Built by North American for the US Army Air Corps, this medium bomber, powered by Wright "Cyclone" engines, first flew on August 19, 1940. The aircraft was officially designated the B-25 "Mitchell" in honor of Brigadier General William Mitchell, considered the father of American aviation. Improvements to the B-25 took into account the use of bombers in the various theaters of war. Production of the B-25D modification began in June 1941.
The B-25D was a twin-engine, all-metal monoplane without external support struts. It had a crew of five: two pilots, a bombardier, a navigator, and a gunner/radioman. The forward section of the fuselage housed the bombardier's compartment and forward-firing armament, with the pilot's compartment behind and above. The navigator sat behind the pilots. His compartment in the upper fuselage had an astronavigation window, later replaced by a convex bubble. The tail was a two-finned cantilever design. The elevator and rudder were made of metal and covered with fabric.
The B-25D, like the B-25C series, was powered by the new Wright "Cyclone" R-2600-13 engines rated at 1,700 hp.
The aircraft received an anti-icing system and an autopilot, and the tail skid was replaced by a fixed skid in a fairing. The B-25D-10 received additional equipment: the aircraft were adapted for use in the Soviet far north and were equipped with an AM compass and an emergency gear release system. In the B-25D-15 series, the nacelles were redesigned: each cylinder now had its own exhaust port, giving the nacelle cover a distinctive appearance. The D-20 series was distinguished by a cockpit canopy with less framing, as well as the presence of an armored backrest on the co-pilot's seat. Additional self-sealing fuel tanks were installed in the bomb bay, and all other aircraft had an additional tank. The B-25D-25 series was characterized by the presence of portable oxygen devices, and the D-30s were prepared for operation in winter conditions. In the Soviet Union, the aircraft was equipped with a system for filling the empty space of the tanks with inert gas.
The small arms armament depended on the modification. In the early series of the D-modification, a 7.62 mm machine gun was mounted in the nose of the bombardier’s compartment with 3 mounts, and the machine gun could be quickly moved from one to another, which extended the field of fire. In the upper and lower (retractable) turrets, there were 2 large-caliber machine guns. The turrets were rotated and the barrels were raised and lowered by electric drives. The lower turret was retracted and extended manually. In the later series, a 12.7 mm fixed machine gun was mounted in the front and the 7.62 mm machine gun in the ball socket was replaced by a large caliber machine gun. The movable machine gun could be fixed in position to fire forward. On the D-30 and D-35 series and later modifications, the lower turret was removed, but a second fixed machine gun was added at the front, and side-mounted 12.7 mm machine guns were added in the windows behind the wing, as well as a rear pin mount.
Initially, the B-25Ds were no different from the B-25Cs, but the B-25D-1 series introduced external bomb racks under the wings and torpedo suspension mounts under the fuselage.
The B-25D was produced until March 1944, with a total of 2,290 produced. The aircraft was delivered to more than just the US Army Air Forces.
The Royal Air Force received 371 B-25Ds. In Great Britain, the B-25C and D were given the same designation, Mitchell Mk. II. They were fitted with British equipment such as radios, bomb sights, etc., and could be fitted with British bombs.
The USSR received 862 aircraft of various modifications, including the B-25D. The Soviets considered it a reliable and easy-to-operate machine, superior to the IL-4. The B-25 was in service with the Long Range Aviation from 1942 to 1953.
The Mitchell played a major role in the Pacific: B-25s operated throughout the Pacific theater, from Burma to New Guinea and Alaska. Island operations were conducted in the absence of good concrete runways, a continuous front line, and well-organized air defenses.
Because the B-25 was undemanding, easy to maintain, easy to operate, and capable of long-range flight, it became the primary heavy machine of this theater. The B-25s terrorized Japanese positions and the coastal islands, strafing and dropping bombs on everything from supply ships to firing positions.
1. "American Warplanes of World War II" by David Donald, 1995
2. V. Kotelnikov "B-25 "Mitchell" Bomber" Journal "Aviakollektsiya" ¹2 2003. 3.
3. materials of the site airwar.ru
Indicated stall speed in flight configuration: 160..191 km/h (100..119 mph)
Indicated stall speed in takeoff/landing configuration: 145..175 km/h (90..109 mph)
Dive speed limit: 544 km/h (340 mph)
Maximum load factor: 6.5 G
Stall angle of attack in flight configuration: 18.3 °
Stall angle of attack in landing configuration: 15.1 °
Maximum true air speed at sea level, engine mode - Combat: 430 km/h (269 mph)
Maximum true air speed at 1400 m, engine mode - Combat: 472 km/h (295 mph)
Maximum true air speed at 3900 m, engine mode - Combat: 495 km/h (310 mph)
Maximum true air speed at sea level, engine mode - Nominal: 419 km/h (262 mph)
Maximum true air speed at 2000 m, engine mode - Nominal: 448 km/h (280 mph)
Maximum true air speed at 4750 m, engine mode - Nominal: 461 km/h (288 mph)
Service ceiling: 7450 m (24442 ft)
Climb rate at sea level: 8.3 m/s (1575 ft/min)
Climb rate at 3000 m: 6.3 m/s (1236 ft/min)
Climb rate at 6000 m: 2.7 m/s (394 ft/min)
Maximum performance turn at sea level: 28.8 s, at 270 km/h IAS.
