Posted tagged ‘aviation’

ACHTUNG!!!! FOKKER!!!!

April 20, 2011

Fokker Dr.I

Role     Fighter
Manufacturer     Fokker-Flugzeugwerke
Designed by     Reinhold Platz
First flight     5 July 1917

Primary user     Luftstreitkräfte
Number built     320

The Fokker Dr.I Dreidecker (triplane) was a World War I fighter aircraft built by Fokker-Flugzeugwerke. The Dr.I saw widespread service in the spring of 1918. It became renowned as the aircraft in which Manfred von Richthofen gained his last 20 victories, and in which he was killed on 21 April 1918.

Design and development

V.4 prototype

In February 1917, the Sopwith Triplane began to appear over the Western Front. The Sopwith swiftly proved itself superior to the Albatros fighters then in use by the Luftstreitkräfte. Fokker-Flugzeugwerke responded by converting an unfinished biplane prototype into the V.4, a small, rotary-powered triplane with a steel tube fuselage and thick cantilever wings, first developed during Fokker’s government-mandated collaboration with Hugo Junkers. Initial tests revealed that the V.4 had unacceptably high control forces resulting from the use of unbalanced ailerons and elevators.
Instead of submitting the V.4 for a type test, Fokker produced a revised prototype designated V.5. The most notable changes were the introduction of horn-balanced ailerons and elevators, as well as longer-span wings. The V.5 also featured interplane struts, which were not necessary from a structural standpoint, but which minimized wing flexing. On 14 July 1917, Idflieg issued an order for 20 pre-production aircraft. The V.5 prototype, serial 101/17, was tested to destruction at Adlershof on 11 August 1917.

Operational history


Fokker produced two pre-production triplanes, designated F.I, which could be distinguished from production Dr.I aircraft by a slight curve to the tailplane leading edge. These aircraft, serials 102/17 and 103/17, were the only machines to receive the F.I designation. They were sent to Jastas 10 and 11 for combat evaluation, arriving at Markebeeke, Belgium on 28 August 1917.
Richthofen first flew 102/17 on 1 September 1917 and shot down two enemy aircraft in the next two days. He reported to the Kogenluft (Kommandierender General der Luftstreitkräfte) that the F.I was superior to the Sopwith Triplane. Richthofen recommended that fighter squadrons be reequipped with the new aircraft as soon as possible. The combat evaluation came to an abrupt conclusion when Oberleutnant Kurt Wolff, Staffelführer of Jasta 11, was shot down in 102/17 on 15 September, and Leutnant Werner Voss, Staffelführer of Jasta 10, was killed in 103/17 on 23 September.
The remaining pre-production aircraft, designated Dr.I, were delivered to Jasta 11. Idflieg issued a production order for 100 triplanes in September, followed by an order for 200 in November. Apart from minor modifications, these aircraft were almost identical to the F.I. The primary distinguishing feature was the addition of wingtip skids, which proved necessary because the aircraft was tricky to land and prone to ground looping. In October, Fokker began delivering the Dr.I to squadrons within Richthofen’s Jagdgeschwader I.

Compared to the Albatros and Pfalz fighters, the Dr.I offered exceptional maneuverability. Though the ailerons were not very effective, the rudder and elevator controls were light and powerful. Rapid turns, especially to the right, were facilitated by the triplane’s marked directional instability. Vizefeldwebel Franz Hemer of Jasta 6 said, “The triplane was my favorite fighting machine because it had such wonderful flying qualities. I could let myself stunt — looping and rolling — and could avoid an enemy by diving with perfect safety. The triplane had to be given up because although it was very maneuverable, it was no longer fast enough.”
As Hemer noted, the Dr.I was considerably slower than contemporary Allied fighters in level flight and in a dive. While initial rate of climb was excellent, performance fell off dramatically at higher altitudes due to the low compression of the Oberursel Ur.II, a clone of the Le Rhône 9J rotary engine. As the war continued, chronic shortages of castor oil made rotary operation increasingly difficult. The poor quality of German ersatz lubricant resulted in many engine failures, particularly during the summer of 1918.
The Dr.I suffered other deficiencies. The pilot’s view was poor during takeoff and landing. The cockpit was cramped and furnished with materials of inferior quality. Furthermore, the proximity of the gun butts to the cockpit, combined with inadequate crash padding, left the pilot vulnerable to serious head injury in the event of a crash landing.

