North American B-25 Mitchell

B-25 Mitchell
A B-25 Mitchell in 2007
Role	Medium bomber
National origin	United States
Manufacturer	North American Aviation
First flight	19 August 1940
Introduction	1941
Retired	1979 (Indonesia)
Primary users	United States Army Air Forces Royal Air Force Soviet Air Force United States Marine Corps
Number built	9,816[1][lower-alpha 1]
Developed from	North American XB-21
Developed into	North American XB-28 Dragon

The North American B-25 Mitchell is an American twin-engine, medium bomber manufactured by North American Aviation (NAA).

The design was named in honor of Major General William "Billy" Mitchell, a pioneer of U.S. military aviation. Used by many Allied air forces, the B-25 served in every theater of World War II and after the war ended many remained in service, operating across four decades. Produced in numerous variants, nearly 10,000 Mitchells rolled from NAA factories.^[1] These included a few limited models, such as the United States Marine Corps' PBJ-1 patrol bomber and the United States Army Air Forces' F-10 reconnaissance aircraft and AT-24 trainers.

Design and development

The Air Corps issued a circular (Number 38-385) in March 1938 describing the performance they required from the next bombers — a payload of 1,200 lb (540 kg) with a range of 1,200 mi (1,900 km) at more than 200 mph (320 km/h).^[2] Those performance specifications led NAA to submit their NA-40 design. The NA-40 had benefited from the North American XB-21 (NA-39) of 1936, which was the company's partly successful design for an earlier medium bomber that had been initially accepted and ordered, but then cancelled. However, the company's experience from the XB-21 contributed to the design and development of the NA-40. The single NA-40 built flew first at the end of January 1939. It went through several modifications to correct problems. These improvements included fitting 1,600 hp (1,193 kW) Wright R-2600 "Twin Cyclone" radial engines, in March 1939, which solved the lack of power.^[2]

In March 1939, North American delivered the substantially redesigned and improved NA-40 (as NA-40B) to the United States Army Air Corps for evaluation.^[2] It was in competition with other manufacturers' designs (Douglas 7B, Stearman X-100, and the Martin Model 167F)^[3] but failed to win orders. The aircraft was originally intended to be an attack bomber for export to the United Kingdom and France, both of which had a pressing requirement for such aircraft in the early stages of World War II. However, the French had already opted for a revised Douglas 7B (as the DB-7). Unfortunately, the NA-40B was destroyed in a crash on 11 April 1939 while undergoing testing. Although the crash was not considered due to a fault with the aircraft design, the Army ordered the DB-7 as the A-20.^[4][5]

The Air Corps issued a specification for a medium bomber in March 1939: 2,400 lb (1,100 kg) over 1,200 mi (1,900 km) at 300 mph (480 km/h)^[6] NAA used the NA-40B design to develop the NA-62, which competed for the medium bomber contract. There was no YB-25 for prototype service tests. In September 1939, the Air Corps ordered the NA-62 into production as the B-25, along with the other new Air Corps medium bomber, the Martin B-26 Marauder "off the drawing board".

Early into B-25 production, NAA incorporated a significant redesign to the wing dihedral. The first nine aircraft had a constant-dihedral, meaning the wing had a consistent, upward angle from the fuselage to the wingtip. This design caused stability problems. "Flattening" the outer wing panels by giving them a slight anhedral angle just outboard of the engine nacelles nullified the problem, and gave the B-25 its gull wing configuration.^[7] Less noticeable changes during this period included an increase in the size of the tail fins and a decrease in their inward tilt at their tops.

NAA continued design and development in 1940 and 1941. Both the B-25A and B-25B series entered USAAF service. The B-25B was operational in 1942. Combat requirements lead to further developments. Before the year was over, NAA was producing the B-25C and B-25D series at different plants. Also in 1942, the manufacturer began design work on the cannon-armed B-25G series. The NA-100 of 1943 and 1944 was an interim armament development at the Kansas City complex known as the B-25D2. Similar armament upgrades by U.S-based commercial modification centers involved about half of the B-25G series. Further development led to the B-25H, B-25J, and B-25J2. The gunship design concept dates to late 1942 and NAA sent a field technical representative to the SWPA. The factory-produced B-25G entered production during the NA-96 order followed by the redesigned B-25H gunship. The B-25J reverted to the bomber role, but it, too, could be outfitted as a strafer.

NAA manufactured the greatest number of aircraft in World War II, the first time a company had produced trainers, bombers, and fighters simultaneously (the AT-6/SNJ Texan, B-25 Mitchell, and the P-51 Mustang). It produced B-25s at both its Inglewood main plant and an additional 6,608 aircraft at its Kansas City, Kansas plant at Fairfax Airport.^[4][5][8]

After the war, the USAF placed a contract for the TB-25L trainer in 1952. This was a modification program by Hayes of Birmingham, Alabama. Its primary role was reciprocal engine pilot training.

A development of the B-25 was the North American XB-28, designed as a high-altitude bomber. Two prototypes were built with the second prototype, the XB-28A, evaluated as a photo-reconnaissance platform, but the aircraft did not enter production.^[9]

Operational history

Asia-Pacific

The majority of B-25s in American service were used in the war against Japan in Asia and the Pacific. The Mitchell fought from the Northern Pacific to the South Pacific and the Far East. These areas included the campaigns in the Aleutian Islands, Papua New Guinea, the Solomon Islands, New Britain, China, Burma and the island hopping campaign in the Central Pacific. The aircraft's potential as a ground-attack aircraft emerged during the Pacific war. The jungle environment reduced the usefulness of medium-level bombing, and made low-level attack the best tactic. Using similar mast height level tactics and skip bombing, the B-25 proved itself to be a capable anti-shipping weapon and sank many enemy sea vessels of various types. An ever-increasing number of forward firing guns made the B-25 a formidable strafing aircraft for island warfare. The strafer versions were the B-25C1/D1, the B-25J1 and with the NAA strafer nose, the J2 sub-series.

