The Boeing Y1B-20 (Boeing Model 316) was designed as an improvement on the Boeing XB-15. (Y1B- indicates a funding source outside normal fiscal year procurement.) It was slightly larger than its predecessor, and used much more powerful engines. It was presented to the Army in early 1938, and two orders were placed soon after. The order was reversed before construction began.

Despite their failure, the XB-15 and Y1B-20 laid the groundwork for the B-29 Superfortress, one of the most famous and most successful World War II bombers.

Specifications (as designed)

General Characteristics

• Crew: 10
• Length: 109 ft 2 in (33.3 m)
• Wingspan: 157 ft 0 in (47.8 m)
• Height: 23 ft 4 in (7.1 m)
• Wing area: ft² ( m²)
• Empty: 87,500 lb (39,700 kg)
• Loaded: 91,500 lb (41,500 kg)
• Maximum takeoff: 105,100 lb (47,700 kg)
• Powerplant: 4× Wright GR-2600 -A73 geared radials, 1350 hp (1000 kW) each

Performance (estimated)

• Maximum speed: 258 mph (415 km/h)
• Cruising speed: 242 mph (389 km/h)
• Range: 4,000 miles (6,000 km)
• Service ceiling: ft ( m)
• Rate of climb: ft/min ( m/min)
• Wing loading: lb/ft² ( kg/m²)
• Power/Mass: .059 hp/lb (.097 kW/kg)

Armament

• 3× .30-calibre machine guns
• 4× .50-calibre machine guns
• 17,600 lb (6,620 kg) of bombs

External links

• USAF Museum description of Y1B-20

Related Content

Related development: Boeing XB-15 - B-29 Superfortress

Comparable aircraft: Boeing XB-15 - Martin XB-16 - B-29 Superfortress

Designation sequence: B-17 - B-18 - XB-19 - Y1B-20 - XB-21 - XB-22 - B-23

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