World War 2 In Review: transport

Douglas B-18 Bolo.

The Douglas B-18 Bolo is an American twin-engined 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 developed by the Douglas Aircraft Company from their DC-2 as a replacement for the Martin B-10.

By 1940 standards, it was slow, had an inadequate defensive armament, and carried too small a bomb load. By 1942, surviving B-18s were relegated to antisubmarine, training and transport duties. A B-18 was one of the first USAAF aircraft to sink a German U-boat, U-654 on 22 August 1942 in the Caribbean.

Design and Development

In 1934, the United States Army Air Corps requested for a twin-engine bomber with double the bomb load and range of the Martin B-10 then entering service. During the evaluation at Wright Field the following year, Douglas offered its DB-1. It was competing against the Boeing Model 299 (later developed into the Boeing B-17 Flying Fortress) and Martin 146.

While the Boeing design was clearly superior, the 299's four engines eliminated it from consideration despite being the favorite, and the crash of the prototype — caused by taking off with the controls still locked — put its purchase on hold. The Martin 146 was a minor improvement on the B-10, and was never seriously considered. During the depths of the Great Depression, the lower price of the DB-1 at $58,500 compared to $99,620 for the Model 299 also favored the Douglas entry, and it was ordered into immediate production in January 1936 as the B-18.

The DB-1 design was modified from that of the DC-2. The wingspan was 4.5 ft (1.4 m) greater, the fuselage was narrower and deeper, and the wings were moved up to a mid-wing position to allow space under the spars for an enclosed bomb bay. Added armament included manually operated nose, dorsal, and ventral gun turrets.

At one point, Preston Tucker's firm received a contract to supply Tucker remote controlled gun turrets but these were unsuccessful, and were never used in service.

Type: Medium bomber

Manufacturer: Douglas Aircraft Company

Status: Retired

Primary users:

United States Army Air Corps

United States Army Air Forces

Royal Canadian Air Force

Brazilian Air Force

Number built: 350

Manufactured: 1936– ca. 1939

Introduction date: 1936

First flight: April 1935

Retired: 1946 from Brazilian Air Force

Developed from: Douglas DC-2

Developed into: Douglas B-23 Dragon

Operational History

The initial contract called for 133 B-18s (including the prototype), 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 in a redesigned nose but this 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 in a wedge shaped nose and the B-18A was fitted with 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, had a maximum speed of 217 mph (349 km/h), cruising speed of 167 mph (269 km/h), and combat range of 850 mi (1,370 km). By 1940, most USAAC bomber squadrons were equipped with B-18s or B-18As.

However, the B-18/B-18A's deficiencies were made apparent when an all-red Soviet Ilyushin TsKB-30 named Moskva (a prototype for the twin-engine DB-3 which flew the same year as the B-18) made a non-stop flight from Moscow to North America in April 1939, a distance of 4,970 mi (8,000 km), which was well beyond the capabilities of the B-18. The TsKB-30/DB-3 was also 25% faster, was capable of carrying a bomb load 2.5 times as large as the B-18, and carried a heavier defensive armament. In August of the same year, a Japanese Mitsubishi G3M2 named Nippon (which also had its first flight the same year as the B-18) flew from Tokyo to the US, and then around the world, with the stage from Chitose, Hokkaido to Nome, Alaska being over 2,500 mi (4,000 km). The military version (code named Nell during WW2) could also carry more than the B-18, further, faster, and was also better armed. Both types had roughly 7,000 ft (2,100 m) higher service ceilings as well.

The Air Corps conceded that the Bolo was obsolete and unsuitable for its intended role. However, in spite of this, the B-18/B-18A was still the most numerous American bomber type deployed outside the continental United States at the time of the attack on Pearl Harbor. The B-18 would be a stopgap until the more capable Boeing B-17 Flying Fortress and Consolidated B-24 Liberator became available in quantity.

World War II

When war came to the Pacific, most of the B-18/B-18A aircraft based overseas in the Philippines and in Hawaii were destroyed on the ground in the initial Japanese onslaught. The few Bolos that remained played no significant role in subsequent operations.

The B-18s remaining in the continental US and in the Caribbean were then deployed in a defensive role in anticipation of attacks on the US mainland. These attacks never materialized. 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. On 2 October 1942, a B-18A, piloted by Captain Howard Burhanna Jr. of the 99th Bomb Squadron, depth charged and sank the German submarine U-512 north of Cayenne, French Guiana.

Two aircraft were transferred to the Brazilian Air Force in 1942, and were used with a provisional conversion training unit set up under the provisions of Lend-Lease. They were later used for anti-submarine patrols. They were struck off at the end of the war.

In 1940 the Royal Canadian Air Force acquired 20 B-18As (as the Douglas Digby Mark I), and also used them for patrol duties, being immediately issued to 10 Squadron to replace the squadron's Westland Wapitis.

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) Squadron, on 30 October 1942, east of Newfoundland. However, the antisubmarine role was relatively short-lived, and the Bolos were superseded in this role in 1943 by B-24 Liberators, which had a much heavier payload and a substantially longer range, which finally closed the mid-Atlantic gap. Some of the Douglas Digbys in Canadian service were converted into transports or used for training.

Surviving USAAF B-18s ended their useful lives in training and transport roles, and saw no further combat action. Two B-18As were modified as unarmed cargo transports under the designation C-58. At the end of the war, remaining examples were sold as surplus on the commercial market. Some postwar B-18s were operated as cargo or crop-spraying aircraft by commercial operators.

Variants

DB-1: Manufacturer's designation for prototype, first of B-18 production run, 1 built.

B-18: Initial production version, 131 or 133 built.

B-18M: Trainer B-18 with bomb gear removed.

DB-2: Manufacturer's designation for prototype with powered nose turret; last of B-18 production run, 1 built.

B-18A: B-18 with more powerful Wright R-1820-53 engines and relocated bombardier's station, 217 built. Manufacturer's designation was DB-4.

B-18AM: Trainer B-18A with bomb gear removed.