In Burma, the B-25 was often used to attack Japanese communication links, especially bridges in central Burma. It also helped supply the besieged troops at Imphal in 1944. The China Air Task Force, the Chinese American Composite Wing, the First Air Commando Group, the 341st Bomb Group, and eventually, the relocated 12th Bomb Group, all operated the B-25 in the China Burma India Theater (CBI). Many of these missions involved battle field isolation, interdiction and close air support.

Later in the war, as the USAAF acquired bases in other parts of the Pacific, the Mitchell could strike targets in Indochina, Formosa and Kyushu, increasing the usefulness of the B-25. It was also used in some of the shortest raids of the Pacific War, striking from Saipan against Guam and Tinian. The 41st Bomb Group used it against Japanese-occupied islands that had been bypassed by the main campaign, such as happened in the Marshall Islands.

Middle East and Italy

The first B-25s arrived in Egypt and were carrying out independent operations by October 1942.^[10] Operations there against Axis airfields and motorized vehicle columns supported the ground actions of the Second Battle of El Alamein. Thereafter, the aircraft took part in the rest of the campaign in North Africa, the invasion of Sicily and the advance up Italy. In the Strait of Messina to the Aegean Sea the B-25 conducted sea sweeps as part of the coastal air forces. In Italy, the B-25 was used in the ground attack role, concentrating on attacks against road and rail links in Italy, Austria and the Balkans. The B-25 had a longer range than the Douglas A-20 Havoc and Douglas A-26 Invaders, allowing it to reach further into occupied Europe. The five bombardment groups – 20 squadrons – of the Ninth and Twelfth Air Forces that used the B-25 in the Mediterranean Theater of Operations were the only U.S. units to employ the B-25 in Europe.^[11]

Europe

The RAF received nearly 900 Mitchells, using them to replace Douglas Bostons, Lockheed Venturas and Vickers Wellington bombers. The Mitchell entered active RAF service on 22 January 1943. At first, it was used to bomb targets in occupied Europe. After the Normandy invasion, the RAF and France used Mitchells in support of the Allies in Europe. Several squadrons moved to forward airbases on the continent. The USAAF did not use the B-25 in combat in the ETO.

USAAF

The B-25B first gained fame as the bomber used in the 18 April 1942 Doolittle Raid, in which 16 B-25Bs led by Lieutenant Colonel Jimmy Doolittle attacked mainland Japan, four months after the bombing of Pearl Harbor. The mission gave a much-needed lift in spirits to the Americans, and alarmed the Japanese, who had believed their home islands to be inviolable by enemy forces. Although the amount of actual damage done was relatively minor, it forced the Japanese to divert troops for home defense for the remainder of the war.

The raiders took off from the carrier USS Hornet and successfully bombed Tokyo and four other Japanese cities without loss. Fifteen of the bombers subsequently crash-landed en route to recovery fields in eastern China. These losses were the result of the task force being spotted by a Japanese vessel, forcing the bombers to take off 170 mi (270 km) early, fuel exhaustion, stormy nighttime conditions with zero visibility, and lack of electronic homing aids at the recovery bases. Only one B-25 bomber landed intact, in Siberia where its five-man crew was interned and the aircraft confiscated. Of the 80 aircrew, 69 survived their historic mission and eventually made it back to American lines.

Following a number of additional modifications, including the addition of Plexiglas dome for navigational sightings to replace the overhead window for the navigator and heavier nose armament, de-icing and anti-icing equipment, the B-25C entered USAAF operations. Through block 20 the B-25C and B-25D differed only in location of manufacture: C series at Inglewood, California; D series at Kansas City, Kansas. After block 20 some NA-96 began the transition to the G series while some NA-87 acquired interim modifications eventually produced as the B-25D2 and ordered as the NA-100. NAA built a total of 3,915 B-25Cs and Ds during World War II.

Although the B-25 was originally designed to bomb from medium altitudes in level flight, it was used frequently in the Southwest Pacific theatre in treetop-level strafing and missions with parachute-retarded fragmentation bombs against Japanese airfields in New Guinea and the Philippines. These heavily armed Mitchells were field-modified at Townsville, Australia, under the direction of Major Paul I. "Pappy" Gunn and North American tech rep Jack Fox, These "commerce destroyers" were also used on strafing and skip bombing missions against Japanese shipping trying to resupply their armies.

Under the leadership of Lieutenant General George C. Kenney, Mitchells of the Far East Air Forces and its existing components, the Fifth and Thirteenth Air Forces devastated Japanese targets in the Southwest Pacific Theater during 1944 to 1945. The USAAF played a significant role in pushing the Japanese back to their home islands. The type operated with great effect in the Central Pacific, Alaska, North Africa, Mediterranean and China-Burma-India (CBI) theaters.

The USAAF Antisubmarine Command made great use of the B-25 in 1942 and 1943. Some of the earliest B-25 Bomb Groups also flew the Mitchell on coastal patrols after the Pearl Harbor attack, prior to the AAFAC organization. Many of the two dozen or so Antisubmarine Squadrons flew the B-25C, D and G series in the American Theater Antisubmarine campaign, often in the distinctive, white sea search camouflage.

