the dangers and difficulties of refueling. Among the most important is a system of electronic beacons with which the planes can find one another, even in soupiest weather.

High Harpoon. When a tanker flies alongside a "receiver" (the plane to be refueled), the receiver lets out a slender line that floats behind in a graceful dropping curve. The tanker fires a kind of harpoon-gun, which shoots another line to tangle with the receiver's line. Clawlike devices on the two ends lock together. The receiver hauls in both lines. Next comes a fuel pipe filled with nitrogen gas to minimize danger of explosion. Then comes gasoline, flowing by gravity at 100 gallons a minute. The tanker can supply up to 2,000 gallons.

After this dragonfly mating, the hose is flushed out with nitrogen and hauled back to the tanker. The contact lines part at a special "weak link" and are hauled in.

Promising Trial. Last summer the flying tankers, rising from a field in the Azores, refueled 21 nonstop flights from London to Bermuda. Every contact went smoothly. If the North Atlantic trials show the same excellent performance, Sir Alan predicts that many airlines will adopt his system.

As for savings and advantages, a refueled Tudor V (British South American Airways Ltd.) could take off from Lisbon with 44 instead of the present 26 passengers, and only 800 gallons of gasoline. In the air it could get more gasoline from a tanker and fly toward Dakar, where another tanker would give it enough fuel to fly on to Natal. The airline could collect 18 extra fares and scrap its expensive Dakar base (passengers would be spared the yellow-fever shots required for a stop at Dakar).

Military airmen are watching the experiments closely. Jet engines (necessary for the new high speeds) have cut the range of bombers. The strategic bombing missions of World War III may have to use flying tankers, rising from forward bases and meeting the bombers part way to their faraway targets.