The CAC Boomerang was a World War II fighter aircraft designed and manufactured in Australia between 1942 and 1945. The Commonwealth Aircraft Corporation gave Boomerangs the model numbers CA-12, CA-13, CA-14 and CA-19.
Development
Background
The Pacific War began on 7 December 1941 with surprise attacks by the Empire of Japan on Pearl Harbor, Thailand, Malaya, and the Philippines. Within a few months, Japanese forces had conquered vast areas of the Pacific and South East Asia. During these campaigns, the ill-prepared Allied air forces in the Pacific suffered devastating losses.
Because of political and cultural ties between the United Kingdom and Australia, British manufacturers were the main source of RAAF aircraft. However, the British aircraft industry had long been hard-pressed to meet the needs of the RAF. Although United States companies had enormous aircraft manufacturing capacity, their output was now intended first and foremost for US air units. The Commonwealth Aircraft Corporation came into its own: work re-commenced on an existing bomber design, the Woomera, and CAC also examined the possibility of designing and building fighters.
The main challenge was the fact that fighter aircraft had never been built in Australia. Only two military aircraft were in production at the time: the Bristol Beaufort twin-engined bomber and the CAC Wirraway armed trainer. Neither was a suitable basis for a state-of-the-art fighter, but the Beaufort did have reasonably powerful 1,200 horsepower (890 kW) Pratt & Whitney Twin Wasp engines, which were being made under license at the CAC plant in Lidcombe, Sydney. As this was the engine that powered Grumman Wildcats used by the US Navy, it was a logical choice for a fighter.
Development
The Wirraway trainer provided a starting point for the Boomerang's airframe. CAC general manager (and former chief designer) Lawrence Wackett and chief designer Fred David began detailed design work at the CAC factory in Fishermans Bend, Melbourne on 21 December 1941. David was a Jewish refugee from Austria, who had worked on aircraft designs for Heinkel in pre-Nazi Germany, as well as for Mitsubishi and Aichi in Japan.[1] As a result, he had a comprehensive knowledge of advanced contemporary fighter designs, including the Heinkel He 112 and A6M Zero.
The RAAF ordered 105 CA-12 (Mark I) Boomerangs on 2 February 1942, before the prototype first flew on 29 May 1942.
The Boomerang was a small fighter, designed with an emphasis on manoeuvrability. It had an overall length of just 7.7 metres (25.5 ft) and an 11 m (36 ft) wingspan. Although the original intention had been to use as many Wirraway components as possible, the final design was quite different, with shorter wings, a shorter, wood-sheathed, aluminium-framed fuselage, increased strength for combat stresses and a new centre section.
Test flights found that the CA-12 handled well. It was very well-armed, with two 20 mm cannon and four .303 calibre (7.7 mm) machine guns, all mounted in the short, thick wings. The Boomerang was also generously equipped with armour plating to protect the pilot. However, general performance was mediocre. Although lively at low level, performance fell away rapidly over 15,000 ft (4,600 m), and at the maximum speed of 265 knots (490 km/h) was not sufficient to make it an effective counter to the Zero. In addition, the best European fighters were reaching almost 350 knots (650 km/h), and even relatively sluggish fighters like the Wildcat and the Kittyhawk were much faster than the Boomerang.
As a result, by early 1942 the CA-14 variant was being designed, around the U.S.-built, 1,700 hp (1,268 kW) Wright Cyclone R-2600 engine, to address the CA-12's deficiencies in speed, climb and ceiling.[2] However, the 145 Cyclones ordered were not delivered as scheduled, and in mid-1942 Wackett authorised use of the 1,850 hp (1,380 kW) Pratt & Whitney R-2800, which could also be obtained from the CAC factory in Lidcombe.[2] However, the significantly greater weight of this powerplant led to an unacceptable risk of undercarriage failure.[3] CAC eventually returned to the Twin Wasp, to which was added a General Electric B-2 turbo-supercharger mounted inside the rear part of the fuselage, new propellor gear, a geared cooling fan (influenced by reports on Focke-Wulfs captured in Europe) and a larger, squared-off tailfin and rudder.[2]
By July 1943, the significantly re-worked CA-14 prototype, now known as the CA-14A, had a top speed which was 25–30% better than the CA-12, and an operational ceiling which was 4,000 ft (1,200 m) higher.[2] Overall, it compared favourably with the Spitfire Vc and early model Thunderbolts and Mustangs.[2] By this time, however, British-built Spitfires had filled the interceptor role and Mustangs had been ordered, to fill the bomber escort, air superiority and close air support roles.[2] In addition, work had begun on the all-new CA-15, also known as the Kangaroo. Consequently, production Boomerangs were never fitted with superchargers.
