Patent GB-788486-A (GB)
Title: Aircraft navigation aid apparatus
IPC: B64D45/00
Filed: 1956-01-27
Abstract: 788,486. Aircraft navigation instruments. SPERRY RAND CORPORATION. Jan. 27, 1956 [Feb. 9, 1955], No. 2752/56. Class 4. [Also in Groups XXXVIII and XL(c)] An aircraft navigation instrument comprises first and second indicating members representing a ground track to or from a station, and the aircraft respectively the relative angular and lateral displacements of the members representing the relative heading and. displacement of the track and the aircraft, wherein the first member has an elongated axis perpendicular to the direction of lateral displacement of the members, and wherein there is provided means for indicating a point (possibly variable) on the axis to represent the station and means to produce relative displacement of the point and the second member, parallel to the axis, to represent movement of the aircraft parallel to the track. In Fig. 4, the instrument comprises a fixed transparent plate 2 bearing a representation of an aircraft 3. Viewed through this is a card 8 over which work crossed pointers 4, 5 actuated by movements 53, 54. The cord and movements are mounted on a yoke 30 rotatable on a shaft 37. In operation, the pilot tunes his navigation receiving equipment (see Group XL(c)) to the frequency of a radio beacon, and turns knob 12 until an indicator 13 shows the bearing. on which the pilot wishes to approach or recede from the beacon. Turning knob 12 rotates the casing of a synchro 43, the stator windings of which are energized by a transmitter coupled to an enslaved gyrocompass. A servo motor 31 is energized by the rotor winding 46, and rotates the winding to the neutral position through gears 33, 34, 35, 36, and 51, this position representing the deviation between the true heading and the desired heading. Shaft 37 is fast to gear 36, and thus the yoke 30 and card 8 are rotated in accordance with the deviation. A pointer 9 on card 8 indicates the deviation on a scale 10. The navigation receiver also supplies a signal representing the difference between the actual bearing of the aircraft from the beacon and the desired bearing set by knob 12. This is fed to movements 53. and 54 to translate pointers 4 and 5 equally across markings 7 to represent horizontal deviation of the aircraft from the track. The navigation receiver also supplies a signal representing the range of the aircraft from the beacon, which is modified by the pilot's sensitivity control and energizes movements 53 and 54 to move the pointers 4 and 5 differentially, whereby their point of intersection 14 moves vertically. Fig. 2a shows the indicator when the aircraft is on the track heading towards the beacon, in Fig. 2b it is over the beacon, and in Fig. 2c it is heading directly away from the beacon. The pilot can also select signals from a localizer beam and glide path transmitter. This energizes a motor 90, Fig. 4, which rotates the movements 53, 54 on gear sectors 93, 94 to render the pointers 4 and 5 parallel, Fig. 2d. The pointers are then displaced together across markings 7 by localizer beam displacement signals from the navigation receiver, and a glide path pointer 11 comes into view and is controlled by a movement 96. An indicator on the instrument shows the pilot whether the receiver is tuned to a localizer beam or to a radio beacon. In the modification of Fig. 8 (not shown), the pointers 4 and 5 are fixed together and move only across the card 8, which is fixed, and the representation 3 of the aircraft is rotatable and movable vertically.