Patent GB-971881-A (GB)
Title: Apparatus for supporting and holding foldable rotor blades of helicopters
IPC: B64C27/50
Filed: 1962-11-30
Abstract: 971,881. Supporting folded helicopter blades. SUD-AVIATION SOC. NATIONALE DE CONSTRUCTIONS AERONAUTIQUES. Nov. 30, 1962 [Dec. 22, 1961; May 28, 1962], No. 45418/62. Heading B7W. [Also in Division E2] Means for supporting the folding blades of a helicopter comprises a clip for each blade, each clip having an upper and a lower jaw engaging the blade, and being carried by a support transmitting the weight of the blade to the fuselage, all or all but one of the supports being pivoted with respect to the fuselage, the blade being pivotally connected to the rotor hub. In Fig. 2, the rotor is arrested with one blade P 1  extending over the tail boom A, the blade clip 5 being supported by two struts attached to the boom by quick-release fastenings 25 (see Division E2). The other blades P 2  are attached to the hub by two pins, of which one can be removed to enable the other pin 4 to act as a folding hinge. Each clip 5 of these blades is supported by a strut 8 connected to the fuselage by a quick release balljoint at 39 (see Division E2), preferably located on the axis of pin 4, so that the blade can be swung between its folded and unfolded positions while supported. A tie cable (not shown) is connected to each clip 5 and extends in a loop round a pulley on the associated pin 4, so that the cable can drop from the pulley when relaxed. A link 46 is universally jointed at 47 to strut 8, and is attached at its free end to the tail boom by a quick-release joint (see Division E2). If joint 39 is not on the axis of pin 4, but is nearly so, strut 8 is telescopic, the two parts being urged towards an extended position by a spring. The strut may be in two readily releasable parts (see Division E2). If joint 39 cannot be on or near the axis of pin 4, the construction of Figs. 12 (elevation) and 13 (plan) is used. The lower end of the strut is in two telescoping parts 70, 71 connected by a pin 72 and slot 71a. Part 71 is pivoted by pin 78 to an arm 79 which can swing about pin 81 in a support 82a extending from the fuselage. A cable 83 extends from anchorage 85, between pulleys 80 on arm 79, round pulley 77 on pin 78, and round pulley 74 on part 71, to pin 72. Arm 79 lies directly over support 82a when the blade is mid-way between its folded and unfolded positions. On either side of this position, the pulleys 80 take up the cable, thus extending parts 70, 71 and lengthening the strut, and if the geometry of the system is appropriately chosen, the lengthening of the strut enables the blade to swing substantially in a plane perpendicular to the axis of pin 4 even though the strut hinge (i.e. the intersection of the axes of pins 78, 81) does not lie on the axis. Fig. 5 shows a blade clip 5, comprising jaws 9a, 10a, with shaped face-plates 9b, 10b, lined with felt or foam rubber 9c, 10c. The jaws are pivoted together at 11, and jaw 9a is connected to its supporting strut by pin 20. A tension spring 12 urges the jaws to the open position, but the jaws are held closed by a toggle linkage 15, 16 in an over dead centre position. A pull-on member 19 breaks the toggle so that the jaws spring open.