The B-25 was named in honor of General Billy Mitchell, a pioneer of U.S. military aviation. By the end of its production, nearly 10,000 B-25s in numerous models had been built.[1] These included a few limited variations, such as the United States Navy's and Marine Corps' PBJ-1 patrol bomber and the United States Army Air Forces' F-10 photo reconnaissance aircraft.The B-25 was a descendant of the earlier XB-21 (North American-39) project of the mid-1930s. Experience gained in developing that aircraft was eventually used by North American in designing the B-25 (called the NA-40 by the company). One NA-40 was built, with several modifications later being done to test a number of potential improvements. These improvements included Wright R-2600 radial engines, which would become standard on the later B-25.
In 1939, the modified and improved NA-40B was submitted to the United States Army Air Corps for evaluation. This 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, those countries changed their minds, opting instead for the also-new Douglas DB-7 (later to be used by the U.S. as the A-20 Havoc). Despite this loss of sales, the NA-40B re-entered the spotlight when the Army Air Corps evaluated it for use as a medium bomber. Unfortunately, the NA-40B was destroyed in a crash on 11 April 1939. Nonetheless, the type was ordered into production, along with the army's other new medium bomber, the Martin B-26 Marauder.
Early production
Interior of huge aircraft factory where rows of bombers covered in a yellow layer are manufactured.
North American B-25 Mitchell production in Kansas City in 1942
To get orders for bombers, North American Aviation designed the XB-21. It lost out to the Douglas B-18, but persisted and developed a more advanced design, which became the B-25 Mitchell bomber.
An improvement of the NA-40B, dubbed the NA-62, was the basis for the first actual B-25. Due to the pressing need for medium bombers by the army, no experimental or service-test versions were built. Any necessary modifications were made during production runs, or to existing aircraft at field modification centers around the world.
A significant change in the early days of B-25 production was a redesign of the wing. In the first nine aircraft, a constant-dihedral wing was used, in which the wing had a consistent, straight, slight upward angle from the fuselage to the wingtip. This design caused stability problems, and as a result, the dihedral angle was nullified on the outboard wing sections, giving the B-25 its slightly gull wing configuration. Less noticeable changes during this period included an increase in the size of the tail fins and a decrease in their inward cant.
North American was the largest producer of aircraft in the war by far. It was 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 planes at its Kansas City, Kansas plant at Fairfax Airport.
A descendant of the B-25 was the North American XB-28, meant to be a high-altitude version of the B-25. Despite this premise, the actual aircraft bore little resemblance to the Mitchell and in some respects more closely resembled the Martin B-26 Marauder.
Operational history
Lt. Peddy and crew, showing how many people were required to keep a B-25 flying
Doolittle Raid B-25Bs aboard USS Hornet
Far East and Pacific
The majority of B-25s in American service were used in the Pacific. They fought on Papua New Guinea, in Burma and in the island hopping campaign in the central Pacific. There, the aircraft’s potential as a ground-attack aircraft was discovered and developed. The jungle environment reduced the usefulness of standard-level bombing, and made low-level attack the best tactic. The ever-increasing number of forward firing guns was a response to this operational environment, making the B-25 a formidable strafing aircraft.
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.
In the Pacific, the B-25 proved itself to be a very capable anti-shipping weapon, sinking many ships. Later in the war, the distances between islands limited the usefulness of the B-25, although it was used against Guam and Tinian. It was also used against Japanese-occupied islands that had been bypassed by the main campaign, as happened in the Marshall Islands.
Middle East and Italy
The first B-25s arrived in Egypt just in time to take part in the Battle of El Alamein. From there the aircraft took part in the rest of the campaign in North Africa, the invasion of Sicily and the advance up Italy. 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 that used the B-25 in the desert and Italy were the only U.S. units to use the B-25 in Europe.
