The Shadower knows …

***image1***One of the main “wish list” items of the radarless, post-World War I navies was a means to detect and surreptitiously maintain contact with an enemy naval force at night.

In 1937, the British Royal Navy tried to solve the problem by issuing a requirement for a carrier-based aircraft with a cruising speed of 38 knots for six hours, an exceptional field of view for the crew, folding wing that would fit in a carrier hangar, and very low noise levels − too low to be heard over a ship’s engines.

Such a “stealthy” fleet shadower aircraft, it was thought, could fly low over an enemy force, watching its wakes and radioing back position information.

One of the aircraft developed to meet the requirement was the awkward looking, high-wing, four engine General Aircraft G.A.L. 38. The main challenge with the requirement was to develop a wing with adequate high lift characteristics it could keep the airplane aloft at slow speed while at the same time have enough lift to allow good maneuvering flight, and the G.A.L. 38 solved this with a number of unique design features.

Its four small 130 horsepower Pobjoy Niagara V engines had twin blade, large-diameter propellers, and the engines were spaced so that along the full length of the wing their prop wash flowed over the wing for added lift. Other high lift devices were slotted flaps and slotted ailerons which drooped 15 degrees as the flaps were lowered. 

Additional flaps ran the complete length of the lower fuselage and out to the wing landing gear sponsons. The devices gave the G.A.L. 38 wing a lift coefficient of about seven times greater than an aircraft with a normal wing.

Tests showed the G.A.L. 38 could cruise 38 knots, and under moderate wind conditions it could fly backwards under full control. The ailerons, covered by the propellers’ slipstream, remained responsive at very slow speeds and lateral stability was good because steady slipstream from the propellers made it less sensitive to wind gusts. The tail surfaces also were effective in slow-speed flight. The high wing layout gave an exceptional field of view to the three man crew, especially the observer, who sat in a cabin-like nose with large, wrap around windows.

The four small engines were very quiet, a feature considerably helped by the low tip speed of the geared propellers, and tests showed the exhaust systems of four small engines were much easier to muffle than a single engine of equivalent power.

While the G.A.L. 38 met all the requirements, the potential of radar made it seem redundant, and it was cancelled. In retrospect this was probably a short sighted decision. The aircraft’s long loiter time, outstanding visibility and ease operation from a carrier would have been ideal for antisubmarine warfare, but when it was cancelled anti-submarine warfare was not a priority for the Royal Navy.

E-mail questions and comments to marshall.michel@ramstein.af.mil.