Patent GB-755408-A (GB)
Title: Improvements relating to signalling systems for aircraft
Inventor: LOBELLE MARCEL JULES ODILON
IPC: G08B5/40
Filed: 1954-12-10
Abstract: 755,408. Visible signalling apparatus; code signalling-mechanisms. M.L. AVIATION CO., Ltd. Dec. 10, 1954, No. 35856/54. Class 118(2) Apparatus t o r injecting powder into the jet-pipe of a jet-propelled aircraft for the production of a smoke signal comprises a number of containers arranged to inject their contents into the jet pipe under pressure exerted by compressed a i r controlled by a selector whereby t h e containers may be caused to inject their contents in a sequence such as to give a required signal. Four cylinders 1, each containing a suitable smoke-producing powder, are arranged to discharge into a common neck 2 and thence through a short pipe 4 into the main jet pipe 5. Each cylinder 1 has a piston (Fig. 3, not shown) which can inject the powder from the cylinder when compressed air is admitted to the top of the cylinder by operation of the appropriate selector valve 33. When some, or all, of the cylinders have been discharged no further operation is possible until they have been reloaded, which has to be done on the ground at the end of a flight. Because of the high temperature in jet pipe 5, the mounting of the device is so constructed as to allow for expansion in any direction. The selector valves 33 are electro-magnetically operated as indicated at 43 in Fig. 4. The valves 43 are operated in a desired sequence by means of a control disc 44 which is driven round in steps by a mechanically coupled homing disc 58. A projection 45 on disc 44 makes contact at each step with one of eleven terminals 46. Valves 43 may be connected by means of selector switch 53 to selected ones of terminals 46. When main switch 57 is closed potential from battery 55 is fed to disc 44, and on pressing start switch 62 impulsing relay 64 is caused to make and break its circuit by contact 63 which also feeds impulses to the operating magnet 67 for driving disc 58. As soon as disc 58 has made one step potential is fed to the impulsing relay 64 from the wipers 59 even if switch 62 is opened. Thus disc 58 continues to step round until wipers 59 again lie in the recesses as shown in the Figure. Thus on pressing switch 62 the disc 44 makes one complete revolution and projection 45 operates valves 43 in the sequence selected by switch 53. A gap of two steps, that is, two of the terminals 46 not being connected through to valves 43, produces a space between smoke puffs, while operation of three selector valves by successive terminals gives a long smoke signal forming a dash. As shown, position 1 of selector switch 53 corresponds to a signal of four dots, position 2 to three dots, position 3 to. two dots, position 4 to one dash, position five to a dot and a dash and position six to a dash and a dot. The speed of rotation of disc 58 is controlled by a variable resistance 69 coupled to the air speed registering instrument in the aircraft so as to vary the time constant of the circuit of relay 64, thereby making the spacing between the dots and dashes of the signal independent of the speed of the aircraft.