Europe
The U.S. Eighth Air Force, based in Britain, concentrated on long-range raids over Germany and occupied Europe. Although it did have a small number of units equipped with twin-engined aircraft, the B-25 was not amongst them. However, 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 strategic targets in occupied Europe. After the D-Day invasion the RAF used its Mitchells to support the armies in Europe, moving several squadrons to forward airbases in France and Belgium.
USAAF
A B-25 Mitchell taking off from USS Hornet for the Doolittle Raid
The B-25 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 were inviolable by enemy forces. Although the amount of actual damage done was relatively minor, it forced the Japanese to divert troops for the 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 windows for the navigator and radio operator, heavier nose armament, and de-icing and anti-icing equipment, the B-25C was released to the Army. This was the second mass-produced version of the Mitchell, the first being the lightly armed B-25B used by the Doolittle Raiders. The B-25C and B-25D differed only in location of manufacture: -Cs at Inglewood, California, -Ds at Kansas City, Kansas. A total of 3,915 B-25Cs and -Ds were built by North American 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 on treetop-level strafing and missions with parachute-retarded fragmentation bombs against Japanese airfields in New Guinea and the Philippines. These heavily armed Mitchells, field-modified at Townsville, Australia, by Major Paul I. "Pappy" Gunn and North American tech rep Jack Fox, were also used on strafing and skip-bombing missions against Japanese shipping trying to resupply their land-based armies.
Under the leadership of Lieutenant General George C. Kenney, B-25s of the Fifth and Thirteenth Air Forces devastated Japanese targets in the Southwest Pacific theater from 1942 to 1945, and played a significant role in pushing the Japanese back to their home islands. B-25s were also used with devastating effect in the Central Pacific, Alaska, North Africa, Mediterranean and China-Burma-India (CBI) theaters.
Use as a gunship
Upper-quarter view of a B-25G, showing rearwards-location of dorsal turret
Because of the urgent need for hard-hitting strafer aircraft, a version dubbed the B-25G was developed, in which the standard-length transparent nose and the bombardier were replaced by a shorter solid nose containing two fixed .50 in (12.7 mm) machine guns and a 75 mm (2.95 in) M4 cannon, one of the largest weapons fitted to an aircraft, similar to the experimental British Mosquito Mk. XVIII (57 mm gun), and German Ju 88P heavy cannon (up to a 75mm long-barrel Bordkanone BK 7,5 cannon) carrying aircraft. The B-25G's cannon was manually loaded and serviced by the navigator, who was able to perform these operations without leaving his crew station just behind the pilot. This was possible due to the shorter nose of the G-model and the length of the M4, which allowed the breech to extend into the navigator's compartment.
The B-25G's successor, the B-25H, had even more firepower. The M4 gun was replaced by the lighter T13E1, designed specifically for the aircraft. The 75 mm (2.95 in) gun fired at a muzzle velocity of 2,362 ft/s (about 720 m/s). Due to its low rate of fire (approximately four rounds could be fired in a single strafing run) and relative ineffectiveness against ground targets, as well as substantial recoil, the 75 mm (2.95 in) 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.
B-25H "Barbie III" showing 75mm M5 gun and 4 Browning 50 cal feeds
Besides that, the -H normally mounted four fixed forward-firing .50 (12.7 mm) machine guns in the nose, four more fixed ones in forward-firing cheek blisters, two more in the manned dorsal turret, one each in a pair of new waist positions, and a final pair in a new tail gunner's position. Company promotional material bragged the B-25H could "bring to bear 10 machine guns coming and four going, in addition to the 75 mm cannon, a brace of eight rockets and 3,000 lb (1,360 kg) of bombs."
The B-25H also featured a redesigned cockpit area, required by the dorsal turret having been relocated forward to the navigator's compartment – just aft of the cockpit and just ahead of the leading edge wing roots, thus requiring the addition of the waist and tail gun positions – and a heavily modified cockpit designed to be operated by a single pilot, the co-pilot's station and controls deleted, and the seat cut down and used by the navigator/cannoneer, the radio operator being moved to the aft compartment, operating the waist guns.] A total of 405 B-25Gs and 1000 B-25Hs were built, the 248 of the latter being used by Navy as PBJ-1H.
