 This was to be a two-seater aircraft, powered by a Rolls-Royce Kestrel S engine, which would be fitted with a similar two-stage supercharger installation, enabling it to generate 500 hp (370 kW).In 1937, the airframe was delivered to Farnborough Airfield for completion, but the engine installation was never completed.The Type 138B was used as a ground instructional trainer instead, and accordingly never flew.