Hello Jack,
The Woomera was an in-house Bomber design at CAC that pre-dated the Boomerang, two prototypes were built, the CA-4 and the later CA-11.
Below info and photo from wiki
http://en.wikipedia.org/wiki/CAC_Woomera
Quote:
In 1941, because of a need to replace the Bristol Beaufort and Lockheed Hudson, the RAAF issued Development Specification No. 241. This stipulated an aircraft suitable for: reconnaissance, general bombing, torpedo delivery and dive bombing.
CAC, under Sir Lawrence Wackett, began to re-work an existing, unbuilt design, the CAC CA-4 (sometimes known as the Wackett, and not to be confused with the unrelated CA-6 Wackett single-engine trainer). A prototype CA-4 took to the air on September 19, 1941. The CA-4 was a low wing, twin-engined, dive bomber with a crew of three. It was armed with four nose-mounted .303 calibre machine guns and two remote-controlled twin machine-gun barbettes mounted at the rear of the engine nacelles. It could carry either 500 lb (230 kg) bombs, 250 lb (110 kg) bombs or two torpedoes. It was originally powered by two Pratt & Whitney Twin Wasp R-1830-S3C3-G radials. (The CA-4 prototype was scrapped in 1943 after it suffered major damage, from a mid-air explosion due to a fuel tank leak and a consequent fire.)
With a re-designed tail and rudder, and an improved nose armament of two 20 mm cannon and two .303 calibre machine guns, the CA-4 became the CA-11
Wiki is in-correct in regards to the date of the development order for the Woomera, it was not issued in 1941, but actually issued in April 1940, and was primarily due to concerns over the progress of the Australian Beaufort construction project which was suffering major technical and management problems at the time, (the first Australian Beaufort didnt fly until August 1941) and the Beaufort itself was intended to replace the Hudson.
It would have been interesting to see how the Woomera would have performed in both the Beaufort and Beaufighter roles, for which it was effectively competing with for production orders.
Had the Beaufort project not been rescued by Essington Lewis and a replacement management team from GMH, the Woomera may well have been rushed into production in response to Pearl Harbour despite the problems with the CA-4, and the improved CA-11 version later developed and used to fill the role of the DAP Beaufighter.
Had the DAP Beaufort project failed, the follow on production of Australian Beaufighters probably would not have occurred, and CAC would have remained the dominant aircraft manufacturer post war.
The Woomera had a steel tube fuselage, and wing/centre-section all based on the Wirraway design and construction methods, so in a similar way to the Boomerang and Ceres, can in someways be considered to be the only twin engined decendent of the NA-16 and cousin in the T6/SNJ/Harvard family.
regards
Mark Pilkington