- Yes
- No
History
In November 1942 an order for an R-2600-engined Boomerang but was rescinded in in the following Feburary and replaced with an order for a completely new aircraft. At the time it was intended that the single speed/single stage turbocharged R-2800-21 engine should be fitted, alternative verisons with the R-2800-43 (single stage/two speed supercharger) and R-2800-21 or -25 (two stage/two speed supercharger) having been considered and rejected.
After a visit to the US in early 1943 Lawrence Wackett suggested the P-51D Mustang be adopted for use by the RAAF. Plans changed from a high altitude emergency design fighter to a low altitude fighter, to avoid competition with te P-51D. As a result the R-2800-21 engine was replaced by a supercharged, water-injected R-2800-10W.
In August 1943 RAAF specification 2/43 was written around the revised design. It called for “The design and construction of a prototype single engine medium altitude fighter by the Commonwealth Aircraft Corporation and referred to as Model C.A 15”
Specifications
The specification asked for:
-optimum performance at or around 20,000ft
- A high rate of climb coupled with a high rate of acceleration
- Good fighting manoeuvrability, particularly in the rolling plane
- high speed
-particular attention to visibility - Flying controls should be positive, light, immediate in response, should work with the least amount of friction and be well harmonised.
- There should be no hesitation in engine power during fighting manoeuvres, an essential being “g” loads
- The aircraft should be designed from the onset for tropical use
- Maximum possible climb was not to be less than 3,500 ft per minute average from ground level to a minimum altitude of 20,000 ft on military power at a combat weight of 9,360 lb.
- The highest possible fighting manoeuvrability was essential particularly in the rolling plane and the turning circle was to be as small as possible, but these requirements were to be balanced against the requirements for climb and speed
- The speed was to be as high as possible consistent with the requirements of high rate of climb and manoeuvrability: the aim was to be 400 mph T.A.S. at or about 20,000 ft, again at a combat weight of 9,360lb
- The aircraft was to land within 1,000 yards from 50ft in still air, landing at full weight less running up and take off fuel allowances
- The aircraft was to be fitted with permanent, self-sealing fuel tanks with a capacity of not less than 220 imperial gallons, as well as the capacity to carry two droppable auxiliary fuel tanks each of 40 imperial gallons or two droppable ‘reinforcing’ (presumably ferry) tanks each of 60 imperial gallons
- Provision was to be made for installation in the mainplanes of either four 20mm cannon with 120 rounds per gun or .5 in Browning machine guns with 250 rounds per gun, the mountings to be interchangeable. In addition, two 500lb. bombs of a “standard pattern” on single hook release slips were to be carried, with alternative fitment of smaller pattern bombs to be provided
- The pilot was to be protected against 20mm fire from 100 yards astern at angles of up to 20° to the aircraft centre line. The windscreen was to be constructed of laminate plate glass 1/2 inches thick. The engine and fuel installations were to be protected as far as possible by the pilots armour, the aircraft structure and heavy gauge cowlings and deflector plates where that could be achieved economically, and the fuel and oil tanks were to be self-sealing against .303" and .5" ammunition. Ammunition was to be positioned so as to obtain the maximum possible protection from the aircrafts structure.
In charge of the designs were Lawrence Wackett and Fred David. Fred David was an Austrian Jew who has previous experience working for Heinkel, Mitsubishi and Aichi, working on designs such as the A5M and the D3A. As a result, early designs share similarities with these designs, and the He 100.
Eventually plans were refined into and aircraft loosely based off the Fw 190, with a R-2800-10W engine. The initial approval of design included and allocation of 50,000 pounds for development purposes and the same amount again for materials and equipment after production approval had been given. In May 1944 CAC learned that the R-2800-10W engine was out of production, and thus no longer available. By this point a full-scale mockup was already being produced.
The specification was changed to include a turbocharged R-2800-57W and the design was redesigned to include it’s turbocharger. This again changed the layout. In August 1944 CAC was once again informed that the engine could not be guaranteed, resulting in another re-design.
In September the aircraft was re-designed to incorporate the Rolls-Royce Griffon 125. This was a substantial redesign, which gave the Ca-15 it’s Mustang-like appearance, with it’s in-line engine and underslung radiator. Despite it’s superficial resemblance, the aircraft were quite different, the Ca-15 being much larger and designed from scratch. The Ca-15 did use the ten-spoked main undercarriage wheels of a P-51D, however the tail wheel and it’s retraction mechanism were also used in the Hawker Tempest, so to call this an Australian P-51D is completely incorrect. In fact this aircraft is fairly similar to the M.B.5!
This however was not the end of CACs woes. On 21 September 1944 the project was cancelled by the War Cabinet and the RAAF lost interest. It was becoming obvious that the jet aircraft appearing in Europe would be the future in aerial warfare. This however upset those involved in the air industry, as the local air industry seeked projects to expand Australia’s aircraft manufacturing capabilities. On 11 October 1944 a case for reinstatement was submitted by Senator Cameron to the Prime Minister.