The final, and the most built, version of the Mitchell, the B-25J, looked much like the earlier B, C and D, having reverted to the longer, glazed bombardier's nose, but with the -H version's relocated-forward dorsal manned turret. The less-than-successful 75 mm (2.95 in) cannon was deleted. Instead, 800 of this version were built with a solid nose containing eight .50 (12.7 mm) machine guns, while other J-models featured the earlier "greenhouse" style nose containing the bombardier's position.
Regardless of the nose style used, all J-models also included four .50 in (12.7 mm) light-barrel Browning AN/M2 guns in a pair of "fuselage package", flank-mount conformal gun pods each containing two Browning M2s, located directly beneath the pilot's and co-pilot's compartment along the external sides of the cockpit, with the co-pilot's seat and dual flight controls restored to their previous cockpit locations. The solid-nose B-25J variant 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 fourteen of the guns either aimed directly forward, or aimable to fire directly forward for strafing missions. No other main series production bomber of World War II carried as many guns.
The first 555 B-25Js (the B-25J-1-NC production block) were delivered without the fuselage package guns, because it was discovered that muzzle blast from these guns was causing severe stress in the fuselage; this problem was cured with heavier fuselage skin patches. Although later production runs returned these fuselage package guns to the aircraft, they were often removed as a field modification for the same reason. The later B-25J was additionally armed with eight 5 in (130 mm) high-velocity aircraft rockets (HVAR).In all, 4,318 B-25Js were built.
Flight characteristics
The B-25 was a safe and forgiving aircraft to fly. With an engine out, 60° banking turns into the dead engine were possible, and control could be easily maintained down to 145 mph (230 km/h). However, 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 would 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.
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. Crew members and operators on the airshow circuit frequently comment that "the B-25 is the fastest way to turn aviation fuel directly into noise". Many B-25s now in civilian ownership have been modified with exhaust rings that direct the exhaust through the outboard bottom section of the cowling.
The Mitchell was an exceptionally sturdy aircraft that could withstand tremendous punishment. One well-known B-25C of the 321st Bomb Group was nicknamed "Patches" because its crew chief painted all the aircraft's flak hole patches with high-visibility zinc chromate primer. By the end of the war, this aircraft had completed over 300 missions, was belly-landed six times and sported 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.
An interesting characteristic of the B-25 was its ability to extend range by using one-quarter wing flap settings. Since the aircraft normally cruised in a slightly nose-high attitude, about 40 gal (150 l) of fuel was below the fuel pickup point and thus unavailable for use. The flaps-down setting gave the aircraft a more level flight attitude, which resulted in this fuel becoming available, thus slightly extending the aircraft's range.
By the time a separate United States Air Force was established in 1947, most B-25s had been consigned to long-term storage. However, a select number continued in service through the late 1940s and 1950s in a variety of training, reconnaissance and support roles. Its principal use during this period was for undergraduate training of multi-engine aircraft pilots slated for reciprocating engine or turboprop cargo, aerial refueling or reconnaissance aircraft. Still 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.
TB-25J-25-NC Mitchell, 44-30854, the last B-25 in the USAF inventory, assigned at March AFB, California as of March 1960, 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 Brig. Gen. A. J. Russell, Commander of SAC's 822d Air Division at Turner AFB, to the Air Proving Ground Center Commander, Brig. Gen. 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, Col. Davy Jones, Col. Jack Simms, Lt. Col. Joseph Manske, and retired Master Sgt. Edwin W. Horton. It was donated back to the Air Force Armament Museum c. 1974 and marked as Doolittle's 40-2344.
Today, many B-25s are kept in airworthy condition by air museums and collectors.
