Douglas B-18 Bolo

The Douglas B-18 Bolo medium bomber served with the United States Army Air Corps and the Royal Canadian Air Force (as the Douglas 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.

Douglas B-18 Bolo
Class Aircraft
Type Bomber
Manufacturer Douglas Aircraft Company
Production Period 1936 - 1940
Origin United States of America
Country Name Origin Year
United States of America 1935
Country Name Operational Year Retirement Year
Brazil 1936 1946 View
Canada View
United States of America 1936 View
ManufacturerName Production From Production To Quantity
Douglas Aircraft Company 1936 1940 350 View

By 1940 it was considered to be underpowered, to have inadequate defensive armament and carried too small a bomb load. Many were destroyed during the attacks on Pearl Harbor and the Philippines in December 1941.

In 1942 the B-18 survivors were relegated to antisubmarine or transport duty. A B-18 was one of the first American aircraft to sink a German U-Boat, the 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 the Boeing 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 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, but this was due to the deeper fuselage. Added armament included nose, dorsal, and ventral gun turrets.

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.

Deliveries of B-18s to Army units began in the first half of 1937, with the first examples being test and evaluation aircraft being turned over to the Materiel Division at Wright Field, Ohio, the Technical Training Command at Chanute Field, Illinois, the Aberdeen Proving Ground, Maryland, and Lowry Field, Colorado. Deliveries to operational groups began in late 1937, the first being the 7th Bombardment Group at Hamilton Field, California.

Production B-18s, with full military equipment fitted, had a maximum speed of 217 mph, cruising speed of 167 mph, and combat range of 850 miles. By 1940, most USAAC bomber squadrons were equipped with B-18s or B-18As.

However, the deficiencies in the B-18/B-18A bomber were becoming readily apparent to almost everyone. In range, in speed, in bomb load, and particularly in defensive armor and armament, the design came up short, and the Air Corps conceded that the aircraft was obsolete and totally unsuited in the long-range bombing role for which it had originally been acquired. To send crews out in such a plane against a well-armed, determined foe would have been nothing short of suicidal.

However, in spite of the known shortcomings of the B-18/B-18A, the Douglas aircraft was the most numerous American bomber type deployed outside the continental United States at the time of the attack on Pearl Harbor. It was hoped that the B-18 could play a stopgap role until more suitable aircraft such as the Boeing B-17 Flying Fortress and Consolidated B-24 Liberator became available in quantity.

Role Medium bomber
Manufacturer Douglas Aircraft Company
First flight April 1935
Introduction 1936
Retired 1946 Brazilian Air Force
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
Developed into B-23 Dragon


General characteristics

  • Crew: 6
  • Length: 57 ft 10 in (17.63 m)
  • Wingspan: 89 ft 6 in (27.28 m)
  • Height: 15 ft 2 in (4.62 m)
  • Wing area: 959 ft² (89.1 m²)
  • Empty weight: 16,320 lb (7,403 kg)
  • Loaded weight: 24,000 lb (10,866 kg)
  • Max. takeoff weight: 27,673 lb (12,552 kg)
  • Powerplant: 2 × Wright R-1820-53 radial engines, 1,000 hp (746 kW) each

Performance

  • Maximum speed: 216 mph (188 knots, 348 km/h) at 10,000 ft (3,050 m)
  • Cruise speed: 167 mph (145 knots, 269 km/h)
  • Range: 900 mi (787 nmi, 1,450 km)
  • Ferry range: 2,100 mi (1,826 nmi, 3,380 km)
  • Service ceiling: 23,900 ft (7,285 m)
  • Climb to 10,000 ft (3,050 m): 9.9 min

Armament

  • Guns: 3 × .30 in (7.62 mm) machine guns
  • Bombs: 4,400 lb (2,000 kg)

End notes