 Wing failures

On 29 October 1917, Leutnant der Reserve Heinrich Gontermann, Staffelführer of Jasta 15, was performing aerobatics when his triplane broke up. Gontermann was fatally injured in the ensuing crash landing. Leutnant der Reserve Günther Pastor of Jasta 11 was killed two days later when his triplane broke up in level flight. Inspection of the wrecked aircraft showed that the wings had been poorly constructed. Examination of other high-time Dr.Is confirmed these findings. On 2 November, Idflieg grounded all remaining triplanes pending an inquiry. Idflieg convened a Sturzkommission (crash commission) which concluded that poor construction and lack of waterproofing had allowed moisture to destroy the wing. This caused the wing ribs to disintegrate and the ailerons to break away in flight.
In response to the crash investigation, Fokker improved quality control on the production line, particularly varnishing of the wing spars and ribs, to combat moisture. Fokker also strengthened the rib structures and the attachment of the auxiliary spars to the ribs. Existing triplanes were repaired and modified at Fokker’s expense.[22] After testing a modified wing at Adlershof, Idflieg authorized the triplane’s return to service on 28 November 1917. Production resumed in early December. By January 1918, Jastas 6 and 11 were fully equipped with the triplane. Only 14 squadrons used the Dr.I as their primary equipment. Most of these units were part of Jagdgeschwadern I, II, or III. Frontline inventory peaked in late April 1918, with 171 aircraft in service on the Western Front.
Despite corrective measures, the Dr.I continued to suffer from wing failures. On 3 February 1918, Leutnant Hans Joachim Wolff of Jasta 11 successfully landed after suffering a failure of the upper wing leading edge and ribs. On 18 March 1918, Lothar von Richthofen, Staffelführer of Jasta 11, suffered a failure of the upper wing leading edge during combat with Sopwith Camels of No. 73 Squadron and Bristol F.2Bs of No. 62 Squadron. Richthofen was seriously injured in the ensuing crash landing.
Postwar research revealed that poor workmanship was not the only cause of the triplane’s structural failures. In 1929, National Advisory Committee for Aeronautics (NACA) investigations found that the upper wing carried a higher lift coefficient than the lower wing — at high speeds it could be 2.55 times as much.
The triplane’s chronic structural problems destroyed any prospect of large-scale orders. Production eventually ended in May 1918, by which time only 320 had been manufactured.[28] The Dr.I was withdrawn from frontline service as the Fokker D.VII entered widespread service in June and July. Jasta 19 was the last squadron to be fully equipped with the Dr.I.[29]
Surviving triplanes were distributed to training and home defense units. Several training aircraft were reengined with the 75 kW (100 hp) Goebel Goe.II. At the time of the Armistice, many remaining triplanes were assigned to fighter training schools at Nivelles, Belgium, and Valenciennes, France. Allied pilots tested several of these triplanes and found their handling qualities to be impressive.

Postwar

Very few triplanes survived the Armistice. Serial 528/17 was retained as a testbed by the Deutschen Versuchsanstalt für Luftfahrt (German Aviation Research Institute) at Adlershof. After being used in the filming of two movies, 528/17 is believed to have crashed sometime in the late 1930s.[32] Serial 152/17, in which Manfred von Richthofen obtained three victories, was displayed at the Zeughaus museum in Berlin. The triplane was destroyed by an Allied bombing raid during World War II. Today, only a few original Dr.I artifacts survive in museums.

 Replica aircraft

While no Dr.I airframes survive, large numbers of flying and static replicas have been built. In 1932, Fokker built a Dr.I from the spare parts of various aircraft. The reproduction appeared in the 1939 film D III 88. Bitz Flugzeugbau GmbH built two Dr.I replicas for use in Twentieth Century Fox’s 1966 film The Blue Max. One of these aircraft currently operates in the United States.
Since April 1994, the National Museum of the United States Air Force at Wright-Patterson Air Force Base has displayed a reproduction Fokker Dr. I. It is painted in the markings of a Jagdstaffel 19 aircraft flown by Leutnant Arthur Rahn in April 1918.
Large numbers of replica aircraft have been built for both individuals and museums. Due to the expense and scarcity of authentic rotary engines, most airworthy replicas are powered by a Warner Scarab or Continental R-670 radial engine. A few, however, feature vintage Le Rhône 9 or reproduction Oberursel Ur.II rotary engines.

