B-25 Mitchell | |
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![]() A B-25J Mitchell over the Chino Airshow 2014 | |
General information | |
Type | Medium bomber |
National origin | United States |
Manufacturer | North American Aviation |
Primary users | United States Army Air Forces |
Number built | 9,816 [1] [a] |
History | |
Introduction date | 1941 |
First flight | 19 August 1940 |
Retired | 1970s (Indonesia) |
Developed from | North American NA-40 |
Developed into | North American XB-28 Dragon |
The North American B-25 Mitchell is an American medium bomber that was introduced in 1941 and named in honor of Brigadier General William "Billy" Mitchell, a pioneer of U.S. military aviation. [2] 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 B-25s were built. [1] It was the most-produced American medium bomber and the third-most-produced American bomber overall. These included several limited models such as the F-10 reconnaissance aircraft, the AT-24 crew trainer, and the United States Marine Corps' PBJ-1 patrol bomber.
On 11 March 1939, the US Army Air Corps issued Proposal No. 39-640 specifying a medium bomber capable of carrying a 3,000 lb (1,400 kg) bombload over a range of 2,000 miles (3,200 km) at top speed in excess of 300 mph (480 km/h). North American Aviation (NAA) used its NA-40B design to develop the NA-62 proposal. More state of the art compared to the competing Martin No. 179 proposal, the North American team included easy field maintenance and repair features, and according to Avery, "It promised to be an easy airplane to fly and placed no special requirements on pilot training programs." On 20 September. the Air Corps issued North American contract No. W353-ac-13258 for 184 B-25s powered by the Wright R-2600. The plane used the NACA 23017 airfoil at the wing root changing to a NACA 4409-R at the wingtip. On 19 August 1940, Vance Breese and NAA test engineer Roy Ferren flew the first flight test, when Ferren noted a severe roll-yaw condition. [3]
Preliminary flights by the Air Corps noted the Dutch roll characteristic, accentuated by wind and gusts and demanded a fix. NAA's first nine aircraft had a constant-dihedral, the wing having a consistent upward angle from the fuselage to the wingtip. "Flattening", or changing the outer wing panels dihedral to zero degrees, was a simple solution that solved the aerodynamic problem. This gave the B-25 its gull wing configuration. The 25 February 1941 flight test confirmed the change resulted in optimum flight characteristics. [4] The vertical tail also went through five variations before being finalized. By the time of the Attack on Pearl Harbor, 130 B-25s had been delivered. [3]
Special variations were made to accommodate photo reconnaissance, armament, long range ferry, anti-submarine patrol, winterizing, and use in a desert environment. By February 1941, the first 24 B-25s were configured with three .30 cal guns and a single .50 cal tail gun. The B-25A had self-sealing fuel cells. The B-25B had top and bottom turrets with twin .50 cal guns each, though the tail gun was removed. By December 1941, the B-25C had additional self-sealing fuel cells outboard the wing center section. By February 1942, the first B-25D, and then in May 1943, the 75mm cannon-armed B-25G series were accepted by the Air Corps. By August 1943, the B-25H had a lighter 75mm cannon, 4 nose guns instead of 2, two waist guns. two in the tail turret, four blister gun packs, and eliminated the co-pilot after Jimmy Doolittle questioned the need. In December 1943, the B-25J was introduced, the final variant and the most produced, reincorporated the co-pilot position and included a bombardier. [3]
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/Harvard, B-25 Mitchell, and the P-51 Mustang). [5] 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. [6] [7] [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 reciprocating engine pilot training. [9]
A development of the B-25 was the North American XB-28 Dragon, 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. [10]
The B-25 was a safe and forgiving aircraft to fly. [11] 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 were 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 its extremely noisy engines; as a result, many pilots eventually suffered from some degree of hearing loss. [12] A Clayton S stack, introduced to quench the exhaust flame, was introduced in the B-25C series. These stacks protruded through the cowling, and though they weighed less than the replaced collector ring, they reduced aircraft speed by 9 mph due to the required aircraft fairings. According to Avery, "The increase in noise as compared to collector rings ported on the outboard side of the nacelles was a general crew complaint." [3]
The Mitchell was exceptionally sturdy and 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 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. [13]
Most B-25s in American service were used in the war against Japan in Asia and the Pacific. The Mitchell fought from the North 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, as well as in the Doolittle Raid. 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. An ever-increasing number of forward firing guns made the B-25 a formidable strafing aircraft for island warfare. The Paul Gunn and Jack Fox modified strafer models with four .50 caliber guns were the B-25C1/D1, while the factory B-25J was equipped with a factory made eight gun strafer nose. [3] : 89–110
In Burma, bridge busting was a primary target of the Tenth Air Force 341st Bomb Group operating B-25C and D airplanes. A glide and skip technique, called "glip" bombing, was most the effective for the Burma Bridge Busters. The 341st ranged as far as the Formosa Strait, the East China coast and French Indochina. [3] : 115–122
