The first Type 508, serial VX129, was a straight-winged jet aircraft fitted with a V-tail ("butterfly") tail intended for use with rubber deck landing techniques, the choice of wide, flattish fuselage and V-tail being designed to provide adequate stability and clearance when landing without a normal undercarriage.
The third Type 508 VX138, built like the others at Supermarine's Hursley Park experimental department, was modified on the production line to closer to Scimitar standards and was redesignated the Type 525.