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North American B-25 Mitchell Medium Bomber (1940)

Authored By Staff Writer | Last Updated: 11/16/2013

The North American B-25 Mitchell proved a crucial medium bomber component to the Allied war effort during World War 2.

The North American B-25 Mitchell series of medium bombers went on to become one of the classic American aircraft designs to emerge during World War Two. Designed as early as 1939, the series was built to specifications as required by the United States Army. The B-25 would go on to gain national fame in the United States as the aircraft used by the famous "Doolittle Raiders", the end result having shown the American ability to bomb the heart of Tokyo from a USN carrier stationed in the Pacific (USS Hornet).

The B-25 was initially designed as a three-crew, high-mounted wing bomber utilizing twin Pratt & Whitney R-1830-S6C-3 radial engines. By the end of its production run, the system would be overhauled to include 5 to 6 crew members in various gun positions, a shoulder-mount wing assembly and twin Wright GR-2600-A71 radial engines. After over 9,800 were produced, the Mitchell had evolved into a host of variants that included trainers, dedicated ground strike, reconnaissance and torpedo carriers.

The more identifiable B-25's were a twin-engine design with the radials mounted underneath either wing element. The forward fuselage was of a greenhouse-type design affording the forward-located gunners and bombardiers a good field of vision. The pilot and co-pilot sat in a raised location just behind the nose assembly and had good vision forward, above and to the sides. A top dorsal turret was included and was mounted with twin .50 caliber machine guns. Waist gunner positions were added with single .50 caliber guns, as was a twin .50 caliber gun position in the tail. The B-25 made use of a powered-tricycle landing gear system and a decent internal bomb bay. Twin rudder assemblies differentiated the system from the other similar-looking twin-engine medium bombers of American design.

Initial B-25 designs limited the crew to just three, whereas a fuselage widening helped to increase width and seat the pilot and co-pilot side-by-side. Armor and self-sealing fuel tanks were already common in about 40 developmental models of the "A" variety. The "B" model would go on to feature 119 production aircraft with powered dorsal and ventral turret emplacements but the rear tail gunner position removed.

It would not be until the valuable and definitive "C" models joined the lines that the B-25 would come into its own. C-model construction would leap into the 1,600's and featured an autopiloting system, underwing hardpoints, provision for torpedo carrying and the identifiable forward-fixed 4 x .50 caliber machine gun pods on either side of the lower-front fuselage.

Following the C-models would be the very similar "D" series that varied in only being produced on a different production line facility. The next "G" models would feature a large-caliber 75mm cannon in the nose followed by "H" models with a similar gun system and upwards of 18 defensive machine guns positioned throughout the aircraft. Dedicated ground strike models were even featured with a devastating array of 8 x .50 caliber machine guns in a forward-fixed assembly mounted in the nose.

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Specifications for the
North American B-25 Mitchell
Medium Bomber


Focus Model: North American B-25C Mitchell
Country of Origin: United States
Manufacturer: North American Aircraft Corporation - USA
Initial Year of Service: 1940
Production: 9,816


Crew: 5


Length: 52.92ft (16.13m)
Width: 67.55ft (20.59m)
Height: 15.75ft (4.80m)
Weight (Empty): 20,300lbs (9,208kg)
Weight (MTOW): 34,000lbs (15,422kg)


Powerplant: 2 x Wright Cyclone R-2600-19 air-cooled piston engines delivering 1,700hp each.


Maximum Speed: 272mph (438kmh; 237kts)
Maximum Range: 1,350miles (2,173km)
Service Ceiling: 24,196ft (7,375m; 4.6miles)
Rate-of-Climb: 1,666 feet per minute (508m/min)


Hardpoints: Up to 8 (model dependent)
Armament Suite:
Model-specific armament included:

8 x 12.7mm machine gun array OR 1 x 75mm cannon in forward-fixed nose assembly.

2 x 12.7mm machine guns in forward-fixed lower-left side fuselage position (beneath and behind cockpit position).
2 x 12.7mm machine gun in forward-fixed lower-right side fuselage position (beneath and behind cockpit position).
2 x 12.7mm machine guns in ventral turret (powered turrets in some models).
2 x 12.7mm machine guns in dorsal turret (powered turrets in some models).
1 x 12.7mm machine gun in left waist port position.
1 x 12.7mm machine gun in right waist port position.
2 x 12.7mm machine guns in tail gun position (some models removed).
1 x Torpedo in under-fuselage arrangement (model-specific fitting).
8 x 250lb bombs on 8 external hardpoints (model-specific fitting).

Maximum internal bombload of 3,000lbs (1,361 kg).


Variants:
NA-62 / B-25 - Further Production Design with wing element lowered to middle position; Widened fuselage to accommodate side-by-side seating for pilot / copilot; Crew increase from 3 to 5 crewmen; Improved offensive armament array and defensive capabilities; R-2600-9 powerplants; 24 initial aircraft produced.


B-25A - At least forty produced with self-sealing fuel tanks and additional armor protection.

B-25B - At least 119 produced with power-operated ventral and dorsal turret systems; Tail gun emplacement removed on some models; Plexiglass nose assembly.

B-25C - Major production model featuring autopilot, provisioning for eight external 250lb bombs or a single under-fuselage torpedo; Some produced with 4 x 12.7mm machine guns in forward-firing position on either lower-side of the cockpit.

B-25D - Based on B-25C model except from a different production line / facility.

B-25G - Featured a 75mm nose cannon; At least 405 produced with this feature; Retractable belly turret.

B-25H - Featured between 14 to 18 x 12.7mm machine guns in various positions; At least 1,000 of this type produced; Solid nose assembly; Belly turret removed; 4 x 12.7mm machine guns in forward-fixed firing position in nose above 75mm cannon; Two aft-fuselage plexiglass blisters with 12.7mm gun mounts; Tail turret reintroduced with 2 x 12.7mm machine guns; Wright R-2600-13 or R2600-29 powerplants.

B-25J - Final Production Model with R-2600-92 radial powerplants; 12 x 12.7mm machine guns in various positions.

F-10 - Reconnaissance Model

AT-25 - Pilot / Crewman Trainer Conversion Model

TB-25 - Pilot / Crewman Trainer Conversion Model

PBJ - Navy Pilot / Crewman Trainer Conversion Model


Operators:
Australia; Argentina; Biafra; Bolivia; Brazil; Canada; China; Chile; Colombia; Cuba; Dominican Republic; France; Indonesia; Mexico; Netherlands; Peru; Poland; Spain; Soviet Union; Taiwan; United Kingdom; United States; Uruguay; Venezuela