Combat developments

Use as a gunship

In anti-shipping operations, the USAAF had urgent need for hard-hitting aircraft, and North American responded with the B-25G. In this series the transparent nose and bombardier/navigator position was changed for a shorter, hatched nose with two fixed .50 in (12.7 mm) machine guns and a 75 mm (2.95 in) M4 cannon,^[12] one of the largest weapons fitted to an aircraft, similar to the British 57 mm gun-armed Mosquito Mk. XVIII and the German Henschel Hs 129B-3, and Ju 88P heavy cannon (up to a 75 mm long-barrel Bordkanone BK 7,5). The shorter nose placed the cannon breech behind the pilot where it could be manually loaded and serviced by the navigator; his crew station was moved to just behind the pilot. The navigator signalled the pilot when the gun was ready and the pilot fired the weapon using a button on his control wheel.

The Royal Air Force, U.S. Navy and the Soviet VVS each conducted trials with this series but none adopted it. The G series comprised one prototype, five pre-production C conversions, 58 C series modifications and 400 production aircraft for a total of 464 B-25G. In its final version, the G-12, an interim armament modification, eliminated the lower Bendix turret and added a starboard dual gun pack, waist guns and a canopy for the tail gunner to improve the view when firing the single tail gun. In April 1945 the air depots in Hawaii refurbished about two dozen of these and included the eight gun nose and rocket launchers in the upgrade.

The B-25H series continued the development of the gunship concept. NAA Inglewood produced 1000. The H had even more firepower. Most replaced the M4 gun with the lighter T13E1,^[12] designed specifically for the aircraft but 20-odd H-1 block aircraft completed by the Republic Aviation modification center at Evansville had the M4 and two machine gun nose armament. The 75 mm (2.95 in) gun fired at a muzzle velocity of 2,362 ft/s (720 m/s). Due to its low rate of fire (about four rounds could be fired in a single strafing run), relative ineffectiveness against ground targets, and the substantial recoil, the 75 mm gun was sometimes removed from both G and H models and replaced with two additional .50 in (12.7 mm) machine guns as a field modification.^[13] In the new FEAF these were re-designated the G1 and H1 series respectively.

The H series normally came from the factory mounting four fixed, forward-firing .50  (12.7 mm) machine guns in the nose; four more fixed guns in forward-firing, individual gun packages; two more in the manned dorsal turret, re-located forward to a position just behind the cockpit; one each in a pair of new waist positions, introduced simultaneously with the forward-relocated dorsal turret; and lastly, a pair of guns in a new tail gunner's position. Company promotional material bragged that the B-25H could "bring to bear 10 machine guns coming and four going, in addition to the 75 mm cannon, eight rockets and 3,000 lb (1,360 kg) of bombs."^[14]

The H had a modified cockpit with single flight controls operated by pilot. The co-pilot's station and controls were deleted, and instead had a smaller seat used by the navigator/cannoneer, The radio operator crew position was aft the bomb bay with access to the waist guns.^[15] Factory production total were 405 B-25Gs and 1,000 B-25Hs, with 248 of the latter being used by the Navy as PBJ-1H.^[12] Elimination of the co-pilot saved weight, moving the dorsal turret forward counterbalanced in part the waist guns and the manned rear turret.^[16]

Return to medium bomber

Following the two gunship series NAA again produced the medium bomber configuration with the B-25J series.. It optimized the mix of the interim NA-100 and the H series having both the bombardier's station and fixed guns of the D and the forward turret and refined armament of the H series. NAA also produced a strafer nose first shipped to air depots as kits, then introduced on the production line in alternating blocks with the bombardier nose. The solid-metal "strafer" nose housed eight centerline Browning M2 .50 calibre machine guns. The remainder of the armament was as in the H-5. NAA also supplied kits to mount eight underwing 5 "high velocity airborne rockets" (HVAR) just outside the propeller arcs. These were mounted on zero length launch rails, four to a wing.

The final, and the most built, series of the Mitchell, the B-25J, looked less like earlier series apart from the well-glazed bombardier's nose of nearly-identical appearance to the earliest B-25 subtypes.^[12] Instead, the J followed the overall configuration of the H series from the cockpit aft. It had the forward dorsal turret and other armament and airframe advancements. All J models included four .50 in (12.7 mm) light-barrel Browning AN/M2 guns in a pair of "fuselage package", conformal gun pods each flanking the lower cockpit, each pod containing two Browning M2s. By 1945, however, combat squadrons removed these. The J series restored the co-pilot's seat and dual flight controls. The factory made available kits to the Air Depot system to create the strafer-nose B-25J-2. This configuration carried a total of 18 .50 in (12.7 mm) light-barrel AN/M2 Browning M2 machine guns: eight in the nose, four in the flank-mount conformal gun pod packages, two in the dorsal turret, one each in the pair of waist positions, and a pair in the tail – with 14 of the guns either aimed directly forward, or aimed to fire directly forward for strafing missions. Some aircraft had eight 5 in (130 mm) high-velocity aircraft rockets (HVAR).^[12] NAA introduced the J-2 into production in alternating blocks at the J-22. Total J series production was 4,318.

Flight characteristics

The B-25 was a safe and forgiving aircraft to fly.^[17] With one engine out, 60° banking turns into the dead engine were possible, and control could be easily maintained down to 145 mph (230 km/h). The pilot had to remember to maintain engine-out directional control at low speeds after takeoff with rudder; if this maneuver was attempted with ailerons, the aircraft could snap out of control. The tricycle landing gear made for excellent visibility while taxiing. The only significant complaint about the B-25 was the extremely high noise level produced by its engines; as a result, many pilots eventually suffered from varying degrees of hearing loss.^[18]

The high noise level was due to design and space restrictions in the engine cowlings which resulted in the exhaust "stacks" protruding directly from the cowling ring and partly covered by a small triangular fairing. This arrangement directed exhaust and noise directly at the pilot and crew compartments.

