Seversky SEV-3

Seversky SEV-3
SEV-3 at Wright Field in the summer of 1934
Type:	Civil amphibious aircraft
Design country:	United States
Manufacturer:	Seversky
First flight:	April 1933

Alexander de Seversky in front of the SEV-3XAR in landplane configuration

The Seversky SEV-3 "Sportsman" was a seaplane made by the American manufacturer Seversky Aircraft Corporation in the early 1930s. Landings on land were also possible thanks to additional extendable wheels, so that the SEV-3 can also be classified as an amphibious aircraft. There was also a version with a wheeled chassis.

history

The SEV-3 was designed by Alexander Kartweli and was the first aircraft built by the Seversky Aircraft Corporation, founded in 1931. The number 3 stood for the three-seat design. In the absence of its own production facilities, the machine was built in the College Point plant of the Edo float factory , which was located in a New York suburb. Seversky later moved into its own production facilities and an airfield in Farmingdale, Long Island.

The SEV-3 ( aircraft registration number NX2106), which was flown for the first time in April 1933, can be regarded as an innovative design, since it was the first time in the USA that a cantilevered all-metal wing was used together with an all-metal fuselage in half-shell construction and a low - resistance NACA canopy . Also unusual were the simply stepped floats, which had hydraulically retractable wheels in the front part. The floats could be swiveled backwards for land use by additional V-struts connected to the fuselage, so that the tail wheel could serve as the third wheel of the landing gear. The extended main wheels were attached directly to the wing via struts integrated into the float strut cladding, so that the forces on landing could be absorbed directly by the wing and did not have to be introduced via the float struts. Swimmers should also allow landings on ice, snow or sand.

A few months after the record flight of October 9, 1933, when a speed record for amphibious aircraft could be set with 289.2 km / h, Seversky swapped the swimmers for a pants-leg landing gear. In this form, the SEV-3 reached a top speed of 338 km / h and a cruising speed of 297.7 km / h. These achievements prompted the US Army to modify the aircraft and subject it to a test at Wright Field to investigate its suitability as a military training aircraft. The machine now known as SEV-3XAR (XAR for Experimental Army) had a 350 hp Wright R-975 radial engine. The engine mounts were lengthened so that the engine, which was now positioned further forward, provided an improved center of gravity. The windshield was also changed, along with a raised cockpit hood. The US Army ordered 30 trainer aircraft of this type under the designation BT-8 .

The prototype was then rebuilt into the amphibious version and received a 715 PS Wright R-1820 -F3 cyclone engine as the SEV-3M . The 1935 Thompson Trophy Race finished this machine in fifth place with an average speed of 311 km / h. A later record flight even reached 370.7 km / h.

In the meantime, a second prototype equipped with a Wright R-1820 as a two-seat land plane SEV-2XP (XP for Experimental Pursuit) had been completed. The undercarriage covered with trouser legs was retained; the cockpit cover was lengthened and now had two sliding hood sections at the front and rear. The SEV-2XP also received armament in the form of two fixed, forward-firing 0.30-in machine guns and a swiveling machine gun in the rear cockpit area.

When the SEV-2XP began its flight tests in 1935, the US Army was looking for a successor to the outdated Boeing P-26 fighter aircraft and Seversky decided to have his machine compete against single-seat fighter planes at Wright Field. On the flight there, the aircraft suffered such accidental damage on June 18, 1935 that it had to be brought back to the Seversky factory in Farmingdale for repairs. There, however, it was converted into the single-seat SEV-1XP and received a Wright R-1820-G5 Cyclone with 850 hp as the engine. In addition to an improved cockpit, the fixed landing gear has also been replaced by one that retracts to the rear in wing panels. The SEV-1XP reached Wright Field on August 15, 1935, where the flight performance turned out to be disappointing due to a lack of engine power. Further testing took place in April 1936 after Seversky had replaced the Wright engine with an 850-hp Pratt & Whitney R-1830-9 Twin Wasp. At the same time the tail unit received some improvements and machine guns with larger caliber were used as forward armament. The USAAC finally declared the SEV-1XP as the winner of the comparison flight and Seversky received an order for 77 P-35s on June 16, 1936 , with some further improvements being incorporated into the final prototype AP-1 (Army Pursuit No. 1) .

A five-seat (SEV-5 "Executive") and a 10-seat variant with two pilots and eight passengers (SEV-7 "Transport") were also planned, but these were not built.

construction

The SEV-3 was an all - metal low- wing aircraft with cantilevered wings and a fuselage in half-shell construction. The radial engine was covered with a NACA hood. The wing paneling was reinforced inside with corrugated iron in the upper area and with beams with a closed cross-section in the lower area. The two passengers sat in their own compartment in the middle of the fuselage. Under the trailing edge of the wing there was an air brake that ran over the entire span , reducing the landing speed by around 24 km / h. Behind the pilot there was room for two passengers. The machine has been rebuilt several times. Initially, the passenger area was covered with a sliding hood.

Technical specifications

Parameter	BT-8 data
crew	2
length	7.42 m
span	10.98 m
height	? m
Wing area	20.4 m²
Empty mass	1317 kg
Takeoff mass	1841 kg
Top speed	282 km / h
Engines	1 Pratt & Whitney R- 985-11 Wasp Junior with 450 PS (336 kW)

See also

• List of aircraft types

literature

• Ken Wixey: Republic's Jug - A production history of the Seversky / Republic P-47 Thunderbolt . In: AIR Enthusiast No. 89, September / October 2000, p. 26
• Fighter A to Z . In: AIR International October 1992, p. 220

Web links

Commons : Seversky SEV-3  - collection of images, videos and audio files

• History of the SEV-3 at 1000aircraftphotos.com (accessed January 2, 2014)
• Overview of Seversky types on aerofiles.com (accessed on January 2, 2014)
• Photo of the SEV-3XAR on Flickr.com (accessed January 2, 2014)

Individual evidence

1. ↑ Fast American Amphibians . In: Royal Aero Club (ed.): Flight . Vol. XXV, No. 46, No. Issue 1299, pg. 1154, November 16, 1933. Retrieved January 17, 2017.
2. ^ FG Swanborough, Peter M. Bowers: United States Military Aircraft since 1909 , Putnam, London, 1963, p. 529