Maximum performance turn at 3000 m: 47.0 s, at 280 km/h IAS.
Flight endurance at 3000 m: 4.6 h, at 330 km/h IAS. Engine mode - Cruise, 1st supercharger stage
Takeoff speed: 165..180 km/h (105..115 mph)
Glideslope speed: 200..215 km/h (125..135 mph)
Landing speed: 176..192 km/h (110..120 mph)
Landing angle: 4.5 °
Note 1: the data provided is for international standard atmosphere (ISA).
Note 2: flight performance ranges are given for possible aircraft mass ranges.
Note 3: maximum speeds, climb rates and turn times are given for aircraft mass with 8 G.P.B. 500 bombs and 58% fuel.
Note 4: climb rates and turn times are given for Nominal power.
Engine:
Model: Wright R-2600-13
Maximum power in Cruise mode at 6700 ft: 1140 HP
Maximum power in Cruise mode at 15000 ft: 1027 HP
Maximum power in Nominal mode at 6700 ft: 1520 HP
Maximum power in Nominal mode at 15000 ft: 1370 HP
Maximum power in Combat mode at 4500 ft: 1725 HP
Maximum power in Combat mode at 12000 ft: 1470 HP
Maximum power in Takeoff mode at sea level: 1725 HP
Engine modes:
(boost value is listed for 1st and 2nd supercharger gears)
Cruise (unlimited time): 2100 RPM, 31.5 / 32.5 inch Hg, mixture "Cruising Lean"
Nominal (unlimited time): 2400 RPM, 38.0 / 39.0 inch Hg, mixture "Full Rich"
Combat (5 min limit): 2600 RPM, 42.0 / 41.0 inch Hg, mixture "Full Rich"
Takeoff (5 min limit): 2600 RPM, 44.0 inch Hg, mixture "Full Rich"
Oil rated temperature in engine output: 80..95 °C
Oil maximum temperature in engine output: 105 °C
Cylinder head rated temperature: 140..235 °C
Cylinder head maximum temperature: 260 °C
Supercharger gear shift altitude: 3350 m (11000 ft)
Empty weight: 8379 kg
Minimum weight (no ammo, 10% fuel): 8829 kg
Standard weight: 11544 kg
Maximum takeoff weight: 15422 kg
Fuel load: 2618 kg / 3688 l / 974 gal
Useful load: 7043 kg
Forward-firing armament:
12.7mm machine gun ANM2 .50, 400 rounds, 850 rounds per minute, nose-mounted
Defensive armament:
Nose: 12.7mm machine gun ANM2 .50, 400 rounds, 850 rounds per minute
Top: 2 x 12.7mm machine gun ANM2 .50, 400 rounds, 850 rounds per minute
Belly: 2 x 12.7mm machine gun ANM2 .50, 400 rounds, 850 rounds per minute
Bombs:
Up to 8 x 500 lb general purpose bomb "500 lb."
Up to 4 x 1000 lb general purpose bomb "1000 lb. M.C."
Length: 16.1 m
Wingspan: 20.5 m
Wing surface: 57.0 m²
Combat debut: spring 1942
Operation features:
- The engine has no manifold pressure automatic governor. For this reason, manifold pressure not only depends on throttle position, but also from RPM and altitude. This requires additional checking of manifold pressure to not cause engine damage.
- The engine is equipped with an automatic fuel mixture control which maintains optimal mixture if mixture lever is set to Full Rich (100%) position. To use automatic mixture leaning to reduce fuel consumption during flight it is necessary to set mixture lever to Cruising Lean (50%) position. To stop the engine mixture lever should be set to the Cut Off (0%) position.
- Engine RPM has an automatic governor and it is maintained at the required RPM corresponding to the governor control lever position. The governor automatically controls the propeller pitch to maintain the required RPM.
- Oil radiators shutters and engine cowl outlet shutters are manually operated.
- The aircraft has trimmers for all flight-controls: pitch, roll and yaw.
- Landing flaps have a hydraulic actuator and they can be extended to any angle up to 45°.
- The aircraft has independent left and right hydraulic wheel brake controls. To apply either brake push the upper part of the rudder pedal.
- The aircraft is equipped with upper formation lights.
- The engine has a two-stage mechanical supercharger which must be manually switched at 3350 m (11000 ft) altitude.
- The nose gear orients by itself, doesn't have brakes and can't be controlled.
- There are white and red signal lamps in the tail: the white one is lit while bomb doors are open and the red one lights up for 5 seconds when bombs are released.
- The aircraft is equipped with a bomb salvo controller. It allows to drop selected bombs in a salvo or drop all bombs in salvo. There is also a controller for a drop delay between each bomb in the salvo.
