CAC Boomerang – Australia’s Forgotten WWII Fighter
During a military emergency, the national effort to procure weapons systems is of the utmost importance, but sometimes the quickest or only choice is far from being the best option. Such is the story of the CAC Boomerang, a fighter program of such national urgency that a relatively mediocre design was accepted into RAAF service, for the simple reason that there was no other choice at the time.
Directly descended from the CAC Wirraway trainer/general purpose aircraft, the Boomerang was hurriedly designed and manufactured to provide Australia with desperately needed fighter aircraft after the start of the Pacific War, but its performance fell well short of expectations.
After a short stint on aerial combat duties, the type found itself performing ground-attack duties with Army co-operation squadrons, where the heavy firepower and manoeuvrability were much appreciated by its pilots.
It is one of the few fighter aircraft of the Second World War that never destroyed a single enemy aeroplane in aerial combat, a somewhat unenviable combat record partially relieved by its sterling service against ground targets.
Of all the Allied nations, Australia could credibly lay claim to the title of being the most unprepared country for the start of the Second World War.
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The outbreak of war in Europe in 1939 saw most of Australia’s naval and ground forces deployed to Britain or the Mediterranean theatre of operations, and the Royal Australian Air Force’s (RAAF) remaining aircraft in the country were obsolescent, with no modern combat fighters in the national inventory.
The shock of the Japanese attacks on Hawaii and Malaya produced extreme anxiety in the Australian Government, as the nation was to all intents and purposes unable to defend itself from aerial attack.
Both Britain and America had promised fighter aircraft to Australia. Still, the calamity that was hitting the Allies during the desperate days of 1941-2 meant that RAF and USAAF needs came first, and there was nothing to spare (at the moment) for the RAAF.
As the Commonwealth Aircraft Corporation (CAC) had been set up by the Australian Government in 1936 to establish a self-sufficient local aviation industry, the head of CAC, Lawrence Wackett decided in late 1941 to develop a design for a locally produced fighter.
As the threat of war in the Pacific increased, it was decided to save time by using components of the only two military aircraft manufactured in Australia to design and assemble the new fighter.
The Wirraway provided most of the fuselage, the tail and wings, and the engine from the locally produced Beaufort torpedo-bomber became the Boomerang’s power plant.
A problem arose with part of the proposed armament fit as the planned Hispano-Suiza autocannon wasn’t being locally manufactured, but the design team illegally reverse-engineered an example that an Australian airman had ‘souvenirs’ in the Middle East, and these were produced in a CAC workshop.
The finalised design showcased a short, stubby fighter with heavy armament that was optimised for manoeuvrability, and the design was approved for manufacture before the first prototype was even constructed, making the Boomerang an ‘off-the-drawing-board’ procurement program.
The project was formally approved for commencement in December 1941, and four prototypes were ordered.
These aircraft were also used as a proof-of-concept for using existing aircraft components in the manufacture of the Boomerang and were delivered in a very short time of three months.
Even though the government had recently put in a large order for American P-40s, the Boomerang project was seen as insurance against any delay in the manufacture and supply of the Kittyhawk, as well as establishing a local capacity to manufacture combat fighter aircraft.
The government did not wait for the first successful flight of a prototype and ordered 105 Boomerangs under the designation of CA-12 in February 1942.
Thankfully, the first test flight in May 1942, and the subsequent test series showed no great problems with the design, except for one massive exception – the Boomerang was somewhat underpowered, and slow.
Despite the arrival of USAAF squadrons equipped with the P-40 providing much-needed fighter cover for Australia’s north, and the prospect of RAAF orders for American and British fighters being filled promptly, the government still decided to go ahead with procurement of the Boomerang into Australian service.
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The disappointing performance figures led to further development of the basic design, and a slightly improved CA-13 version was ordered in late 1943, after the production run of the CA-12 was completed in June 1943. 95 examples of the CA-13 were manufactured.
Further development work led to the CA-14, of which only one test example was constructed. With a turbo-supercharger fitted to the engine, the CA-14 had much-improved performance figures, to the extent that it was compared favourably (under certain conditions) to the Spitfire Mk V, and early marques of the Thunderbolt and Mustang.
However by this time Australia had received a large delivery of the superb Spitfire Mk VIII for home defence duties and was manufacturing the Mustang under licence at CAC, and the CA-14 was never put into production.
The last model of the Boomerang to be put into production was the CA-19, a specialised reconnaissance version.
Fitted with a belly camera and the larger tailfin trialled in the CA-14, 49 examples of this variant were constructed, with the last CA-19 rolling off the production line in February 1945. Total production figures for all variants of the CAC Boomerang stand at 250 units.
The CAC Boomerang
All dimensions and performance figures are for the CA-12 variant.