Durability

The Mitchell was an exceptionally sturdy aircraft that could withstand tremendous punishment. One B-25C of the 321st Bomb Group was nicknamed "Patches" because its crew chief painted all the aircraft's flak hole patches with the bright yellow zinc chromate primer. By the end of the war, this aircraft had completed over 300 missions, had been belly-landed six times and had over 400 patched holes. The airframe of "Patches" was so distorted from battle damage that straight-and-level flight required 8° of left aileron trim and 6° of right rudder, causing the aircraft to "crab" sideways across the sky.^[19]

Post war (USAF) use

In 1947 legislation created an independent United States Air Force and by that time the B-25 inventory numbered only a few hundred. Some B-25s continued in service into the 1950s in a variety of training, reconnaissance and support roles. The principal use during this period was undergraduate training of multi-engine aircraft pilots slated for reciprocating engine or turboprop cargo, aerial refuelling or reconnaissance aircraft. Others were assigned to units of the Air National Guard in training roles in support of Northrop F-89 Scorpion and Lockheed F-94 Starfire operations.

In its USAF tenure, many B-25s received the so-called "Hayes modification" and as a result, surviving B-25 often have exhaust system with a semi-collector ring that splits emissions into two different systems. The upper seven cylinders are collected by a ring while the other cylinders remain directed to individual ports.

TB-25J-25-NC Mitchell, 44-30854, the last B-25 in the USAF inventory, assigned at March AFB, California as of March 1960,^[20] was flown to Eglin AFB, Florida, from Turner Air Force Base, Georgia, on 21 May 1960, the last flight by a USAF B-25, and presented by Brigadier General A. J. Russell, Commander of SAC's 822d Air Division at Turner AFB, to the Air Proving Ground Center Commander, Brigadier General Robert H. Warren, who in turn presented the bomber to Valparaiso, Florida Mayor Randall Roberts on behalf of the Niceville-Valparaiso Chamber of Commerce. Four of the original Tokyo Raiders were present for the ceremony, Colonel (later Major General) David Jones, Colonel Jack Simms, Lieutenant Colonel Joseph Manske, and retired Master Sergeant Edwin W. Horton.^[21] It was donated back to the Air Force Armament Museum c. 1974 and marked as Doolittle's 40-2344.^[22]

U.S. Navy and USMC

The U.S. Navy designation for the Mitchell was the PBJ-1 and apart from increased use of radar, it was configured like its Army Air Forces counterparts. Under the pre-1962 USN/USMC/USCG aircraft designation system, PBJ-1 stood for Patrol (P) Bomber (B) built by North American Aviation (J), first variant (-1) under the existing American naval aircraft designation system of the era. The PBJ had its origin in an inter-service agreement of mid-1942 between the Navy and the USAAF exchanging the Boeing Renton plant for the Kansas plant for B-29 Superfortress production. The Boeing XPBB Sea Ranger flying boat, competing for B-29 engines, was cancelled in exchange for part of the Kansas City Mitchell production. Other terms included the inter-service transfer of 50 B-25C and 152 B-25D to the Navy. The bombers carried Navy bureau numbers (BuNos), beginning with BuNo 34998. The first PBJ-1 arrived in February 1943 and nearly all reached Marine Corps squadrons, beginning with Marine Bombing Squadron 413 (VMB-413). Following the AAFAC format, the Marine Mitchells had search radar in a retractable radome replacing the remotely-operated ventral turret. Later D and J series had nose mounted APS-3 radar; and later still, J and H series mounted radar in the starboard wingtip. The large quantities of B-25H and J series became known as PBJ-1H and PBJ-1J respectively. These aircraft often operated along with earlier PBJ series in Marine squadrons.

The PBJs were operated almost exclusively by the Marine Corps as land-based bombers. To operate them, the U.S. Marine Corps established a number of Marine bomber squadrons (VMB), beginning with VMB-413, in March 1943 at MCAS Cherry Point, North Carolina. Eight VMB squadrons were flying PBJs by the end of 1943, forming the initial Marine medium bombardment group. Four more squadrons were in the process of formation in late 1945, but had not yet deployed by the time the war ended.

Operational use of the Marine Corps PBJ-1s began in March 1944. The Marine PBJs operated from the Philippines, Saipan, Iwo Jima and Okinawa during the last few months of the Pacific war. Their primary mission was the long range interdiction of enemy shipping trying to run the blockade which was strangling Japan. The weapon of choice during these missions was usually the five-inch HVAR rocket, eight of which could be carried. Some VMB-612 intruder PBJ-1D and J series flew without top turrets to save weight and increase range on night patrols, especially towards the end of the war when air superiority existed.

During the war the Navy tested the cannon-armed G series and conducted carrier trial with an H equipped with arresting gear. After World War II, some PBJs stationed at the Navy's then-rocket laboratory site in Inyokern, California, site of the present-day Naval Air Weapons Station China Lake, tested various air-to-ground rockets and arrangements. One arrangement was a twin-barrel nose arrangement that could fire 10 spin-stabilized five-inch rockets in one salvo.^[23]

Royal Air Force

The Royal Air Force (RAF) was an early customer for the B-25 via Lend-Lease. The first Mitchells were given the service name Mitchell I by the RAF and were delivered in August 1941, to No. 111 Operational Training Unit based in the Bahamas. These bombers were used exclusively for training and familiarization and never achieved operational status. The B-25Cs and Ds were designated Mitchell II. Altogether, 167 B-25Cs and 371 B-25Ds were delivered to the RAF. The RAF tested the cannon-armed G series but did not adopt the series nor the follow on H series.