U.S. Navy and USMC
The PBJ-1 was a navalized version of the USAAF B-25, the designation standing 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 a deal cut in mid-1942 between the Navy and the USAAF. As part of the deal, 50 B-25Cs and 152 B-25Ds were transferred to the Navy from the USAAF. The bombers carried Navy bureau numbers (BuNos) beginning with BuNo 34998. The first PBJ-1s arrived in February 1943 and were used by Marine Corps pilots, beginning with Marine Bombing Squadron 413 (VMB-413). Many of PBJs were equipped with a search radar with a retractable radome fitted in place of the ventral turret.
Large numbers of B-25H and J variants were delivered to the Navy as PBJ-1H and PBJ-1J respectively. These aircraft joined, but did not necessarily replace, the earlier PBJs.
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 that was 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 on underwing racks.
Many of the PBJ-1C and D versions carried a rather ugly, bulbous antenna for an APS-3 search radar sticking out of the upper part of the transparent nose. On the PBJ-1H and J, the APS-3 search radar antenna was usually housed inside a ventral or wingtip radome. Some PBJ-1Js had their top turrets removed to save weight, especially towards the end of the war when Japanese fighters had become relatively scarce.
After World War Two, some PBJs were stationed at the Navy's rocket laboratory at Inyokern, California, the present-day Naval Air Weapons Station China Lake, to test various air-to-ground rockets and arrangements, including a twin-barrel nose arrangement that could fire ten spin-stabilized five inch rockets in one salvo.
Royal Air Force
The Royal Air Force (RAF) was an early customer for the B-25 via Lend-Lease. The RAF was the only force to use the B-25 on raids against Europe from bases in the United Kingdom, as the USAAF used the Martin B-26 Marauder and Boeing B-17 Flying Fortress for this purpose instead.
The first Mitchells were designated 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.
A total of 93 Mitchell Is and IIs had been delivered to the RAF by the end of 1942 and served with 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, 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.
No 305 (Polish) Squadron flew Mitchell IIs from September to December 1943 before converting to Mosquitos. In addition to the 2nd 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-25Js 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) was an important user of the B-25 Mitchell, although most of the RCAF use of the 162 Mitchells delivered was postwar. The first B-25s for the RCAF 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. They operated Mitchell IIs on high-altitude aerial photography sorties. The No. 5 OTU (Operational Training Unit) at Boundary Bay, British Columbia and Abbotsford, British Columbia operated the 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.
No 418 (Auxiliary) Squadron received its first Mitchell IIs in January 1947. It was followed by No 406 (auxiliary) which flew Mitchell 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 good attrition and to equip various second line units.
Royal Australian Air Force
The Australians got 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 both 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 of the Dutch B-25s from Florida to Australia 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 would be staffed jointly by Australian and Dutch aircrews plus a smattering of aircrews from other nations, but would operate at least initially under Royal Australian Air Force command.
The B-25s of No. 18 Squadron would be painted with the Dutch national insignia (at this time a rectangular Netherlands flag) and would carry 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 in Indonesia.
Soviet Air Force
The U.S. supplied 862 B-25 (of B, D, G, and J types) aircraft to the Soviet Union under lend-lease during the Second World War 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 Air Force
Well over 100 B-25Cs and Ds were supplied to the Nationalist Chinese during the Second World 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-25. 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 civil war, Chinese Mitchells fought alongside de Havilland Mosquitos.
In December 1948, the Nationalists were forced to move 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
B-25J Mitchell 44-30069 at Museu Aerospacial in Campos dos Afonsos Air Force Base, Rio de Janeiro
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
At least 21 Mitchell IIIs were issued by the Royal Air Force to No 342 Squadron, which was made up primarily of Free French aircrews.
Following the liberation of France, this squadron was transferred to the newly formed French air force (Armée de l'Air) as GB I/20 Lorraine. These aircraft were operated by GB I/20 after the war, some being converted from bomber configuration into fast VIP transports. They were finally struck off charge in June 1947.
