When, in 1936, the USAAC Materiel Division placed an order for the SEV-1XP as the P-35, it had stipulated that the 77th and last series aircraft be fitted with a more powerful supercharged engine. The chosen engine was the Pratt & Whitney R-1830-19 of 1,200hp, fitted with an integral medium-altitude two-stage mechanical supercharger.

A contractual modification enabled Seversky to complete the airframe to a standard similar to that of the private-venture AP-4. The AP-9 was, in fact, used for competitive evaluation at Dayton in lieu of the XP-41 until the latter became available. Power plant apart, the aircraft was in virtually all respects similar to the AP-4.

The XP-41 36-430 was delivered to Wright Field for USAAC evaluation in February 1939, but the Air Corps preferred the turbo-supercharged AP-4 and further development of the XP-41 was discontinued, although trials continued at Langley. This was the last of the Kartveli-designed fighters to bear the Seversky appellation, as the company thereafter became the Republic Aviation Corporation.

Engine: P&W R-1830, 1200hp
Wingspan: 10.97 m / 36 ft 0 in
Wing area: 20.44 sq.m / 220.01 sq ft
Length: 8.23 m / 27 ft 0 in
Height: 3.78 m / 12 ft 5 in
Max take-off weight: 3175 kg / 7000 lb
Empty weight: 2445 kg / 5390 lb
Useful load: 1210 lb
Max. speed: 520 km/h / 323 mph
Cruise speed: 290 mph
Ceiling: 7000 m / 22950 ft
Range: 789 km / 490 miles
Armament: 1 x 7.62mm + 1 x 12.7mm machine-guns

The 1937 Seversky AP-1 was rejected P-35 36-354 refitted with a 750hp P&W R-1830 engine. First flown on 4 May 1937, piloted by A de Seversky, only the one was built, X/NR1390 c/n 44, for Wright Field and NACA testing. It was used as a company demonstrator until it was destroyed in a 1938 hangar fire.

Engine: 750hp P&W R-1830
Wingspan: 36’0″
Length: 25’4″
Top speed: 277 mph

The 1938 Seversky EP1-68 NX2587 c/n 147 was a European demonstrator, but sold to the Ecuador AF in 1941.

Engine: 1200hp P&W P-1830-S1C Wasp
Wingspan: 36’0″
Length: 26’10”
Speed: 290 mph
Seats: 1
Undercarriage: retractable

The Alexander de Seversky SEV-S2 was a modified civil competition version of the Army P-35 for the Nationals.

Registered NR70Y c/n 43 and piloted by Frank Fuller Jr, it raced in the 1937 and 1939 Bendix Trophy, and reached second place in the 1938 Bendix.

SEV-S2 1937
Engine: 950hp P&W R-1830 Twin Wasp SC
Seats: 1

The 1936 Seversky SEV-X-BT NX189M c/n 6 was built for military evaluation as a basic trainer, but lost out to North American BT-9.

It was dismantled for parts, much of which went into the 2PA-L. The registration was possibly transferred to 2PA.

SEV-X-BT
Engine: 550hp P&W R-1340-S3H1
Wingspan: 36’0″
Length: 20’5″
Speed: 180 mph
Seats: 2

Societe Francaise De Constructions Aeronautiques / SFCA had license for Peyret “tandem monoplane” renamed and developed as Taupin.

The 1930 Taupin was essentially an enlarged, powered derivative of the Alérion glider. 2-seat tandem-wing.

The wing span was recorded as 7.2m but Sailplane & Glider 31 Mar 1933 says 8.4m main and 6.5m rear wing spans.

Engine: 1 x 50hp Beaussier
Also flown with 30 hp ABC Scorpion horiz-opposed 2-cylinder

The SFCA-Peyret Taupin, aka “Le Taupin” (flown 1937) was an amateur-construction Peyret VI with 1 x 30 hp flat-2 cylinder Mengin 2 A1.

A two-seat version appeared in 1937as the “Cinq-demi Taupin”, known as the Lignel 44.

Lignel 44
Engine: Regnier 4-J0, 65 hp
Wing span: 28 ft 7 in
Forward wing area: 140 sq.ft
Rear wing area: 75.3 sq.ft
Length: 19 ft 10 in
Height: 8 ft 11 in
Empty weight: 543 lb
Loaded weight: 1276 lb
Max speed: 84 mph
Cruise: 74.5 mph
Service ceiling: 13,776 ft
Range: 310 mi