By the end of 1942 the RAF had taken delivery of a total of 93 Mitchell marks I and II. Some served with squadrons of No. 2 Group RAF, the RAF's tactical medium bomber force. The first RAF operation with the Mitchell II took place on 22 January 1943, when six aircraft from No. 180 Squadron RAF attacked oil installations at Ghent. After the invasion of Europe (by which point 2 Group was part of Second Tactical Air Force), all four Mitchell squadrons moved to bases in France and Belgium (Melsbroek) to support Allied ground forces. The British Mitchell squadrons were joined by No. 342 (Lorraine) Squadron of the French Air Force in April 1945.

As part of its move from Bomber Command, No 305 (Polish) Squadron flew Mitchell IIs from September to December 1943 before converting to the de Havilland Mosquito. In addition to No. 2 Group, the B-25 was used by various second-line RAF units in the UK and abroad. In the Far East, No. 3 PRU, which consisted of Nos. 681 and 684 Squadrons, flew the Mitchell (primarily Mk IIs) on photographic reconnaissance sorties.

The RAF was allocated 316 B-25J which entered service as the Mitchell III. Deliveries took place between August 1944 and August 1945. However, only about 240 of these bombers actually reached Britain, with some being diverted to No. 111 OTU in the Bahamas, some crashing during delivery and some being retained in the United States.

Royal Canadian Air Force

The Royal Canadian Air Force (RCAF) used the B-25 Mitchell for training during the war. Post-war use saw continued operations with most of 162 Mitchells received. The first B-25s had originally been diverted to Canada from RAF orders. These included one Mitchell I, 42 Mitchell IIs, and 19 Mitchell IIIs. No 13 (P) Squadron was formed unofficially at RCAF Rockcliffe in May 1944 and used Mitchell IIs on high-altitude aerial photography sorties. No. 5 OTU (Operational Training Unit) at Boundary Bay, British Columbia and Abbotsford, British Columbia, operated the B-25D Mitchell in the training role together with B-24 Liberators for Heavy Conversion as part of the BCATP. The RCAF retained the Mitchell until October 1963.^[24]

No 418 (Auxiliary) Squadron received its first Mitchell IIs in January 1947. It was followed by No 406 (auxiliary), which flew Mitchell IIs and IIIs from April 1947 to June 1958. No 418 Operated a mix of IIs and IIIs until March 1958. No 12 Squadron of Air Transport Command also flew Mitchell IIIs along with other types from September 1956 to November 1960. In 1951, the RCAF received an additional 75 B-25Js from USAF stocks to make up for attrition and to equip various second-line units.^[25]

Royal Australian Air Force

The Australians received Mitchells by the spring of 1944. The joint Australian-Dutch No. 18 (Netherlands East Indies) Squadron RAAF had more than enough Mitchells for one squadron, so the surplus went to re-equip the RAAF's No. 2 Squadron, replacing their Beauforts.

Dutch Air Force

During World War II, the Mitchell served in fairly large numbers with the Air Force of the Dutch government-in-exile. They participated in combat in the East Indies as well as on the European front. On 30 June 1941, the Netherlands Purchasing Commission, acting on behalf of the Dutch government-in-exile in London, signed a contract with North American Aviation for 162 B-25C aircraft. The bombers were to be delivered to the Netherlands East Indies to help deter any Japanese aggression into the region.

In February 1942, the British Overseas Airways Corporation (BOAC) agreed to ferry 20 Dutch B-25s from Florida to Australia travelling via Africa and India, and an additional ten via the South Pacific route from California. During March, five of the bombers on the Dutch order had reached Bangalore, India and 12 had reached Archerfield in Australia. It was agreed that the B-25s in Australia would be used as the nucleus of a new squadron, designated No. 18. This squadron was staffed jointly by Australian and Dutch aircrews plus a smattering of aircrews from other nations, and operated under Royal Australian Air Force command for the remainder of the war.

The B-25s of No. 18 Squadron were painted with the Dutch national insignia (at this time a rectangular Netherlands flag) and carried NEIAF serials. Discounting the ten "temporary" B-25s delivered to 18 Squadron in early 1942, a total of 150 Mitchells were taken on strength by the NEIAF, 19 in 1942, 16 in 1943, 87 in 1944, and 28 in 1945. They flew bombing raids against Japanese targets in the East Indies. In 1944, the more capable B-25J Mitchell replaced most of the earlier C and D models.

In June 1940, No. 320 Squadron RAF had been formed from personnel formerly serving with the Royal Dutch Naval Air Service who had escaped to England after the German occupation of the Netherlands. Equipped with various British aircraft, No. 320 Squadron flew anti-submarine patrols, convoy escort missions, and performed air-sea rescue duties. They acquired the Mitchell II in September 1943, performing operations over Europe against gun emplacements, railway yards, bridges, troops and other tactical targets. They moved to Belgium in October 1944, and transitioned to the Mitchell III in 1945. No. 320 Squadron was disbanded in August 1945. Following the war, B-25s were used by Dutch forces during the Indonesian National Revolution.

Soviet Air Force

The U.S. supplied 862 B-25s (B, D, G, and J types) to the Soviet Union under Lend-Lease during World War II via the Alaska–Siberia ALSIB ferry route.

Other damaged aircraft arrived or crashed in the Far East of Russia, and one Doolittle Raid aircraft landed there short of fuel after attacking Japan. The lone airworthy aircraft to reach the Soviet Union was lost in a hangar fire in the early 50s while undergoing routine maintenance. In general, the B-25 was operated as a ground-support and tactical daylight bomber (as similar Douglas A-20 Havocs were used). It saw action in fights from Stalingrad (with B/D models) to the German surrender during May 1945 (with G/J types).

