A-20 Douglas Model 7A Douglas Model 7B DB 7 B 3 Boston Mks.I &

Douglas DB-7B Boston III

Description
Role	Medium Bomber
Crew	3-4
First Flight	October 26, 1938 (Model 7B)
Entered Service
Manufacturer	Douglas, Boeing
Dimensions
Length	47ft 4in	14.4 m
Wingspan	61ft 4in	18.7 m
Height	18ft 1in	5.5 m
Wing Area	464 ft²	43.1 m²
Weights
Empty	0 lbs	0 kg
Loaded	24,000 lbs	10,880 kg
Maximum takeoff	lbs	kg
Powerplant
Engine	2 × Wright GR-2600-A5B Cyclone
Power (each)	1,350 hp	1,010 kW
Performance
Maximum speed	350mph @ 12,000ft	563km/h @ 3,660m
Combat range	1,080 miles	1,740 km
Ferry range	km	miles
Service ceiling	23,600 ft	7,190 m
Rate of climb	ft/min	m/min
Wing loading	51.7 lb/ft²	252.4 kg/m²
Power/Mass	0.113 hp/lb	0.186 kW/kg
Armament
Guns	8 × 0.303 machine-guns
Bombs	2,000 lbs	900 kg

In March 1937 a design team headed by Donald Douglas, Jack Northrop and Ed Heinemann produced a proposal for a light bomber powered by a pair of 450hp (340kW) Pratt & Whitney R-985 Wasp Junior engines mounted on a high-mounted wing. It was estimated it could have carried 1000lb (450kg) bombload at 250mph (400km/h). Reports of aircraft performance from the Spanish Civil WarTeruel, east of Madrid. For an article about the 1820-1823 civil war in Spain, see: Spanish Civil War, 1820-1823 The Spanish Civil War ( 1936 1939) was the result of complex political differences between the Republicans — supporters of the government of t indicated that this design would be seriously underpowered, and it was not progressed.

2 Douglas Model 7B

In the autumn of the same year, the Army Air CorpsThe Army Air Corps is a vital component of the British Army. There are currently seven regiments of the AAC as well as five flights deployed in support of British Army operations across the world. They are currently located in Belize, Brunei, Canada, Cypr issued its own specification for an attack aircraft. The Douglas team, now headed by Heinemann, took the model 7A design, upgraded massively to 1100hp (820kW) Pratt & Whitney R-1830 S3C3-G Twin Wasp engines, and submitted the design as the Model 7B. It faced competition from the North American NA-40B-25 Mitchell was a twin-engined, medium bomber manufactured by North American Aviation in the United States and used during World War II. By the time production of the plane ended, roughly 10,000 had been built, including PBJ-1 Navy Patrol Bomber and an, the Stearman X-100 , and the Martin 167F . The Model 7B was maneuverable and fast, but did not attract any US orders.

The model did, however, attract the attention of a French Purchasing Commission visiting the USA. The French participated in the flight trials, discretely so as not to attract criticism from US isolationistsIsolationism is a diplomatic policy whereby a nation seeks to avoid alliances with other nations. Most nations are not in a political position to maintain strict isolationist policies for extended periods of time, even though most nations have historical. The French ordered 100 production aircraft, which order was increased to 270 when the war began.

3 DB-7 B-3

The French order called for substantial modifications, and the new designation DB-7 (for Douglas Bomber 7) was introduced. It had a narrower deeper fuselage, 1000hp (750kW) Pratt & Whitney R-1830-SC3-G radials, and French guns and metric instruments. Midway through the delivery, engines were switched to 1100 hp (820kW) Pratt & Whitney R-1830-S3C4-G. The French designation was DB-7 B-3 (the B-3 meaning "three-seat bomber").

The DB-7s were shipped in sections to CasablancaFor the 1942 film, see Casablanca (movie . For the famous Cuban chess player, see Jose Raul Capablanca . Casablanca ( Arabic: , pronounced Dar-al-Baida is a city in western Morocco with an estimated population of 3. Located on the Atlantic Ocean, Casablan for assembly and service in France and French North Africa. When the Germans invadedIn World War II, Battle of France or Case Yellow Fall Gelb in German) was the German invasion of France and the Low Countries, executed 10 May, 1940 which ended the phony war. German armored units punched through the Ardennes, outflanking the Maginot Line France on May 10May 10 is the 130th day of the year in the Gregorian Calendar (131st in leap years). There are 235 days remaining. Events 1291 Scottish nobles recognize the authority of King Edward I of England. 1497 Amerigo Vespucci allegedly leaves Cadiz for his first, 1940Events January-February January 5 FM radio is demonstrated to the FCC for the first time. January 6 World War II: Mass execution of Poles, committed by Germans in the Poznan, Warthegau. January 12 World War II: Russia bombs cities in Finland. February 2 F the 64 available DB-7s were deployed against the advancing Panzers. Before the armistice they returned to North Africa, and some were used by Vichy French forces on the Axis side. A few were still operating under Free French colours to the end of the war in Europe.

4 Boston Mks.I & II

The Royal Air Force agreed to take up the balance of the now-frustrated French order was diverted to Britain, and the aircraft were designated Boston Mk.I or Mk.II according to the earlier or later engine type.

5 Havoc Mk. I

The aircraft was not really suitable for RAF use as its range was too limited for day-time raids on Germany. Many of the Boston Mk.II, plus some re-engined Mk.Is, were converted for nighttime duties - either as intruders with 2,400lbs (1,100kg) bombs, or as night-fighters with AI Mk. IV radar. These were known collectively as Havoc Mk. I. 181 Bostons were converted to Havocs. Havoc Intruders caused considerable damage to German targets.

