Category Archives: U.S. Army Air Force

U.S.A.

Fighter

Bell XP-83 (Anigrand, Resin)

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TYPE: Long range escort fighter

ACCOMMODATION: Pilot only

POWER PLANT: Two General Electric J33-GE 5 turbojets, rated at 1,835 kp each

PERFORMANCE: 522 mph at 15,700 ft

COMMENT: The Bell XP-83 was a United States prototype escort fighter designed by Bell Aircraft  during World War II. It first flew in 1945. As an early jet fighter, its limitations included a lack of power and it was soon eclipsed by more advanced designs. The early jet fighters consumed fuel at a prodigious rate which severely limited their range and endurance.
In March 1944, the United States Army Air Forces requested Bell to design a fighter with increased endurance and formally awarded a contract for two prototypes on 31 July 1944.Bell had been working on its “Model 40” interceptor design since 1943. It was redesigned as a long-range escort fighter while retaining the general layout of the Bell P-59 Airacomet. The two General Electric-GE-5 turbojet engines were located in each wing root which left the large and bulky fuselage free for fuel tanks and armament. The fuselage was an all-metal semimonocoque capable of carrying 4,350 l of fuel. In addition, two 950 l drop tanks could be carried. The cabin was pressurized and used a small and low bubble style canopy. The armament was to be six 12.7 mm machine guns in the nose.
Early wind tunnel reports had pinpointed directional instability but the “fix” of a larger tail would not be ready in time for flight testing. The first prototype was flown on 25 February 1945, demonstrating that the aicraft was under-powered and unstable. The limited flight testing provided satisfactory flight characteristics although spins were restricted until the larger tail fin was installed. The second prototype did incorporate the extended tail and an aileron boost system. One unique characteristic was the XP-83’s refusal to slow down due to its sleek aerodynamic shape and lack of drag brakes. This meant that test pilots were forced to fly “stabilized approaches” (i.e. very long and flat landing approaches).
The first prototype was used in 1946 as a ramjet test-bed with an engineer’s station located in the fuselage behind the pilot. The second prototype flew on 19 October and was later scrapped in 1947. Apart from range, the XP-83 was inferior to the Lockheed P-80 Shooting Star and this led to the cancellation of the XP-83 project in 1947 (Ref.: 24).

Fighter, Fighterbomber

Boeing F8B-1 (Sword)

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TYPE: Fighter, Interceptor, Ground attack aircraft

ACCOMMODATION: Pilot only

POWER PLANT: One  Pratt & Whitney R-4360-10, rated at 3,000 hp

PERFORMANCE: 432 mph

COMMENT: The estimated excellent performance of  this aircraft, designed for the US Navy, was of great interest for the US Army Air Force, too. So the third (of three) prototype was delivered to the US Army Air Force and tested at Eglin Air Force base. But the advent of new jet fighters led to the cancellation of many wartime piston-engined projects. So consequently, the USAF lost interest in pursuing the project and the prototype was scrapped.

Fighter

Republic XP-72 (Revell, Parts scratch built)

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TYPE: Long-range Escort Fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Pratt & Whitney R-4360-13 Wasp Major, rated at 3,450 h.p.

PERFORMANCE: 490 m.p.h. at 25,000 ft

COMMENT:  The second prototype of the Republic XP-72, first flown on 26 June 1944, had Aero Products contra props in place of the four bladed propeller of the first prototype of the Republic XP-72.

Fighter, Projects

Republic XP-69 (Anigrand, Resin)

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TYPE: High Altitude Fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Wright R-2160-6 Tornado super-charged liquid-cooled radial engine, rated at 2,500 h.p. and driving 6-bladed Hamilton Standard contra-rotating propellers,

PERFORMANCE: 453 m.p.h.