B-18B: Anti-submarine conversion, 122 converted by adding a radar and magnetic anomaly detector.

B-18C: Anti-submarine conversion, 2 converted. Fixed forward-firing .50 in (12.700 mm) machine gun, starboard side of the fuselage near lower nose glazing.

XB-22: Improved B-18 with 1,600 hp (1,200 kW) Wright R-2600-3 radial engines. Not built, due to better designs being available.

C-58: Transport conversion.

Digby Mark I: Royal Canadian Air Force modification of B-18A. Named for RAF Digby.

Operators

Brazil

Brazilian Air Force

1st Bomber Group (3 examples)

Canada

Royal Canadian Air Force

No. 10 Squadron RCAF, Halifax, Nova Scotia (Digby Mk.1)

United States

United States Army Air Corps/United States Army Air Forces

1st Search Attack Group, Langley Field, Virginia (B-18A/B/C)

2nd Bombardment Group, Langley Field, Virginia (B-18A)

3rd Bombardment Group, Barksdale Field, Louisiana (B-18)

5th Bombardment Group, Hickam Field, Hawaii (B-18)*

6th Bombardment Group, Rio Hato Airfield, Panama, (B-18/B-18A/B)

7th Bombardment Group, Hamilton Field, California, (B-18)

5th Bombardment Group, Luke Field, Oahu, Hawaii Territory (B-18)*

9th Bombardment Group, Caribbean; Panama and South American air bases (B-18/B-18A/B)

11th Bombardment Group, Hickam Field, Hawaii Territory (B-18)*

13th Bombardment Group, Langley Field, Virginia (B-18A/B)

17th Bombardment Group, McChord Field, Washington (B-18)

19th Bombardment Group, Clark Field, Philippines Commonwealth (B-18)*

22nd Bombardment Group, Muroc Field, California (B-18)

25th Bombardment Group, Caribbean (B-18/B)

27th Bombardment Group, Barksdale Field, Louisiana (B-18)

28th Bombardment Group, California, (B-18)

28th Composite Group, Elmendorf Field, Alaska, (B-18A)

29th Bombardment Group, Langley Field (B-18A)

40th Bombardment Group, Panama, Puerto Rico (B-18/B)

41st Bombardment Group, California, (B-18)

42nd Bombardment Group, Portland, Oregon (B-18)

45th Bombardment Group, Savannah Airfield, Georgia (B-18A)

47th Bombardment Group, McChord Field, Washington (B-18)

479th Antisubmarine Group, Langley Field, Virginia (B-18A/B)

* Most aircraft were destroyed on 7 and 8 December 1941 during the Japanese attacks on the outbreak of war between Japan and the US.

Aircraft on Display

Six B-18s are known to exist, five of them preserved or under restoration in museums in the United States, and one is a wreck still located at its crash site:

B-18

36-446 – Kohala Mountains, Hawaii. Tail code "81 50R". Crashed in 1941 and abandoned. The Air Force recovered the nose turret for 37-029 and the dorsal turret for 37-469. The Pacific Air Museum in Honolulu has had plans to recover the airframe.

37-029 – Castle Air Museum at the former Castle Air Force Base in Atwater, California. Dropped from USAAF inventory in 1944, it was registered as NC52056 in 1945, later to N52056. The B-18 was used by Avery Aviation and then Hawkins and Powers, as a firebomber, dropping borate for many years.

B-18A

37-469 – National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio. One of the first production Bolos, was delivered to Wright Field in 1937 for evaluation testing. Sold as N56847, converted to crop sprayer; by May 1969 stored derelict at Tucson, Arizona. It sat outdoors for many years, before being restored to static display condition. This aircraft has an incorrect dorsal turret. The museum has been attempting to locate a correct turret for this aircraft for many years.

39-025 – Wings Over the Rockies Air and Space Museum at the former Lowry Air Force Base in Denver, Colorado. This Bolo spent World War II at several airfields as a bombardier trainer and as a light transport. It was dropped from inventory on 3 November 1944, and was later sold, acquiring the civil registry NC62477. It spent 14 years on the civil registry before going to Cuba in 1958. In November 1958 the aircraft was seized in Florida by US Treasury agents when it was hauling guns to Fidel Castro. In 1960, the aircraft was parked at Cannon AFB, New Mexico, until being presented to the National Museum of the United States Air Force at Wright-Patterson AFB. It flew to the museum in April 1961. In 1988, the aircraft was transferred to the Wings Over The Rockies Aviation and Space Museum where it was restored through the 1990s. It is displayed there as AAC Ser. No. 39-522.

B-18A/B

37-505 – On display at McChord Air Museum, Washington. Built as a B-18, converted during WWII to B-18B. Later sold as N67947 for agricultural chemical spraying, then Mexican registration XB-LAJ transporting fish. Donated to Tucson Air Museum Foundation, Pima County, Arizona, this was the last flyable B-18, making its final flight to Tucson on 10 April 1971. Subsequently acquired by the National Museum of the United States Air Force and stored at Davis-Monthan AFB until moved by C-5A to McChord Air Museum in 1983 for restoration. Rebuilt as model B-18A and displayed from 2007.

B-18B

38-593 – Pima Air & Space Museum adjacent to Davis-Monthan Air Force Base in Tucson, Arizona. This Bolo spent the early part of WWII on anti-submarine patrol. In 1943 began use a light transport. She was retired and struck from the inventory in 1945. Was operated as a firebomber as N66267, 1954–1970. In storage at Phoenix Goodyear Airport, Litchfield Park, Arizona by September 1969, then delivered to Pima on 5 September 1976. The aircraft sat outside in the desert for many years, before being restored and moved indoors for display. The aircraft is still equipped with an antisubmarine search radar dome.