20 Havocs were Havoc Mk. I (Pandora) intruder aircraft, trailing the Long Aerial Mine (LAM) which was an explosive charge trailed on a long cable in the path of enemy aircraft in the hope of scoring a hit. It was not successful and they were converted back to Mk.I intruders.

A further 31 were Havoc Mk. I Turbinlite fitted with a 2700 million candlepower (2.7Gcd) searchlight in the nose. They were unarmed and were supposed to illuminate targets for accompanying Hurricanefighters, but in practice they just made nice bright targets for German gunners.

6 DB-7A Havoc Mk.II

The French Purchasing Commission ordered a further 200 bombers, to be fitted with 1600hp (1190kW) Wright R-2600-A5B Double Cyclone engines. This variant was designated DB-7A by Douglas. None had been delivered before the fall of France, and they served instead as night-fighters with the RAF under the name of Havoc Mk.II. They had an impressive top speed of 344mph (550 km/h) at altitude. 39 of them were used briefly in Turbinlite roles.

7 DB-7B Boston Mk. III, DB-73, DB-7C

The DB-7B was the first batch of the series to be actually ordered by Britain, in February 1940. Powered by the same engines as the DB-7A, with better armor and, crucially, larger fuel tanks, these were at last suitable for British use in the light bomber role. This was the batch for which the name Boston was first reserved, but since the commandeered DB-7s entered service first, this batch became known as Boston Mk.III. Amongst other operations they took part in the attacks on the Scharnhorst, Gneisenau and Prinz Eugen during their escape dash through the English Channel in February, 1942. 300 were delivered and some were used in Intruder and Turbinlite roles.

The DB-73 was a very similar design for France, which again were diverted to England as Boston Mk.IIIA. Many of these were built under licence by Boeing. Events further overtook this shipment after the German attack on the Soviet Union on June 22, 1941 and the Attack on Pearl Harbor on December 7, when many Bostons were sent to Russia and many more retained by the USAAF for its own use. Some 22 were also sent to the RAAF.

The DB-7C was a Netherlands order intended for service in the Netherlands East Indies, but the Japanese invasion was complete before they were delivered and they were sent instead to the Soviet Union under Lend-Lease.

8 A-20

The original American indifference to the Model 7B was overcome by the improvements made for the French and British, and the Army Air Corps ordered two models, the A-20 for high-altitude bombing and the A-20A for lower-altitude work. Both were similar to the DB-7B, the A-20 was to be fitted with turbosupercharged Wright R-2600-7 engines, but these were bulky and the prototype suffered cooling problems, so the remainder were completed with the un-supercharged R-2600-11, 59 as P-70 fighters and 3 as F-3 reconnaissance panes (of which more later).

9 A-20A

The US Army ordered 123 A-20As with R-2600-3 engines, and a further 20 with more powerful R-2600-11. They entered service in spring, 1941. The Army liked the A-20A because of its excellent performance and because it had no adverse handling characteristics. 9 of them were transferred to Australia in 1943. The British name Havoc was adopted for the A-20A.

10 A-20B

The A-20B received the first really large order - 999 - from the US Army. They resembled the DB-7A rather than the DB-7B, with light armor and stepped rather than slanted glazing in the nose. In fact, 665 were exported to the Soviets, so rather few actually served with the USAAC.

11 A-20C

The A-20C was an attempt to standardize on a common British and American version, produced from 1941. It reverted to the slanting nose-glass and had RF-2600-23 engines, self-sealing fuel tanks and additional armor. They were equipped to carry an external 2000 lbs (900kg) naval torpedo. 948 were built for Britain and the Soviet Union, but many were retained by the USAAF after Pearl Harbor.

12 A-20G & A-20H

The A-20G, delivered from February 1943, would be the most produced of all the series - 2850 were built. The glazed nose was replaced by a solid nose contain four 20mm cannon and two 0.50in Colt-Browning machine guns, making the aircraft slightly longer than previous versions. After the first batch of 250 the unreliable cannon were replaced by more machine guns. Some had a wider fuselage to accommodate a power driven gun turret. Many A-20Gs were delivered to the Soviet Union. The powerplant was the 1600hp R-2600-23. US A-20Gs were used on low-level sorties in the New Guinea theatre.

The A-20H was the same continued with the 1700hp (1270kW) R-2600-29. 412 of these were built. The take-off weight was raised to 24,170lbs (10,960 kg).

13 A-20J, Boston Mk. IV

The A-20J carried an additional bombardier in an extended plexiglass nose section. These were intended to lead bombing formations, with the following standard A-20s dropping their bombs when signalled by the leader. 450 were built, 169 for the RAF which designated them Boston Mk. IV from summer 1944.

14 A-20K, Boston Mk. V

The A-20K (Boston Mk. V in RAF parlance) was the final production version of the A-20 series, the same as the A-20J except for R-2600-29s instead of -23s.

15 P-70

In October 1940 the USAAC felt a need for long-range fighters more than attack bombers, so most of the production run of A-20s were converted to P-70 night-fighters. They were equipped with British AI Mk. IV radar, the glazed nose often painted black to reduce glare, and had four 20mm cannon. Further P-70 variants were produced from A-20C G and J variants, later models having American centimetric radar fitted.

16 F-3A

The F-3A was a conversion of 46 A-20J and K models for night-time photographic reconnaissance (F-3 were a few conversions of the original A-20).

17 Conclusion

When A-20 series production finally ended on September 20, 1944, a total of 7098 had been built by Douglas and a further 380 by Boeing.

18 External links

Douglas A-20 Havoc

Related content
Related Development	Douglas DC-5
Similar Aircraft
Designation Series	A-17 - A-18 - A-19 - A-20 - A-21 - A-22 - A-23
Related Lists	List of military aircraft of the United States - List of aircraft of the RAF

US bomber aircraft 1930-1939

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1 Douglas Model 7A