Lockheed XF-90A - USAF's First Jet With Afterburners

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Lockheed XF-90A

   Hello everybody. I’d like to suggest the Lockheed XF-90A for US aviation in War Thunder. The Lockheed XF-90A was a prototype escort and penetration fighter built in response to the United States Air Force requirement in 1945. It was the first USAF swept-wing fighter jet to be equipped with afterburners. Due to woefully underpowered Westinghouse J34 powerplants, the XF-90A lost to the McDonnell XF-88A Voodoo in the competition and never entered production.

Key Characteristics

  • Long-Range Jet Fighter
  • Sturdy airframe with swept wings and wingtip fuel tanks, inheriting some traits from the F-80A design
  • Two Westinghouse J34-WE-15 axial-flow turbojet engines with an afterburning capability
  • 6 x 20-mm cannons (not installed in the prototype but planned)

Credit goes to @Disco_Shrimp for some historical corrections. Thank you!

History

On August 28, 1945, the United States Army Air Forces (later separated as the United Air Forces) announced a new requirement for a twin-engine penetration fighter with swept wings capable of escorting jet-power bombers over enemy territory and back. It was required to have a combat radius of at least 900 miles.

By this time, World War II was over in Europe and the Pacific. The air doctrine was reshaped and advocated that the large formations of bombers, escorted by long-range fighters, would cause mass destruction on enemy targets below. The fighter escort was essential for the survival of bombers in enemy airspace. With the Soviet Union being the chief Cold War contender, it was undoubtedly attempting to outpace the West with its numerous jet-powered fighters and bombers.

The requirement sought a new fighter that fulfills the long-range penetration fighter and bomber escort roles. Although both terms had similar concepts, they differed in tactical movements. The penetration fighter’s role would not operate in close formation with bombers. Instead, it would penetrate deeper enemy airspace and neutralize any threats ahead of the bombers. These fighters could return to the bombers and continue the escort duty after the incursion. The North American P-51 Mustangs had demonstrated this part of the air doctrine during the turning points of the air war in World War II. In the post-war period, the development of jet-powered strategic bombers made propeller-driven fighters and earlier non-afterburning jet fighters difficult to keep up. Hence, this requirement was created in the first place to bring more modern aircraft designs powered by the after-burning jet engines.

Competitors for the contract included McDonnell’s XF-88A, North America’s YF-93, and Lockheed’s XF-90. Lockheed received a contract to construct two prototype XF-90s on June 20, 1946.

In 1947, the XF-90 had originally been a delta-winged design, but wind tunnel tests indicated that such a configuration would not be viable. It was later redesigned with 35-degree sweptback wings, a sharply-pointed nose, and two Westinghouse J34-WE-11 axial-flow turbojet engines mounted side-by-side in the rear fuselage and fed by side-mounted air intakes. The wings were featured with the leading-edge slats, Fowler flaps, and ailerons on the trailing edge. The cockpit was pressurized and fitted with an ejector seat and a bubble canopy. The internal fuel could be supplemented by wingtip-mounted tanks, totaling a capacity of 1,665 US gallons. One of the most innovative features of the XF-90 design was its variable incidence vertical tail fin, which could be adjusted to move forward or back to assist in adjusting the horizontal stabilizers. The aircraft was designed to be fitted with six 20-mm cannons horizontally below the engine intakes, with three guns to each intake. It was also capable of carrying two 1,000-lb bombs and eight 5-inch rockets.

Consequently, the early changes to the XF-90 designs forced a delayed first flight. The first prototype XF-90 (46-687) was finally ready for flight testing in the spring of 1949. The prototype was initially fitted with non-afterburning J-34-WE-11 turbojet engines. It was found to lack the necessary power for take-off, so it was fitted with Rocket-Assisted Take-Off canisters for support. The prototype made its maiden flight on June 3, 1949, out of Edwards Air Force Base. Although the test flight was completed without problems, the performance was disappointing because of its excess weight and the power of its non-afterburning J-34 engines. In search of more power, this prototype was also the first to be retrofitted with afterburning engines and redesignated XF-90A. It flight-tested with the afterburners on September 16, 1949, during 24th flight testing.

