B-18 Bolo: Wikis


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From Wikipedia, the free encyclopedia

B-18 Bolo
Role Light bomber
Manufacturer Douglas Aircraft Company
First flight April 1935
Introduced 1936
Retired 1940s
Primary users United States Army Air Corps
United States Army Air Forces
Royal Canadian Air Force
Brazilian Air Force
Produced 1936-
Number built 350
Unit cost US$58,500 (1935)
Developed from Douglas DC-2
Variants Douglas XB-22

The Douglas B-18 Bolo was a United States Army Air Corps and Royal Canadian Air Force bomber of the late 1930s and early 1940s. The Bolo was built by Douglas Aircraft Company and based on its DC-2. Although not the latest or most advanced design, the B-18 was pressed into service where it performed wartime patrol duties early in World War II.


Design and development

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 the B-17 Flying Fortress) and Martin Model 146. While the Boeing design was clearly superior, the crash of the B-17 prototype (caused by taking off with the controls 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, but this was due to the deeper fuselage. Added armament included nose, dorsal, and ventral gun turrets.

Operational history

Douglas B-18 deployed at an airfield in Panama.

The initial contract called for 133 B-18s (including DB-1), using Wright R-1820 radial engines. The last B-18 of the run, designated DB-2 by the company, had a power-operated nose turret. This design did not become standard. Additional contracts in 1937 (177 aircraft) and 1938 (40 aircraft) were for the B-18A, which had the bombardier's position further forward over the nose-gunner's station. The B-18A also used more powerful engines.

By 1940, most US Army Air Force bomber squadrons were equipped with B-18s or B-18As. Many of those in the 5th Bomb Group and 11th Bomb Group in Hawaii were destroyed in the attack on Pearl Harbor. B-17s supplanted B-18s in first-line service in 1942. Following this, 122 B-18As were modified for anti-submarine warfare. The bombardier was replaced by a search radar with a large radome. Magnetic anomaly detection (MAD) equipment was sometimes housed in a tail boom. These aircraft, designated B-18B, were used in the Caribbean on anti-submarine patrol. Two aircraft were transferred to Força Aérea Brasileira in 1942. The Royal Canadian Air Force acquired 20 B-18As (designated the Douglas Digby Mark I), and also used them for patrol duties.

On 2 October 1942, a B-18A depth charged and sank the German U-boat U-512 north of Cayenne, French Guiana.[1] Bolos and Digbys sank an additional two submarines during the course of the war. RCAF Eastern Air Command (EAC) Digbys carried out 11 attacks on U-boats. U-520 was confirmed sunk by Flying Officer F. Raymes' crew of No 10 (BR) Sqn, on 30 October 1942.[2] east of Newfoundland.[3]


Prototype, first of B-18 production run, 1 built.
Initial production version, 131 or 133 built.[4]
Bomb gear removed from B-18 to serve as trainer.
Powered nose turret prototype; last of B-18 production run, 1 built.
B-18 with more powerful Wright R-1820-53 engines and moved bombardier's station, 217 built.[5]
Bomb gear removed from B-18A to serve as trainer.
Antisubmarine conversion, 122 converted.[6]
Antisubmarine conversion, 2 converted. Fixed forward-firing .50 cal machine gun, starboard side of the fuselage near lower nose glass
Improvement on B-18 using Wright R-2600-3 radial engines (1,600 hp/1,194 kW). Never built, largely due to better light bombers such as the B-23 Dragon.[7]
Transport conversion.
Digby I
Royal Canadian Air Force modification of B-18A.


RCAF Digby c. 1942
 United States


B-18B at Pima Air Museum
B-18A at Wings Museum

Only six B-18s still exist, five of which are preserved in museums in the United States:[8]

B-18 s/n 36-446
Sitting in a gulch on Laupahoehoe Nui LLC property, Hamakua, Hawaii.
B-18 s/n 37-0029
On display at Castle Air Museum, Atwater, California.
B-18A s/n 39-25/64
On display at Wings Over the Rockies Air and Space Museum, Denver, Colorado.
B-18A s/n 37-469
On display at National Museum of the United States Air Force, Wright-Patterson AFB, Ohio. This aircraft has an incorrect dorsal turret. The museum has been attempting to locate a correct turret for this aircraft for many years.[9]
B-18B s/n 37-505
On display at McChord Air Museum, McChord AFB, Washington.
B-18B s/n 38-593
On display at Pima Air & Space Museum Tucson, Arizona.

Specifications (B-18A)

General characteristics

  • Crew: 6
  • Length: 57 ft 10 in (17.6 m)
  • Wingspan: 89 ft 6 in (27.3 m)
  • Height: 15 ft 2 in (4.6 m)
  • Wing area: 959 ft² (89.1 m²)
  • Empty weight: 16,321 lb (7,400 kg)
  • Loaded weight: 22,123 lb (10,030 kg)
  • Max takeoff weight: 27,500 lb (12,600 kg)
  • Powerplant:Wright R-1820-53 radial engines, 1,000 hp (750 kW) each



  • Guns: 3 × .30 in (7.62 mm) machine guns
  • Bombs: 4,500 lb (2,200 kg)

See also

Related development

Related lists


  • Francillon, René. McDonnell Douglas Aircraft Since 1920: Volume I. London: Putnam, 1979. ISBN 0-87021-428-4.
  • Gradidge, Jennifer M. The Douglas DC-1, DC-2, DC-3 - The First Seventy Years (two volumes), Tunbridge Wells, Kent, UK: Air-Britain, 2006. ISBN 0-85130-332-3.
  • Kostenuk, Samuel and John Griffin. RCAF Squadron Histories and Aircraft: 1924–1968. Toronto: Samuel Stevens, Hakkert & Company, 1977. ISBN 0-88866-577-6.

External links



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