These 4 prototypes are to be evaluated further before a winning design will be selected for adoption. These will be the first jet bombers adopted by the US military, and are all capable of carrying atomic weapons as well as conventional.

North American XB-45 - March 1947

For service in the USAF as a jet-propelled medium bomber.

General characteristics

Crew: 3
Length: 75 ft 4 in (22.96 m)
Wingspan: 89 ft 0 in (27.13 m)
Height: 25 ft 2 in (7.67 m)
Wing area: 1,175 sq ft (109.2 m2)
Empty weight: 45,694 lb (20,726 kg)
Gross weight: 81,418 lb (36,931 kg)
Max takeoff weight: 91,775 lb (41,628 kg)
Powerplant: 4 × General Electric J47-GE-13 turbojet engines, 5,200 lbf (23 kN) thrust each

Performance

Maximum speed: 566 mph (911 km/h, 492 kn)
Cruise speed: 365 mph (587 km/h, 317 kn)
Range: 1,192 mi (1,918 km, 1,036 nmi)
Ferry range: 2,170 mi (3,490 km, 1,890 nmi)
Service ceiling: 46,000 ft (14,000 m)
Rate of climb: 5,200 ft/min (26 m/s)
Wing loading: 69.3 lb/sq ft (338 kg/m2)
Thrust/weight: 0.26

Armament

Guns: 2 × 0.50 in (13 mm) M3 machine guns (tail turret).
Bombs: Up to 22,000 lb (10,000 kg)

Convair XB-46 - April 1947

For service in the USAF as a jet-propelled medium bomber.

General characteristics

Crew: 3
Length: 105 ft 9 in (32.23 m)
Wingspan: 113 ft 0 in (34.44 m)
Height: 27 ft 11 in (8.51 m)
Wing area: 1,285 sq ft (119.4 m2)
Empty weight: 48,018 lb (21,781 kg)
Gross weight: 91,000 lb (41,277 kg)
Max takeoff weight: 95,600 lb (43,363 kg)
Powerplant: 4 × Allison J35-A-3 turbojet engines, 4,000 lbf (18 kN) thrust each

Performance

Maximum speed: 545 mph (877 km/h, 474 kn)
Cruise speed: 439 mph (707 km/h, 381 kn)
Range: 2,870 mi (4,620 km, 2,490 nmi)
Service ceiling: 40,000 ft (12,000 m)
Time to altitude: 35,000 ft (10,668 m) 19 minutes

Armament

Guns: 2× .50 in (12.7 mm) M2 Browning machine guns
Bombs: 22,000 lb (10,000 kg)

Boeing XB-47 - April 1947

For service in the USAF as a jet-propelled medium bomber.

General Characteristics

Crew: 3
Length 106 feet 9 inches
Wingspan 116 feet 0 inches
Height 27 feet 8 inches
Wing area 1428 square feet
Empty weight: 73,240 lb
Max takeoff weight: 157,000 lb
Gross weight: 106,060 lb
Powerplant: 4 × General Electric J47-GE-11 turbojet engines, 5200 lbf thrust each

Performance

Maximum speed: 600 mph at 8800 ft
Range: 2650 mi
Service ceiling: 38,000 ft

Armament

Guns: 2 × 0.50-inch machine guns in tail turret
Bombs: 22,000 lb

Martin XB-48 - June 1947

For service in the USAF as a jet-propelled medium bomber.

General characteristics

Crew: 3
Length: 85 ft 9 in (26.14 m)
Wingspan: 108 ft 4 in (33.02 m)
Height: 26 ft 6 in (8.08 m)
Wing area: 1,330 sq ft (123.5 m2)
Empty weight: 58,500 lb (26,535 kg)
Gross weight: 92,600 lb (42,000 kg)
Max takeoff weight: 102,600 lb (46,540 kg)
Powerplant: 6 × General Electric J35 axial flow turbojet, 3,820 lbf (17.0 kN) thrust each

Performance

Maximum speed: 454 kn (523 mph, 841 km/h) at 35,000 ft
Cruise speed: 361 kn (415 mph, 668 km/h)
Range: 1,566 nmi (1,802 mi, 2,900 km)
Combat range: 691 nmi (795 mi, 1,280 km)
Service ceiling: 39,400 ft (12,009 m)
Rate of climb: 4,200 ft/min (21.3 m/s)

Armament

Guns: 2 × .50 in (12.7 mm) M-2 machine guns in tail turret
Bombs: 1 × 20,000 lb (9,980 kg) or 36 × 250 lb (113 kg)