The Curtiss-Wright CW-21 was a lightweight export fighter that was purchased in small numbers by the Chinese and Dutch, and that saw limited combat during the defence of the Dutch East Indies in 1942.
The CW-21 was developed from the earlier CW-19, which had been developed as a civilian cabin monoplane in 1934-35, but quickly redesigned as a military trainer and light attack aircraft. The CW-19 wing, with a tapered leading edge and straight trailing edge, would later be used as the basis of the CW-21 wing. The CW-19 was soon given a more powerful engine, which made it rather too ‘hot’ for the civilian market, then turned into military aircraft as the CW-19R. This saw the cabin cockpit replaced with a two –man tandem cockpit under a sliding canopy, power increased from 145hp up to 350-450hp depending on the engine chosen, and the ability to carry three fixed machine guns, one flexibly mounted rear firing gun and light bombs.
In 1938 Willis Wells from Curtiss’s St Louis produced the Model CW-21 by matching the wing from the CW-19 with a new light-weight fighter fuselage. The wing was modified to carry retractable wheels. On the original CW-21 this was done rather clumsily, with the main wheels retracting backwards into a large clamshell fairing that jutted out below the wings. This changed on the CW-21B, which had its wheels folding inwards towards the fuselage.
The CW-21 was powered by the 850hp Wright R-1820-G5 Cyclone engine. This had a much larger cross section than the light-weight fuselage, so there was a sudden change in size just behind the engine – both below and to the sides. The cockpit was mounted about half way along the fuselage, just behind the wings, and the top of rear fuselage sloped down rapidly from the back of the cockpit to the tail. The fuselage was of all-metal stressed skin construction. The basic model was armed with two 0.5in machine guns in the nose and could carry an extra 0.3in gun in each wing.
The prototype made its maiden flight on 22 September 1938. It was examined by the Army, but rejected (partly for ‘requiring a genius to land it’). In February 1939 this aircraft was sold to the Curtiss-Wright Export Sales Division, and then sent to China as a demonstrator in February 1939. The Chinese were impressed enough to purchase the demonstrator, order three more aircraft to be built in American and the parts for 27 aircraft to be assembled in China by CAMCO.
The first of the three production aircraft made its maiden flight on 20 March 1940. However the type never entered Chinese service. The prototype was lost in a crash in China. The three production aircraft were built in March 1940 and shipped to Rangoon in May 1940, but were then lost to engine failures while being flown from Lashio to Kunming on 23 December 1940 (probably due to dirty fuel). The kits reached Loiwing, and two of them were almost complete when a Japanese advance forced CAMCO to evacuate to India. On 1 May 1942 their factory at Loiwing and the partly completed aircraft were all burnt to prevent them falling into Japanese hands.
The CW-21A was a proposal for a version of the aircraft that would have been powered by the Allison V-1710 engine. None were built, but it did feature a new undercarriage that was then used on the CW-21B and the single CW-23 trainer, although it isn’t entirely clear in which order these aircraft were produced). The CW-23 flew in April 1939 and the CW-21B was ordered in 1940, but the date of the CW-21A is unclear.
The CW-21B was the second version of the CW-21 to reach production. It had a new inwardly retracting undercarriage that was fully enclosed in the wings when retracted and hydraulically activated flaps. The Dutch ordered twenty four on 17 April 1940, but the country was overrun by the Germans before any could be delivered. The order was then changed to send them to the Dutch East Indies. The first aircraft made its maiden flight in mid-September 1940, and they were delivered in October-December 1940. These aircraft were armed with four .303in Browning Machine Guns, and equipped the 2nd Fighter Squadron of the Netherlands East Indies Army Aviation Section.
At the start of 1942 the CW-21Bs were posted on Java, along with a larger number of Brewster Buffaloes and a handful of Curtiss P-36s. Thirteen of them were at Surabaya in eastern Java when the Japanese attacked on 3 February 1942. Six were destroyed during the first raid, which was carried out by about 26 bombers and 50 fighters. Seven took off to face the second raid, of which only two returned. The remaining aircraft did a little better, but they flew their last combat mission for the Dutch on 5 March 1942.
The CW-21B’s lightweight construction made it vulnerable, especially the lack of any protection for the fuel tank, and it was also outgunned by most Japanese fighters. It was also used in dogfights, despite not being suited for that role. However the big problem was that it was massively outnumbered by the Japanese, and like all of the Allied defenders of the Dutch East Indies overwhelmed.
Engine: Wright R-1820-G5 Cyclone nine-cylinder radial engine
Span: 35ft 0in
Length: 27 ft 2in
Height: 8ft 8in
Empty weight: 3,382lb
Loaded weight: 4,500lb
Maximum take-off weight:
Max speed: 314mph at 12,200ft
Climb Rate: 4,800ft/ min (4,500ft/ min)
Service ceiling: 34,300ft
Endurance: 630 miles
Range: 530 miles (630 miles)
Armament: Four .303in Browning machine guns