DescriptionThe Douglas B-18 Bolo is an American medium bomber which served with the United States Army Air Corps and the Royal Canadian Air Force (as the Digby) during the late 1930s and early 1940s.
The Bolo was built by the Douglas Aircraft Company, based on its DC-2, and was developed to replace the Martin B-10.
By 1940, it was considered to be underpowered, to have inadequate defensive armament, and to carry too small a bomb load. Many were destroyed during the attacks on Pearl Harbor and the Philippines in December 1941.
In 1942, the surviving B-18s were relegated to antisubmarine, transport duty, and training. A B-18 was one of the first American aircraft to sink a German U-boat, U-654 on 22 August 1942 in the Caribbean.
In 1934, the United States Army Air Corps put out a request for a bomber with double the bomb load and range of the Martin B-10, which was just entering service as the Army's standard bomber. In the evaluation at Wright Field the following year, Douglas showed its DB-1. It competed with the Boeing Model 299 (later developed into the Boeing B-17 Flying Fortress) and Martin 146.
While the Boeing design was clearly superior, the crash of the B-17 prototype (caused by taking off with the controls still locked) removed it from consideration. During the depths of the Great Depression, the lower price of the DB-1 ($58,500 vs. $99,620 for the Model 299) also counted in its favor. The Douglas design was ordered into immediate production in January 1936 as the B-18.
The DB-1 design was essentially that of the DC-2, with several modifications. The wingspan was 4.5 ft (1.4 m) greater. The fuselage was deeper, to better accommodate bombs and the six-member crew; the wings were fixed in the middle of the cross-section rather than to the bottom due to the deeper fuselage. Added armament included nose, dorsal, and ventral gun turrets.
Preston Tucker's firm received a contract to supply a remote controlled gun turret for the aircraft.
For information on the operational history and variants, click here.
Specifications below are for the B-18A model.
- Crew: 6
- 57 ft 10 in (17.63 m)
- 89 ft 6 in (27.28 m)
- 15 ft 2 in (4.62 m)
- Wing Area:
- 959 sq ft (89.1 sq m)
- Wing Loading:
- 25 lb/sq ft (120 kg/sq m)
- Empty Weight:
- 16,320 lb (7,403 kg)
- 27,673 lb (12,552 kg). Gross weight: 24,000 lb (10,886 kg)
- 2 × Wright R-1820-53 Cyclone 9-cylinder air-cooled radial piston engines, 1,000 hp (750 kW) each
- Maximum speed: 216 mph (348 km/h, 188 kn) at 10,000 ft (3,000 m)
- Cruise Speed:
- 167 mph (269 km/h, 145 kn)
- 900 mi (1,400 km, 780 nmi). Ferry range: 2,100 mi (3,400 km, 1,800 nmi)
- Rate of Climb:
- Time to altitude: 10,000 ft (3,000 m) in 9 minutes 54 seconds
- Service Ceiling:
- 23,900 ft (7,300 m)