B-25s that remained in Soviet Air Force service after the war were assigned the NATO reporting name "Bank".

China

Well over 100 B-25Cs and Ds were supplied to the Nationalist Chinese during the Second Sino-Japanese War. In addition, a total of 131 B-25Js were supplied to China under Lend-Lease.

The four squadrons of the 1st BG (1st, 2nd, 3rd, and 4th) of the 1st Medium Bomber Group were formed during the war. They formerly operated Russian-built Tupolev SB bombers, then transferred to the B-25. The 1st BG was under the command of CACW (Chinese-American Composite Wing) while operating B-25s. Following the end of the war in the Pacific, these four bombardment squadrons were established to fight against the Communist insurgency that was rapidly spreading throughout the country. During the Chinese Civil War, Chinese Mitchells fought alongside de Havilland Mosquitos.

In December 1948, the Nationalists were forced to retreat to the island of Taiwan, taking many of their Mitchells with them. However, some B-25s were left behind and were impressed into service with the air force of the new People's Republic of China.

Brazilian Air Force

During the war, the Força Aérea Brasileira (FAB) received a few B-25s under Lend-Lease. Brazil declared war against the Axis powers in August 1942 and participated in the war against the U-boats in the southern Atlantic. The last Brazilian B-25 was finally declared surplus in 1970.

Free French

The Royal Air Force issued at least 21 Mitchell IIIs to No 342 Squadron, which was made up primarily of Free French aircrews. Following the liberation of France, this squadron transferred to the newly formed French Air Force (Armée de l'Air) as GB I/20 Lorraine. The aircraft continued in operation after the war, with some being converted into fast VIP transports. They were struck off charge in June 1947.

Variants

NA-40

Twin-engined five-seat bomber to meet 1938 USAAF requirement for attack bomber. Powered by two 1,100 hp (820 kW) Pratt & Whitney R-1830-56C3G radials. Wingspan 66 ft (20.12 m), length 48 ft 3 in (14.71 m) length. First flew on 29 January 1939 but proved to be underpowered and unstable.^[26][27]

NA-40B

The NA-40B (also known as the NA-40-2) was a modification of the NA-40 prototype with two 1,600 hp (1,193 kW) Wright R-2600-A71-3 radials and numerous minor changes. First flew in revised form on 1 March 1939. Crashed: 11 April 1940.^[26]

B-25

Initial production version of B-25, powered by 1,350 hp (1,007 kW) R-2600-9 engines. Up to 3,600 lb (1,600 kg) bombs and defensive armament of three .30 machine guns in nose, waist and ventral positions, with one .50 machine gun in the tail. The first nine aircraft were built with constant dihedral angle. Due to low stability, the wing was redesigned so that the dihedral was eliminated on the outboard section. (Number made: 24.)^[26][28]

B-25A

Version of the B-25 modified to make it combat ready; additions included self-sealing fuel tanks, crew armor, and an improved tail gunner station. No changes were made in the armament. Re-designated obsolete (RB-25A) in 1942. (Number made: 40.)^[29]

B-25B

Tail and gun position removed and replaced by manned dorsal turret on rear fuselage and retractable, remotely operated ventral turret, each with a pair of .50 in (12.7 mm) machine guns. A total of 120 were built (this version was used in the Doolittle Raid). A total of 23 were supplied to the Royal Air Force as the Mitchell Mk I.^[30][31]

B-25C

Improved version of the B-25B: powerplants upgraded from Wright R-2600-9 radials to R-2600-13s; de-icing and anti-icing equipment added; the navigator received a sighting blister; nose armament was increased to two .50 in (12.7 mm) machine guns, one fixed and one flexible. The B-25C model was the first mass-produced B-25 version; it was also used in the United Kingdom (as the Mitchell II), in Canada, China, the Netherlands and the Soviet Union. (Number made: 1,625.)

ZB-25C

B-25D

Through block 20 the series was near identical to the B-25C. The series designation differentiated that the B-25D was made in Kansas City, Kansas, whereas the B-25C was made in Inglewood, California. Later blocks with interim armament upgrades were the D2. First flew on 3 January 1942. (Number made: 2,290.)

F-10

An F-10 reconnaissance aircraft

The F-10 designation distinguished 45 B-25D modified for photographic reconnaissance. All armament, armor and bombing equipment was stripped. Three K.17 cameras were installed, one pointing down and two more mounted at oblique angles within blisters on each side of the nose. Optionally, a second downward-pointing camera could also be installed in the aft fuselage. Although designed for combat operations these aircraft were mainly used for ground mapping.

B-25D Weather reconnaissance variant

In 1944, four B-25Ds were converted for weather reconnaissance. One later user was the 53d Weather Reconnaissance Squadron, originally called the Army Hurricane Reconnaissance Unit, now called the "Hurricane Hunters". Weather reconnaissance first started in 1943 with the 1st Weather Reconnaissance Squadron, with flights on the North Atlantic ferry routes.^[32][33]

ZB-25D

XB-25E

Single B-25C modified to test de-icing and anti-icing equipment that circulated exhaust from the engines in chambers in the leading and trailing edges and empennage. The aircraft was tested for almost two years, beginning in 1942; while the system proved extremely effective, no production models were built that used it prior to the end of World War II. Many surviving warbird-flown B-25 aircraft today use the de-icing system from the XB-25E. (Number made: 1, converted.)

ZXB-25E

XB-25F-A

Modified B-25C with insulated electrical coils mounted inside the wing and empennage leading edges to test the effectiveness as a de-icing system. The hot air de-icing system tested on the XB-25E was determined to be the more practical of the two. (Number made: 1, converted.)

