The Martin B-33 was designed by the Glenn L. Martin Company as the Martin Model 190 and was a high-altitude derivative of the company's B-26 Marauder. Two different designs were developed, first as a twin-engined aircraft and then as a four-engined aircraft. The four-engined version was ordered by the United States Army Air Forces but the program was cancelled before any aircraft were built.

Design and development

XB-33

Schematic blueprint drawing of the XB-33.

The first version of the B-33 design, the XB-33, was a twin-tailed medium bomber with two Wright R-3350 engines and pressurised crew compartments; its design began in 1940. It would carry around 4,000 lb (1,814 kg) of bombs. Soon after design of the XB-33 began it became clear that a twin-engined aircraft would not achieve the performance requested by the army. The company moved on to developing a larger four-engined design and the two prototypes ordered by the USAAF were not built.

XB-33A

Following the abandoment of the original twin-engined design the company continued to design a larger four-engined design and two prototypes were ordered by the USAAF as the XB-33A; its bombload was to have been 12,000 lb (5,443 kg), as much as that of the B-24 Liberator, the heaviest US bomber flown in combat prior to the B-29.

The original XB-33 design was to be powered by the R-3350, the redesigned XB-33A was to use Wright R-2600 engines. The main reason for this was demand for R-3350s for the B-29, one of the most highly valued projects of the Army Air Forces.

On January 17, 1942, the USAAF placed an order for 400 B-33As to be built at the government-owned plant in Omaha, Nebraska operated by Martin. On November 25, 1942 the project was cancelled to allow the Omaha plant to concentrate on manufacturing B-29s.

Variants

XB-33

Prototype medium bomber powered by two 1,800 hp (1,343 kW) R-3350 engines, two cancelled.^[1]

XB-33A

Prototype medium bomber powered by four 1,800 hp (1,343 kW) R-2600-15 engines, two cancelled.^[1]

B-33A Super Marauder

Production variant of XB-33A, 400 on order cancelled.^[1]

Specifications (B-33A, as designed)

General characteristics

• Crew: 7
• Length: 79 ft 10 in (24.3 m)
• Wingspan: 134 ft (40.8 m)
• Height: 24 ft (7.32 m)
• Wing area: 1,646 ft² (153 m²)
• Empty weight: 85,000 lb (39,000 kg)
• Loaded weight: 95,000 lb (43,000 kg)
• Powerplant: 4 × Wright R-2600-15 radial engines, 1,800 hp (1,300 kW each) each

Performance (estimated)

• Maximum speed: 345 mph (300 kn, 555 km/h)
• Cruise speed: 242 mph (210 kn, 389 km/h)
• Range: 2,000 mi (1,700 nmi, 3,000 km)
• Service ceiling: 39,000 ft (12,000 m)
• Rate of climb: ft/min (m/s)
• Wing loading: 58 lb/ft² (280 kg/m²)
• Power/mass: 0.076 hp/lb (55 W/kg)

Armament

• Guns: 8× .50 in (12.7 mm) machine guns
• Bombs: 10,000 lb (4,500 kg)

See also

Related development

• B-26 Marauder
  

Related lists

• List of military aircraft of the United States
• List of bomber aircraft
  

References

• Encyclopedia of American Aircraft
• Andrade, John (1979). U.S.Military Aircraft Designations and Serials since 1909. Midland Counties Publications. ISBN ISBN 0-904597-22-9.