A full scale glider was built and made its first flight on 1 October 1954.

Most unusually the pilot lay prone and looked out through the clear nose.

Flight performance was deemed excellent and manufacture of a prototype powered by a Rolls-Royce Derwent V began in 1955.

This engine was selected as it was readily available, but lacked the thrust desired for the fighter.

Shortly afterwards the program was split with the current aircraft becoming a subsonic trainer and a new, more powerful fighter, designated as the I.Ae.