The Boomerang had a height of 9 feet 7 inches (2.92 metres), a length of 25 feet 6 inches (7.77 metres) and a wingspan of 36 feet (10.97 metres). Empty, the Boomerang weighed in at 5,373 pounds (2,437 kilograms) and the fully-loaded gross mass of the aircraft tipped the scales at 7,699 pounds (3,492 kilograms).
The Boomerang was fitted with a Pratt & Whitney R-1830 Twin Wasp 14-cylinder air-cooled piston engine driving a three-blade constant-speed airscrew, and this power plant developed 1,200 HP.
The performance figures of this variant were not impressive: a top speed of 305 mph (491 km/h) and a service ceiling of 29,000 feet (8,800 metres). The range of the Boomerang on internal fuel was 930 miles (1,500 kilometres) but this could be extended by a drop tank carried under the fuselage.
The Boomerang was heavily armed in the fashion of most fighters of the period, with two Hispano-Suiza/CAC 20 mm autocannon and four Browning 7.7 mm machine guns mounted in the wings. When the drop tank was not being utilised, a single bomb or smoke markers could be carried on the ventral hard point.
The first deliveries of the Boomerang to the government started in July 1942, and by April 1943 the type was operating with RAAF squadrons in the Torres Straight region in air-defence roles.
A series of interceptions of Japanese bombers occurred during May 1943, but the CA-12 was found to be far too slow to catch up to Japanese ‘Betty’ bombers and was unable to attack these intruders successfully.
Accordingly, the type was removed from air-defence duties, and sent to Army co-operation squadrons in the South-West Pacific Area (SWPA) of operations.
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In this new role of ground attack and observation duties, the Boomerang was far more capable, being appreciated for its heavy firepower, manoeuvrability and ability to loiter at low speed and height over the battle area.
Boomerangs would often operate in pairs, with the wingman observing Japanese ground fire directed at the leader and then bringing the hostile ground troops under strafing attack, or dropping bombs to counter the ground fire.
As designed, the canopy of the Boomerang was heavily armoured with bulletproof glass of great thickness, and the airframe had armour plates shielding the bottom of the cockpit area as well.
This level of protection, along with the robust construction of the airframe and the reliability of the Twin Wasp engine saw Boomerangs able to absorb a large amount of battle damage and still safely return to base, and the pilots of the aircraft greatly appreciated this.
Several RAAF squadrons were equipped with the Boomerang for Army cooperation duties, and the platform saw service over New Guinea, the Solomon Islands, Borneo and finally during the Bougainville Campaign.
In this last campaign, the RAAF Boomerang squadrons were paired with Royal New Zealand Air Force (RNZAF) Corsairs for ground-attack sorties, with the Boomerangs observing and marking targets with smoke markers, and the Corsairs attacking with bombs and rockets.
This pairing worked very well indeed and allowed the Boomerang to finish its service with the RAAF on a high note.
By August 1945 active operations had come to an end, but one squadron employed the Boomerang in the air-sea rescue role for a period after the war ended. The sole CA-14 was used for research by the RAAF and also employed by the Bureau of Meteorology for some time.
The CAC Boomerang was an emergency program, and such urgency meant that an inferior design was authorised for manufacture, due to the desperation of the times.
Conceived as an air-combat fighter, it was a dismal failure in this role, enjoying even less success than its predecessor the slower, lightly armed Wirraway, which had managed to down an Oscar fighter of the Japanese Army in 1942 – admittedly, the first burst from the Wirraway killed the Japanese pilot, thereby winning the engagement on the first trick.
Had the Boomerang encountered Japanese fighters in its career, it would have suffered the same fate as the despised Brewster Buffalo, being hacked down in large numbers by Japanese fighters and suffering total defeat in the air.
Gaining a new lease of life operating with Army co-operation squadrons, the Boomerang enjoyed combat success and relevance by successfully performing ground attack and observation tasks.
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Fighting on with Allied forces in the SWPA until the end of the war, the Boomerang ended the conflict with a fine record in its new field of expertise and was well-liked by its pilots for its toughness and durability.
As such, the CAC Boomerang has a somewhat mixed legacy but earns its place in Australian military history and aviation writings as a weapon quickly forged in a desperate time, and successfully used in combat.
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- 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)
- Empty weight: 5,373 lb (2,437 kg)
- Gross weight: 7,699 lb (3,492 kg)
- Powerplant: 1 × Pratt & Whitney R-1830 Twin Wasp 14-cylinder air-cooled radial piston engine, 1,200 hp (890 kW)
- Maximum speed: 305 mph (491 km/h, 265 kn) at 15,500 ft (4,724 m)
- Range: 930 mi (1,500 km, 810 nmi)
- Service ceiling: 29,000 ft (8,800 m)
- Rate of climb: 2,940 ft/min (14.9 m/s)