Variants

    * V.3 – Initial prototype
    * V.4 – First production prototype
    * V.5 – Prototype with Goebel Goe.III engine
    * V.6 – Enlarged prototype with Mercedes D.II engine
    * V.7 – Prototype with Siemens-Halske Sh.III engine
    * V.10 – Prototype with Oberursel Ur.III engine

Operators

 German Empire

    * Luftstreitkräfte

 Specifications (Dr.I)

General characteristics

    * Crew: One
    * Length: 5.77 m (18 ft 11 in)
    * Wingspan: 7.20 m (23 ft 7 in)
    * Height: 2.95 m (9 ft 8 in)
    * Wing area: 18.70 m² (201 ft²)
    * Empty weight: 406 kg (895 lb)
    * Loaded weight: 586 kg (1,292 lb)
    * Powerplant: 1× Oberursel Ur.II 9-cylinder rotary engine, 82 kW (110 hp)
    * Zero-lift drag coefficient: 0.0323
    * Drag area: 0.62 m² (6.69 ft²)
    * Aspect ratio: 4.04

Performance

    * Maximum speed: 185 km/h at sea level (115 mph at sea level)
    * Stall speed: 72 km/h (45 mph)
    * Range: 300 km (185 mi)
    * Service ceiling: 6,095 m (20,000 ft)
    * Rate of climb: 5.7 m/s (1,130 ft/min)
    * Lift-to-drag ratio: 8.0

Armament

    * 2 × 7.92 mm (.312 in) “Spandau” lMG 08 machine guns.

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B-25 : The Pistol Packing Bomber

May 16, 2010

B-25 Mitchell

The North American B-25 Mitchell was an American twin-engined medium bomber manufactured by North American Aviation. It was used by many Allied air forces, in every theater of World War II, as well as many other air forces after the war ended, and saw service across four decades.The B-25 was named in honor of General Billy Mitchell, a pioneer of U.S. military aviation. The B-25 is the only American military aircraft named after a specific person. By the end of its production, nearly 10,000 B-25s in numerous models had been built. 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.

Design and development

Flight Performance School also included work in evaluating the performance of this B-25 Mitchell medium bomberThe 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 US 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

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 re-design 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 wing tip. 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.A total of 6,608 B-25s were built at North American’s Fairfax Airport plant in Kansas City, Kansas.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. It had much more in common with the B-26 Marauder.

Operational history

The B-25 first gained fame as the bomber used in the 18 April 1942 Doolittle Raid, in which sixteen B-25Bs led by the legendary 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 troops. While 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. However, 15 subsequently crash-landed en route to recovery fields in Eastern China. These losses were the result of the task force being spotted by Japanese fishing vessels forcing the bombers to take off 170 mi early, fuel exhaustion, stormy nighttime conditions with zero visibility, and lack of electronic homing aids at the recovery bases. Only one landed intact; it came down in the Soviet Union, 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 deicing 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 theater (SWPA) on treetop-level strafing and parafrag (parachute-retarded fragmentation bombs) missions 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 re-supply 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 SWPA 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 theaters.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 machine guns and a 75 mm M4 cannon, one of the largest weapons fitted to an aircraft, similar to the experimental British Mosquito Mk. XVIII, and German Ju 88P heavy cannon carrying aircraft. The 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 gun fired at a muzzle velocity of 2,362 ft/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 gun was sometimes removed from both G and H models and replaced with two additional .50 in machine guns as a field modification. The -H also mounted four fixed forward-firing .50 machine guns in the nose, four more fixed ones in forward-firing cheek blisters, two more in the top 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 of bombs.”

The B-25H also featured a redesigned cockpit area, with the top turret moved forward to the navigator’s compartment (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 1,400 B-25Gs and B-25Hs were built.

