Patent GB-576043-A (GB)
Title: Improvements relating to apparatus for teaching celestial navigation
IPC: G09B9/52
Filed: 1944-03-02
Abstract: 576,043. Teaching navigation. LINK AVIATION DEVICES, Inc. March 2, 1944, No. 3944. Convention date, March 24, 1943. [Class 146 (ii)] [Also in Group XXXIII] A device for teaching navigation comprising a dome-like structure, simulating a portion of the celestial sphere, with means for rotating it at a rate equal to or proportional to the apparent rotation of the real celestial sphere about an observer on the earth, is provided with means for rapidly resetting the dome to any required position upon disconnection of the normal driving means. The normal driving means comprises a constant speed motor 40 to simulate the passage of time, and a variable speed reversible motor 46, to simulate changes of longitude, both driving the dome through a differential gear as described in Specification 576,037. The apparatus is associated with a Link trainer as described in that Specification. The dome, with representations of the stars, is mounted on a hub 244 on a spindle, not shown in Fig. 3, extending into a gear-box which is suspended from an arcuate rail 32 as described in the prior Specification. The constant speed motor 40 and the variable speed reversible motor 46 drive a shaft 50 through a differential gear 44. This shaft drives a gear-wheel 54 rotatable upon the dome spindle, but adapted to be clutched thereto by a slidable cone 102, splined to the dome shaft and movable by a hinged yoke 126 actuated by a slidable cam 120. The cam 120 is linked to a member 192 on the upper end of a second yoke 144 by which a gear-wheel 170 can be clutched to a spindle 154 having a bevel pinion 160 geared to a bevel wheel 150 fixed to the dome spindle. The member 192 is moved by an eccentric 200 on a spindle 196 driven by an electromotor 194 so that as one clutch is engaged the other is disengaged, a neutral position in which both are disengaged being provided for. The gear 170 can be driven in either direction by a motor 182 through the belt and worm gearing shown. The position of the dome is indicated at the instructor's desk by connections to a transmitting device 258 driven from a gear 246 on the hub. The motor 194 is controlled by a three-position switch for selecting the normal, neutral and reset positions of the two clutches. The shaft 196 controls three switches 206, 208, 210, whereby the motor 194 is stopped when the clutches are in the required position and an appropriate signal lamp lighted. In addition, whenever the clutches are in neutral position a signal lamp, visible from any part of the chamber housing the apparatus, is lighted to indicate that the dome may be turned by hand without risk of damage. Also whenever the motor 194 is working, the circuits controlling the motors 46 and 182 are broken. As an additional precaution against damage, the pinion 160 is secured to its shaft 154 by a pin which readily shears should an undue resistance to rotation of the dome be encountered. The motor 182 is controlled by selecting tappings on an autotransformer and by a reversing switch. Specifications 370,128 and 481,375, [Group XXXIII], relating to Link trainers, also are referred to.