CAC Boomerang

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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.

Contents

1 Background
2 Development
3 Service record

3.1 Units equipped with the Boomerang

4 Variants
5 Specifications (CA-12 Boomerang)
6 Operators
7 References
8 Related content

Background

Japan entered the war in December 1941 and within just a few months had conquered vast areas of the Pacific and South-east Asia, in the process destroying the great majority of Allied aircraft opposed to them. As early as January 1942, Japanese forces were occupying bases just a few miles to the north of Australia and threatening to invade. For Australia, the situation was desperate: her elite fighting forces were half a world away in Europe or the North African desert helping Britain to fight Germany and Italy, and there was not a single modern fighter aircraft in the country.

Australia's traditional aircraft supplier, Britain, was already hard pressed to meet its own needs, and the Churchill government took the attitude that the defence of British colonies was relatively unimportant. The United States was the only other possibility, but the enormous manufacturing resources of that country were only just starting to produce fighter aircraft in quantity, and there was no certainty that any could be spared for Australia.

Within days of the Japanese surprise attacks on Pearl Harbor, Siam, Malaya, and the Philippines—some reports say only three days—the tiny Australian aircraft industry had started designing a fighter with whatever components were available. Only two aircraft were in production in Australia at that time: the Bristol Beaufort torpedo bomber, and the CAC Wirraway advanced trainer. The twin-engined Beaufort was obviously unsuitable as the basis of a fighter, but it did have reasonably powerful engines, 1,200 horsepower (890 kW) Pratt & Whitney Twin Wasps, which were already being made under license in Sydney. With its high frontal area it was not the most promising engine for a fighter, but it was the only one available.

Development

For the airframe, the Wirraway trainer could provide a starting point. From the roughed-out plans, CAC general manager (and former chief designer) Lawrence Wackett and chief designer Fred David began detailed design work on 21 December 1941. The RAAF ordered 105 Boomerangs on 2 February 1942, and the prototype flew on 29 May 1942.

It was a very small aircraft by fighter standards, designed for manoeuvrability more than speed, with an overall length of just 7.7 m and an 11 m wingspan. Although the original intention had been to use as many Wirraway components as possible, the final design was quite different, with shorter wings and shorter, wood-sheathed, aluminium-framed fuselage, increased strength for combat stresses, and a new centre section.

The Boomerang handled well and unlike most initial models of fighter aircraft, was well-armed from the start with two 20 mm cannon and four .303 machine guns (~7.7 mm), all mounted in the short, thick wings, and it was generously equipped with armour plating to protect the pilot. Outright performance was mediocre, however. Although lively at low level, it fell away rapidly over 15,000 feet (4,600 m) and at 265 knots top speed (490 km/h) was not sufficient to make it an effective counter to the Zero.

By 1942 and '43, the best European fighters were reaching almost 350 knots (650 km/h), and even relatively sluggish aircraft like the Wildcat and the Kittyhawk were much faster.

Later, more powerful radial engines, such as the Bristol Hercules could not be used in the Boomerang without a major re-design. The only CA-14 produced — an experimental prototype produced in 1943 — is said to have had a significantly better rate of climb and high altitude performance, thanks to a General Electric B-2 turbo-supercharger and squared-off tailfin. However, by this time the air defence/interceptor role had been filled and work had already begun on the Boomerang's successor, the CA-15 (also known as the CAC Kangaroo).

Service record

Despite the astonishing speed of design and production (particularly so given that Australia was a country that up until then had never made a fighter) by the time the Boomerang entered squadron service the immediate need for fighters had been filled, initially by Curtiss Kittyhawks from the United States (starting in March 1942), and then by the return from Europe of two RAAF squadrons equipped with Spitfire Vs which, together with an RAF Spitfire squadron, arrived in Darwin in January 1943. Of the first three operational Boomerang units, No. 83 and No. 85 Squadrons were used for home defence but the continuing shortage of fighters saw No. 84 Squadron deployed to New Guinea for use as interceptors, with only modest success. 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. After using Boomerangs for eight months in New Guinea, 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, an endless 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, 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, rather than on not flying into the terrain. Sprightly low-level handling helped avoid ground fire, the unusually extensive armour plating protected pilots, and the simple wood and aluminium airframe proved very capable of resisting battle damage.

No. 4 Squadron and No. 5 Squadron flew Boomerangs in New Guinea, the Solomons, and Borneo in the close support role with marked success. Tasks included bombing, strafing, close infantry support, and artillery spotting. For larger enemy formations, Boomerangs often operated together with heavier aircraft, the Boomerang getting in close to confirm the identity of a target and mark it with a 20 lb (9 kg) smoke bomb, the heavier craft delivering the major ordinance from a more practical distance. The partnership between 4 and 5 Sqn Boomerangs and RNZAF Corsair fighter-bombers was said to be particularly effective.

See also the North American P-64 which is another single seat fighter that evolved from the basic NA-16 trainer design.

Units equipped with the Boomerang

The following units were issued with Boomerang aircraft:

No. 2 Operational Training Unit (October 1942-1945)
No. 4 Squadron (August 1943 - August 1945)
No. 5 Squadron (November 1943 - August 1946)
No. 83 Squadron (September 1943 - August 1945)
No. 84 Squadron (April 1943 - October 1943)
No. 85 Squadron (May 1943 - January 1945)
No. 8 Communications Unit (February 1944 - August 1944)

Variants

CA-12: First fighter version, 105 built
CA-13: Improved CA-12, 95 built
CA-14: One aircraft fitted with a turbosupercharged engine, did not enter production
CA-19: Tactical reconnaissance variant with a single vertical camera in the fuselage, 49 built

Specifications (CA-12 Boomerang)

Operators

Australia.

The Boomerang compared with other fighters of 1942-43
Aircraft	Span	Length	Weight	Engine			Speed		Climb
(m)	(m)	(kg)	(hp)	(kW)		(knot)	(km/h)	(ft/min)	(m/min)

Boomerang	11	7.8	2,436	1,200	890	radial	265	491	2,940	896
Grumman Wildcat	11.6	8.8	2,674	1,200	890	radial	278	515	1,950	524
Mitsubishi Zero	12	9	1,710	950	710	radial	288	533	3,150	960
Curtiss Kittyhawk	11.4	9.7	2,858	1,150	860	in-line	314	582	2,050	624
Spitfire V	11.2	9.1	2,313	1470	1,100	in-line	325	602	3,250	991
Messerschmitt 109F	9.9	8.9	2,353	1,270	950	in-line	337	624	4,290	1,308