The final version of the Mitchell, the B-25J, looked much like the earlier B, C and D, having reverted to the longer nose. The less-than-successful 75 mm cannon was deleted on the J model. Instead, 800 of this version were built with a solid nose containing eight .50 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 two .50 in guns in a “fuselage package” located directly under the pilot’s station, and two more such guns in an identical package just under the co-pilot’s compartment. The solid-nose B-25J variant carried an impressive total of 18 .50 in guns: eight in the nose, four in under-cockpit packages, two in an upper turret, two in the waist, and a pair in the tail. No other bomber of World War II carried as many guns. However, the first 555 B-25Js (the B-25J-1-NC production block) were delivered without the fuselage package guns, because it was discovered muzzle blast from these guns was causing severe stress in the fuselage;this was cured with heavier fuselage skin patches, while later production runs returned these guns, they were often removed as a field modification for the same reason. In all, 4,318 B-25Js were built.

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 . However, the pilot had to remember to maintain engine-out directional control at low speeds after take off with rudder – if this 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 various 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” protuding directly from the cowling ring and partly covered by a small triangular fairing. This 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-25’s 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 also an amazingly sturdy aircraft and 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 paint. 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 was so bent, 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 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 F-89 Scorpion and 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[6], 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 822nd 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. Donated back to the Air Force Armament Museum circa 1974 and marked as Doolittle’s 40-2344.

Empire State Building incident

On Saturday, 28 July 1945, at 0940 (while flying in thick fog), a USAAF B-25D crashed into the north side of the Empire State Building, hitting between the 79th and 80th floor. Fourteen people were killed — 11 in the building, along with Colonel William Smith and the other two occupants of the bomber. Betty Lou Oliver, an elevator attendant, survived the impact and a subsequent accident with the elevator. It was partly because of this incident that towers 1 and 2 of the World Trade Center were designed to withstand the impact of a Boeing 707 aircraft (unfortunately NOT Arab terrorist hijacked airliners).

Variants

B-25

The first version of the B-25 delivered. No prototypes were ordered. 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.)
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 designation) in 1942. (Number made: 40.)
B-25B
Rear turret deleted; manned dorsal and remotely-operated ventral turrets added, each with a pair of .50 in (12.7 mm) machine guns. The ventral turret was retractable, but the increased drag still reduced the cruise speed by 30 mph (48 km/h). 23 were delivered to the RAF as the Mitchell Mk I. The Doolittle Raiders flew B-25Bs on their famous mission. (Number made: 120.)
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.)
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 prop 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 one 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 made 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, ColoradoAn improved version of the B-25G. It 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. 316 were delivered to the Royal Air Force 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.

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

PBJ-1C
Similar to the B-25C for the US Navy; often fitted with airborne search radar and used in the anti-submarine role.
PBJ-1D
Similar to the B-25D for the US Navy and US Marine Corps. Differed in having a single .50 in (12.7 mm) machine gun in the tail turret and beam gun positions similar to the B-25H. Often fitted with airborne search radar and used in the anti-submarine role.
PBJ-1G
US Navy/US Marine Corps designation for the B-25G
PBJ-1H
US Navy/US Marine Corps designation for the B-25H
PBJ-1J
US 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.

Survivors

There are more than one hundred surviving B-25 Mitchells scattered over the world, mainly in the United States. Most of them are on static display in museums, but about 45 are still airworthy.

On 18 April 2010, 17 airworthy B-25s took off from the airfield behind the National Museum of the United States Air Force and flew over in formation to commerate the 68th anniversary of the Doolittle Raid. Four of the surviving members of the Raid were in attendance for the reunion; Cole, Griffin, Hite and Thatcher, although Hite departed before the flyover. Secretary of the Air Force Michael Donley, Commander of Air Force Material Command General Donald Hoffman and the Director of the National Museum of the United States Air Force Major General Charles Metcalf were there also.

