Patent GB-868818-A (GB)
Title: Apparatus for visually indicating the translatory motion of helicopters
Inventor: KENYON THEODORE WHITMAN
IPC: B64D45/00
Filed: 1959-01-22
Abstract: 868,818. Aircraft instruments. KENYON LABORATORIES Inc. Jan. 22, 1969, No. 2418/59. Class 4. Apparatus for indicating visually the translational motion of a helicopter an endless belt provided with indicia and driven by a motor generator set, an electric circuit including the motor and generator for controlling the band, and means in said circuit for modifying the input to the motor in dependence on the inclination of the swash plate. Fig. 7 is a plan view of an indicator 15 in which rollers 19, 20 supported in a frame 16, support endless wires 22, 23, between which extend bars 24. Further rollers 19<SP>1</SP>, 20<SP>1</SP> similarly supported, support endless wires 22<SP>1</SP>, 23<SP>1</SP> between which extend bars 24<SP>1</SP> at right angles to bars 24. The rollers 19, 19<SP>1</SP> are driven by motors 25, 25<SP>1</SP> in accordance with the horizontal components of aircraft yelocity, so that a pilot looking at the indicator sees a rectangular array apparently moving in the same direction relatively to the fuselage as the ground does or would appear to move. The frame 16 is filled with a liquid of high refractive index, which facilitates the illusion that the two sets of bars appear as a single rectangular array, and enables the bars to be seen from a wider range of positions. The bars are dark, and viewed against a light coloured plate. The bars are arranged horizontally in the aircraft, and a third set of bars may be similarly mounted and movable in a frame attached to frame 16, so that these bars move vertically in accordance with the vertical speed of the aircraft. Fig. 17 shows a schematic diagram of the electrical circuits used in a helicopter instrument. A transistor amplifier Tr L, described in Fig. 18 (not shown), provides an output at T, to drive one set of bars in frame 16 forwardly or rearwardly in accordance with the fore-and-aft velocity of the helicopter. Input data is fed to the amplifier by rotating the shafts 39, 40, 48, and 52 of potentiometers (not shown), within the amplifier. Shaft 39 is rotated by inclination of the swash plate about a transverse axis, or by the corresponding movement of the cylic pitch control. Shaft 40 is rotated by pitching movements of a gyro vertical 62. Shaft 52 is rotated in accordance with wind data, set by the pilot or provided automatically by received radio signals. A further input (not shown), to the amplifier is provided by a generator driven by the motor which is energized by the amplifier. The result is that the application by the pilot of fore-and-aft cyclic pitch, or pitching of the helicopter, either of which result in fore-and-aft translational movement of the helicopter, produces fore-and-aft movement of the laterally extending indicator bars, this movement being connected for wind. Shaft 48 is rotated in accordance with air speed or altitude or both, so that the higher the altitude, the more slowly the bars move, to reproduce the apparently slower passage of the ground at altitude. The fore-and-aft extending bars are moved laterally in accordance with the output at T<SP>1</SP>, of amplifier Tr T, the arrangement being as described for the first set of bars, except that tilting of the swash plate about a fore-and-aft axis, and roll signals from the gyro vertical, control amplifier Tr T. An amplifier Tr V has an output at T<SP>11</SP>, controlling the speed of the vertically moving third set of bars in frame 15a, the amplifier being controlled by an altitude responsive device V, a rate of climb instrument Cr, any desired information available at a radio receiver Rs, and airspeed and/or altitude signals as used for amplifiers Tr L and Tr T. A centre zero indicator 71 is also energized by the out put at T1<SP>1</SP>, to assist the pilot in preventing lateral deviations from a straight path. The gyro vertical may be mounted in the fuselage or on the swash plate. One way of controlling shafts 39 and 39<SP>1</SP> by tilting of the swash plate is shown in Fig. 4. A bracket 55 on the rotor pylon 56 supports a potentiometer R 1 , in amplifier Tr L, whose shaft 39 is attached to a gear wheel 57 engaging a rack 58 having an abutment 59 urged by a swing 60 to contact the swash plate 12. Tilting movements of the swash plate are followed by the rack, and hence by the potentiometer arm. Similar apparatus controls shaft 39<SP>1</SP> of a potentiometer in amplifier Tr T.