COMMENT: The Republic XP-69 was an American fighter aircraft proposed by Republic Aviation in 1941 in response to a requirement by the United States Army Air Corps for a high-speed fighter. Manufacturers were encouraged to consider unorthodox designs; although the design was ordered as a prototype it was canceled because of delays with the engine that was to power it.
he United States Army Air Corps began the R40-C fighter competition in February 1940. The competition encouraged manufacturers to propose unorthodox high-speed fighter aircraft that met the requirements of Type Specification XC-622. The specification called for a single-engined high-performance fighter aircraft, with a maximum speed between 425 and 525 mph, armed with both machine guns and cannons, and be capable of landing on a 3,000 ft long grass runway
Republic was one of six companies selected for the competition, and one of the aircraft proposed to the USAAC by Republic was the AP-12 Rocket. As proposed, the AP-12 was to be powered by a 2,500 hp Wright R-2160-3 Tornado 42-cylinder liquid-cooled radial engine mounted in the mid-section of the aircraft’s streamlined, cigar-shaped fuselage, behind the cockpit, which drove a pair of three-bladed contra-rotating propellers. It was to be armed with four nose-mounted machine guns firing through the propeller arc, and a single 20 mm cannon firing through the propeller hub. The AP-12 placed 13th out of 26 contestants, forcing Republic to go back to the drawing board to improve its proposal.
In July 1941, Republic submitted an improved design, the AP-18. The AP-18 had little in common with the AP-12. It retained the original aircraft’s R-2160 engine, which was now mounted in the nose of a completely new small-cross section airframe. The large radiator was to be mounted under the fuselage. The pressurized cockpit was to feature a bubble canopy, and an armament of four .50 in machine guns and two 37 mm cannons mounted in a laminar flow wing was planned.
In December 1941, the United States Army Air Forces (successor to the USAAC) ordered two prototypes of the AP-18 under the designation XP-69. A mockup was built and was inspected by the USAAF in June 1942. Construction of the first prototype began in November of that year. However, due to development troubles and delays with the R-2160 engine, the XP-69 project was canceled in favor of a parallel development, the Republic XP-72, on May, 1943. By that time engineering on the project was 75% complete and the prototype was still in the early stages of construction (Ref.: 24).

Fighter

Convair XP-81 (Anigrand, Resin)

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TYPE: Long-Range Escort Fighter

ACCOMMODATION: Pilot only

POWER PLANT: One General Electric T31-GE-1 turboprop engine, rated at 2,300 h.p. and one Allison J 33-GE-5 turbojet engine, rated at 703 kp

PERFORMANCE: 507 m.p.h. at 30,000 ft

COMMENT: The Consolidated Vultee XP-81was a development of the Consolidated Vultee Aircraft to build a single seat, long range escort fighter that combined use of both turbojet and turboprop engines. Although promising, the lack of suitable engines combined with the end of World War II doomed the project.
Two prototype aircraft were ordered on February 1944 that were designated XP-81. The engine selection was an attempt to couple the high-speed capability of the turbojet engine with the endurance offered by the propeller engine. The XP-81 was designed to use the General Electic TG-100 turboprop engine in the nose driving a four-bladed propeller and a General Electric J33 turbojet in the rear fuselage. The turboprop would be used for normal flight and cruising and the turbojet added for high-speed flight.
The first XP-81 was completed in January 1945 but because of developmental problems the turboprop engine was not ready for installation. A decision was then made to mount a complete Packard V-1650-7 Merlin engine package from a North American P-51D Mustang aircraft in place of the turboprop for initial flight tests. This was done in a week and the Merlin-powered XP-81 was sent to the Muroc airbase where it flew for the first time on 11 February 1945. During 10 flight test hours, the XP-81 displayed good handling characteristics except for inadequate directional stability due to the longer forward portion of the fuselage. This was rectified by enlarging the vertical tail.
While 13 Convair YP-81 pre-production aircraft had been ordered, the capture of Guam and Saipan eliminated the need for long-range, high-speed escort fighters and then, just before VJDay the contract was cancelled, after 85% of the engineering was completed. The YP-81 was to be essentially the same as the prototype but with a lighter and more powerful General Electric TG-110 (XT41) turboprop engine, the wing moved aft 0.25 m, and armament of either six 12.7 mm machine guns or six 20 mm cannon.
After the XP-81 was returned to Vultee Field, the TG-100 turboprop was installed and flight testing resumed, including the first flight by an American turboprop-powered aircraft on 21 December 1945. However, the turboprop engine was not able to produce its designed power; producing only the same output as the Packard Merlin (1,490 hp) with the resultant performance limited to that of the Merlin-engined version.
With the termination of hostilities, the two prototypes continued to be tested until 1947 when they were both consigned to a bombing range as photography targets (Ref.: 24).

Medium Bomber

North American XB-28 Dragon (Anigrand, Resin)

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TYPE:  Medium Bomber

ACCOMMODATION: Crew of five

POWER PLANT: Two Pratt & Whitney R-2800-27 air-cooled radial turbocharged engines, rated at 2,000 hp each

