369,249. Supporting and propelling aircraft. PLATT, H. H., 162, East 80th Street, New York, U.S.A. Dec. 11, 1930, No. 37411. [Class 4.] A propelling mechanism particularly for aircraft comprising one or more pairs of rotors each having a plurality of pivotally mounted aerofoil blades peripherally arranged on the rotor and adjustable eccentric means for causing rocking of the blades about their pivots on each revolution of the rotor, the said eccentric means comprising two or more interengaging eccentrics adjustable together or individually, is characterized by the provision of control means for effecting differential or equal control movements of corresponding eccentrics of the two rotors of a pair from a single control handle. Rotors 16, 17, Fig. 1, are mounted on a common shaft 19 driven by an engine 90 through bevel gearing and a clutch 87. Shaft 19 is supported in bearings 21 at the ends of a tubular casing 22 and terminates in a flange 24. A driving spider 25 is clamped between flange 24 and a similar flange 29 on an extension shaft 28. Aerofoil blades 18 formed as hollow shells of light alloy with or without internal bracing are pivoted to arms 27 of the driving spider 25. The blades 18 are further interconnected bv spiders 31, 32, Fig. 3, the latter being fixed to the extension shaft 28. The pivots of each blade are arranged on an axis passing through the centre of gravity of the section. The blades are connected to a normally. stationary dual eccentric by an eccentric strap 38 and deflecting rods 39 attached to the leading edge of the blade one of which rods is rigid with strap 38 and the others pivoted thereto. The dual eccentric comprises an outer eccentric 40, Fig. 5, rotatably mounted on an inner eccentric 41 in turn mounted on a sleeve 23 integral with the shaft and gear housing 22. The eccentric 41 is rotated by a spur gear 43 connected to it by an integral sleeve 42 upon which is loosely mounted a gear wheel 44 having a flange 45 slotted radially for the reception of a peg fixed to eccentric 40. Gear wheels 43, 44 are rotated by gears 54, 51 mounted on concentric shafts 48, 49 carried by the housing 22, on the inner ends of which are fixed sprocket wheels 55, 52 connected by chains to sprockets 58, 57 on a control device within reach of the pilot's seat 92, Fig. 3. The sprockets 57, Fig. 7, movement of which controls the position of the outer eccentrics 40 are mounted on tubular shafts 59 journalled in brackets 61 on either side of the body. Formed integrally with the sprockets are toothed sectors 62 connected by a bevel gear 67 on a hand-wheel shaft 66 to form a differential gear. The hand-wheel shaft is carried by a bracket 63 rotatably mounted on one shaft 59. The sprockets 58 are carried by shafts 73 journalled in the shafts 59 and terminating in opposed lever arms 74, 75, Figs. 6 and 7, which carry arcuate extensions 76, 77, Figs. 3 and 6. These portions may be interlocked with one another and one or other may be interlocked with an arcuate portion 80 of the bracket 63 by means of handles 78, 79. When these levers are so interlocked fore and aft the movement of the hand-wheel 68 causes simultaneous movement of both the eccentrics 40, 41 simultaneously on either side of the craft, thus adjusting the phase of the feathering and altering the direction of the resultant thrust produced by the rotors. If, however, the levers 74, 75 are freed and moved simultaneously and independently of the hand-wheel the inner eccentrics on both sides of the machine are adjusted to alter the maximum pitch of the blades and hence the magnitude of the resultant thrust. Rotation of the wheel 68 causes differential movements of the outer eccentrics thereby altering both the phase and the pitch of the rotor vanes on either side of the machine to produce a banked turn. The clutch 87 can be disengaged by the pilot through a lever 88, Fig. 3, enabling the rotors to be driven by the relative wind during descent. The direction of rotation of the rotors is such that the torque reaction on the craft in forward motion tends to raise the tail thereof.