XB-25G

Modified B-25C in which the transparent nose was replaced to create a short nosed gunship carrying two fixed .50 in (12.7 mm) machine guns and a 75 mm (2.95 in) M4 cannon, then the largest weapon ever carried on an American bomber. (Number made: 1, converted.)

B-25G

The B-25G followed the success of the prototype XB-25G and production was a continuation of the NA96. The production model featured increased armor and a greater fuel supply than the XB-25G. One B-25G was passed to the British, who gave it the name Mitchell II that had been used for the B-25C. The USSR also tested the G. (Number made: 463; 5 converted Cs; 58 modified Cs; 400 production.)

B-25H

An improved version of the B-25G. This version relocated the manned dorsal turret to a more forward location on the fuselage just aft of the flight deck. It also featured two additional fixed .50 in (12.7 mm) machine guns in the nose and in the H-5 onward, four in fuselage-mounted pods. the T13E1 light weight cannon replaced the heavy M4 cannon 75 mm (2.95 in). Single controls from factory with navigator in right seat. (Number made: 1000; two airworthy as of 2015)

B-25J-NC

Follow-on production at Kansas city, the B-25J, could be called a cross between the B-25D and the B-25H. It had a transparent nose, but many of the delivered aircraft were modified to have a strafer nose (J2). Most of its 14–18 machine guns were forward-facing for strafing missions, including the two guns of the forward-located dorsal turret. The RAF received 316 aircraft, which were known as the Mitchell III. The J series was the last factory series production of the B-25. (Number made: 4,318.)

CB-25J

Utility transport version.

VB-25J

A number of B-25s were converted for use as staff and VIP transports. Henry H. Arnold and Dwight D. Eisenhower both used converted B-25Js as their personal transports. The last VB-25J in active service was retired in May 1960 at the Eglin Air Force Base in Florida.^[34]

Trainer variants

Most models of the B-25 were used at some point as training aircraft.

TB-25D

Originally designated AT-24A (Advanced Trainer, Model 24, Version A). Trainer modification of B-25D often with the dorsal turret omitted. In total, 60 AT-24s were built.

TB-25G

Originally designated AT-24B. Trainer modification of B-25G.

TB-25C

Originally designated AT-24C. Trainer modification of B-25C.

TB-25J

Originally designated AT-24D. Trainer modification of B-25J. Another 600 B-25Js were modified after the war.

TB-25K

Hughes E1 fire-control radar trainer (Hughes). (Number made: 117.)

TB-25L

Hayes pilot-trainer conversion. (Number made: 90.)

TB-25M

Hughes E5 fire-control radar trainer. (Number made: 40.)

TB-25N

Hayes navigator-trainer conversion. (Number made: 47.)

U.S. Navy / U.S. Marine Corps variants

PBJ-1C

Similar to the B-25C for the U.S. Navy; often fitted with airborne search radar and used in the anti-submarine role.

PBJ-1D

Similar to the B-25D for the U.S. Navy and U.S. Marine Corps. Differed in having a single .50 in (12.7 mm) machine gun in the tail turret and waist gun positions similar to the B-25H. Often fitted with airborne search radar and used in the anti-submarine role.

PBJ-1G

U.S. Navy/U.S. Marine Corps designation for the B-25G. Trials only.

PBJ-1H

U.S. Navy/U.S. Marine Corps designation for the B-25H

One PBJ-1H was modified with carrier takeoff and landing equipment and successfully tested on the USS Shangri-La, but the Navy did not continue development.

PBJ-1J

U.S. Navy designation for the B-25J-NC (Blocks −1 through −35) with improvements in radio and other equipment. Beside the standard armament package, the Marines often fitted with 5" underwing rockets and search radar for the anti-shipping/anti-submarine role. The large Tiny Tim rocket-powered warhead saw use in 1945.

Operators

 Australia

• Royal Australian Air Force operated 50 aircraft
  • No. 2 Squadron RAAF^[35]

 Biafra

• Biafran Air Force operated two aircraft.^[36]

 Bolivia

• Bolivian Air Force operated 13 aircraft

 Brazil

• Brazilian Air Force operated 75 aircraft including B-25B, B-25C, B-25J)

 Canada

• Royal Canadian Air Force – operated 164 aircraft in bomber, light transport, trainer and "special" mission roles
  • 13 Squadron (Mitchell II)

 Republic of China

• Republic of China Air Force operated more than 180 aircraft

 People's Republic of China

• People's Liberation Army Air Force operated captured Nationalist Chinese aircraft.

 Chile

• Chilean Air Force operated 12 aircraft

 Colombia

• Colombian Air Force operated three aircraft

 Cuba

• Cuban Army Air Force operated six aircraft
• Fuerza Aérea del Ejército de Cuba
• Cuerpo de Aviación del Ejército de Cuba

 Dominican Republic

• Dominican Air Force operated five aircraft

 France

• French Air Force operated 11 aircraft
• Free French Air Force operated 18 aircraft

 Indonesia

• Indonesian Air Force received some B-25 Mitchells from Netherlands, the last example retired in 1979.

 Mexico

• Mexican Air Force received three B-25Js in December 1945, which remained in use until at least 1950.^[37]
• Eight Mexican civil registrations were allocated to B-25s, including one aircraft registered to the Bank of Mexico but used by the President of Mexico.^[38]

 Netherlands

• Royal Netherlands Air Force operated 62 aircraft
  • No. 18 (Netherlands East Indies) Squadron RAAF
  • No. 119 (Netherlands East Indies) Squadron RAAF
  • No. 320 Squadron RAF
• Dutch Naval Aviation Service operated 107 aircraft
  • No. 320 Squadron RAF
• Royal Netherlands East Indies Army Air Force – operated 149 aircraft, including many postwar

 Peru

• Peruvian Air Force received 8 B-25Js in 1947, which formed Bomber Squadron N° 21 at Talara.

