hafner AR 111 autogyro

[gyronuts]

Hi,
I was wondering if anyone on the forum had any information and possibly a 3 view drawing of the hafner AR111 autogyro.
A friend is trying to build a radio controlled scale version of it and is finding it difficult to find any data.
Many thanks. Bill

[C. Beaty]

Try this..........

[WHY]

Chuck

Was the Hafner AR111 a basic truss box frame, shaped out with fairings and fabric ??
About what hp was used ??

Tony

[C. Beaty]

Take a look at the earlier picture, Tony. The steel tube frame is indicated by dotted lines.

The Hafner machine had twisted rotorblades, the tips twisted upward by 2.85 degrees (0.05 radians) from ~30% radius to the tips.

The engine on the prototype was an 80 hp Pobjoy Niagara; 90 hp on the second model.

The rotor had central flap hinges by a somewhat complex interleaving at the hub.

Hafner, an Austrian national, was interned as an enemy alien when WWII broke in 1940 but was released after taking out British citizenship.

Hafner was the designer of the Rotachute, Bensen’s inspiration for the Gyrocopter.

[WHY]

Thanks for that info Chuck, interesting how little hp was used in this gyro.

Tony

[C. Beaty]

Raoul Hafner, in a paper read before the Royal Aeronautical Society on Oct. 14, 1937, said:

“…………The tailplane consists of two identical planes of cambered section, arranged to counteract torque, the flat surface being below on the starboard side……….”

That produces a clockwise torque on the airframe, British engines rotating in a direction opposite to that of US engines.

[Doug Riley]

Chuck, I stared at that first set of drawings for awhile, looking for the offset gimbal pivot. Your second post cleared it up. Hafner copied your cyclic pitch "spider!"

The centralized flap hinges look expensive, as they appear to use purpose-made forgings.

[C. Beaty]

Another name for spider might be coplanar swash plate, Doug.

I believe Rauel Hafner was the first to implement feathering cyclic pitch control in a practical rotorcraft although the equivalence between tilt head cyclic and feathering cyclic was well understood by the 1930s.

Hafner went on to design the Bristol Sycamore helicopter taking an approach similar to that of The AR-111: