Engine Jacobs R

Kellett XR-3

KellettXR-3 rebuilt from YG-IB as test bed for cyclic rotor control system. Blades to be used on theXR-8 helicopter were said to be tested o this craft. (Kellett Photc

The XR-3 was used as a flying test bed for rotor blades and components to be used on Kellett's XR-8 helicopter that was being designed.

In general it had the same dimensions as the YG-1B using the fuselage, tail and landing gear with no changes. The only change to the powerplant was the use of the Y0-60 power takeoff. As in the Y0-60, the intermediate gear box was eliminated driving from the hack of the engine to a modified Y0-60 rotor head.

The head was locked so that it did not tilt. Control, instead, was done by feathering the blades cyclically as is done now in a helicopter. Jump takeoff was provided by manually operated "collective" pitch control of the blade pitch angle for takeoff and a quicker descent. The normal blade for the XR-3 was tapered in thickness and plan form. Plywood ribs were spot welded through their metal collars to the heat-treated 4130 steel spar tube. Plywood covered the leading edge of the blade then the blade was fabric covered and doped. Because of the extra weight of the hub controls and blade controls, blade-to-blade dampers had to be added.

Specifications

Gross weight 2640 It

Empty weight Useful load

Top speed 106 mp

Cruise speed Landing speed

The rotor pylon was mounted on rubber at tl fuselage to eliminate vibration. This was lat> blocked out and extra struts were added to tl pylon to brace it.

A movie camera was mounted on the top the rotor head, rotating with the blade that cou take pictures of one blade that was going to I used on the XR-8 helicopter. The blades we flown, photographed and studied while tl autogiro was flown in various modes of fligl" When pilots saw the pictures of the wild gyr tions the blades went through—bending, fla; ping and twisting— they almost quit flyir the autogiro.

Pilots who flew the XR-3 like it very muc One takeoff was made with the autogiro buric

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