There have been many proposed, but few practical, methods of refuelling in flight since the first early experiments in 1923, and until some three years ago the only tried and accepted method was the “ looped hose ” system developed since 1934 by Flight Refuelling Limited, and still in use (with British equipment) by the United States Air Force.

This system consisted, briefly, in carrying a hose unit with a capacity of some 230 ft. of hose in the tanker aircraft, and a hauling line and windlass in the receiver aircraft. Operators were employed for both tanker and receiver aircraft.

To make contact between the aircraft, the receiver operator first trailed his hauling line, with a “ sinker ” weight on the end of it, so that the line curved downwards. The tanker aircraft then flew alongside and a projectile, attached to a “contact line,” was fired from a line–throwing gun, so as to pass the contact line under the hauling line.