Boeing XB-15

The Boeing XB-15 (Boeing 294) was a United States bomber aircraft designed in 1934 as a test for the USAAC to see if it would be possible to build a heavy bomber with a 5,000 mi (8,000 km) range.

For one year, beginning in mid-1935 it was designated the XBLR-1.

When it first flew in 1937, it was the most massive and voluminous airplane ever built in the US.

It set a number of load-to-altitude records for land-based aircraft, including carrying a 31,205 lb (14,154 kg) payload to 8,200 ft (2,500 m) on 30 July 1939.

The aircraft’s immense size allowed flight engineers to enter the wing through a crawlspace and make minor repairs in flight.

A 5,000 mi (8,000 km) flight took 33 hours at its 152 mph (245 km/h) cruising speed, the crew was made up of several shifts, and bunks allowed them to sleep when off duty.

Specifications

Crew

Ten

Length

87 ft 7 in (26.70 m)

Wingspan

149 ft 0 in (45.43 m)

Height

25 ft 10 in (7.87 m)

Wing area

2,780 sq ft (258.4 m2)

Empty weight

37,709 lb (17,141 kg)

Max take-off weight

70,706 lb (32,139 kg)

Powerplant

4 × 14-cylinder Pratt & Whitney R-1830-11 radial engines,

1000 (take-off) 850 hp at 6,000ft hp (634 kW) each

Performance

Maximum speed

197 mph (317 km/h, 171 kn) at 5,000 ft (1,500 m)

Cruise speed

152 mph (245 km/h, 132 kn) at 6,000 ft (1,800 m)

Range

5,130 mi (8,260 km, 4,460 nmi)

Combat range

3,400 mi (5,474 km, 2,957 nmi)

Service ceiling

18,900 ft (5,760 m)

Armament

Guns

3 × .30 in (7.62 mm) M1919 Browning machine guns

3 × .50 in (12.7 mm) M2 Browning machine guns

Bombs

12,000 lb (5,400 kg).