Specifications (B-25J)

North American B-25 Mitchell

Role Medium bomber

Manufacturer North American Aviation

First flight 19 August 1940

Introduction 1941

Retired 1979 (Indonesia)

Primary users United States Army Air Forces,Royal Canadian Air Force,Royal Air Force,Soviet Air Force

Number built 9,984

Developed from XB-21

Developed into North American XB-28

General characteristics

Crew: six (two pilots, navigator/bombardier, turret gunner/engineer, radio operator/waist gunner, tail gunner
Length: 52 ft 11 in (16.1 m)
Wingspan: 67 ft 6 in (20.6 m)
Height: 17 ft 7 in (4.8 m)
Wing area: 610 sq ft (57 m²)
Empty weight: 21,120 lb (9,580 kg)
Loaded weight: 33,510 lb (15,200 kg)
Max takeoff weight: 41,800 lb (19,000 kg)
Powerplant: 2× Wright R-2600 “Cyclone” radials, 1,850 hp (1,380 kW) each
Performance

Maximum speed: 275 mph (239 kn, 442 km/h)
Cruise speed: 230 mph (200 kn, 370 km/h)
Combat radius: 1,350 mi (1,170 nmi, 2,170 km)
Ferry range: 2,700 mi (2,300 nmi, 4,300 km)
Service ceiling: 25,000 ft (7,600 m)
Rate of climb: 790 ft/min (4 m/s)
Wing loading: 55 lb/ft² (270 kg/m²)
Power/mass: 0.110 hp/lb (182 W/kg)
Armament

Guns: 12-18 × .50 in (12.7 mm) machine guns
Hardpoints: 2,000 lb (900 kg) ventral shackles to hold one external Mark 13 torpedo[15]
Rockets: 3,000 lb (1,360 kg) bombs + eight 5 in (130 mm) high velocity aircraft rockets (HVAR)
Bombs: 6,000 lb (2,700 kg)

Stalking the Clouds: F7F Tigercat

May 13, 2010

F7F Tigercat

The Grumman F7F Tigercat was the first twin-engined fighter aircraft to enter service with the United States Navy. Designed for the new Midway-class aircraft carriers, the aircraft were too large to operate from earlier decks. Although delivered to United States Marine Corps combat units before the end of World War II, the Tigercat did not see combat service in that war. Most F7Fs ended up in land-based service, as attack aircraft or night fighters; only the later F7F-4N was certified for carrier service. They saw service in the Korean War and were withdrawn from service in 1954.

Design and development

Based on the earlier Grumman XP-50 that eventually was canceled, the company further developed the XP-65 (Model 51) for a future “convoy fighter” concept. In 1943, work on the XP-65 was terminated in favor of the design that would eventually become the F7F. The contract for the prototype XF7F-1 was signed on 30 June 1941. Grumman’s aim was to produce a fighter that out-performed and out-gunned all existing fighter aircraft, and that had an auxiliary ground attack capability. Armament was heavy: four 20 mm cannons and four 0.50 in machine guns, as well as underwing and under-fuselage hardpoints for bombs and torpedoes. Performance met expectations too; the F7F Tigercat was one of the highest-performance piston-engined fighters, with a top speed well in excess of the US Navy’s single-engined aircraft—71 mph faster than a F6F Hellcat at sea level. The opinion of Capt. Fred M. Trapnell, one of the Navy’s premier test pilots, was that “It’s the best damn fighter I’ve ever flown.”[4]The Grumman F7F was originally named the “Tomcat” but this name was rejected as it was considered at the time too suggestive. The name would much later be used for the Grumman F-14.All this was bought at the cost of heavy weight and a high landing speed, but what caused the aircraft to fail carrier suitability trials was poor directional stability with only one engine operational, as well as problems with the tail-hook design. Therefore, the initial production series was only used from land bases by the USMC, as night fighters with APS-6 radar. At first, they were single-seater F7F-1N aircraft, but after the 34th production aircraft, a second seat for a radar operator was added; these aircraft were designated F7F-2N. The next version produced, the F7F-3 was modified to correct the issues that caused the aircraft to fail carrier acceptance and this version was again trialled on the USS Shangri-La (CV-38). A wing failure on a heavy landing caused the failure of this carrier qualification too. F7F-3 aircraft were produced in day fighter, night fighter and photo-reconnaissance versions.A final version, the F7F-4N, was extensively rebuilt for additional strength and stability, and did pass carrier qualification, but only 12 were built.

