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Curtiss P-36
Curtiss P-36 with pre-war U.S. Army Air Corps colors and the Wright Field arrow (identifying it as a test machine) on its flank

Uncertain Wings: Curtiss Hawk 75 in China

By Richard L. Dunn © 2008

     At the outbreak of the Sino-Japanese conflict in July 1937 the Curtiss-Wright Corp. was already well established in China. It had exported over one hundred Hawk biplane fighters to China and also had part ownership in an aircraft production company (CAMCO) that produced licensed built versions of the same aircraft and manufactured or repaired other models. Curtiss biplane fighters made up a substantial part of China’s air power and were able to compete on roughly equal terms with the Japanese army and navy biplane fighters at the beginning of the conflict.

     The first months of the war saw Chinese air power suffer from combat and operational losses. The Japanese navy was receiving a new fighter. The first of their new Type 96 fighters arrived in China several weeks after the fighting started. The performance of the monoplane Type 96 was significantly better than any of the available Chinese fighters. The Chinese needed more and better fighters. China sought help to bolster its aviation capability from a variety of sources including its established supplier the Curtiss-Wright Corp.

     In mid-August 1937 China purchased a demonstration model of the Curtiss Hawk 75 upon the recommendation of Lt. Col. Claire L. Chennault, air advisor to Generalissimo Chiang Kai Shek. The Hawk 75 demonstrator was an export version of the P-36 fighter (Curtiss designation Hawk 75A) being acquired by the U.S. Army Air Corps. The P-36 was not then available for export but the Hawk 75 version with fixed rather than retractable landing gear and certain other changes of equipment was. The Chinese made a preliminary decision for the purchase of thirty Hawk 75’s plus purchase of additional Hawk III biplanes with Chennault’s blessing on August 24, 1937. Detailed negotiations to complete the contract then took place. Dr. H.H. Kung represented the Chinese government and apparently William D. Pawley, President of CAMCO and Curtiss-Wright representative in China, negotiated for Curtiss.

     The Hawk 75/P-36 originated as a privately financed venture of Curtiss that competed for an Air Corps contract in 1935 but lost to the Seversky P-35 which received a production contract for 77 aircraft in 1936. Curtiss presented a revised version (Y1P-36) which caught Air Corps attention and eventually (July 1937) received a production contract for an unprecedented 210 aircraft of which the first was delivered in April 1938. Export versions of the P-36 later performed creditably for the French in 1939-40. Though becoming somewhat dated P-36’s intercepted the Japanese over Hawaii in December 1941; flew for the Dutch in the East Indies in 1942; and, were for a time in 1942 the sole British fighter defense over Assam (India) and soldiered on in various roles in the Burma campaign through 1943. In addition to its other service it is perhaps ironic that the Hawk 75 also flew against America’s Allies. The Finns flew captured Hawks against the Russians and the Germans used a number of them as training aircraft.

Hawk Demonstrator. Curtiss began development of the export version of their model 75 early in 1937. In its original form the demonstrator had less power, fixed landing gear and was simplified as much as possible both to accommodate export concerns and to make it suitable for operations from airfields with austere facilities. Powered by a Curtiss-Wright GR-1820-G3 engine (875 h.p. for take off) another selling point for the Hawk 75 was the fact that it could be equipped with a variety of engines.

     The Hawk 75H flown in China bore U.S. civil registration No. NR1276. It was maneuverable, had a service ceiling of 31,800 feet, and, credited with a maximum speed of 280 m.p.h. at 10,700 feet was far faster than Japanese biplane fighters. It even had an edge on the Type 96 Carrier Fighter just entering service with the Japanese. NR1276 was considered eminently satisfactory for service in China. After its purchase it was often flown personally by Chennault. The production order for thirty additional Hawks was concluded in late summer 1937.

