Patent GB-731353-A (GB)
Title: Improvements in and relating to flying controls for aircraft
Inventor: MORRALL JOHN WILLIAM
IPC: B64C13/24
Filed: 1952-01-31
Abstract: 731,353. Controlling aircraft. BOULTON PAUL AIRCRAFT, Ltd. Feb. 2, 1953 [Jan. 31, 1952], No. 2635/52. Class 4. An aircraft flying control has means for varying the datum position relative to which the control surface is movable by the pilot's control member, said means comprising a turnbuckle or the like, rotatable under the control of the pilot to vary the length of a link between the control member and the control surface. In Figs. 1 and 2 is shown an application to the elevons of a tailless aircraft, the upper control being for the starboard elevon, and the lower control for the port. The link 6 in the control transmission of each elevon is split, and to each part is pivotally secured the head 3 of oppositely threaded shafts 2, both adapted to be received by an internally threaded, externally splined shaft 1 whose splines are engaged by internal splines on the elongated boss 14 and 15 of a worm wheel 16, permitting axial movement of the transmission. The worm wheels for both elevons are driven by an electric motor (not shown) preferably controlled by push buttons on the pilot's control column, through a universal joint 27, an overload release clutch 25, and bevel gears 20, 21. The starboard worm wheel is driven directly from shaft 18 attached to bevel gear 20, and the port worm wheel drive is taken from this shaft by bevel gears 32 and 29. A shaft 28, Fig. 2, mounts the worm for the port elevon, and has on it a freely rotatable bevel gear 29 meshing with an idler bevel 30, which meshes with bevel 32 fixed to shaft 18. Mounted on shaft 28 with axial freedom is a clutch unit with pins 37 adapted to engage either bevel 32 or bevel 29. As shown in Fig. 2, there is a direct drive between shafts 18 and 28, bevel 29 running idly on its shaft. When the clutch unit is shifted so that it engages bevel 29, freeing bevel 32, a reversed drive is obtained through gears 32, 30 and 29, and the clutch unit to shaft 28. Thus the datum position of the elevons may be varied for their action as either elevators or ailerons. The position of the clutch unit is controlled by lever 39, Fig. 1, fast to shaft 40 operated by bell crank 46, 49, and rod 51. This rod is actuated by an electric device 53, operated by the pilot. Rod 51 bears a pivotally mounted lever 57 pivoted at one end to the rod 59 resiliently positioned by spring box 60, and adapted by its other end to operate a microswitch 54, which ensures that current is not supplied to the motor operating the turnbuckles, when the elevons are set to operate as ailerons, until the rod 51 is fully actuated and clutch 36 in its correct position. The extended bosses 15 of each worm wheel 16 are externally threaded, and carry collars 69 (see port elevon control), on which are mounted two micro switches 63, 64 (see starboard elevon control) adapted to be operated by contacts 65, 66, to switch off the motor when the datum shift has reached its maximum permissible value in either direction. Members 72 with end flanges 73, 74 also act as mechanical limit stops. Specification 730,010 is referred to.