|CA-18 Mustang Mk 21 in 2005|
|Manufacturer||Commonwealth Aircraft Corporation|
|First flight||29 April 1945|
|Introduction||4 June 1945|
|Retired||1959 (Citizen Air Force)|
|Primary user||Royal Australian Air Force|
|Developed from||North American P-51 Mustang|
The CAC Mustang is an Australian variant of the North American P-51 Mustang. It was built under license by Commonwealth Aircraft Corporation in the final stages of World War II, and though it was too late to see combat, it did participate in the Occupation of Japan after VJ-Day.
At the beginning of 1942, as it faced the prospect of numerous Japanese air raids, the Australian War Cabinet found it impossible to obtain sufficient numbers of operational, up-to-date fighter aircraft, in any form. At CAC, a light-weight "emergency fighter", which could be built quickly from scratch in Australia, was designed and a prototype built. As the CAC CA-13 Boomerang, it first flew in May 1942, and was rushed into full production.
It was acknowledged from the outset that the CA-13 was compromised by the only, low-powered engines then being manufactured in Australia. While Curtiss P-40 Kittyhawks were slowly becoming available to the RAAF, CAC became actively involved in three parallel solutions: upgrading the Boomerang when better engines became available (as the CA-14 and CA-19); local assembly, from components made elsewhere, of an already-proven fighter, and; development of an all-new replacement, with a full-sized airframe that was capable of mounting the largest class of aircraft engines then available (a project that later resulted in the CAC CA-15).
Plans to assemble a proven fighter locally began to bear fruit in December 1942, the War Cabinet began to make arrangements with North American Aviation (NAA) for CAC to assemble the P-51 Mustang. These arrangements were finalized in November 1943, with CAC scheduled to build 690 P-51Ds, from kits made in the United States by NAA. (As it awaited arrival of the kits, CAC privately continued work on the CA-15, as a possible back-up or even replacement for, the Mustang. However, the US-built radial engines intended for the CA-15 became unavailable, also hampering that project.)
Only 100 unassembled P-51s were ever delivered, and four reportedly had the "razorback" style canopy of the P-51B/C variant. In either late 1944 or early 1945, assembly of 80 of the P-51D kits commenced, under the designation CA-17 Mustang Mk 20 with Packard V-1710-3 Merlin engines, with the remainder being used for spare parts. The end of the war led to cancellation of the remainder of the kits ordered from NAA.
In late 1946, CAC received a contract to build 170 (later reduced to 120) Mustangs locally from scratch. These aircraft carried the new designation CA-18.
Additional orders for the CA-18, as well as 250 two-seat variants, designated CA-21, were canceled in favor of further, US-built P-51D and P-51K variants.
The first production CA-17 Mustang Mk 20, serial number A68-01 (not to be confused with the US-built prototype A68-1001), made its first flight on 29 April 1945 from Fishermans Bend, Victoria. The aircraft was handed over to the RAAF on 4 June 1945 and was tested by the No. 1 Aircraft Performance Unit. Trials ended in October 1946, and the aircraft was placed in storage until 1953. Only 17 CA-17s were delivered to the RAAF by VJ-Day.
The first operational units to receive the CAC Mustang were No. 84 and No. 86 Squadron. Additional squadrons equipped with Mustangs (both American and locally-built) were No. 3, No. 4, No. 76, No. 77, and No. 82 Squadron as well as No. 21, No. 22, No. 23, No. 24, and No. 25 Squadron of the Citizen Air Force. The RAAF replaced its last Mustangs with de Havilland Vampires in 1959, while the last Mustang-equipped Citizen Air Force squadron, No. 24, retained its Mustangs until the CAF was disbanded in 1960.
Main article: List of surviving North American P-51 Mustangs
A full-scale replica of a CA-18 Mustang Mk 23 is located at the Queensland Air Museum at the Caloundra Airport. Construction of the replica began in May 2005 and was placed on static display on 27 December 2008. It carries the fictitious serial number A68-201, continuing the original sequence which ended with A68-200.
Data from 
Aircraft of comparable role, configuration, and era