     More than a year later two additional demonstrator aircraft were produced. They bore the designation Hawk 75Q. With its R-1820-G105A engine this version had in excess of 200 more horse power than the earlier demonstrator. This aircraft was fitted with under wing gun pods for cannon. Some published accounts say two Hawk 75Q’s were supplied to China with fixed landing gear but one was converted to retractable gear. Only one Hawk 75Q was involved in official trials in the spring of 1939 and it had retractable landing gear. In fact it was routinely referred to as a P-36. The High Country
Illuminator

Curtiss Hawk 75 three-view
Hawk 75 showing the large landing gear fairings with which it was originally equipped, and which are also seen on the H-75Ns purchased by Thailand

     Once the reports from China indicating deficient performance were received, Curtiss carried out a detailed test program (June 7 – August 8, 1938) using Hawk 75M No. 9 and No. 30. The production aircraft obtained a maximum speed of 247 m.p.h. in these tests. Curtiss then fitted cut off exhaust stacks and employed a new design of landing gear. Subsequently equipment to modify the aircraft to the new configuration was shipped to China.

     In its final form as tested in Buffalo, New York, the Hawk 75M obtained a maximum speed of 233 m.p.h. at sea level, 265 m.p.h. at 10,700 feet, and, 266 m.p.h. at 16,400 feet. Rate of climb at sea level was 2,370 feet per minute. Climbing time to 16,400 feet was 7 min. 41 secs. Service ceiling was 31,860 feet.

     After arriving in China the Hawk 75M equipped the 16th, 18th and 25th Pursuit Squadrons of the Chinese Air Force. The 25th was a veteran pursuit squadron but pilots of the 16th and 18th squadrons had been flying single engine bombers and the squadrons had to be reorganized and retrained as pursuit units. Chennault aided in the retraining. All these squadrons received Hawk 75Ms by autumn 1938. However, as of mid-December only two Hawks had received the modifications that made them combat worthy. All the fighters were at bases in the interior of China while the modification kits had been shipped to a coastal port (presumably Hong Kong) and the exact means and timing of getting the required equipment to the fighters was uncertain.

     On 2 January 1939 tragedy befall the 25th Squadron. While on a cross country flight from Chungking to Sichuan crashes killed five pilots. Apparently a sixth aircraft was washed out on the same occasion. The squadron then transferred to Lanzhou to reform. Later it received old Hawk III biplanes to supplement its few remaining Hawk 75s. Also during January the 16th and 18th Squadrons transferred to Kunming where they continued training under Chennault’s tutelage. Apparently either training or modifying the fighters failed to progress satisfactorily. On April 8th, 1939 when twenty-three Japanese bombers raided Kunming no Chinese fighters rose to oppose them. Given the efficiency of the Chinese warning net around Kunming the failure to launch intercepting fighters could only have been a premeditated decision. Nine Chinese aircraft were destroyed on the ground. Some of these might have been Curtiss fighters but this is not certain.

     In August 1939 the 25th Squadron at Lanzhou was disbanded with its pilots going to other units. In the same month the 16th Squadron was also disbanded. The 18th Squadron transferred to Chungking. There is no record of these units being in combat with their Hawks. The majority of their Hawk 75’s had apparently been lost or rendered unserviceable in routine operations.

     The 18th Squadron continued to fly Hawk 75’s for the next year. In the spring of 1940 Hawk III biplanes supplemented the Hawk 75’s. Later in the summer the 18th was brought back up to strength on Hawk 75’s. In December 1940 the newly formed 11th Pursuit Group at Chengtu also had five Hawk 75’s among its forty-three fighters. The others were various versions of Soviet supplied I-15 and I-16 types. The Curtiss fighters had been refurbished in maintenance facilities before being issued to the 11th.

     The summer of 1940 saw the introduction of the Japanese Type Zero Carrier Fighter to China. The Zero was a superior fighter and the Chinese adopted a policy of avoiding combat with the Zero. On October 4, 1940 six Hawk 75’s of the 18th Squadron were following that policy by clearing out of the Chengtu area as twenty-seven navy Type 96 medium bombers approached with an escort of eight Zero fighters. After finding no aerial opposition the Zeros led by Lt. Tamotsu Yokoyama left the bombers to seek prey. Among the Chinese aircraft they encountered were the Hawk’s of the 18th. They shot down one Hawk (No. 5044) with the pilot killed when his parachute failed to open and sent two other disabled Hawks to crash landings with wounded pilots. Two others possibly suffering battle damage returned to the airfield. These were among the five “I-16’s” claimed by the Japanese. They also shot down a DB-3 bomber (claimed as an SB-2). Later the Japanese strafed Taipingsi airfield and claimed several Chinese aircraft destroyed on the ground. Two of these were the Hawk 75’s recently returned from combat. This was the famous attack in which four Zero pilots actually landed on the enemy airfield in order to burn Chinese aircraft that their strafing attacks failed to destroy.

