In 1950, "Perseus" was fitted with an experimental steam catapult. The catapult was placed on top of the carrier's existing flight deck and the deckhouse to port of the island was removed to accommodate it. Some 1,560 launches were made by the catapult, beginning with over 1,000 wheeled dead-loads, of gradually increasing weight, and moving on to with unmanned aircraft with their wings truncated to reduce their ability to glide. The final tests were made by manned aircraft of every type flown by the Fleet Air Arm. After this, the ship arrived in Philadelphia on 14 January 1952 to demonstrate the catapult to the United States Navy. Between them, some 127 launches of manned aircraft were made by the British and the Americans. "Perseus" arrived back at Portsmouth on 21 March and had the catapult removed. All of her remaining maintenance equipment was removed and she was converted for use as a ferry carrier.