Refuelling in Flight: The Background to Refuelling in Flight and a Description of Techniques and Equipment Currently being Developed by Flight Refuelling Ltd.

EVER since the inception of the hcavier‐than‐air flying machine, the need to refuel in flight has been apparent. The cartoon reproduced in fig. 1 was first published in Punch in 1909, at a time when the payload of the aeroplane was very small, due to the large tare weight of the airframe and engine. Present day aircraft have a much higher payload capability, in relation to tare weight, but it is still necessary to carry the energy for propulsion within the aircraft, with the result that long range can only be achieved at the expense of payload. The propulsion energy in orthodox aircraft has always been carried in the form of hydrocarbon fucls,bccause of their ready availability, high calorific value per pound weight and high calorific value per cubic foot. Work has been in progress for some years to develop solid fuel conversion, in the interests of saving weight and space, but such fuels are likely to be extremely expensive and potentially dangerous to handle. However, the problem remains that a consumable fuel source must be carried in the aircraft, with consequent reduction of payload or range. The use of nuclear engines for aircraft has been contemplated, but it seems probable that the weight of shielding and coolant, associated with this type of engine, will limit its use to very large aircraft.