The first B-25s arrived in Egypt and were carrying out independent operations by October 1942. [14] 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 Invader, 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. [15]
In October 1943, the Ninth Air Force 340th was transferred from the African and Mediterranean theater to England in support of the assault on Germany. In November 1944 the medium bombers eliminated the use of electric locomotives along Brenner Pass. [3] : 128–129 [16]
In antishipping operations, the USAAF had an 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 manually loaded 75 mm (2.95 in) M4 cannon. [17]
The B-25H series continued the development of the gunship version. NAA Inglewood produced 1000. The H had even more firepower; most replaced the M4 gun with the lighter T13E1, [17] 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 slow 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. [18]
The H series normally came from the factory mounting four fixed, forward-firing .50 in (12.7 mm) machine guns in the nose; four in a pair of under-cockpit conformal flank-mount gun pod packages (two guns per side); two more in the manned dorsal turret, relocated forward to a position just behind the cockpit (which became standard for the J-model); 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." [19]
The H had a modified cockpit with single flight controls operated by the pilot. The co-pilot's station and controls were removed and replaced by a smaller seat used by the navigator/cannoneer, The radio operator crew position was aft of the bomb bay with access to the waist guns. [20] Factory production totals were 405 B-25Gs and 1,000 B-25Hs, with 248 of the latter being used by the Navy as PBJ-1Hs. [17] Elimination of the co-pilot saved weight, and moving the dorsal turret forward partially counterbalanced the waist guns and the manned rear turret. [21]
The final, and most numerous, 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. [17] 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 packages", 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 kits available 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-inch (130 mm) high-velocity aircraft rockets. [17]
In 1947, legislation created an independent United States Air Force (USAF) and by that time, the B-25 inventory numbered only a few hundred. Some B-25s continued in service into the 1950s in training, reconnaissance, and support roles. The principal use during this period was as pilot trainers, radar control trainers, weather reconnaissance, and transports. 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. [3] : 141–143
During its USAF tenure, many B-25s received the so-called "Hayes modification" and as a result, surviving B-25s often have exhaust systems with a semicollector 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, [22] was flown to Eglin AFB, Florida, from Turner Air Force Base, Georgia, on 21 May 1960, the last flight by a USAF B-25. It was 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. He 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. [23] It was donated back to the Air Force Armament Museum around 1974 and marked as Doolittle's 40-2344. [24]
The U.S. Navy designation for the Mitchell B-25 was the PBJ-1, similarly the PBJ-1C and PBJ-1D reflected their AAF counterparts. Night search PBJs incorporated a retractable APS-3 radome scope. 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. In early 1943, the Navy took delivery of an initial 706 B-25s, assigned to the AMrine Corps for patrol and anti-submarine duties initially, but then transitioning into an attack aircraft with bombs, torpedoes and radar directed rockets. 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. On 1 March 1943, VMB-413 was the first of sixteen USMC squadrons equipped with PBJs, all commissioned at MCAS Cherry Point. The large quantities of B-25H and J series became known as PBJ-1H and PBJ-1J, respectively. [3] : 65–72
From 1944 onwards, the Marine PBJs flew from the Philippines, Saipan, Iwo Jima, and Okinawa. Their primary mission was radar directed night strikes against enemy shipping. Weapons included the five-inch HVAR rocket, and the 11.75 inch "Tiny Tim" rocket. Long range night operations meant more fuel, with weight reductions achieved removing the top turret and slide blisters. [25] [3] : 67–68
During the war, the Navy tested the cannon-armed G series and conducted carrier trials with an H equipped with arresting gear. After World War II, some PBJs stationed at the Navy's rocket laboratory in Inyokern, California, site of the present-day Naval Air Weapons Station China Lake, tested air-to-ground rockets and arrangements. One arrangement was a twin-barrel nose that could fire 10 spin-stabilized five-inch rockets in one salvo. [26]
Great Britain received 910 B-25s during WWII, but many were returned afterwards. [3] : 192
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 became operational. 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 93 Mitchells, marks I and II. Some served with squadrons of No. 2 Group RAF, the RAF's tactical medium-bomber force, including No. 139 Wing RAF at RAF Dunsfold. 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 Royal Canadian Air Force (RCAF) used the B-25 Mitchell for training during the war. Postwar use continued operations with most of the 162 Mitchells received. The first B-25s had 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 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. [27]
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. [28]
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.
