TYPE: Long-range escort fighter

ACCOMMODATION: Crew of two

POWER PLANT: Two Allison V-3420 engines, rated at 3,000 hp each

PERFORMANCE: 436 mph at 25,000 ft

COMMENT: The Lockheed XP-58 Chain Lightning was an American long-range fighter developed during WW II. Although derived from the successful Lockheed P-38 Lightning,  the XP-58 was plagued by technical problems with its various engines that eventually led to the cancellation of the project. Initially, the design was powered by two Continental IV-1430 engines. In July 1940, Lockheed decided to switch to Pratt & Whitney XH-2600 engines as the aircraft would be underpowered with the Continental engine. However, soon Lockheed was advised the development of the XH-2600 engine was terminated. So again engine alternatives were needed and the design was changed to use two Wright R-2169 Tornado engines. In February 1943, use of another engine, the Allison V-3420, was necessary due to poor progress with the Tornado engine development. Parallel to this the design was revised as a second crew member was added and the defensive armament was changed. Two turrets, one upper and the other lower on the fuselage, each  containing two .50 in machine guns, were installed and directed by a gunner in the rear fuselage. The XP-58 finally flew on 6 June 1944 for the first time, but after 25 test flights were completed and clarified many more problems further work on the XP-58 was reduced and in October 1944 the program was stopped and no further flights were done. The construction of the second prototype was abandoned. (Ref.: 23)

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).

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.

TYPE: Interceptor fighter

ACCOMMODATION: Pilot only

POWER PLANT: Wright R-3350-17 Cyclone, rated at 2,300 h.p.

PERFORMANCE: 488 m.p.h.

COMMENTS: Only two prototypes ordered

Type: Long-range escort fighter

Accommodation: Pilot only

Power Plant: One × Allison V-3420-23 liquid-cooled engine, rated at 2,885 hp driving three-blade contra-rotating propellers

Performance: 433 mph at 20,000

Comment: The disappointing results of the test program with the General Motors/Fisher XP-75 “Eagle” led to a complete re-design of the aircraft. Furthermore, in mid-1943, the need for long-range escort fighters became more urgent than fast climbing interceptors so a decision was made to order six more XP-75 airplanes modified for the long-range role. At this time, an order for 2,500 production aircraft was also let, but with the stipulation that if the first production version P-75A was not satisfactory the complete order might be canceled.
At the time, General Motors was busy in several projects towards the war effort, including the mass production of several different aircraft types, among them the Grumman TBM “Avenger”. Redesigns of the P-75A “Eagle” were introduced including a new outer wing section from the North American P-51 “Mustang”, a modified tail assembly, new “bubble” canopy, and a V-3420-23 engine that corrected most of the deficiencies by the time the first P-75A “Eagles” entered flight test in September 1944.
By this time, the Army Air Forces decided to limit the number of combat aircraft types in production and not enter into large-scale production of new types that might not be available before the war ended. As the twin-engine Lockheed P-38 “Lightning” and North American P-51 “Mustang” demonstrated excellent long-range capabilities the production run of the P-75A “Eagle” was substantially terminated on October 1944. Although the “Eagle” was given extensive media coverage prior to its first flight, being trumpeted as a “wonder plane”, it was decided to use the six completed production aircraft for experimental work and development of the V-3420 engine. As a result of these events, the P-75A did not complete formal performance trials due to termination of the production contract. Ultimately, only eight XP-75s and six P-75As were built (Ref. 24).

Type: High-altitude interceptor fighter

Accommodation: Pilot only

Power Plant: One × Allison V-3420-19 liquid-cooled engine, rated at  2,600 hp, driving three-blade contra-rotating propellers

Performance: 433 mph at 20,000

Comment: The General Motors/Fisher XP-75 “Eagle” was a fighter aircraft designed by the Fisher Body Division of General Motors. Development started in September 1942 in response to USAAF requirement for a fighter possessing an extremely high rate of climb, using the most powerful liquid-cooled engine then available, the Allison V-3420.
In October 1942, the contract for two prototypes was signed. The design concept was to use the outer wing panels from the Curtiss P-40 “Warhawk”, the tail assembly from the  Douglas A-24 (SBD) “Dauntless”, and the undercarriage from the Vought F4U-1 “Corsair” in a general layout much as in the Bell P-39 “Airacobra” with the engine located amidships with the propeller driven through an extension shaft.
In mid-1943, the need for long-range escort fighters became more urgent than fast climbing interceptors so a decision was made to order six more XP-75 airplanes modified for the long-range role. At this time, an order for 2,500 production aircraft was also let, but with the stipulation that if the first P-75A was not satisfactory the complete order might be canceled.
Powered by a V-3420-19 24-cylinder engine rated at 2,600 hp driving co-axial contra-rotating propellers, the XP-75 flew for the first time on 17 November 1943. The second XP-75 flew shortly thereafter, with all six long-range XP-75s entering the test program by the spring 1944. The test program brought up numerous teething problems, including miscalculation of the fighter’s center of mass, failure of the engine to produce its expected power, inadequate engine cooling, high aileron forces at high speed, and poor spin characteristics. These failures led to a complete redesign of the aircraft to a long-range escort fighter with the unchanged designation P-75 “Eagle” (Ref. 24).

TYPE: Long-range Escort Fighter

ACCOMMODATION: Pilot only

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

PERFORMANCE:  490 m.p.h. at 25,000 ft

COMMENT: At the time when the famous Republic P-47 “Thunderbolt” was not ordered by USAAF for mass production, Republic worked on a completely different fighter, the Republic XP-69. But in 1943 this project was cancelled in favour of a less radical design, the XP-72, and two prototypes were ordered. The first flew on 2 February 1944 with a four bladed propeller; the second XP-72 prototype had Aero Product contra props. An initial production contract for 100 aircrafts was ordered, which were foreseen as being useful for combat with V-1s, being launched in Europe at that time. But the need for long-range escort fighters declined, so the order was cancelled