Patent GB-359574-A (GB)
Title: Improvements in or relating to apparatus for discharging fluid from aircraft
IPC: G09F21/16
Filed: 1928-03-26
Abstract: 359,574. Smoke-producing apparatus. PURVES, R., Air Ministry, Adastral House, Kingsway, London, and STEWART, C. J., Royal Aircraft Establishment, South Farnborough, Hampshire. March 26, 1928, No. 9077. [Class 81 (i).] An apparatus for discharging a fluid from an aircraft especially for producing smoke screens comprises a container 2, Fig. 1, divided into two compartments for holding the liquid and compressed air respectively, a pipe system 9, 10 connecting the two compartments and provided with valves for controlling the supply of compressed air to the fluid compartment, a pipe line 3 extending aft from the fluid compartment and provided with a discharge nozzle 4 and a discharge cock 5, and means 6 for controlling the discharge cock from the pilot's cockpit. As a modification, the compressed air may be in a container separate from the liquid container and housed in the fuselage or in the wings. The air compartment 7, Fig. 3, is at the front end of the container 2 and is provided with a union 29 having a branch 30 connected to the pipe 9. The union contains a high pressure stop valve 12, Fig. 10, the stem 33 of which screws in a bush 34 fitted with packing 39, the bush 34 being itself screwed into the union and secured in place by a set-screw 37. This valve must be opened before the aircraft starts its flight, and when fully opened forms a tight joint against a seat 35 in the bushing 34. The pipe 9 leads from the union 29 to a pressure reducing valve 11, Fig. 9, which is controlled by the action of the reduced air pressure underneath a diaphragm 16 loaded by a spring 17 adjusted to the desired pressure by a hand-wheel 18. The pad of the reducing valve 11 is fitted to a plug 24 which screws into the hollow stem 15 of the diaphragm 16 and is secured in place by washers 26, 28 around the square shank of the screw plug. Below this valve, a relief valve 21 is provided, the loading spring 22 of which is adjusted by a screwed thimble 23. The high and reduced pressures are indicated by gauges 19, 20 respectively. The low pressure air from the valve 11 passes through a low pressure stop valve 13 within reach of the pilot and through a non- return spring-controlled ball valve 43 to a pipe 10, which leads to a three-way connector 51, Fig. 3, on the air inlet pipe of the fluid compartment 8, the third way of the connector 51 being a vent normally sealed by a screw cap with a lead washer. The inner end 49 of the air inlet pipe is at the top of the compartment, and at the bottom of the compartment is the beginning 48 of the discharge pipe 3. The compartment is also fitted with a heating coil 50. The discharge cock 5, Fig. 12, is pressed against its seat by a spring washer 62 and is stopped in its open and closed positions by projections on the inside of the cover 157. The stem of the valve rotates in a gland box 59 screwed against a lead washer 54 and secured in place by a set-screw 61. A lever is attached to the valve stem by a bolt 64 and is connected by cables 65, 66, Fig. 1, to a winch 6 concentric with a hand-wheel 67 in the pilot's cockpit. The cables are adjusted by a turnbuckle. The discharge nozzle 4 is provided with a drip stopper 70, Fig. 24, pivoted at 82 on a lever 71 fulcrumed at 74 in a slot 75 and pivoted at its other end 77 to a three-armed lever 73, which is connected by cables 80, 81 to the pilot's cockpit. The levers 71, 73 form a toggle which is kept in the closed position (full lines) and in the open position (dotted lines) on either side of a dead-centre by a tension spring 72, the arrangement being such that at the point of closure the stopper moves along the axis of the nozzle. In a modification, the discharge cock is situated near the container 2 and is operated by a worm gear connected by cables to the winch 6 in the pilot's cockpit; and the cables 80, 81 for operating the drip stopper are connected to a lever coupled by links to another lever worked by one of the cables of the winch 6 in such a way that the stopper is opened before the discharge cock opens and is closed after the closure of the discharge cock. The plug of the discharge cock may be of stainless steel. The discharge pipe 3 may be of steel and is built up in sections connected by joints sealed by a lead ring fitting in a circular recess in one part and pressed by a circular projection on the other part. When the sections are disconnected, they are closed by plugs sealed by similar lead ring joints. Similarly, the outlet of the stop cock 5 may be closed by a cap 130, Fig. 22, fitted with a lead washer 54 and operated <3> by a screw 131 in a clamp provided with jaws 132 for engagement with the flange of the stop cock. The gland box 59 of the stop cock may also be covered by a cap fitted with a lead washer and screwed to the body of the stop cock. The sections of the pipe 3 are secured to the aircraft by struts 97, Fig. 1, and brackets 100, the sections being detachably clamped to the struts and brackets, the struts being attached to the bottom longerons of the aircraft by vice screw fittings, and the brackets 100 being attached to wooden cross members added to the fuselage for this purpose. The pipes 9, 10 are also made in three sections detachably connected together by unions at 9a, 9b, 10a, 10b. The container 2, Figs. 1 and 27, is positioned by bands 84, 85 thereon against a torpedocarrying crutch 83, and a strap 86 is used for the rearward end of the container. The crutch and the strap are steadied by diagonal transverse tie-rods and the fuselage is reinforced by fore and aft tie-rods 88. The container is supported by slings 91, 92 fitted with turnbuckles 93 and carried by the top and bottom longerons 89, 90 in conjunction with cross tubes 95, 96 and fore and aft thrust members 94. For loading or reloading the container 2, the pipe 9 is detached from the union 29 and this is connected by a pipe 31, Fig. 2, to the distributer 102 of air storage cylinders 32 ; the vent of the connector 51 is unsealed and connected to a rubber hose 108 leading away from the aircraft or to an overflow receptacle 111 ; and the discharge nozzle is replaced by a supply nozzle 107 connected by a flexible pipe 106 to the siphon 105 of a drum 104 containing the liquid and connected by a pipe 110 to a reducing valve 103 on an air cylinder 101. During the loading operation, the container 2 is made to lie in an approximately horizontal position by levelling the aircraft by means of a trestle 109 placed under the tail of the aircraft. For successful production of smoke curtains, the velocity of discharge should be approximately equal to the speed of the aircraft.