Specifications (B-18A)

Crew: Six

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 sq ft (89.1 m2)

Airfoil: root: NACA 2215; tip: NACA 2209

Empty weight: 16,320 lb (7,403 kg)

Gross weight: 24,000 lb (10,886 kg)

Maximum takeoff weight: 27,673 lb (12,552 kg)

Powerplant: 2 × Wright R-1820-53 Cyclone 9-cylinder air-cooled radial piston engines, 1,000 hp (750 kW) each

Propellers: 3-bladed fully-feathering Hamilton Standard Hydromatic propellers

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)

Range: 900 mi (1,400 km, 780 nmi)

Ferry range: 2,100 mi (3,400 km, 1,800 nmi)

Service ceiling: 23,900 ft (7,300 m)

Time to altitude: 10,000 ft (3,000 m) in 9 minutes 54 seconds

Wing loading: 25 lb/sq ft (120 kg/m2)

Power/mass: 0.0833 hp/lb (0.1369 kW/kg)

Guns: 3 × 0.30 in (7.62 mm) machine guns

Bombs: 2,000 lb (910 kg) normal; 4,400 lb (2,000 kg) maximum

Avionics:

B-18B (only)

SCR-517-T-4 ASV radar

Mark IV Magnetic anomaly detector (MAD)

Notable Appearances in Media

Douglas B-18 Bolos are prominently featured in the 1943 RKO picture Bombardier, filmed at Kirtland Field, New Mexico.

Bibliography

Francillon, René J. (1979). McDonnell Douglas Aircraft Since 1920. London: Putnam.

Francillon, René J. (1988). McDonnell Douglas Aircraft Since 1920. Vol. 1. Annapolis, Maryland: Naval Institute Press.

Gradidge, Jennifer M. (2006). The Douglas DC-1, DC-2, DC-3 – The First Seventy Years (two volumes). Kent, UK: Air-Britain (Historians).

Kostenuk, Samuel; Griffin, John (1977). RCAF Squadron Histories and Aircraft: 1924–1968. Toronto, Canada: Samuel Stevens, Hakkert & Co.

Lehto, Steve; Leno, Jay (2016). Preston Tucker and His Battle to Build the Car of Tomorrow. Chicago Review Press.

Wolf, William (2007). Douglas B-18 Bolo - The ultimate look: from drawing board to U-boat hunter. Atglen, PA: Schiffer.

B-18 from Barksdale Field, Louisiana, summer 1941.

Douglas B-18A airplane of the 3rd Bombardment Group.

Douglas B-18 sits on airfield in Panama.

B-18 Digby (VHCWB) "Goober Dust" operated by Australian National Airways on behalf of the USAAF, flying above the Brisbane River near Eagle Farm, Queensland, circa 1943.

B-18 (VHCWB) "Goober Dust", probably at Townsville.

Unidentified B-18 "DMFINO" at Townsville. This could have been VHCWC.

21st Reconnaissance Squadron B-18 Bolo at Miami Municipal Airport, Florida, 1940.

Douglas B-18 Bolo, 4th Reconnaissance Squadron, 1939.

Douglas B-18 of the 3rd Bomb Group (BC 20) after over-running the runway.

The same Douglas B-18 of the 3rd Bomb Group (BC 20) as the previous photo after over-running the runway on the beach.

B-18, first U.S. bomber on new runway at airbase, Cumuto, Trinidad, 1 June 1941.

Douglas B-18 Bolo of the 21st Reconnaissance Squadron.

Douglas B-18s are on their way to intercept reported enemy submarines in the Caribbean. 12th Bombardment Squadron flying over British Guiana. 1943.

Douglas B-18, General Headquarters, Air Force.

Bomb damage to Hangars 15-17 and 11-13 at Hickam Field, Oahu, at 1700 hrs on 7 December 1941. In the right foreground is a machine gun emplacement in a bomb crater. A Douglas B-18 bomber is visible inside the badly damaged hangar.

View of a bomb crater between hangers 7 and 11 at Hickam Field, Hawaii, after the Japanese attack on Pearl Harbor, 7 December 1941. Note the Douglas B-18 in the hangar.

Rear view of the heavily damaged Hangar No. 11 at Hickam Field, Hawaii, on 7 December 1941. In front is the tail of a damaged Douglas B-18 Bolo bomber from the 18th Bombardment Group (Heavy). The two men near the hangar are Captain Ronald D. Boyer of the Signal Corps and Private Elliot C. Mitchell from the 50th Reconnaissance Squadron. The photo was taken just as a Japanese plane began machine-gunning the area.

Damaged Douglas B-18 Bolo, 31st Bombardment Squadron. Hickam Field, Hawaii, December 1941.

Douglas B-18 parked on the flying field.

B-18 over San Francisco, California, 17 January 1938.

USAAF Seversky P-35 fighters and Douglas B-18 bombers at Del Carmen Field, Philippines, October 1941.

Douglas B-18 (37-51).

Douglas B-18 of the 88th Reconnaissance Squadron.

Douglas B-18A of the 19th Bombardment Group.

Douglas B-18 flying field, 19th Bombardment Group.

U.S. Army Air Corps Douglas B-18 test aircraft that came from the 3rd Attack Group, Barksdale Field, Louisiana, at the Langley Aeronautical Laboratory at Hampton, Virginia. In the spring of 1941 Langley installed an experimental low-drag laminar flow test panel on the wing of a Douglas B-18 bomber. Here, 5 November 1941, the same B-18 was used to test an airfoil (NACA 0012) which was mounted just forward of the vertical stabilizer. The purpose of this test was to conduct boundary-layer and profile-drag tests in which Reynolds Number and angle of attack were varied independently.

Douglas B-18.

The same Douglas B-18 as in the previous photo.

Douglas B-18A of the 31st Bombardment Squadron, 19th Bombardment Group.

Douglas B-18, 19th Bomb Group.

Douglas B-18A (37-450), Santa Monica, California.

Douglas B-18A Bolo assigned to the 99th Bombardment Squadron (Heavy) on patrol from Zandery Field, Dutch Guiana, 1942.

Douglas B-18B (37-530), originally a B-18A with the MAD (Magnetic Anomaly Detection) tail boom.

