 During structural testing performed at the Royal Aircraft Establishment, Farnborough, the proposed structure demonstrated not only the required strength factor of six, but reached 11 without any sign of failure, proving the geodesic airframe to possess a strength far in excess of normal levels.This strength allowed for the structure design to be further developed to reduce the size of individual members and adopt simplified standard sections of lighter construction.Vickers studied and compared the performance of various air- and liquid-cooled engines to power the bomber, including the Bristol Pegasus IS2, Pegasus IIS2, and Armstrong Siddeley Tiger radials, and the Rolls-Royce Goshawk I inline.