871,050. Rotary wing aircraft. HILLER AIRCRAFT CORPORATION. Jan. 1, 1959 [Jan. 17, 1958], No. 36/59. Class 4. [Also in Group XXV] A rotary wing aircraft comprises a generally upright main body chassis on which a rotor column is mounted, rotor blades hingedly connected to the column, and landing gear hingedly connected adjacent the bottom of the chassis, the rotor blades and landing gear being pivotable to lie substantially parallel to the axis of the chassis and to the axis of rotation of the rotor. The principal structural member of the aircraft is a body 3, Fig. 2, formed from a main front section 13 shaped to accommodate the back of a pilot on a seat 113, and an auxiliary rear section 14, secured to section 13 at extensions 15 (the port one shown). The body is completed by top and bottom plates 29, 31. Sections 13 and 14 have reinforcing ribs, and are of aluminium. Apertures 34 in section 13, and 32 formed between the sections allow cooling air to flow over an internal combustion engine 33 mounted on plate 31. The drive shaft from the engine extends to a transmission housing 58 mounted on plate 29 from which extends a rotor shaft 37 supporting the rotor head (not shown). A fuel tank 19 is disposed in an aperture in the rear face of section 13, co-operating flanges on the section and tank being secured together. The tank is isolated from the remainder of the interior of section 13 by a fire wall which also braces section 13. The rotor has two blades, each of which may be folded to lie along the body 3. Fig. 8 shows a suitable hinge with the blade folded. The root 40 of a blade 36 is pivoted on a bolt 52 to a part 44 of the rotor head 7. The root has outstanding members 49 with aligned apertures 51, and the part 44 has outstanding members 46 with aligned apertures 47, so that when the blade is in its operative radial position, a pin can be inserted through apertures 51 and 47 to lock the blade in position This and other pins used may be chained to suitable points to prevent loss. A suitable pin is described (see Group XXV). Two control blades (not shown), used to control the pitch of the rotor blades as in Specifications 662,319 and 645,234 are similarly mounted on the rotor heads. The cyclic pitch, control lever 8 is hingedly and adjustably connected to the swash plate as in Fig. 16. An extension 83 of the swash plate assembly has a fork 84 (one arm shown) to which the lever 8 is pivoted by a bolt 88. The fork 84 has several bores 89, and the arm has several bores 91, so disposed that the pilot can select the angle of lever 8 to the swash plate assembly by choosing the pair of bores 89, 91 which are to be held aligned by insertion of a pin P. The neutral position of the lever 8 is determined by a spring 94 extending between an anchorage 95 in the housing 58, and an anchorage 92 on the lever. Anchorage 92 is adjustable by a screw 93 for trimming purposes. The tail boom 6, Fig. 2, supports an anti-torque rotor 12, and its mounting to the transmission housing 58 is shown in Fig. 13. A collar 64 is secured to one end of the boom, and has two pairs of upstanding apertured fingers 66, 67. A plate 59 is secured to the housing 58, and has a cylindrical recess 68 to receive the end of the boom, and two sets of outstanding apertured fingers 62, 63. For assembly, the fingers 66 are interleaved with fingers 62, and fingers 67 with fingers 63, and removable pins are placed in the aligned apertures. The anti-torque rotor is driven by a shaft 71 having splines 72 which, when the boom is assembled, engage an internally splined drive shaft 69 driven from the transmission. The undercarriage comprises two rearwardly, laterally, and downwardly extending legs 100 (one shown) Fig. 2, and a longer forwardly and downwardly extending leg 102. Each leg terminates in a downwardly convex ground contacting member, that on leg 102 being shaped to act as a skid. The undercarriage connections are shown in Fig. 17. A plate 106 attached to the base plate 31 is formed with three downwardly open channels 107. Each of legs 100 is pivoted in one channel by a bolt 108, allowing the legs to be folded to a position parallel to the vertical axis of body 3, or locked in the operative position by insertion of a pin P into alinged apertures in the channel and leg. Leg 102 is similarly mounted except that it is pivoted to its channel 107 by a bolt 112 passing through the channel and a collar 109 on the leg. Fig. 17 also shows a bracket 114 mounted on leg 102 by a collar 116, and having a plurality of holes 116<SP>1</SP>. The seat frame 115 may be pinned to the bracket by insertion of two pins P into holes in the frame and two holes 116<SP>1</SP>, allowing the pilot to select the longitudinal position of the seat. Fig. 17 also shows one anchoring 151 for a pilot's safety belt B, an engine starting handle 150, and an ignition control 152. The collective pitch lever 9, Fig. 2, which bears a twist grip throttle contol, is arranged to fold downwardly, Fig. 23 (not shown). An instrument panel (not shown) is connected to leg 102, so that the pilot has his legs passing either side of the panel when his feet are on pedals 118, Fig. 2, pivoted to leg 102, and controlling the pitch of the anti-torque rotor. One pedal and its control wire run is shown in Fig. 2. The pedal is forwardly biased by a spring 121, and is connected by a wire 124 to a lever 126 pivoted to base plate 31. Wire 129 runs from lever 126 to a bell crank C on the rail boom 6 and wire 133 runs from bell crank C to pitch change mechanism 123. The wires are maintained taught by spring 121. Wire 129 may be released from lever 126 for complete removal of the tail boom, the fastening being shown in Fig 20. Wire 129 terminates in a clevis 136 spanned by a bolt 137 normally engaged in a hook T formed on lever 126. A leaf spring 138 guards the hook. To release the wire, lever 126 is pivoted upwardly by an extension 127 sloped to accommodate the hand, thus stressing spring 121 of Fig. 2, and slackening wire 129. Spring 138 is depressed, and the clevis bolt 137 removed from the hook T. A similar procedure is followed to re-engage the wire. The clevis 136 and that on the control run for the other pedal are made different widths as are the corresponding hooks, so that crossing of the control runs is prevented. When dis-assembled, the free ends of wires 129 are attached to the boom by clips 141 (Fig. 2). Specification 735,572 also is referred to.