Douglas B-18B Bolo with power nose turret.

In the spring of 1941 Langley installed an experimental low-drag test panel on the wing of a Douglas B-18 airplane. The panel was fitted with suction slots and pressure tubes for a free flight investigation of the transition from laminar to turbulent flow in the boundary layer. The pressure at each tube was measured by liquid manometers installed in the fuselage.

Boeing P-26s and Douglas B-18s were parked on the ramp at Hickam Field, Hawaii, in January 1940.

Douglas B-18 (36-26), Magnetic Anomaly Detection (MAD) ASW tests.

Douglas B-18 Bolo, medium bomber, USAAC.

B-18 wing sections manufactured at the Santa Monica plant in California.

Douglas B-18 Bolos under construction.

Douglas B-18A, 37-503, 14, 28 July 1939.

Douglas DB-1.

Douglas B-18, Mitchel Field, Long Island, New York.

Two Douglas B-18s, Westfield airport. Appear to have water-based paint camouflage, possibly for war games.

Douglas B-18 with power turret raised.

Douglas B-18 Bolo.

Douglas B-18.

Douglas B-18A.

Douglas B-18A (37-624).

Douglas B-18. 19th Bomb Group.

Douglas B-18.

A bad day for Douglas B-18 Bolo (37-002) in the Hawaiian Air Depot (HAD) scheme. Four colors are visible on the nose, and a close inspection shows another color separation just aft of the second small window on the fuselage. The port aileron is a replacement and will need replacement again, as will the rudder. Hickam Field, May 1943.

Douglas B-18 Bolo, Randolph Field, Texas.

Douglas B-18 Bolos.

Douglas B-18 Bolo.

Douglas B-18 Bolo, 7th Bomb Group, over San Francisco, 1938.

Douglas B-18 Bolos, 7th Bomb Group, over California, September 18, 1938.

Douglas B-18 Bolos 237 and 235 on the flight line at March Field, 5 May 1941.

Douglas B-18A Bolos over Floyd Bennett Field, 1940.

Douglas B-18A Bolos over San Juan, Puerto Rico.

Douglas B-18 Bolo.

Men of the 19th U.S. Infantry Machine Gun Company boarding a Douglas B-18 Bolo to participate in maneuvers on Kauai Island, Hawaiian Territory, 18 June 1939. The entire company of 110 members was moved in 11 B-18 bombers at Hickam Field.

The Director of Flying at the Air Corps Advanced Flying School, Kelly Field, Texas, in the Douglas B-18 Bolo, cruises past a six-ship student echelon of advanced trainers. Closely supervising all air work, the Director of Flying, Captain B. M. Hovey, frequently goes aloft cruising from one of the 50 formations in the air over Kelly Field to another, checking the progress of the fledgling pilots.

Douglas B-18 Bolo at the 1937 Cleveland Air Race.

Douglas B-18 Bolos fly overhead as the 51st Coast Artillery passes in review, Puerto Rico.

Douglas B-18A Bolo (37-557), Canada, circa late 1942.

Publicity photo of a Douglas B-18 Bolo tail.

Douglas B-18A Bolo (37-557), Canada, circa late 1942.

Douglas B-18 Bolo.

Douglas B-18 Bolos, Hickam Field, pre-World War II.

Douglas B-18A Bolo, 9th Bombardment, October 1939.

Douglas B-18A Bolo with water-based paint camouflage, possibly for wargame maneuvers.

Douglas B-18 Bolo, 72nd Bomb Squadron, 5th Bomb Group.

5th Bomb Group unit insignia, a winged death's head with the motto "Kiai O Ka Lewa" on a scroll beneath the skull as seen on the nose of the Douglas B-18 Bolo in the above photo, which is very similar to this 72nd Bomb Squadron (5th Bomb Group) leather jacket patch.

Douglas B-18A Bolos, 11th Bomb Squadron, with unit insignia (seen below) on the fuselage sides.

11th Bomb Squadron insignia.

Douglas B-18 Bolo, 25th Bomb Squadron.

On top is the 25th Bomb Squadron unit insignia painted on a leather jacket patch. The same basic design is on the nose of the aircraft in the above photo. The insignia illustration below it is from a wartime book on insignia, which is very similar to the insignia on the aircraft’s nose.

Douglas B-18A Bolo, 30th Bomb Squadron, August 1939.

The 30th Bomb Squadron unit insignia as seen on the fuselage sides of the B-18 in the above photo.

Douglas B-18A Bolo of the 21st Reconnaissance Squadron.

The insignia of the 21st Reconnaissance Squadron seen on the above B-18’s nose. Illustration from a wartime book on insignia.

Douglas B-18 Bolos, date unknown.

Douglas B-18A Bolo, date unknown.

Douglas B-18A Bolo.

Douglas B-18A Bolo crash landed at Buckly Bombing Range, Colorado, circa 1939.

Douglas B-18 Bolo interior detail.

Juanita Black, artist in animation studio of Air Corps motion picture unit, sketches a Douglas B-18 Bolo from an exact scale model of the original ship.

Douglas B-18A Bolo (39-20), Barksdale Field.

Douglas B-18A Bolo with shark teeth motif on nose, Big Spring or Childress, Texas, 1943.

Douglas B-18 Bolo and North American BT-9 over Randolph Field.

Aircrew walking past a Douglas B-18A Bolo. Two have pistols drawn and the two men between them are carrying a bag, possibly a Norden bomb sight. This is most likely a publicity photo as emphasis was placed on protecting the Norden bomb sight. Whenever a bombardier or ordnance technician carried a sight out to an aircraft, two armed guards accompanied him. Security was finally relaxed in late 1943 as Allied officials realized that after hundreds of Norden-equipped bombers had been shot down over enemy territory, the bombsight was no longer a secret.

Cockpit of Douglas B-18A Bolo (37-534), 14 September 1943.

Cockpit of a Douglas B-18 Bolo.

