Bell TP-39

The TP-39 was a dual seat training version of the P.39 Airacobra.

The Soviet Airacobras were frequently involved in fatal accidents due to a specific issue related to the aircraft’s centre of gravity.

This issue was attributed to the rearward-shifted centre of gravity (CG), which caused the aircraft to enter a flat spin.

In order to address this problem, a high-level Soviet delegation, consisting of two of the NII VVS’s top test pilots, visited the Bell Corporation.

Their purpose was to find a solution to the flat spin issue and also to evaluate the two-seater TP-39Q at the Bell factory in Buffalo in April 1944.

As a result of this visit, some P-39s in the Soviet Union were converted into P-39 UTI trainers.

It is likely that these conversions were carried out using conversion kits provided by Bell.

However, it is important to note that the Soviet variant of the two-seater differed slightly from the US versions.

One notable difference was observed in the design of the extended canopy, which included additional frames.

Upon examining photographs, it can be inferred that there were at least two Soviet versions of the two-seater aircraft.

These versions may have been derived from different models of the fighter, as there were variations in the canopy and ventral fin designs.

Variants

TP-39F-1 

A P-39F was modified into a two-seat trainer with an extra cockpit in the nose and without armament.

TP-39Q-5 

One model was converted into a two-seat training variant with an additional cockpit in the nose, and it carried no armament.

It also featured an enlarged tail fillet and a shallow ventral fin.

RP-39Q-22 

Twelve P-39Q-20s were converted into two-seat trainers.

Specifications

Crew

Two

Length

30 ft 2 in (9.19 m)

Wingspan

34 ft 0 in (10.36 m)

Height

12 ft 5 in (3.78 m)

Wing area

213 sq ft (19.8 m2)

Empty weight

6,516 lb (2,956 kg)

Gross weight

7,570 lb (3,434 kg)

Max take-off weight

8,400 lb (3,810 kg)

Powerplant

1 × Allison V-1710-85, V-12 liquid cooled piston engine,

1,200 hp (890 kW) at 9,000 ft (2,743 m)

(Emergency power)

Propellers

3 bladed constant speed propellers

Performance

Maximum speed

389 mph (626 km/h, 338 kn)

Stall speed

95 mph (153 km/h, 83 kn) power off,

Flaps and undercarriage down

Never exceed speed

525 mph (845 km/h, 456 kn)

Range

525 mi (845 km, 456 nmi) on internal fuel

Service ceiling

35,000 ft (11,000 m)

Rate of climb

3,805 ft/min (19.33 m/s) at 7,400 ft (2,300 m)

(Using emergency power)

Time to altitude

15,000 ft (4,600 m) in 4 minutes, 30 seconds, at 160 mph (260 km/h)

Wing loading

34.6 lb/sq ft (169 kg/m2)

Power/mass

0.16 hp/lb (0.26 kW/kg).

Sources

U.S. Experimental & Prototype Aircraft Projects: Fighters 1939–1945-B Norton.

The American Fighter from 1917 to the present – E Angelucci.

Bell Aircraft Since 1935-A J Pelletier.