Empire State Building incident
Main article: B-25 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 – eleven in the building and the three occupants of the aircraft including the pilot, Colonel William Smith. Betty Lou Oliver, an elevator attendant, survived the impact and a subsequent uncontrolled descent in the elevator.
Variants
B-25C Mitchell
USAAF B-25C/D. Note the early radar with Yagi antenna fitted to the nose
B-25J
NA-40
Twin-engined five-seat bomber to meet 1938 USAAF requirement for attack bomber. Powered by two 1,100 hp (825 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.
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 (1,200 kW) Wright R-2600-A71-3 radials and numerous minor changes. First flew in revised form on 1 March 1939. Crashed 11 April 1940.
B-25
Initial production version of B-25, powered by 1,350 hp (1,012 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. 24 built.
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. 40 built.
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. 120 were built (this version was used in the Doolittle Raid). 23 were supplied to the Royal Air Force as the Mitchell Mk I.
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. First mass-produced B-25 model. (Number made: 1,625.)
ZB-25C
B-25D
Identical to the B-25C, the only difference was that the B-25D was made in Kansas City, Kansas, whereas the B-25C was made in Inglewood, California. First flew on 3 January 1942. (Number made: 2,290.)
F-10
A F-10 reconnaissiance aircraft
The F-10 was given to 45 B-25Ds that were modified for photographic reconnaissance. All armament, armor and bombing equipment was stripped. Three K.17 cameras were installed, one mounted vertically, with the other two mounted at oblique angles within blisters on each side of the nose. Also a vertical cameras could also be installed in the aft fuselage. Although designed for combat operations, these aircraft were mainly used for ground mapping.
WB-25D
In 1944, four B-25Ds were converted for weather reconnaissance by the 53d Weather Reconnaissance Squadron, originally called the Army Hurricane Reconnaissance Unit, now called the "Hurricane Hunters". Weather recon first started in 1943 with the First Weather Reconnaissance Squadron, with flights on the North Atlantic ferry routes.
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 XB-25E system. (Number made: 1, converted.)
ZXB-25E
XB-25F-A
Modified B-25C that tested the use of insulated electrical de-icing coils mounted inside the wing and empennage leading edges as a de-icing system. The hot air de-icing system tested on the XB-25E was more practical. (Number made: 1, converted.)
XB-25G
Modified B-25C in which the transparent nose was replaced by a solid nose 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
To satisfy the dire need for ground-attack and strafing aircraft, the B-25G was built following the success of the prototype XB-25G. 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. (Number made: 420.)
B-25H
B-25H Barbie III taxiing at Centennial Airport, Colorado
An improved version of the B-25G. This version permanently relocated the manned dorsal turret to a more forward location on the fuselage, between the rear of the cockpit and the leading edge of the wings. It also featured two additional fixed .50 in (12.7 mm) machine guns in the nose and four in fuselage-mounted pods; the heavy M4 cannon was replaced by a lighter 75 mm (2.95 in) T13E1. (Number made: 1,000; number left flying in the world: 1.)
B-25J
The last production model of the B-25, often called a cross between the B-25C and the B-25H. It had a transparent nose, but many of the delivered aircraft were modified to have a solid nose. Most of its 14–18 machine guns were forward-facing for strafing missions, with the guns of the forward-located dorsal turret of both the B-25H and J models being two of this number. The RAF received 316 aircraft, which were known as the Mitchell III. (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.
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. 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
A PBJ-1H of VMB-613.
Two PBJ-1Ds on Mindanao,1945.
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
PBJ-1H
U.S. Navy/U.S. Marine Corps designation for the B-25H
PBJ-1J
U.S. Navy designation for the B-25J-NC (Blocks −1 through −35) with improvements in radio and other equipment. Often fitted with "package guns" and wingtip search radar for the anti-shipping/anti-submarine role.
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.
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