Improvements relating to towing devices for aircraft with particular reference to tow cable tension control

摘要

552,749. Towing. KRONFELD, R. Oct. 21, 1941, No. 13514. [Class 78 (ii)] [Also in Groups XXXIII and XXXV] A towing device for aircraft, drogues or targets includes means responsive to variations in the tension of the tow rope for automatically restoring the tension to its predetermined value. Fig. 1 shows the tail end of a towing aircraft carrying a fitting 3 slidable along a bar 11 against the tension of a spring 10. The towing cable 2 is connected to the fitting 3 by a quick-release device 4 and the fitting 3 is connected by a cable 5 to the throttle control so that an increase of tension in the cable 2 causes a reduction of the throttle opening. The cable 5 is connected to an intermediate member-such as a toothed wheel to which the throttle lever can be coupled by a spring pawl. The elevator or screw-pitch control may be actuated by the variations in cable tension. Alternatively the cable may be passed over a pulley and around a winch which is driven by a reversible electro-motor or hydraulic motor to wind up or pay out the cable as the pulley is displaced against centring springs by the variations in the tension of the cable. Fig. 4 shows the two sections 2a, 2b of a towing cable of a glider connected through springs 29, 30 to quick release points 31, 32 on the wings, and by extensions of these cables to air brakes 27, 27a, so that relaxation of tension in either cable results in the air brake being raised. Actuation of the quick release devices also moves catches for retaining the air brakes in their inoperative position. Where electric transmission is used the tension spring assembly may actuate the controls of both the towed and towing aircraft.