Douglas B-18 Bolo (37-009), a second B-18 and a C-47, Albrook Field, Canal Zone, 25 January 1943.

Douglas B-18A Bolos, 21st Reconnaissance Squadron, 5 April 1940.

459th Ordnance Company men load a Douglas B-18A Bolo with 100-pound practice bombs at Midland Bombardier School.

Douglas B-18A Bolos, 38th Reconnaissance Squadron, March Field, California, 8 April 1939.

Allied officers with a Douglas B-18 Bolo, Iceland, March 1943.

Douglas B-18 Bolos over San Quentin, California, October 1939.

Douglas B-18A Bolos over Langley, Virginia, 5 April 1940.

Crashed Douglas B-18A Bolo (37-494), 16 April 1943.

Douglas B-18A Bolo and Curtiss P-40E Warhawks, Iceland, March 1943.

Cadet Bombardier with Douglas B-18 Bolo at Albuquerque Flying School.

Douglas B-18 Bolo (AR84), Hawaii. Practice bombs in foreground.

Loading bombs into a Douglas B-18A Bolo.

Early Douglas B-18 Bolo, Wright Field.

Douglas B-18A Bolo bow turret interior.

Douglas B-18A Bolo, 17th Bomb Group, Felts Field, 1940.

Douglas B-18A Bolo, aircraft 6 (37-537), 1944.

Douglas B-18 Bolo, aircraft 81, 1938.

Douglas B-18A Bolo (38-586), Santa Monica.

Douglas B-18 Bolo nose turret.

Douglas B-18 Bolo, BS 2, 19th Bomb Group.

Douglas B-18 Bolo, BS 31, 19th Bomb Group.

Douglas B-18A Bolo upper turret exterior details.

Douglas B-18 Bolo, RE 9.

Douglas DB-2 Bolo (37-34).

Douglas B-18A Bolo, aircraft 75.

Douglas B-18A Bolo retro bomb tests, 1942.

Douglas B-18A Bolos, 19th Bomb Group, over the Grand Canyon, 1939.

B-18 with visible dish radar.

Douglas B-18A Bolo upper turret exterior.

The ground crew for a Douglas B-18A Bolo.

Douglas B-18 Bolo, Wright Field.

Douglas B-18A Bolo, R 33, 1st Reconnaissance Group, March Field, 4 January 1939.

Douglas B-18A Bolo bow turret interior.

Douglas B-18 Bolo, R 16, 21st Reconnaissance Squadron, 1st Reconnaissance Group, 30 August 1938.

Douglas B-18 Bolo, R 65 and R 64, 88th Reconnaissance Squadron, 1st Reconnaissance Group.

Douglas DB-1 Bolo.

Douglas DB-2 Bolo (37-34).

Douglas B-18 Bolo, Pacific, 1942.

Douglas DB-2 Bolo (37-34).

Douglas B-18A Bolo (37-450), Santa Monica.

Douglas DB-1 Bolo, Wright Field.

Douglas B-18A Bolo (37-465) on right, B-24 on left, Hawaii, 1944.

Douglas B-18A Bolo during Louisiana maneuvers, 1941.

Two Douglas B-18 Bolos and Boeing B-17 Flying Fortress wreck, Pearl Harbor.

Douglas B-18As are on their way to intercept reported enemy submarines in the Caribbean.

Major Gerald E. Williams with Douglas B-18A Bolo, aircraft 73, Paramaribo, Dutch Guiana, 1941.

Olympic distance runner Louis Zamperini atop Douglas B-18A Bolo, Midland Flying School, 1943.

Douglas B-18B Bolo (37-530) with Magnetic Anomaly Detection (MAD) tail antenna on patrol, July 1942.

USAAF Cadet Bombardiers with Douglas B-18 Bolo, aircraft 26, Albuquerque Flying School, 1942.

Douglas B-18 Bolo, medium bomber, USAAC.

Douglas B-18 Bolo. Aircraft Mechanics Graduation Class 2A, 5 June 1940, Hickam Field, Oahu, Hawaii.

Douglas B-18 Bolos, Hawaii.

B-18s in formation over Oahu, 6 April 1940.

Douglas B-18 Bolo.

General “Hap” Arnold awarding Doolittle Raiders at Bolling Field, Washington, D.C., 27 June 1942. Note Douglas B-18 Bolo aircraft in background.

Douglas B-18 Bolo.

Radioman on a B-18 Bolo lets loose a carrier pigeon.

Douglas B-18 Bolo.

Douglas B-18 Bolos.

Douglas B-18 Bolo.

B-18 (VHCWB) at Iron Range strip on Cape York Peninsula, Queensland, Australia, 1942.

Douglas B-18 Bolo aircraft 53 of the 25th Bomb Group.

Interior photo of Douglas B-18 Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Interior photo of Douglas B-18A Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Interior photo of Douglas B-18 Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

USAAC B-18 pilot, circa 1940.

Interior photo of Douglas B-18 Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Exterior photo of Douglas B-18 Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Interior photo of Douglas B-18 Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Interior photo of Douglas B-18A Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Exterior photo of Douglas B-18 Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Exterior photo of Douglas B-18A Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Interior photo of Douglas B-18 Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Douglas B-18 being serviced at Barksdale Field, Louisiana, summer 1941.

Douglas B-18A being serviced at Barksdale Field, Louisiana, summer 1941.

Douglas B-18 being serviced at Barksdale Field, Louisiana, summer 1941.

Douglas B-18s being serviced at Barksdale Field, Louisiana, summer 1941.

Douglas B-18 and B-18A being serviced at Barksdale Field, Louisiana, summer 1941.

Douglas B-18 being serviced at Barksdale Field, Louisiana, summer 1941.

Douglas B-18A being serviced at Barksdale Field, Louisiana, summer 1941.

Refueling B-18 bomber, USAAC, circa 1940.

Douglas B-18A being serviced at Barksdale Field, Louisiana, summer 1941.

Douglas B-18As being serviced at Barksdale Field, Louisiana, summer 1941.

Loading camera into B-18, USAAC, circa 1940.