PERFORMANCE: 372 m.p.h. at 25,000 ft

COMMENT: The North American XB-28 (NA-63) Dragon was an aircraft proposed by North American Aviation to fill a strong need in the United States Army Air Corps for a high-altitude medium bomber. It never entered production, with only two prototypes being built.
The order for a high-altitude medium bomber was put out on 13 February 1940; the XB-28 first flew on 26 April 1942. The XB-28 was based on North American Aviation‘s’s highly successful B-25 Mitchell, but as it evolved it became a completely new design, much more reminiscent of the Martin B-26 Marauder. The overall configuration of the B-25 and XB-28 were fairly similar; the most important distinction was that the twin tail of the B-25 was changed to a single tail on the XB-28. It was among the first combat aircraft with a pressurized cabin.
The XB-28 proved an excellent design, with significantly better performance than that of the B-25, but it was never put into production. High-altitude bombing was hampered significantly by factors such as clouds and wind, which were frequent occurrences in the Pacific. At the same time, medium bombers were becoming much more effective at lower altitudes. The gains in aircraft performance that came with high-altitude flight were not considered sufficient to justify switching from low-altitude bombing.
Even though the Army Air Forces rejected the XB-28 as a bomber, they ordered another prototype. Designated XB-28A, it was meant to explore the possibility of use as a reconnaissance aircraft. The XB-28A crashed into the Pacific Ocean off Southern California after the crew bailed out on 4 August 1943 (Ref.: 24).

Fighter

Curtiss XP-62 (Anigrand, Resin)

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TYPE: Interceptor fighter

ACCOMMODATION: Pilot only

POWER PLANT: One Wright R-3350-17 Duplex Cyclone radial piston engine, rated at 2,300 hp, and driving six-bladed contra-rotating constant-speed propellers

PERFORMANCE: 448 mph at 27,000 ft

COMMENTS: The Curtiss XP-62 was a prototype single-engine interceptor aircraft, that was built for the United States Army Air Forces, by the Curtiss-Wright Corporation. It first flew in 1943.
The design sought to have an improved high-altitude performance and higher speeds, at all altitudes, which was to be assisted by the 18-cylinder Wright R-3350 Duplex-Cyclone engine. It was to be armed with four 0.79 in autocannons, a heavier armament than contemporary USAAF fighter aircraft, and was fitted with a pressurized cockpit.
The terms of the contract proposal of 29 April 1941 called for the first flight within fifteen months of the award and meet the following objectives:
Maximum level flight speed at 27,000 ft had to exceed 468 mph, it was to feature an air-conditioned pressurized cockpit , armament to be either eight 0.79 in cannons or twelve 0.50 in machine guns, mounted in the wings.
Two prototypes were ordered; the first designated XP-62 and the second designated XP-62A.
On 2 August 1941, the specifications were amended for the XP-62, reducing the maximum speed to 448 mph with eight 0.79 in cannons, and increasing the loaded weight by 1,537 lb (697 kg).
During a project review of 1 January 1942, the specification was again revised, with the loaded weight reduced by eliminating four cannons and removing the propeller de-icing  equipment.
On 25 May 1942 a contract for 100 P-62 fighters was awarded. However, on July 1942, before production could begin, the contract for the P-62 was terminated by the USAAF because of the effect on deliveries of Curtiss-built Republic P-47G-CU Thunderbolts.
While work on the XP-62A continued, it progressed slowly, owing to its low priority. Delays in delivery of the pressure-cabin supercharger and engine modifications delayed the first flight until 21 July 1943. Only a limited amount of flight testing was carried out before the XP-62A was canceled on 21 September 1943 and full performance characteristics were not obtained. The prototype was scrapped in early 1944 (Ref.: 24).

Fighterbomber

Vultee XA-41 (Anigrand, Resin)

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TYPE: Dive bomber, ground attack aircraft

ACCOMMODATION: Pilot only

POWER PLANT: One Pratt & Whitney R-4360 radial engine, rated at 3,000 hp

PERFORMANCE: 363 mph

COMMENT: The Vultee XA-41 was originally ordered as a dive bomber. After combat experience led the U.S. Army Air Corps to believe dive-bombers were too vulnerable to enemy fighters, the contract was amended to change the role to low-level ground attack. Although the XA-41 was a potent weapons system, the design was overtaken by more advanced technology, and never entered production.
The Vultee engineering team decided early in the design process to build the XA-41 (company Model 90) around the 3,000 hp Pratt & Whitney R-4360 “Wasp Major” radial engine. The large wing resembled that of the two-seat attack aircraft/dive bomber Vultee A-31/A-35 “Vengeance including a straight leading edge, forward-tapered trailing edge and pronounced dihedral on the outer wing panels. Designed to carry both a large internal load and external stores, the XA-41 was large for a single-engine aircraft. The single-place cockpit, set in line with the wing root, was 15 ft off the ground when the airplane was parked. As operational priorities shifted during its development phase, the original order for two XA-41 prototypes was cancelled, although the USAAF pressed for the completion of one prototype as an engine testbed for the R-4360, the same engine used by the Boeing B-50 “Superfortess” bomber.
Flying for the first time on February 1944, the sole XA-41 proved to have good performance with a maximum speed of 354 mph reached in testing and superb maneuverability, being able to out-turn a P-51B “Mustang”. However, with the reduction in military orders due to the approaching end of the war, no production contract was placed, and the aircraft was used as an engine testbed for the USAAF as well as being evaluated by the U.S. Navy in comparison with other contemporary attack aircraft, especially the Douglas AD-1 “Skyraider” and Martin AM-1 “Mauler”. After its Navy trials, the XA-41, bearing civil registration, was consigned to the Pratt & Whitney division of United Aircraft to continue engine tests. These continued until 1950 before the XA-41 was scrapped (Ref.: 24).