 Poland

• Polish Air Forces on exile in Great Britain
  • No. 305 Polish Bomber Squadron

 Spain

• Spanish Air Force operated 1 ex-USAAF example interned in 1944 and operated between 1948 and 1956.^[39]

 Soviet Union

• Soviet Air Force (Voyenno-Vozdushnye Sily or VVS) received a total of 866 B-25s of the C, D, G* & J series.^[40] * trials only (5).

 United Kingdom

• Royal Air Force received just over 700 aircraft.^{[lower-alpha 2][41]}
  • No. 98 Squadron RAF – September 1942 – November 1945 (converted to the Mosquito^[41]
  • No. 180 Squadron RAF – September 1942 – September 1945 (converted to the Mosquito)^[41]
  • No. 226 Squadron RAF – May 1943 – September 1945 (disbanded)^[41]
  • No. 305 Squadron RAF – September 1943 – December 1943 (converted to the Mosquito)^[41]
  • No. 320 Squadron RAF – March 1943 – August 1945 (transferred to Netherlands)^[41]
  • No. 342 Squadron RAF – March 1945 – December 1945 (transferred to France)^[41]
  • No. 681 Squadron RAF – January 1943 – December 1943 (Mitchell withdrawn)^[41]
  • No. 684 Squadron RAF – September 1943 – April 1944 (Replaced by Mosquito)^[41]
  • No. 111 Operational Training Unit RAF August 1942 – August 1945 (disbanded)^[41]
• Royal Navy Fleet Air Arm
  • operated 1 aircraft for evaluation

 United States

• United States Army Air Forces

see B-25 Mitchell units of the United States Army Air Forces

• United States Navy received 706 aircraft, most of which were then transferred to the USMC.
• United States Marine Corps

 Uruguay

• Uruguayan Air Force operated 15 examples

 Venezuela

• Venezuelan Air Force operated 24 examples

Surviving aircraft

Many B-25s are currently kept in airworthy condition by air museums and collectors.

Specifications (B-25H)

Data from United States Military Aircraft since 1909^[42]

General characteristics

• Crew: 6 (one pilot, one co-pilot, navigator/bombardier, turret gunner/engineer, radio operator/waist gunner, tail gunner)
• Length: 52 ft 11 in (16.13 m)
• Wingspan: 67 ft 7 in (20.60 m)
• Height: 16 ft 4 in (4.98 m)
• Wing area: 610 sq ft (56.7 m²)
• Empty weight: 19,480 lb (8,855 kg)
• Max. takeoff weight: 35,000 lb (15,910 kg)
• Powerplant: 2 × Wright R-2600-92 Twin Cyclone 14-cylinder air-cooled radial engine, 1,700 hp (1,267 kW) each

Performance

• Maximum speed: 272 mph (237 kn, 438 km/h) at 13,000 ft (3,960 m)
• Cruise speed: 230 mph (200 knots, 370 km/h)
• Range: 1,350 mi (1,174 nmi, 2,174 km)
• Service ceiling: 24,200 ft (7,378 m)

Armament

• Guns: 12–18 × .50 in (12.7 mm) machine guns and 75 mm (2.95 in) T13E1 cannon
• Hardpoints: 2,000 lb (900 kg) ventral shackles to hold one external Mark 13 torpedo^[43]
• Rockets: racks for eight 5 in (127 mm) high velocity aircraft rockets (HVAR)
• Bombs: 3,000 lb (1,360 kg) bombs

Accidents and incidents

Empire State Building crash

At 9:40 on Saturday, 28 July 1945, a USAAF B-25D crashed in thick fog into the north side of the Empire State Building between the 79th and 80th floors. Fourteen people died — 11 in the building and the three occupants of the aircraft, including the pilot, Colonel William F. Smith.^[44] Betty Lou Oliver, an elevator attendant, survived the impact and the subsequent fall of the elevator cage 75 stories to the basement.^[45]

Notable appearances in media

See also

• GT-1 (missile)

Related development

• North American XB-21
• North American XB-28 Dragon

Aircraft of comparable role, configuration and era

• Armstrong Whitworth Albemarle
• de Havilland Mosquito
• Douglas A-26 Invader
• Junkers Ju 188
• Martin B-26 Marauder
• Mitsubishi Ki-67 Hiryū
• Nakajima Ki-49 Donryu
• Vickers Wellington

Related lists

• List of aircraft of World War II

Notes

References

Notes

Bibliography

External links

Wikimedia Commons has media related to B-25 Mitchell.

• North American B-25 Mitchell Joe Baugher, American Military Aircraft: US Bomber Aircraft
• "How to Fly the North American B-25 "Mitchell" Medium Bomber (1944)" on YouTube
• I Fly Mitchell's, February 1944 Popular Science article on B-25s in North Africa Theater
• Flying Big Gun, February 1944, Popular Science article on 75 mm cannon mount
• Early B-25 model's tail gun position, extremely rare photo
• A collection photos of the Marine VMB-613 post in the Kwajalein Island at the University of Houston Digital Library
• Hi-res spherical panoramas; B-25H: A look inside & out – "Barbie III"
• (1943) Report No. NA-5785 Temporary Handbook of Erection and Maintenance Instructions for the B-25 H-1-NA Medium Bombardment Airplanes
• "The B-25 Mitchell in the USSR", an account of the service history of the Mitchell in the Soviet Union's VVS during World War II
• Lake Murray's Mitchell
• B-25 Recovery and Preservation Project Rubicon Foundation