Lockheed built the second prototype XF-90 (46-688) and initially fitted it with afterburning J34 turbojets. This prototype was never redesignated XF-90A. The XF-90 completed its first flight on April 12, 1950. It had achieved a maximum speed of 668 mph in level flight at sea level and reached a maximum speed of Mach 1.12 in a dive. It went on to exceed the sound barrier several times without any structural problems. This XF-90 had almost cost the life of an experienced test pilot when it had great difficulty in pulling out of a dive but avoided a total crash towards the earth.

Although the improved performance was better than most early fighter jets, it was still insufficient to be considered acceptable to the USAF. The fly-off between the Lockheed XF-90A, the McDonnell XF-88A, and the North American YF-93A occurred between June 30, 1950, and July 8, 1950, for the final evaluation by the USAF officials. On August 15, 1950, the Evaluation Board declared the McDonnell XF-88A the winner. McDonnell secured the production contract in September 1950, but the penetration fighter project was later canceled and abandoned due to the changes in Air Force priorities, along with a budget deficit.

The XF-90s’ inadequate performance was mainly attributed to the excessive weight and underpowered powerplants. The XF-90s were built with 75ST aluminum rather than the then-standard 24ST aluminum alloy, along with heavy forgings and machined parts. These materials made the airframe very sturdy. However, these materials resulted in an aircraft with an empty weight more than 50% heavier than its competitors. The bottom line of the issue with this overall aircraft design was described as “overbuilt and underpowered.”

After losing the production contract, the two remaining prototypes were subjected to additional testing. The disposition of the first prototype (46-687) was unknown. Despite conflicting sources, It was not handed over to any NACA tests as it did not show up in NACA records. Presumably, it was destroyed during the crash fire tests along with almost 100 other aircraft. The other XF-90A (46-688) had survived three atomic blasts at Frenchman Flat within the Nevada Test Site in 1952. In 2003, the XF-90A (46-688) was recovered from the Nevada Test Site; it was decontaminated and restored as the museum aircraft on display at the National Museum of the United States Air Force in Dayton, Ohio.

Specifications

Lockheed XF-90A

General Characteristics

  • Crew: 1 (Pilot)
  • Length: 56 ft 2 in (17.12 m)
  • Height: 15 ft 9 in (4.78 m)
  • Span: 40 ft (12.20 m)
  • Wing area: 345 sq ft (28.4 sq m)
  • Powerplant: 2 x Westinghouse J34-WE-15 afterburning axial-flow turbojet engines
    → 8,400 lbf (37.4 kN) thrust A/B
    → 6,000 lbf (26.7 kN) thrust dry
  • Internal Fuel: 1,665 US gal. (6302 L)
  • Empty weight: 18,050 lb (8,204 kg)
  • Gross weight: 27,200 lb (12,363 kg)
  • Max. Takeoff Weight: 31,060 lb (14,118 kg)

Performance

  • Thrust-Weight Ratio: 0.30
  • Sea Level Speed: 668 mph (1,075 km/h)
  • Wing Loading: 79 lb/sq ft (386 kg/sq m)
  • Rate of Climb: 5,555 fpm (28.2 m/s)
  • Time of Climb: 4.5 minutes to 25,000 ft (7,620 m)
  • Service Ceiling: 39,000 ft (11,890 m)
  • Range: 2,300 miles (3,680 km)

Armament

  • Guns:
    • 6 x 20-mm M24 cannons (unknown # of rounds)
  • Bombs:
    • 2 x 1000-lb bombs
  • Rockets:
    • 8 x 5-inch (127-mm) HVARs
  • Others:
    • RATO Canisters
Diagrams

Cockpit

Images

Conclusion | Why it should be in the game

   The XF-90A was the first USAF jet with an afterburner and the first Lockheed jet to fly supersonic, only in a dive. Along with other innovative features, its underpowered performance did not win the contest. However, I feel it should be added as the earliest jet fighter with an afterburning capability for US aviation in War Thunder. It would serve as a transitional aircraft between the F-80 Shooting Star and the F-104 Starfighter. Its subpar acceleration and excessive weight, combined with the sturdy airframe to withstand some substantial damage, would make it a decent energy fighter and support fighter at best in the game.

See Also

I made a suggestion of the North American YF-93A Sabre, the XF-90A’s competitor. If you’re interested in this suggestion, check this out!

Sources

Thank you for taking the time to read my suggestion! 😃

6 Likes
2

How could anyone say no? But ol’ +1 from me man!

