Initially, the aircraft was to use Frank Whittle's latest engine, the Power Jets W.2/700, which would only reach supersonic speed in a shallow dive. To develop a fully supersonic version of the aircraft, an innovation incorporated was a "reheat jetpipe" – also known as an afterburner. Extra fuel was to be burned in the tailpipe to avoid overheating the turbine blades, making use of unused oxygen in the exhaust. Finally, the design included another critical element the use of a shock cone in the nose to slow the incoming air to the subsonic speeds needed by the engine.