Case for reinstatement as summarised in Agendum No.554/1944
- The CA.15 prototype is the first aircraft to be designed in Australia which will receive the full benefit of the research and educational facilities provided by the commonwealth at the C.S.I.R. Division of Aeronautics and by the endowment of the Chair of Aeronautics at the Sydney University. The project has proved to be of great value in developing and exercising the whole complex system required to provide a new type of aircraft.
- The ability to produce aircraft of Australian design is important to the defence of the Commonwealth for the reason that Australia cannot depend on being able to obtain from overseas proven designs which are in every respect suitable for manufacture in Australian factories and capable of meeting in all respects the operational requirements of the R.A.A.F.
- The termination of the project will not result in the diversion of any considerable number of personnel, as only 65 men were employed upon the project at the date of suspension of operation. Of this number, 15 are young aeronautical engineers including graduates of the School of Aeronautics at the University of Sydney, and some others comprise young men with overseas experience in aircraft design and development. These men cannot be employed upon other work of a similar character, and their talents and specialised experience will be lost to Australia.
- The cancellation of the project will retard aeronautical development in Australia and it will vitally affect the work of the Aeronautics Division of C.S.I.R. as the same time will disintegrate entirely the design and development group now employed thereon.
- Aircraft production in Australia cannot continue successfully unless there are aeronautical engineers available to work on modifications and changes necessary in order to make aircraft of overseas design suitable operationally for the R.A.A.F.
- The value of the R.A.A.F. in peace time and in preparation for war will be quite seriously reduced if Australia does not possess an aircraft manufacturing industry, backed by organised research, design and development facilities. An aircraft manufacturing industry without such facilities will remain seriously handicapped due to the absence of means fundamental to its continued existence and future development.
- The elimination of design and development work on the CA.15 project is seriously regarded by the C.S.I.R. because this project provides the only opportunity at present in Australia for the gaining of local experience and the exercise of originality in design, bringing out those problems (many of them peculiar to Australian conditions) which demand a scientific research of the type with which the Aeronautics Laboratory is thoroughly competent to deal.
Faced with this pressure, the War Cabinet revised it’s decision and reversed it’s decision on 7 December 1944, subject to ratification by the Aircraft Advisory Committee, this did not occur until 25 January 1945. Another hit came when the Griffon 125 could not be obtained, and 2 Griffon 61s had to be loaned from Rolls-Royce instead. The aircraft would never fly with the Griffon 125. As a result production was delayed and taxying trials did not begin until 12 February 1946, several months since the war had ended. The aircraft made it’s first flight on 4 March 1946 at the hands of Jim Schofield, CAC’s test pilot. The landing struts were over pressured, resulting in bouncing while landing, which lead to the nickname “Kangaroo”, however this was never formally adopted. On 27 June 1946 the Ca-15 was handed over to 1APU after making 23 demonstration and test flights totalling 16 3/4 hours with CAC.
On 10 December 1946 a hydraulic failure caused the landing gear to fail, resulting in a gear-up landing at Point Cook. This caused extensive damage, particularly to the propeller, radiator housing and lower fuselage. Repairs were delayed as an official investigation had to be held, which lasted until June 1947. The aircraft would not return to ARDU (formerly known as 1APU) until May 1948. The repairs were slow, taking 1,700 man-hours and costing 5,540 pounds. By this point the De Havilland Vampire was entering service with the RAAF and the P-51D was in production, sealing the fate of the Ca-15.
On 25 may 1948 Flight Lieutenant Lee Archer dived the aircraft, reaching a speed of 502.2mph (808 km/h) over Melbourne, after he had levelled off at 5,000 ft (1,524 m) following a modest dive from 9,000 ft (2,743 m). Unfortunately on May 1 1950 the aircraft was handed to No. 1 Aircraft Depot and “converted to components”, which marked the end of the road for this beast of an aircraft.
Specifications
Type
- Single-seat Fighter
Armament
- 6 x 0.5-inch (12.7mm) MG (wing mounted), 250 rounds per gun - proposed 4x 20mm (140 rpg) or 2x 20mm and 2x 0.5-inch MG
- 2 x 1000lb (450 kg) bombs or 2 x 500lb
- 10 x 5" T64 rockets
- 6 X 5" T64 rockets + 2 wing-mounted tanks
Weight
- Empty 7,540lb
- Gross - 10,764 (4,882 kg)
- Max takeoff 12,340lb
- Fuel capacity: 220 imp gal (260 US gal, 1,000L) in two wing tanks + 30 imp gal (36 US gal, 140L) in one fuselage tank, 2 optional under-wing tanks of 110 imp gal (130 US gal, 500L) undroppable, 100 imp gal (120 US gal, 450L) droppable or 40 imp gal (48 US gal, 180L) droppable.