 

Medium Bomber

Douglas XB-43 “Jetmaster” (Anigrand, Resin)

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TYPE: High-speed medium bomber

ACCOMMODATION: Crew of three

POWER PLANT: Two General Electric J35-GE-3 turbojet engines, rated at 1,835 kp each

PERFORMANCE: 507 mph

COMMENT: USAAF leaders in the Air Material Command began to consider the possibilities of jet-propelled bombers as far back as October 1943. At that time, Douglas Aircraft was just beginning to design a promising twin-engine bomber designated the XB-42 “Mixmaster”. Reciprocating engines powered this aircraft but they were buried in the fuselage, leaving the laminar flow-airfoil wing clean of any drag-inducing pylon mounts or engine cowlings. The airframe appeared ideally suited to test turbojet propulsion. Douglas confirmed the feasibility of the concept and the USAAF amended the XB-42 contract in March 1944 to include the development of two turbojet-powered XB-43 prototypes, reduced from an initial order of 13 test aircraft. The Douglas design team convinced the Army that modifying the XB-42 static test airframe into the first XB-43 was a relatively straightforward process that would save time and money compared to developing a brand new design. Douglas replaced the two Allison V-1710 engines with a pair of General Electric J35 turbojets, then cut two air intakes into each side of the fuselage, aft of the pressurized cockpit. Removing the propellers and drive shafts freed enough space for two long jet exhaust ducts. Without any propellers present, there was no chance of striking the blade tips on the runway, so the entire ventral fin/rudder unit of the earlier XB-42’s full four-surface cruciform tail was omitted. Douglas compensated for the loss of yaw stability by enlarging the dorsal fin/rudder unit. The end of World War II caused a general slowdown within the aviation industry and General Electric was late delivering the engines. So America’s first turbojet bomber finally flew for the first time on 17 May 1946. Douglas Aircraft was keen to mass-produce the new bomber and the USAAF considered ordering 50, but these plans never became realized. The USAAF was already moving ahead with a new bomber, the North American XB-45 “Tornado”, designed from the outset for turbojet power and promising a quantum leap in every category of performance (Ref.: 24).

Medium Bomber

Douglas XB-42 “Mixmaster” (Anigrand, Resin)

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TYPE: High-speed medium bomber

ACCOMMODATION: Crew of three

POWER PLANT: Two Allison V-1710-125 liquid-cooled engine, rated at 1,325 hp each, driving three-bladed, contra-rotating propellers

PERFORMANCE: 410 mph at 23,440 ft

COMMENT: The XB-42 was developed initially as a private venture; an unsolicited proposal was presented to the USAAF in May 1943. This resulted in a contract for two prototypes and one static test airframe, the USAAF seeing an intriguing possibility of finding a bomber capable of the Boeing B-29 “Superfortress” range without its size or cost. The aircraft mounted a pair of Allison V-1710-125 liquid-cooled V-12 engines behind the crew’s cabin, each driving one of the twin propellers. Air intakes were in the wing leading edge. The landing gear was tricycle and a full, four surface cruciform tail was fitted, whose ventral fin/rudder unit prevented the coaxial propellers from striking the ground. The pilot and co-pilot sat under twin bubble canopies, and the bombardier sat in the extreme front behind a plexiglass nose. Defensive armament was two 0.50 in machine guns each side in the trailing edge of the wing, which retracted into the wing when not in use. These guns were aimed by the copilot through a sighting station at the rear of his cockpit. The guns had a limited field of fire and could only cover the rear, but with the aircraft’s high speed it was thought unlikely that intercepting fighters would be attacking from any other angle. The first XB-42 was delivered to the Army Air Force and flew at on 6 May 1944. Performance was excellent, being basically as described in the original proposal: as fast or even faster than the de Havilland “Moquito” but with defensive armament and twice the bomb-load. The end of World War II allowed the Air Force to consider possibilities with a little more leisure. Although with the second prototype additional Westinghouse 19XB-2A jet engines were mounted under the wings to enhance performance (XB-42A) it was decided to wait for the development of better jet bombers rather than continue with the XB-42 program (Ref.: 24).