Patent GB-676430-A (GB)
Title: Improvements in apparatus for towing and refuelling aircraft in flight
IPC: B64D39/00
Filed: 1949-04-01
Abstract: 676,430. Aircraft flight refuelling and/or towing apparatus. FLIGHT REFUELLING, Ltd., COBHAM, A. J., Sir, NEEDHAM, C. H., LATIMER-, SMITH, C. H., and MACGREGOR, P. S. April 27, 1950 [April 1, 1949; Sept. 16, 1949], Nos. 8887/49 and 23956/49. Class 4. [Also in Group XXVIII] Airborne apparatus for flight refuelling or / and for picking up and casting off a tow in flight comprises in combination on a first (leading) aircraft a trailed element, such as a flexible hose or hawser, or jointed or telescopic pipe or rod, of which the terminal portion at least is caused to trail substantially in the line of flight and yieldingly to resist forward pressure applied to it externally from behind, and on a second (following) aircraft a rigid element, extending forwardly substantially in the line of flight, which element may have an internal fuelconveying passage, the two elements terminating in the cooperating parts of a self-engaging plug and socket coupling, of which the plug part has a tapered portion and a circumferential groove, and the socket part has a tapered throat and flared mouth and carries spring-loaded latches resiliently engageable with the groove of the plug part. In the refuelling arrangement shown in Fig. 1 a hose 32 is trailed from beneath the fuselage of the leading aircraft 30 and terminates in the socket 33 which is engaged by the end of the plug or probe 34 at the nose of the fuselage of the following aircraft 31. The socket 33 is provided with a flared portion serving as a drogue to stabilise the end of the trailed element and also to develop sufficient resistance to the thrust of the probe to enable the spring latches to be engaged. Fig. 11 shows a modification in which the plug portion 60 of the coupling is carried at the end of the trailed hose 32 and the socket portion 121 is fitted at the front of the probe 34. Instead of being in the form of a flexible hose, the trailed element may be composed of a number of articulated rigid elements, Fig. 3 (not shown), liquid-tight joints, Figs. 5-7 (not shown), being provided at the joints. The hose or similar element may be trailed from the fuselage or wing tip of the leading aircraft, while the probe may project from the fuselage nose or wing tip of the following aircraft. Details of the hose coupling are shown in Fig. 8, the socket member 59 being connected to the end of the hose 32 by a ball joint 61, and the drogue portion 33 forming a flared mouth for the guidance of the end of the probe 98. The throat of the socket portion is normally closed by a valve 85 loaded by a spring 85b, and the end of the probe is closed by a hydraulicallyactuated mushroom valve 88. In operation the pilot of the following aircraft inserts the end of the probe into the mouth of the trailed socket. the resistance of the drogue portion 33 enabling the rollers 69 of the spring-loaded latches 68 to be engaged with the circumferential groove 60b at the end of the probe. Pressure fluid is then supplied through a pipe 95 to move the mushroom valve 88 from its seating and thus unseat the socket valve 85, to establish fuel-transmitting communication between the hose 32 and the interior of the probe 98, past webs 86, the pressure of the fuel being transmitted by pipes 84 to cylinders 79, pistons in which move pins 82 into position to effect positive locking of the latches 68 to prevent separation of the coupling elements. At the end of refuelling, pressure fluid is supplied to a pipe 96 to close the probe valve 88, the valve 85 being closed by the spring 85b, and upon closing the fuel supply valve the pins 82 are withdrawn from the latches 68, which can then be disengaged from the probe by applying a predetermined tension to the coupling elements, for example, by reducing the speed of the following aircraft. The axial force required to disengage the latches is greater than that required for their engagement, and this is obtained by appropriate shaping of the tapered portion and groove at the end of the probe. Instead of being fixed rigidly the probe may be mounted on the following aircraft by a ball joint, centring being effected by spring-loaded pistons, Fig. 10 (not shown). Alternatively the probe may be telescopic and capable of being projected forwardly from a normal retracted position within the following aircraft to effect engagement with the coupling socket, Figs. 20- 23 (not shown). An arrangement intended for towing purposes without refuelling is shown in Fig. 13, and comprises a socket member 59 trailed from the end of a cable 32x. The latch levers 68x are loaded by spring plungers 75, and the end of the probe 98 is formed with a hydraulic or pneumatic cylinder 133 housing a piston 135 carrying a forwardly-extending locking bar 137. In operation the probe is engaged with the socket and the latch rollers 69 engaged in the normal manner, after which pressure fluid is supplied to the cylinder 133 to advance the bar 137 which engages further rollers 130 on the latch levers to positively lock the latter. Upon exhausting the cylinder 135 the bar is withdrawn by a return spring 136, to allow disengagement of the rollers 69 by the application of axial tension. The hose or cable is wound on a windlass, the drum of which is subjected continuously to a torque less than that imposed by the drag of the drogue and tending to wind in the trailed element, so that any slack in the latter is taken up when the probe is pushed into engagement with the coupling socket. A warning light visible to occupants of the following craft and controlled by means responsive to extension of the trailed element may be fitted, such light being illuminated when the trailed element is fully extended.