Operational history

Marine Corps night fighter squadron VMF(N)-513 flying F7F-3N Tigercats saw action in the early stages of the Korean War, flying night interdiction and fighter missions and shooting down two Polikarpov Po-2 biplanes. This was the only combat use of the aircraft.
Most F7F-2Ns were modified to control drones for combat training, and these gained bubble canopies over the rear cockpit for the drone controller. A F7F-2D used for pilot transitoning also had a rear sliding, bubble canopy.In 1945, two Tigercats were evaluated, but rejected, by the British Royal Navy, preferring a navalized version of the de Havilland Hornet.

Variants

XF7F-1
Prototype aircraft, two built.
F7F-1 Tigercat
Twin-engine fighter-bomber aircraft, powered by two Pratt & Whitney R-2800-22W radial piston engines. First production version, 34 built.
F7F-1N Tigercat
Single-seat night fighter aircraft, fitted with an APS-6 radar.
XF7F-2N
Night-fighter prototype, One built.
F7F-2N Tigercat
Two-seat night fighter, 65 built.
F7F-2D
Small numbers of F7F-2Ns converted into drone control aircraft. The aircraft were fitted with an F8F Bearcat-windshield behind the     cockpit.
F7F-3 Tigercat
Single-seat fighter-bomber aircraft, powered by two Pratt & Whitney R-2800-34W radial piston engines, 189 built.
F7F-3N Tigercat
Two-seat night fighter aircraft, 60 built.
F7F-3E Tigercat
Small numbers of F7F-3s were converted into electronic warfare aircraft.
F7F-3P Tigercat
Small numbers of F7F-3s were converted into photo-reconnaissance aircraft.
F7F-4N Tigercat
Two-seat night-fighter aircraft, fitted with an arrester hook and other naval equipment, 13 built.

Operators

United States

* United States Marine Corps
* United States Navy

Survivors

Beginning in 1949, F7Fs were flown to the US Navy storage facility at Litchfield Park in Arizona. Although the vast majority of the airframes were eventually scrapped, a number of examples were purchased as surplus. The surviving Tigercats were primarily used as water bombers to fight forest fires in the 1960s and 1970s. A total of 12 examples exist today with six F7Fs remaining airworthy.
As warbird racers, in 1976, Robert Forbes qualified an F7F-3N but did not race at Reno. Another modified F7F-3N Tigercat, (Bu No. 80503) “Big Bossman” owned by Mike Brown presently competes in the national air racing circuit.

At least four F7F Tigercats are preserved in aviation museums:

* F7F-3 (Serial no. 80373/N7654C) National Museum of Naval Aviation, NAS Pensacola, Florida
* F7F-3 (Serial no. 80410) Pima Air & Space Museum, Tucson, Arizona
* F7F-3P (Serial no. 80390/N700F) Kalamazoo Aviation History Museum, Kalamazoo, Michigan
* An F7F (Model & Serial no. TBD) is maintained at the Historic Flight Foundation at Paine Field in Everett, Washington

Specifications (F7F-4N Tigercat)

General characteristics

Role     Fighter aircraft

Manufacturer     Grumman

First flight     2 November 1943

Introduced     1944

Retired     1954

Primary users     United States Navy, United States Marine Corps

Produced     1943–1946

Number built     364

* Crew: 2 (pilot, radar operator)
* Length: 45 ft 4 in (13.8 m)
* Wingspan: 51 ft 6 in (15.7 m)
* Height: 16 ft 7 in (5.1 m)
* Wing area: 455 ft² (42.3 m²)
* Empty weight: 16,270 lb (7,380 kg)
* Max takeoff weight: 25,720 lb (11,670 kg)
* Powerplant: 2× Pratt & Whitney R-2800-34W “Double Wasp” radial engines, 2,100 hp (1,566 kW) each


Performance

* Maximum speed: 460 mph (400 knots, 740 km/h)
* Range: 1,200 mi (1,000 nmi, 1,900 km)
* Service ceiling: 40,400 ft (12,300 m)
* Rate of climb: 4,530 ft/min (1,381 m/min)

Armament

* Guns:
o 4 × 20 mm (0.79 in) M2 cannon
o 4 × 0.50 in (12.7 mm) M2 Browning machine gun
* Bombs:
o 2 × 1,000 lb (454 kg) bombs under wings or
o 1 × torpedo under fuselage

Avionics

* AN/APS-19 radar