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Thursday, March 17, 2011

Revisiting The Synchrogyro Giro Copter-Autogyro

Model Airplane as published in Model Builder Magazine in September 1979. Designed by George Chaulet to be flown with 2 channel RC control for the engine and rudder and said to be simple to fly.

Testing continued as the wind speed increases from 5 to 15 kph. The copter manages a takeoff during ground trials but, a blade strike on landing caused the testing to be suspended while design changes are contemplated.

Looking back on the results of the flight trials last season I have to say that control flight has not been demonstrated at least not with this particular one.

Conclusions:- I have come to the conclusion that maybe Cierva was right when he stated that the rotor must be of the articulated type for successful controlled flight of an auto gyro aircraft. Initially I believed that since the Synchrogyro had two inclined rotors, it would be capable of controlled flight in the same way as a fixed wing airplane with high dihedral was rudder controllable. Now I am beginning to look for a simple way to modify the Synchrogyro rotors to articulating type. During the ground testing the model tipped over several times due to the high center of gravity and the rough surface of the flying field. The aircraft was originally fitted with a tricycle landing gear and that set-up proved to be unsatisfactory so the nose wheel was replaced with an axle with two more wheels plus a tail wheel for steering. This set-up improved things somewhat but it did tip over occasionally even then. There was not enough clearance  between the rotor blades and the vertical tails, which resulted in one of the three rudders being clipped off by a rotor strike shortly after takeoff.

Modifications:- Several modifications were made to the craft to correct the problems noted above. 1. The rotor head is now fully articulating and is controlled by roll and pitch servos;
2. The rotor head has been raised by 3.4 inches to provide additional tail clearance; and,
3. The main wheels track has been widened by 3 inches to cure tip over problem.

Watch a short video clip which demonstrates the modification process.


Weight....................... 5.86 Pounds
Rotor Diameter.......... 46 inches X 2
Power........................ OS 46 2 Stroke Nitro
Servos........................5 standard Size
Controls.................... Rotor Pitch, Rotor Roll, Rudder, Elevator, and Motor

Rotor Head Control Limits