     By December 1940 the 18th Squadron was down to its last serviceable Hawk 75 and was hors de combat leaving the 11th Pursuit Group and its five Hawk 75’s as the only operational unit still flying the Curtiss fighter. The Chinese continued to avoid confrontations with the Japanese Zero fighters so the Chinese Air Force saw little combat during 1941. Its operational strength declined through normal wear and tear, insufficient maintenance and lack of spares. By 1942 the Hawk 75’s were not among the American supplied aircraft listed as operational with the Chinese Air Force.

Remains - A Story of the Flying Tigers

Hawk 75A. By early 1939 Chennault had prevailed in his squabble with Bill Pawley over who was to blame for the poor performance of the Hawk 75M’s delivered to China. Pawley was in the dog house. This presented an opening to Pawley’s competitor A.L. Patterson. Patterson represented the interests of Seversky, Chance-Vought, and other American aviation companies. On March 25, 1939 Patterson signed a contract with the Chinese Government worth over $8 million to supply 54 Seversky fighters, 25 Vought dive bombers, and 120 Ryan and North American training planes.

     Rather than a straight cash deal the contract required only 25% of the purchase price in cash with the remainder financed over a period of thirty months backed only by bearer bonds of the Chinese finance minister. The deal was complicated by a number of factors including the financial troubles of the Seversky Company which was in receivership having lost money on its P-35 contract with the U.S. Army. Moreover, Seversky was in disfavor with U.S. authorities for having sold fighters to Japan in 1938. Pawley made sure actual and potential difficulties with the Patterson deal were well known to important Chinese officials.  

Curtiss Hawk 75 demonstrator
Curtiss Hawk 75 demonstrator in Chinese Air Force warpaint

     Soon after the Patterson contract was signed Chinese government officials influenced by Pawley’s information began to have doubts that the contract could be fulfilled. Meanwhile two Curtiss demonstrator fighters had made their way to China. One was an entirely new design from the Curtiss branch in St. Louis – the CW-21. The other was the demonstration version of the Hawk 75A – the P-36 finally made available for export.

     The two fighters made an impression in their various appearances in western China and by March were in Chungking for official trials. The CW-21 with an extreme climb rate (reputedly 5,000 feet per minute and actually only somewhat less) was light and rakish in appearance. The other demonstrator, although referred to as a P-36, was the Hawk 75Q which differed somewhat from the standard U.S. fighter version. It mounted two 23mm Madsen cannon in under wing pods in addition to its nose mounted .50 and .30 caliber machine guns. No other fighter in China came near matching that fire power. Despite its external gun pods the P-36 demonstrated in China attained a maximum speed of 305 m.p.h. according to a report of the U.S. military attaché in Chungking (the French rated their original P-36 version at 304 m.p.h.).

     As stated earlier the export P-36 gave a good account of itself in French service in Europe in 1939-40. A maximum speed of 305 m.p.h. as demonstrated in China may not sound impressive but needs to be put in perspective along with other performance data. The average maximum speed of several R.A.F. Hurricanes tested at the time of the Battle of Britain (mid/late-1940) was, according to Air Marshall Dowding head of Fighter Command, 305 m.p.h. as contrasted to their official maximum speed of 335 m.p.h. Later the U.S. National Advisory Committee on Aeronautics tested the P-36, Spitfire and Hurricane fitted with special test instruments to determine roll rate and found the P-36 equal or superior to the two supposedly superior British fighters. The British also tested the fighter against the Spitfire and found it had superior combat maneuvering capabilities but could not match the Spitfire in speed.

