was used primarily as a platform for testing the rocket motors. The GAP/RTV.1 efforts would be directed at the Stage 1 design, which would essentially be the Seaslug requirement. The relatively small CTV could safely be launched at the Larkhill Range, part of the Royal School of Artillery. It was equipped with a parachute that allowed it to be recovered. This was not possible for the much longer-ranged RTV, which was fired from RAF Aberporth out over Cardigan Bay in Wales. The desire to reclaim the RTVs as well led to the opening of a parallel launch facility at the RAAF Woomera Range Complex and a program that led development of supersonic parachutes. As RTV testing continued, the decision was made to build a larger version, RTV.2, which would be more typical of a production missile. During early testing, the design was further modified and renamed GPV, for General Purpose Test Vehicle. Several liquid rocket motors were tested as part of this program. Early tests demonstrated shifts in the center of gravity that required active damping, which in turn led to the lengthening of the overall fuselage to become the "long round". This version used forward-mounted boosters, which were mounted so their exhaust was just in front of the mid-mounted wings. Project 502 As experimental work progressed, the Ministry of Supply began forming an industry team to build production systems. In 1949 this gave rise to the 'Project 502' group from industry, with Armstrong Whitworth Aircraft and Sperry in March and GEC in September. The 29 July 1949 update of the Staff Target called for a maximum range of and a minimum of . Maximum altitude should be 55,000 ft, but 45,000 would be considered acceptable. A later updated pushed the range to against a , later , target. It was assumed the targets would "jink" at 1G, so the missile needed to maneuver at 4G at sea level and 2.5G at 40,000 ft. Additional requirements were the ability to switch between targets in 6 seconds. The designers ultimately selected a maximum range of 30,000 yards, which included of coasting after motor burn-out. This was about 50% better than the contemporary US Terrier design. Hit probability was estimated to be 40% at maximum range, so salvos of three missiles would be fired at once, demanding a three-place launcher. This was later reduced back to a twin-launcher when it was realized