Boomerangs underwent various improvements and modifications, which were grouped under three CAC designations: CA-12, CA-13 and CA-19. A total of 250 aircraft of these marques were built: 105 CA-12s, (RAAF serial numbers A46-1/105), 95 CA-13s (A46-106/200) and 49 CA-19s (A46-201/249).[4] The CA-13 and CA-19 are sometimes known collectively as the Boomerang Mark II.
The sole CA-14A was used for research by No. 1 Aircraft Performance Unit RAAF, and was also seconded to the Bureau of Meteorology for a period after the war ended.[5]
Operational history
A No. 4 Squadron Boomerang and ground crew at Nadzab, New Guinea in October 1943 (AWM P02531.013)
CAC Boomerang during assembly
Following the devastating first air raids on Darwin on 19 February 1942, the need for interceptors became more pressing. Despite the Boomerang's astonishingly short development phase — especially since the Australian aviation industry had never built fighters before, let alone designed them — by the time the Boomerang entered service, an adequate number of Curtiss P-40 Kittyhawks had arrived from the United States. In January 1943, these were replaced in the air defence role over Darwin by No. 1 (Fighter) Wing RAAF, which had returned from Europe, equipped with the Spitfire Mk Vc.
Two of the first three operational Boomerang units, No. 83 Squadron and No. 85 Squadron, were used for home defence. No. 84 Squadron was deployed to Horn Island in Torres Strait and Dutch New Guinea (West Papua), in an attempt to address the continuing shortage of fighters in this area. The squadron was only modestly successful however. The Boomerang's low top speed and poor high altitude performance meant that No. 84 Squadron could drive off enemy attacks but rarely get close enough to Japanese aircraft to bring their guns to bear. On the only occasion when a Boomerang did close with a Japanese aircraft, its guns jammed. Fortunately, there were not many air raids in this area, and after using Boomerangs for eight months No. 84 Squadron upgraded to the Kittyhawk.
The Boomerang found its real use as a close support aircraft. In contrast to Europe or North Africa, the ground war in the jungles of the south-west Pacific was, in broad terms, a series of small unit actions fought at very close quarters by widely dispersed forces with no clear front lines. It was here that the Boomerang found its niche: as close to the troops on the ground as possible.
It had the range to go wherever it was needed (usually the aircraft were based closed to the area of ground operations), heavy armament by the standards of the day and, because it was easier to fly than most fighters, the pilot could get in close to the objective and have time to concentrate on the ground forces. Sprightly low-level handling helped avoid ground fire and rough terrain and the unusually extensive armour plating protected pilots. In addition, the aircraft's simple wood and aluminium airframe proved capable of absorbing battle damage. Nonetheless, several of the aircraft were shot down, including two accidental kills by US units,citation needed and more were damaged during landing accidents, as the Boomerang was prone to ground looping.
No. 4 Squadron and No. 5 Squadron flew Boomerangs in New Guinea, the Solomon Islands Campaign and Borneo Campaign, also in the close support role, with marked success. Flying in pairs (one to observe the ground, the other to observe the air around them), their tasks included bombing, strafing, close infantry support and artillery spotting. When attacking larger enemy formations Boomerangs often operated in conjunction with larger aircraft. In this role the Boomerang would get in close to confirm the identity of the target and mark it with a 20 lb (9 kg) smoke bomb with the "cooperating" aircraft delivering the major ordnance from a safer distance. The partnership between 5 Squadron Boomerangs and Royal New Zealand Air Force Corsair fighter bombers during the Bougainville Campaign was said to be particularly effective.
The other user of Boomerangs in New Guinea was No. 8 Communications Unit, which used the aircraft to assist with air sea rescue operations.
Variants
- CA-12 (Mark I)
- The first single-seat fighter version, 105 built. Serial numbers A46-1 to A46-105.
- CA-13 (Mark II)
- Improved version of the CA-12, 95 built. Serial numbers A46-106 to A46-200.