Dimensions and structure
- Laminar flow cantilever wings, semi monocoque all metal fuselage with stressed metal skinning, all metal cantilever tail unit; hydraulically operated metal flaps (0, 20 and 50 degrees settings); hydraulically operated retractable Dowty main undercarriage, retractable tailwheel.
- Wingspan 36 feet (10.97m)
- length 36.2 1/2 feet
- 14.24 ft (4.34m)
- Airfoil: NACA 66 series
- wing loading: 37.5 lb/sq ft (183 kg/m2) normal load
48.8 lb/sq ft (238 kg/m2) - Power/mass: 0.243 hp/lb (0.399 kW/kg)
- Wing chord at root 10ft 3in (3.12m)
- Wing aspect ratio 5.12:1
- Wing dihedral (30% chord) 5 degrees
- Thickness ratio - Root: 15.71% - tip: 11.0%
- Aileron span 8ft 9.6in (2.68m
- Flap span 6ft 11.3in (2.11m)
- Wheels track 14ft 0.4in (4.28m)
- Wheelbase 23ft 7.2in (7.19m)
- Tailplane span 13ft 10in (4.22m)
- Tailplane dihedral 10 degrees
- Elevator span 6ft 5in (1.95m)
- Wing gross 253sq ft (23.50sq m)
- Wing nett 219.4sq ft (20.38sq m)
- Aileron 9.50 sq ft (0.88sq m)
- Tailplane gross 25.70sq ft (2.38sq m)
- Elevator 15.70sq ft (1.46sq m)
- Fin 12.1sq ft (1.12sq m)
- Rudder 13.2sq ft (1.22sq m)
Power
- Rolls Royce Griffin Mk 61 V-12 liquid-cooled piston engine, 2035hp (1,517 kW) with 18 psi (120 kPa) boost. Two speed/two stage super-chargers rated at 1,540hp for t/o (+12lb boost), 2,035hp at 7,000ft (+18lb boost) and 1,820hp at 21,000ft (+18lb boost)
- 4-bladed Rotol wooden 12ft 6 in (3.81m) diameter constant-speed propeller. Propellor reduction ratio 0.45. Supercharger gear ratios (MS) 5.838, (FS) 7.58. Initially a 12 ft 1in (3.68m) propeller used due to damage.
Climb
- 4,900 feet/min (24.9 m/s)
- time to altitude: 20,000 ft (6,100m) in 5 minutes 30 seconds
- Initial climb 3,650 ft (1,112m)/min
- Mac climb 4,990ft (1,520m)/min
- At 30,000ft, 2,250ft (686m)/min
Ceiling
- 39,000 feet (12,162m)
Max speed
- 368 mph (592 km/h, 320 kn) at sea level
- 442 mph (711 km/h, 384 kn) at 25,600 ft (7,800m)
- 448 mph (720km/h) at 26,400 ft (8,047m)
- 432 mph (695km/h) at 32,000 ft (9,754m)
Endurance
- Range: 1,150 miles (1,850km, 1,000 nmi) on internal fuel at 5,000ft
- Ferry range: 2,540 miles (4,090km, 2,210nmi) at 5,000 feet (1,500m) at 1,600 rpm
Drag summary
Drag: lb at 100 f.p.s
Wing: 15.7
Fuselage: 22.7
Tail unit: 5.1
Wing fus. Inter: 1.5
Tail interference: 0.5
Tail induced drag: 0.5
Cabin: 1.4
Pitot tube: 0.5
Radio mast: 0.8
Control gaps: 0.0
Roughness: 0.0
Cooling: 1.5
Total Drag: 50.2lb
Note: Fuselage drag includes radiator form drag and leak drag
In game
This aircraft truly deserves a place in War Thunder. It would make a perfect tier 4 premium aircraft for the British tree, or a high tier 4 tech tree aircraft in a Commonwealth/Australia tree. It’s performance would hold it’s own against other superprops and has enough speed to contend with low br jets.
It’s bombs and rockets give it solid CAS potential. The specifications request the option to interchange the 0.5 inch MGs for 20mm Cannons, and these are shown in blueprints, however I am not sure if the actual prototype had this option. The ability to add 20mm cannons to the Ca-15 in game would be amazing and would make this a seriously deadly aircraft.
Sources
CAC CA-15 | Aircraft of World War II - WW2Aircraft.net Forums
The Incomplete Guide to Airfoil Usage
Commonwealth Aircraft Corporation CA-15 ‘Kangaroo’ | Old Machine Press
https://simpleflying.com/cac-ca-15-kangaroo-australia-fighter-aircraft-history/
CAC CA-15 (Kangaroo) Fighter-Interceptor / Bomber Escort Prototype
The CAC CA-15 “Kangaroo’; Aussie Mega-Mustang - Forgotten Aircraft - Military Matters
Australia’s Lost Fighter The CA-15 and its Demise by David Clark
Wirraway, Boomerang & CA-15 In Australian Service by Stewart Wilson
Australia’s Military Aircraft by Ross Gilbert