The Douglas Y1B-7 was the first monoplane given the B- 'bomber' designation. The monoplane was more practical and less expensive than the biplane, and the United States Army Air Corps chose to experiment with monoplanes for this reason. At the time the XB-7 was ordered, it was being tested by Douglas Aircraft as an observational plane.

The original XB-7 was an experimental version of a set of monoplanes made by Douglas, which were designated XO-35 and XO-36. The plane was built as a competitor to Fokker YO-27, which eventually led to the Fokker XB-8. The Douglas plane had a single set of wings, which were mounted relatively high (hence their nickname 'gull wings'). The wings were covered by corrugated duralumin. On 1930 March 26, two planes of the design were ordered by the Army Air Corps. Due to minor differences between the two planes, one was designated XO-35 and the other XO-36. Because these two planes had much better performance than most of their predecessors, they were a promising alternative to the slow, bulky biplanes Keystone Aircraft Corporation that made up the entire Army Air Corps bomber fleet.

Impressed by the pair of planes submitted by Douglas, the Army Air Corps chose to complete the XO-36 as a bomber. It was redesignated XB-7, and was equipped with bomb racks capable of carrying up to 1,200 lb of bombs. In August of 1931, the Army Air Corps ordered seven Y1B-7 bombers for service testing (along with five Y1O-35s). The XB-7 was delivered to Wright Field in July of 1932, where testing was commenced. A few months later, the first Y1B-7s were delivered.

The prototype XB-7 was a Light bomber, carrying only 1,200 pounds of bombs. The skin of the fuselage was corrugated for ease of production. The gull wing was braced externally to increase strength. While this brace also increased drag, the XB-7 was still faster than any of its biplane predecessors. The crew complement consisted four: a pilot and a copilot; in addition, two gunners (one in the nose and one at the tail).

Despite positive evaluation, the Y1B-7 was never entered into mass production, mainly because of its small bomb load. Also, better aircraft, such as the Martin B-10 were on their way.

Specifications (Y1B-7)

General Characteristics

• Crew: 4
• Length: 45 ft 7 in (13.9 m)
• Wingspan: 65 ft 3 in (19.9 m)
• Height: 12 ft 1 in (3.7 m)
• Wing area: 621.2 ft² (57.71 m²)
• Empty: 5,519 lb (2,503 kg)
• Loaded: 9,953 lb (4,515 kg)
• Maximum takeoff: 11,177 lb (5,070 kg)
• Powerplant: 2× Curtiss V-1570 -27 'Conquerors' of 675 hp (504 kW) each

Performance

• Maximum speed: 182 mph (193 km/h)
• Combat Range: 600 miles (1,000 km)
• Ferry Range: 400 miles (600 km)
• Service ceiling: 20,400 ft (6,220 m)
• Wing loading: 16.02 lb/ft² (78.24 kg/m²)
• Power/Mass: 0.136 hp/lb (0.224 kW/kg)

Armament

• Guns: 2× .30-calibre (7.62 mm) Browning machine guns
• Bombs: 1,200 lb (540 kg)

References and external links

• Wagner, Ray (1982). American Combat Planes. New York: Doubleday. ISBN 0930083172.
• Encyclopedia of American aircraft
• Photograph of Y1B-7
• USAF Museum article on Y1B-7

Related Content

Comparable aircraft: Fokker XB-8

Designation sequence: B-4 - B-5 - B-6 - Y1B-7 - XB-8 - Y1B-9 - B-10

Related Lists: List of military aircraft of the United States - List of bomber aircraft