Crews get instructions from instructor, before heading for Douglas B-18 Bolo bombers, USAAC, circa 1940.

Douglas B-18s and crews at Barksdale Field, Louisiana, summer 1941.

Douglas B-18 being serviced at Barksdale Field, Louisiana, summer 1941.

Exterior photo of Douglas B-18A Bolo bomber based at Barksdale Field, Louisiana, summer 1941.

Douglas B-18 Bolo, aircraft 233, Barksdale Field, Louisiana, summer, 1941.

Douglas B-18 Bolo, aircraft 240, Barksdale Field, Louisiana, summer, 1941.

Douglas B-18 Bolo, aircraft 242, Barksdale Field, Louisiana, summer, 1941.

Douglas B-18 Bolos, Barksdale Field, Louisiana, summer, 1941.

Douglas B-18 Bolo, aircraft 235, Barksdale Field, Louisiana, summer, 1941.

Douglas B-18 Bolos, Barksdale Field, Louisiana, summer, 1941.

This image shows the front-firing antennas of an ASV Mk. II radar as installed on a Royal Canadian Air Force Douglas Digby (B-18 Bolo) aircraft. Note the shaping of the transmitter antenna, seen just below the bombsight window. It has been bent into a curved shape to closely follow the shape of the aircraft fuselage, using the fuselage itself as a reflector to make a Yagi antenna using only a single wire. Similar "tricks" were used on a variety of ASV and AI radars, but made it difficult to move to different aircraft designs. This aircraft is part of 751 Squadron RCAF stationed at Rockcliffe (Ottawa). It is not clear whether this is the same aircraft as seen in other images. July 1942.

Douglas Digby, RCAF.

This image shows what appears to be an experimental receiver antenna array for the ASV Mk. II radar, as installed on a Douglas Digby (B-18 Bolo) aircraft of 751 Squadron, RCAF in Rockcliffe, Ottawa. The ASV Mk. II is normally received on two antennas that look similar to a log-periodic antenna, similar to those used to receive over-the-air VHF TV signals. This antenna is much larger, and appears to be an experimental design, likely an attempt to improve the Mk. II's relatively short range in the forward direction. 1 October 1941.

Another view of the side-looking antennas of the ASV Mk. II radar as installed on a Douglas Digby (B-18 Bolo) aircraft of 751 Squadron, RCAF at Rockcliffe in Ottawa. This image shows the transmitter antenna on the top of the aircraft, and the right-hand receiver antenna on the side - a similar antenna is installed on the left-hand side of the aircraft as well. The circular object on top of the aircraft is a radio direction finder loop antenna. The mid-upper gun turret is partially popped-up. 1 October 1941.

This image shows the ASV Mk. II side-looking antennas installed on a Douglas Digby of No. 751 Squadron, RCAF, seen at RCAF Rockcliffe on 1 October 1941. ASV Mk. I was the first airborne radar system, reaching operational status in 1939. It allowed aircraft to search the surface of the ocean for objects like ships and U-boats. It proved almost useless for this role, but navigators used it extensively for station keeping with convoys as well as a navigational tool. The Mk. II was a cleaned up version, which also added an optional second set of antennas looking to the sides of the aircraft. Because these antennas lay along the top and side of the aircraft they were more streamlined and could be made much larger without effecting performance, which greatly improve detection range. A Mk. II aircraft would fly a search pattern with the side antennas selected, reaching both sides for any objects to appear. When one was seen, they would mark its position on a map, switch the radar to the front-firing antennas, and commence a run on the target. Examples of the ASV were supplied to the Canadians in August 1940 as part of the Tizard Mission. They began producing sets at Research Enterprises in Toronto, and these were widely used on Canadian and US aircraft. This aircraft, a Douglas Digby (B-18 Bolo) must be one of the earliest Canadian aircraft to be fitted with this radar.

Getting ready to pull a Royal Canadian Air Force Douglas Digby Mark I, PR-N, from the sea. This was near Hare Bay (now called Dover) Newfoundland.

Pulling a Royal Canadian Air Force Douglas Digby Mark I, PR-N, out of Newfoundland waters during World War II.

Removing one engine from the salvaged Digby that crashed on January 2, 1941 in Lockers Bay, just off the coast of Dover, Newfoundland.

Douglas Digby Mk. I, RCAF (Serial No. 748), coded PB-V, No. 10 (Bomber) Squadron, RCAF, Halifax, Nova Scotia, 1943. This Digby was taken on charge by No. 12 Technical Detachment on 9 March 1940. It went to RCAF Station Rockcliffe, Ontario on 11 July 1940. To storage with Eastern Air Command on 9 August 1940. Issued from storage on 18 June 1941, for use by No. 10 (BR) Squadron, RCAF Station Dartmouth, NS, and Gander, Newfoundland. Coded "PB-V". Reported Category A in Newfoundland on 3 October 1941. Aircraft settled into trees shortly after takeoff. This was second aircraft crashed by pilot F/L R.A. Butts. To No. 4 Repair Depot at Scoudouc, NB on 13 December 1941 for repairs. Returned to service at Gander on 15 September 1942. To Clark Ruse aircraft for further work, 27 October 1942 to 30 August 1943. To Eastern Air Command when completed. Used by No. 167 (Comm) Squadron, RCAF Station Dartmouth, NS, 1943 to 1945. Pending disposal from 21 August 1945. Stored at No. 6 Reserve Equipment Maintenance Unit at Mont Joli, PQ by 27 November 1945, when it had 985:00 total time. Struck off to War Assets Corporation on 22 March 1946.

Douglas Digby (740), RCAF.

Douglas Digby Mk. I, RCAF (751) No. 10 "North Atlantic" (BR) Squadron, based at Halifax, Nova Scotia, 15 July 1941.

Douglas Digby Mk. I, RCAF, view of the nose gunner position.

Douglas Digby Mk. I, RCAF, view of the nose gunner position. The forward gunner is in the lower position and the bomb aimer up above.

