The Seversky P-35 was the first American fighter with a retractable landing gear, the first of all-metal construction, and the first with an enclosed cockpit. However, it was produced at a time in which fighter designs were evolving quite rapidly, and rapidly became obsolete. It is best noted for its role as an advanced trainer for fighter pilots but it did serve in the Far East from 1940 through to 1942 as part of the rapid American build-up in that part of the world.
In 1935, the Seversky company produced a privately-financed experimental fighter known as SEV-2, powered by an 850 hp Wright R-1820 radial air-cooled engine driving a three-bladed propeller. The design used a low-mounted elliptical wing. The two cremembers sat in tandem under a transparent cockpit hood, and the rear crewmember was provided with a flexible gun mount for protection against attacks from the rear. The SEV-2 had a fixed undercarriage enclosed by large wheel pants. Seversky decided to enter a modified version of the aircraft in the USAAC's May 1935 competition for a single-seat monoplane to replace the Boeing P-26 currently in service. Major de Seversky quickly learned that his two competitors, the Curtiss Model 75 and the Northrop 3A, both had retractable undercarriages. On June 18, 1935, the SEV-2 was "badly damaged" in an accident while on its way by road to Wright Field for entry into the competition, and the airplane was taken back to the Farmingdale factory for repairs.
The Seversky company stalled the USAAC competition while they hastily modified the SEV-2. The two-seater became a single-seater, and a retractable undercarriage was fitted. A new 850 hp Wright R-1820-G5 Cyclone air-cooled radial engine was fitted. The company redesignated the aircraft as SEV-1. Armament was two 0.30-cal machine guns mounted in the upper fuselage, synchronized to fire through the propeller arc. The SEV-1 finally arrived at Wright Field on August 15, 1935. During early test flights at Wright Field, the SEV-1XP was able to attain only 289 mph at 10,000 feet, rather than the 300 mph actually promised. The engine was replaced by an 850 hp Pratt & Whitney R-1830-9 Twin Wasp. However, the Twin Wasp engine was found to yield only 738 hp, and the top speed of the new fighter dropped still further, down to 277 mph.
After some further modifications, the designation was changed to AP-1. Although the Seversky fighter never lived up to its promised maximum speed of 300 mph, it was judged by the USAAC as the best of the entries, and on June 16, 1936, Seversky was awarded a contract for 77 examples under the designation P-35. Serial numbers were 36-354/430.
The P-35 was similar to the SEV-7, with a cantilever, low-mounted wing. The wing was entirely of metal with the exception of the control surfaces, which were fabric covered. The 850 hp Pratt & Whitney R-1830-9 radial engine was enclosed by a tight cowling. Armament was the American standard of the day, one 0.50-inch and one 0.30-inch machine gun in the upper fuselage deck, synchronized to fire through the propeller arc. The first production P-35 had no wing dihedral and large bulging fairings that completely enclosed the wheels. Testing at Wright Field revealed that the aircraft was extremely unstable and had some rather dangerous flying characteristics. Stability was improved by adding several degrees of dihedral to the wing and replacing the full wheel fairings by partial fairings.
The first delivery of a P-35 to the USAAC was in July 1937. Deliveries of the P-35 to the USAAC were exceedingly slow because of the Seversky company's inexperience with mass production, and it was not until the spring of 1938 that the 17th, 27th, and 94th Squadrons of the First Pursuit Group at Selfridge Field, Michigan actually received their first P-35s. The last P-35 of the original order was delivered in August 1938. After flying for a few months with the 1st Pursuit Group, the P-35s were redistributed among squadrons of the 31st, 49th, 50th, 53rd, and 58th Groups, pending the arrival of P-36 fighters into service.
By 1940, it was clear that the rapid advances in military aviation were quickly making the P-35 fighter obsolete. The P-35 was too slow, too lightly-armed, and was lacking in such protections as armor for the pilot or self-sealing fuel tanks. The shotgun engine starter often jammed, the engine tended to leak oil, and the gear retraction mechanism was often found to be faulty. Consequently, the service life of the P-35 with the USAAC was rather brief. As P-35s were removed from service with front-line combat units, they were transferred to training units or were used at ground schools for the training of mechanics.
Specifications of Seversky P-35
Maximum speed of the P-35 at 10,000 feet was 282 mph. An altitude of 15,000 feet could be reached in 6.9 minutes. Service ceiling was 30,600 feet. Empty and loaded weights were 4315 lb and 5599 lb respectively. Maximum range was 1150 miles. Armament was one 0.3 inch an one 0.5 inch machine guns.
With the Halifax-Butler Coup of 1940, the U.S. started a major mobilization process. This involved placing large orders for aircraft using whatever designs happened to be available. The standard supplier of fighter aircraft to the USAAC was Curtiss who were already at maximum capacity, building P-40 aircraft. Reluctantly, the USAAC turned to Seversky hoping to order that company’s P-43 or P-44 fighters, both of which were under Air Force test. However, neither was ready for production so the AAC placed an order for 120 P-35A aircraft. The P-35A was quite similar to the P-35 but was fitted with the more-powerful 1050 hp Pratt & Whitney R-1830-45 radial and had two nose-mounted 0.50-in guns and two 0.30-in guns in the wings. The aircraft were assigned to the Philippines On December 8, 1941, where they formed an important part of the first line of defense of these islands. They were, of course, completely inadequate for the task. By late 1940 standards, the P-35A was hopelessly obsolescent. It was too lightly armed and lacked either armor around the cockpit or self-sealing fuel tanks. However, it was believed that Japanese aircraft were equally deficient and the fact of large numbers of American fighters arriving in the Philippines would be a valuable deterrent. This indeed proved to be the case. By 1942, the P-35As had been replaced by more modern fighters and they returned to the States for use as advanced trainers.
Specifications of Seversky P-35A
The P-35A had a maximum speed of 310 mph at 14,300 feet. Initial climb rate was 1920 ft/min. Service ceiling was 31,400 feet. Maximum range was 950 miles. Weights were 4575 lbs empty and 6118 lbs normal loaded. Armament was two 0.5 inch and two 0.3 inch machine guns. Two 100 pound bombs could be carried under the wings