- CA-14
- One aircraft fitted with a turbo-supercharged engine, did not enter production. Serial number A46-1001.
- CA-14A
- The CA-14 prototype was later modified to have a square tail and rudder
- CA-19
- Tactical reconnaissance variant with a single vertical camera in the fuselage, 49 built. Serial numbers A46-201 to A46-249.
Operators
 Australia
Survivors
Temora Aviation Museum's CA-13 Boomerang VH-MHR/"A46-122"
Two Boomerangs remain airworthy today, both in Australia: CA-12 A46-122 "Suzy Q" (VH-MHR) with the Temora Aviation Museum and A46-206 which was formerly with Lynette Zuccoli at Toowoomba, Queensland until donated to the Museum of Australian Army Flying at the Army Aviation base located at the nearby town of Oakey. A full-scale, airworthy replica with many original parts is based in the United States. Several others are under restoration to fly in both Australia and the USA. This includes A46-90 which is currently being restored to airworthy status.[6]
Specifications (CA-12)
Data from The Great Book of Fighters[7]
General characteristics
- Crew: 1
- Length: 25 ft 6 in (7.77 m)
- Wingspan: 36 ft 0 in (10.97 m)
- Height: 9 ft 7 in (2.92 m)
- Wing area: 225 ft² (20.9 m²)
- Empty weight: 5,373 lb (2,437 kg)
- Loaded weight: 7,699 lb (3,492 kg)
- Powerplant: 1× Pratt & Whitney R-1830 Twin Wasp radial engine, 1,200 hp (895 kW)
Performance
Armament
- Guns:
- Bombs: Could be fitted when the large drop tank was not carried
See also
Related development
Comparable aircraft
Related lists
References
Notes
- ^ Ross 1995, p. 316. Gary Sunderland, "Elliptical Wings Part 2: The Fred David Story" (Small Scale Squadron Down Under, v.6 no.3, September 2002).
- ^ a b c d e f Ross 1995, p. 321.
- ^ Ross 1995, p. 321. The R-2800 engine would later be the basis of design work on the larger and more robust CAC CA-15, also known as the CAC Kangaroo.
- ^ adf-serials.com RAAF Museum 2007, "A46 CAC Boomerang". Retrieved: 5 December 2007.
- ^ adf-serials.com "RAAF A46 CAC CA-12/CA-13/CA-14/CA-19 Boomerang" 2007. Retrieved: 5 December 2007.
- ^ www.warbirdregistry.org
- ^ Green, William and Gordon Swanborough. The Great Book of Fighters. St. Paul, MN: MBI Publishing, 2001. ISBN 0-7603-1194-3.
Bibliography
- Francillon, René J. The Commonwealth Boomerang, Aircraft in Profile number 178. Leatherhead, UK: Profile Publications, 1967.
- Green, William. War Planes of the Second World War, Fighters, Volume One. London: Macdonald, 1960 (10th impression 1972). ISBN 0-356-01445-2.
- Luranc, Zbigniew. Commonwealth Boomerang, Skrzydła W Miniaturze 24 (in Polish). Gdańsk: Wydawnicto Avia-Press, 2000. ISSN 1234-4109.
- Pentland, Geoffrey. Commonwealth Boomerang Described. Dandenong, Victoria, Australia: Kookaburra Technical Publications, 1964.
- Pentland, Geoffrey.RAAF Camouflage & Markings, 1939-1945, Vol. 1. Dandenong, Victoria, Australia: Kookaburra Technical Publications Pty Ltd., 1980. ISBN 0-85880-036-5.
- Pentland, Geoffrey. Wirraway and Boomerang Markings. Dandenong, Victoria, Australia: Kookaburra Technical Publications, 1970. ISBN 0-85880-007-1.
- Ross, A.T. Armed and Ready: The Industrial Development and Defence of Australia 1900-1945. Wahroonga, New South Wales, Australia: Turton & Armstrong, 1995. ISBN 0-908031-63-7.
- Wilson, Stewart. Wirraway, Boomerang & CA-15 in Australian Service. Sydney, Australia: Aerospace Publications, 1991. ISBN 0-958797-88-9.
- Zbiegniewski, Andre R. and Jacek Nowicki. CAC Boomerang & CAC Wirraway, Wydawnicto Militaria 43 (in Polish). Warszawa: Wydawnicto Militaria, 1997. ISBN 83-86209-57-7.
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