Douglas Digby Mk. I, RCAF.

Douglas Digby (738), RCAF.

Douglas Digby Mk. I, RCAF), coded PB-L, No. 10 (Bomber) Squadron, RCAF, Halifax, Nova Scotia, 1943.

A rare B-18 (36-4460), 50th Reconnaissance Squadron (RS) and assigned aircraft number 81. that crashed into the Kohala summit swamps west of Waimanu on 25 February 1941. Everyone survived.

Douglas B-18A Bolo (37-0469), from the 38th Reconnaissance Squadron on display at the National Museum of the U.S. Air Force.

Douglas B-18A Bolo at the National Museum of the U.S. Air Force, Dayton, Ohio.

Douglas B-18A Bolo (37-0469), from the 38th Reconnaissance Squadron on display at the National Museum of the U.S. Air Force.

Douglas B-18 Bolo at the National Museum of the United States Air Force.

Cockpit of Douglas B-18A Bolo at the National Museum of the U.S. Air Force, Dayton, Ohio.

Interior view of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery. The B-18 in the museum was stationed at Wright Field from 1939 to 1942.

Interior view of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Interior detail of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Interior view of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Interior detail of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Interior view of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Interior detail of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Interior view of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Interior detail of the Douglas B-18 Bolo bomber on display at the National Museum of the U.S. Air Force in the World War II Gallery.

Douglas B-18B Bolo at Pima Air Museum, Tucson, Arizona.

Douglas B-18 Bolo at Castle Air Museum, Atwater, California.

Douglas B-18A 39-25 (39-0025) at Wings Over the Rockies Air and Space Museum, Denver, Colorado.

Douglas B-18 Bolo, Yellow '7', 19th Bomb Wing, 28th Bomb Squadron, Clark Field, Philippines, December 1941-January 1942.

Douglas B-18 Bolo, 42nd Bombardment Squadron, Hickam Field.

Douglas B-18 Bolo, USAAF, Philippines 1942.

Wartime silhouette of the Douglas B-18 Bolo, September 1942.

Douglas B-18 Bolo.

Douglas B-18A Bolo.

Douglas B-18, B-18A and B-18B.

Douglas B-18 Bolo.

35th Bombardment Squadron B-18, 1943.

Douglas B-18 Bolo formation over Manhattan, New York City.

Against the morning sun a Douglas B-18 takes off for anti-submarine patrol in the Caribbean.

A Douglas B-18 on a patrol flight sighted and sank a German submarine cruising in the Caribbean. The plane was piloted by Capt. Howard Burhanna, Jr. The crew members included, front row, left to right: Capt. Lloyd L. Reynolds, co-pilot; Sgt. Jack Ascher, radio operator; Sgt. Albert Will, assistant bombardier; Capt. Burhanna; back row: Pfc. Jack McNellis, assistant radio operator; S/Sgt. Theron R. Jones, bombardier; T/Sgt. William Ludkiewicz, aerial engineer and gunner; and S/Sgt. Alexander Bloshko, assistant engineer.

View of bomb bay of a Douglas B-18 Bolo.

Douglas B-18 drops bombs during practice bombing in the Caribbean, 16 November 1942.

Another view of the Douglas B-18 dropping bombs during practice bombing in the Caribbean, 16 November 1942.

B-18A, 19th Air Group, California.

B-18 (37-16) with nose art at Parafield, Australia, early 1942 while being operated by USAAC 22nd Troop Carrier Squadron.

Douglas B-18 Bolo formation during exercises over Hawaii, taken in 1940-1941.

Another unidentified ex-Philippines B-18 was this aircraft with "6" on tail and nose, at Essendon early 1942.

1st Bombardment Squadron B-18 Bolo, Trinidad, 1942.

Douglas B-18s are on their way to intercept reported enemy submarines in the Caribbean. 12th Bombardment Squadron flying over British Guiana. 1943

Surplus B-18, Vail Field, Montebello, California, May 1946.

B-18 (NC-66267) at Sacramento, California on 14 February 1948.

Douglas RB-18C (38-604).

B-18 Bolo, BE40. This aircraft was used by one of the three squadron commanding officers assigned to the 5th Bombardment Group [redesignated 5th Bombardment Group (Medium) on 6 December 1939], 18th Wing, Hawaiian Department, U.S. Army and based at Hickam Field. The engine cowling is painted red and the two stripes aft of the door, indicating a squadron commander’s aircraft, are also painted red. The Airplane Designator is “BE 40,” the “B” indicating the aircraft was assigned to a bombardment group and the letter “E” is the fifth letter of the alphabet indicating that this was the 5th Bombardment Group. The numeric '40' indicated that this plane was assigned to the “second” squadron of the group.

Douglas B-18 Bolo.

One of two Douglas B-18s configured to a C-58 cargo plane.

Douglas B-18A.

Douglas B-18A (37-62 or 37-563), 6th Reconnaissance Squadron (Medium), municipal airport, Sacto, California, 23 February 1942.

Douglas B-18A (37-572).

Douglas B-18A (39-25), Wright Patterson Air Force Base Museum, 1971. Currently at the Wings Over the Rockies Museum in Denver, Colorado.

Douglas B-18A Bolo being refueled, 1940.

Douglas B-18 Bolo, Rapid City Army Air Base.

Douglas B-18 Bolo.

Douglas B-18 Bolo (36-343), 21st Troop Carrier Squadron, Australia, 1943.

Some B-18s, like this one, could also launch rocket-propelled depth charges rearward toward subs. (U.S. Navy photo) On August 22, 1942, Oberleutnant-zur-See Ludwig Forster was enjoying a brief respite from torpedoing Allied merchant ships in the Caribbean Sea when U-654’s lookout spotted an aircraft approaching. Forster, who promptly ordered a crash dive, had no clue that the aircraft that was attacking his submarine would one day be derided as obsolete and incapable of combat operations. All Forster knew was that the Douglas B-18 bomber was a threat to his ship. Captain P.A. Koenig’s B-18 swooped down, dropping all four of its 600-pound depth charges on the German submarine. U-654 was torn apart by the subsequent explosion, making it the first victim of B-18 antisubmarine warfare (ASW) patrols.