     Here it might be worth recounting some of the tall tales related to the CW-21 and Hawk 75Q. According to one story Robert Fausel in the CW-21 and Arch McEwen in the Hawk 75Q stood alert duty at Chungking in late March 1939. After an initial abortive scramble by both pilots, Fausel in the CW-21 took off on another attempt four days later and engaged Japanese army BR-20 bombers shooting one down (there were no Japanese raids on Chungking in March or April 1939). In another version George Weigel, described as a member of the Chinese Air Force International Squadron, took off in a “modified Hawk 75M with a heavy cannon fitted beneath each wing.” Martin Caiden, the author of this version, has Weigel as the lone intercepting fighter and engaging in “impossible maneuvers” as he flashes through a formation of Japanese bombers shooting down four of them. After the combat Weigel, according to Caiden, returned in his bullet-riddled fighter. Weigel was actually employed by CAMCO to fly the demonstrator. According to Caiden, Weigel died the next day in an accident caused by mechanical failure. The U.S. military attaché reported a raid by 45 Japanese bombers on 3 May intercepted by seventeen Chinese fighters in which two Chinese fighters and two Japanese bombers were shot down (both number of attackers and losses confirmed by Japanese sources) and a raid on 4 May by 27 Japanese bombers that was not intercepted. Given the tense commercial competition at the time one can speculate where these stories came from. It would be interesting to know if they were made up from whole cloth or whether there might be a grain of truth in them somewhere.

     On May 5th in a flight at Chungking the P-36 pulled up sharply into a climb and stalled at about 3,000 feet. Pilot Weigel was unable to recover and died in the crash. Despite the tragic loss of the P-36 and its pilot the two Curtiss demonstrators had given Pawley a new opportunity. His aircraft production plant which had been twice relocated was at Loiwing, China nearly ready for operation. He was wheeling and dealing for a new contract. At the same time he continued to cast aspersions on the Patterson deal, a deal made vulnerable as it became less likely that the Seversky fighters could be delivered in a timely fashion. Pawley also opened another front pointing out that Russian supplied I-15 fighters were, due to their slow speed, ineffective in attacking Japanese bombers which re-appeared over Chungking in May 1939.

Tales of the Flying Tigers

     The upshot of all these events was that the Patterson contract was cancelled and that Pawley gained a contract for the Hawk 75A, CW-21 and other aircraft. For the most part the Hawk 75A and CW-21 were to be shipped to China as materials and components. Construction and assembly of most of the fighters (55 P-36’s and 33 CW-21’s) would take place at the CAMCO factory at Loiwing. International events soon conspired to assure that no Hawk 75A’s would ever fly for China.

     Ports of entry to China via Hong Kong and Hanoi were soon effectively closed as transit points to China. Only Rangoon (port of Rangoon, river or rail to upper Burma, transshipment to China via the Burma Road) remained as a major supply route to China. Even this route was closed for several months in the summer of 1940 due to Japanese diplomatic pressure on the British. A huge backlog of goods for China accumulated at Rangoon including components and machine tools for manufacture of the P-36’s ordered for China. Once the Burma Road was reopened supplies began to move again but the road’s capacity was limited. In October 1940 before Loiwing had turned out a single P-36 or CW-21 the Japanese bombed the factory.

     The damage to the Loiwing factory was not severe but it brought production activity to a virtual halt. The hand writing was on the wall for Pawley. By spring 1941 he worked out a deal to transfer machine tools and aircraft components to India. In India CAMCO assets, some from the Loiwing factory, including P-36 components became the basis for the formation of the Hindustani Aircraft Company at Bangalore. Having established the first aircraft factory in China Pawley gained the additional distinction of establishing the first aircraft factory in India. The Hindustani factory actually got into production and beginning in July 1942 turned out four P-36’s (designated Mohawk IV and provided to R.A.F. squadrons) before Allied authorities determined it would be more useful as a repair and overhaul facility. None of the Hawk 75A’s ever got to the Chinese Air Force.

     Some production facilities and components from Loiwing were later sent to a Chinese aircraft factory established at Kunming. The Chinese produced a number of prototype aircraft with this material – certainly two and as many as nine according to some reports. Possibly some P-36 components were included in these aircraft.

      At the time they were demonstrated in China both the fixed landing gear Hawk and later the P-36 export version were competitive with, if not superior to, the Japanese fighters that were their potential opposition. In that sense the decision to acquire these fighters for China was a correct one. As this article shows, however, in the end the Curtiss Hawk 75M contributed little to the Chinese war effort and the P-36 (Hawk 75A) nothing at all.

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