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 threatened expansion into the region. [3] : 81–87
In February 1942, the British Overseas Airways Corporation agreed to ferry 20 Dutch B-25s from Florida to Australia travelling via Africa and India, and an additional 10 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. The B-25s in Australia were used as the nucleus of a new squadron, No. 18 (Netherlands East Indies) Squadron RAAF. [3] : 81–87
In June 1940, No. 320 (Netherlands) 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 antisubmarine patrols, convoy escort missions, and performed air-sea rescue duties. In March 1943, they acquired the B-25 Mark II nd III Mitchells. In October 1944, they deployed to Belgium, but then disbanded in August 1945. [3] : 86
The USSR received 862 B-25s (B, C, D, G, and J types) from the United States under Lend-Lease during World War II [29] via the Alaska–Siberia ALSIB ferry route. A total of 870 B-25s were sent to the Soviets, [30] meaning that 8 aircraft were lost during transportation.
Other damaged B-25s arrived or crashed in the Far East of Russia, and one Doolittle Raid aircraft landed there short of fuel after attacking Japan. This lone airworthy Doolittle Raid aircraft to reach the Soviet Union was lost in a hangar fire in the early 1950s while undergoing routine maintenance. In general, the B-25 was operated as a ground-support and tactical day bomber (as similar Douglas A-20 Havocs were used). It saw action in fights from Stalingrad (with B/C/D models) to the German surrender during May 1945 (with G/J types).
The B-25s that remained in Soviet Air Force service after the war were assigned the NATO reporting name "Bank".
Well over 100 B-25Cs and Ds were supplied to the Nationalist Chinese during the Second Sino-Japanese War. An unknown number were abandoned with the retreat to Formosa. [3] : 192
During the war and after WWII, Brazil received 80 B-25s, with the first delivery prior to December 1941. [3] : 191
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.
In October 1967, during the Nigerian Civil War, Biafra bought two Mitchells. After a few bombings in November, they were put out of action in December. [31]
Indonesian Air Force received 25 ex-Dutch B-25 Mitchells after the end of Indonesian National Revolution in 1950, [32] consisting of 5 B-25C photo-reconnaissance, 1 B-25C transport, 10 B-25J bombers and 9 B-25J gunship/strafer variants. [33] A pair of B-25J were used to attack a radio station in Ambon during South Maluku rebellion in August 1950. [34] They were used to bomb rebel targets during the PRRI and Permesta rebellions in 1958, where one was hit by anti-aircraft fire and three were damaged by strafing run from rebel-flown B-26 Invader. [35]
The B-25s were sent to Hong Kong for overhaul in 1959–1960. [33] Indonesian B-25s once again saw combat during the Operation Trikora against the Dutch in 1962, where one was used for strafing runs against a Dutch warship, while two others were used in Maluku. [36] The B-25s were already grounded by 1975. [37]
Most models of the B-25 were used at some point as training aircraft.
On 1 November 1941, a B-25 on a training mission flying out of Wright-Patterson Air Force Base, crashed near Benton Ridge, Ohio. [56]
At 9:40 on 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. [57] Betty Lou Oliver, an elevator attendant, survived the impact and the subsequent fall of the elevator cage 75 stories to the basement. [58]
French general Philippe Leclerc was aboard his North American B-25 Mitchell, Tailly II, when it crashed near Colomb-Béchar in French Algeria on 28 November 1947, killing everyone on board. [59]
A bit after 16:00 on 27 August 1967, a converted civilian B-25 mistakenly dropped eighteen skydivers over Lake Erie, four or five nautical miles (7.5–9.3 km) from Huron, Ohio. The air traffic controller had confused the B-25 with a Cessna 180 Skywagon that was trailing it to take photographs, causing the B-25 pilot to think he was over the intended drop site at Ortner Airport. Sixteen of the jumpers drowned, while two were rescued. [60] A National Transportation Safety Board report faulted the pilot, and to a lesser extent the skydivers, for executing a jump when they could not see the ground, and faulted the controller for the misidentification. [61] [62] The United States was subsequently held liable for the controller's negligence. [63]
Many B-25s are currently kept in airworthy condition by air museums and collectors.
Data from United States Military Aircraft since 1909 [64]
General characteristics
Performance
Armament
Related development
Aircraft of comparable role, configuration, and era
Related lists
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