Douglas B-18 Bolo, Wright Field.

Douglas DB-1 Bolo.

Douglas B-18 Bolo, BE 22, 5th Bomb Group.

Douglas DB-2, the last B-18, with a power turret in the nose.

Douglas B-18A Bolo.

B-18 retractable upper turret.

B-18, 7th Air Group, 1938.

B-18 Bolos en route to Manila.

Douglas B-18 at Clark.

Douglas Digby Mk. I, RCAF (751) No. 10 "North Atlantic" (BR) Squadron, based at Halifax, Nova Scotia, 15 July 1941.

Douglas Digby Mk. I, RCAF (Serial No. 740), coded R, No. 10 (Bomber) Squadron, RCAF. This Digby was taken on charge on 30 Dec 1939 at No. 1 (E) Depot at Ottawa, Ontario. It went to RCAF Station Trenton, Ontario, on 17 May 1940. With No. 10 (BR) Squadron, Eastern Air Command, at RCAF Station Dartmouth, Nova Scotia, from 17 June 1940; coded "PB-L", later "R". 740 carried out the first RCAF attack on a U-boat on 25 October 1941, while coded "PB-L". This was EAC's first U-boat sighting and first attack. Both depth charges failed to explode. Loaned, with crew, to No. 164 (T) Squadron, RCAF Station Moncton, New Brunswick, 24 January to 22 March 1943. Flew freight to Goose Bay, Newfoundland. Used by No. 167 (Comm) Squadron, RCAF Station Dartmouth, Nov Scotia, 1943. To No. 4 Repair Depot for scrapping, in lieu of overhaul, on 18 November 1943. Struck off, reduced to spares, 16 May 1944.

Douglas Digby Mk. I, RCAF (Serial No. 740), coded R, No. 10 (Bomber) Squadron, RCAF.

Douglas Digby Mk. I, RCAF (serial no. 740), coded R, No. 10 (Bomber) Squadron, RCAF.

Douglas Digby Mk.I (serial no. 740) coded R, No. 10 (Bomber) Squadron, RCAF, Santa Monica, California, December 1939.

Douglas Digby Mk. I, RCAF (Serial No. 740), coded R, No. 10 (Bomber) Squadron, RCAF.

Douglas Digby Mk. I, RCAF (Serial No. 755), coded J, No. 10 (Bomber) Squadron, RCAF.

Douglas Digby Mk. I, RCAF (Serial No. 749), No. 10 (Bomber) Squadron, RCAF, Jan 1944. This Digby was taken on charge by Eastern Air Command on 23 March 1940. Category A crash near Riviere du Loup, Quebec on 18 November 1940. Aircraft was en route from Newfoundland to St. Hubert, Quebec when it was forced to divert due to bad weather. Crew abandoned aircraft, probably as fuel ran low. Aircraft not located for some time. Ownership assigned to No. 4 Repair Depot in Scoudouc, NB on 3 March 1941, for write off. Struck off on 3 Aug 1941.

Douglas Digby Mk. I, RCAF (Serial No. 751), coded JK-K, No. 10 "North Atlantic" (BR) Squadron, based at Halifax, Nova Scotia.

Douglas Digby Mk. I, RCAF (Serial No. 738), coded PB-N, No. 10 "North Atlantic" (BR) Squadron. This Digby was taken on charge at No. 1 (E) Depot, Ottawa, Ontario, on 29 Dec 1939. It was flown by Air Force Headquarters Communications Flight (formed from No. 7 (GP) Squadron in September 1939, and sometimes still identified as this unit into 1940), RCAF Station Rockcliffe, Ontario, for VIP flights from May 1940. First aircraft to regularly fly IFR missions with this unit. Fly A/V/M Croil to Dartmouth, NS on 30 May 1940. To Eastern Air Command later in 1940, for use by No. 10 (BR) Squadron, RCAF Station Dartmouth. Crashed in flames near Fresh Water Bay, Newfoundland on 2 January 1942. Ownership passed to No. 4 Repair Depot at Scoudouc, NB that date, for write off. It was struck off on 22 June 1942.

Douglas Digby Mk. I, RCAF (Serial No. 740), coded R, No. 10 "North Atlantic" (BR) Squadron, based at Halifax, Nova Scotia, January 1944.

Douglas Digby Mk. I, RCAF (Serial No. 749), No. 10 Squadron, Halifax, Nova Scotia, Jan 1944. This Digby was taken on charge by Eastern Air Command on 23 March 1940. It suffered a Category A crash near Riviere du Loup, Quebec on 18 November 1940. 749 was en route from Newfoundland to St. Hubert, Quebec, when it was forced to divert due to bad weather. The crew abandoned the aircraft, probably as fuel ran low. 749 was not located for some time. Ownership was assigned to No. 4 Repair Depot in Scoudouc, New Brunswick on 3 March 1941, for write off. It was struck off charge on 3 August 1941.

Douglas Digby Mk. I, RCAF (Serial No.), No. 10 "North Atlantic" (BR) Squadron, based at Halifax, Nova Scotia.

West Point Cadets examine a Douglas B-18B Bolo.

Loading "Blackout" leaflets into a B-18 on May 18, 1940.

Members of the 42nd Bombardment Squadron, 11th Bombardment Group, posing by a Douglas B-18 Bolo, Schofield Barracks, Hawaii, circa 1940.

Douglas B-18 Bolo.

Douglas B-18A Bolo.

Douglas B-18 Bolo.

Douglas B-18A Bolo.

Officers and crew rushing to their Douglas B-18 on practice operation order. Caribbean, 1942.

Corporal Jules Meylan and Sgt. William Hoeflich, at their posts under the wing of their Douglas B-18, conforming with the practice of constantly being on the ‘alert.’ Caribbean area, 1942.