1 Like
3

Looks so damn cool! +1

1 Like
4

+1 Beautiful, Just Beautiful!

1 Like
5

Yeah I could see this as a great premium

6

Oh, it isn’t the hundredth clone of already existing plane? Wow!.. Good one.

7

… what? In what way does that indicate it was a clone of the already existing plane? Do you even look up and read on this particular aircraft?

1 Like
8

Definite +1!

Though hopefully not in the condition I found it in Dayton

Spoiler

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2 Likes
9

A +1 from me, I would absolutely love to have the XF-90 in-game!

1 Like
10

-1

This plane was a neither a technological milestone nor it had any any impact on military aviation history. Even as i would describe myself as aviation enthusiast i see no point of adding a “loser plane” to war thunder - this aircraft is just a typical example of failed aircraft design & engineering.

The game lacks a lot of actually important early jets like the F-94 Starfire which saw combat in Korea - there is no need to waste any resources on prototypes (i exclude aircraft which were not built due to political reasons like the YF-23) which were inferior to their rivals.

12

“No loser aircraft! But also trust me the YF-23 was not a loser because uhhh.”
But you’re right the F-94 family should be a priority.

2 Likes
13

Definite plus one, gorgeous looking aircraft.

1 Like
14

Well. Counter question. Did you even read what I wrote? If so does “isn’t” mean something?

This thread definitely not bad, as is the specific craft. Which can’t be said about most of your other threads with two hundred thousand clone vehicles (with a million more well on the way for sure). Forgive me my lack of sarcasm restraint, huh. Plane’s good, pretty interesting it is.

1 Like
15

You missed the point regarding the XF-90:

Despite the area rule was discovered long before and was even applied to real aircraft (Ju 287 in 1944) the Lockheed engineers were unable to understand it - that’s why it was a failed design. Without the “coke bottle design” the drag increase ~ Mach 1 required way more power than the engines could deliver. Look up the F-102 story for more details.

Underpowered jets were nothing special at this time as the engine technology was either inferior (radial flow like the UK) or the demands / requirements of the USAF were too ambitious (=increasing weight) and could not be met due to a lack of power / thrust like in this case.

The YF-23 is a complete other story - and the fact that the F-22s was planned to retire from 2030 onwards whilst other nations are working on planes looking quite similar to the YF-23 might give you a hint that the claim that the YF-23 was the best fighter never going into production might be more than a myth / legend.

16

Just some small corrections in your history section:

  1. The first XF-90 prototype was also the first to be fitted with afterburning engines, the 24th test flight being the first with afterburners on 16 September 1949. Initial flights did use the XJ34-WE-22 before being replaced with the XJ34-WE-11 on the 24th flight. The second prototype wouldn’t fly until 12 April 1950, as stated in your history section. On top of this, the aircraft was never designated XF-90A; the confusion probably comes from the competing XF-88, which was redesigned to accept afterburning engines and redesignated XF-88A. The XF-90 was designed to take an afterburning engine from the start, with the first studies dating back to November 1947.

  2. The disposition of the first prototype is entirely unknown. It does not show up in any NACA records. If by chance it did elude all surviving records, it was most likely destroyed during the Crash Fire tests along with almost 100 other aircraft.

The XF-90 was definitely a great design, the downfall being the terrible engines it was fitted with. The initial afterburning XJ34-WE-11 engines, which were simply the XJ34-WE-22 engines fitted with afterburning equipment, were found to be much worse than expected, providing 20% less (!) thrust than the Westinghouse guarantee when not afterburning and 17.5% less thrust than the guarantee when afterburning. New XJ34-WE-11 engines were acquired for tests in November 1949 to replace the initial engines while they were being inspected (these engines had severe reliability issues and were prone to damage). Static tests of these engine revealed that afterburning only increased thrust by 35% while increasing fuel consumption by a whopping 80%. It was also determined from these tests that the non-afterburning thrust could be increased by 15.5% if false afterburners were fitted. Starting from the 63rd test flight, false afterburners were fitted until Westinghouse could develop an improved afterburner. The first XF-90 would never receive these engines, for it was the second XF-90 that would be fitted with the XJ34-WE-15 engines.

2 Likes
17

Great info, thanks! I presumed you got that information from Lockheed XF-90 Penetration Fighter by William Simone, which is an excellent source to read and research on this particular aircraft.

I have updated the history section.

1 Like