The CAC CA-15, also known unofficially as the CAC Kangaroo, was an Australian propeller-driven fighter aircraft designed by the Commonwealth Aircraft Corporation (CAC) during World War II. Due to protracted development, the project was not completed until after the war, and was cancelled after flight testing, when the advent of jet aircraft was imminent. During 1943, following its success in rapidly designing and mass-producing the Boomerang fighter for the Royal Australian Air Force (RAAF), CAC began design work on a fully-fledged interceptor and escort fighter. Because the Boomerang had become more and more obsolete against Japanese fighters like the Mitsubishi A6M Zero, Sir Lawrence Wackett (as head of CAC) proposed designing a new high-performance fighter from scratch. Fred David, who had designed the Boomerang, was to lead an in-house design team at CAC. In June 1943, the design concept proposal was approved by the government and RAAF, which issued specification 2/43, enabling work to commence. The design was inspired by contemporary fighters – especially the German Focke-Wulf Fw 190, details of which were available to the designers through Allied intelligence reports on captured aircraft. Although the CA-15 bore a superficial resemblance to the North American P-51 Mustang, the CAC design was not based directly on the American aircraft and had quite different performance objectives. For much of its development, the CA-15 was designed around radial engines, rather than the inline engines used in fighters like the Mustang. In fact, development of the CA-15 was slowed by a recommendation from Wackett, that CAC build Mustangs under licence, rather than bear the cost of developing a unique design. Nevertheless, it was believed that the CA-15 promised capabilities that would enable it to replace the P-51. At first, the CAC designers planned to use the 2,300 hp (1,715 kW) radial Pratt & Whitney R-2800, with a turbocharger. However, that engine became unavailable, causing further delays in development, and it was decided to fit an in-line Rolls-Royce Griffon Mk 61 (2,035 hp/1,517 kW). Engines for a prototype were leased from Rolls-Royce. It was intended that any production engines would have a three-stage supercharger. For details of the operational history of the CA-15, click here.