Curtiss XP-60 - A Series of Misdirected Attempts to Get Things Right (I)

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Curtiss XP-60 (Model 90/90A)

   Hello, everyone. I’d like to introduce the Curtiss XP-60 as a potential addition to US aviation in War Thunder. Developed in 1940 for the US Army Air Corps, the XP-60 was one of the final efforts to design a successor to the P-40 Warhawk. The aircraft was initially built using the P-40D airframe, featuring a low-drag laminar-flow wing and powered by a Rolls-Royce Merlin engine. However, it did not enter production due to concerns about a potential shortage of Packard-built Merlins. Ultimately, the XP-60 underwent extensive experimentation with various engines and significant modifications to the airframe, with development continuing until late 1944.


TL;DR:

An initial prototype XP-60 of Model 90/90A built with a Merlin engine, laminar-flow wings, and eight machine guns that closely resemble the P-40 Warhawk


History

Background

With the Curtiss P-40 Warhawk entering production by 1940, Curtiss began an ambitious effort to develop a superior aircraft that could replace the P-40. The US Army Air Corps (USAAC) was interested in supporting these efforts and awarded a contract to fund the development of potential successors.

Curtiss initially designed the XP-46 prototype, which shared similarities with the P-40, except it was built to be smaller and equipped with an inward-retracting undercarriage. The XP-46 took its first flight on February 15, 1941, but it offered no meaningful performance improvements over the P-40 and was outright rejected by the USAAC.

After the XP-46 did not secure production orders, Curtiss shifted focus to a new design: the Model 88, later designated the XP-53 by the Army. This model was intended to use a Continental XIV-1430-3 engine. However, engine development issues led to the cancellation of the XP-53 before it could be built.

Curtiss then moved on to the development of Model 90, which was designated XP-60. At the Army’s request, the XP-60 was initially designed to be powered by a Rolls-Royce Merlin engine and include laminar-flow wings, a type of airfoil designed to reduce drag and make the aircraft fly faster. Curtiss produced four airframes during this project, which resulted in nine different designations: XP-60, XP-60A, YP-60A, P-60A, XP-60B, XP-60C, XP-60D, XP-60E, and YP-60E. These versions represented Curtiss’ long and desperate attempts to develop a worthy successor to the P-40—efforts that lasted until late 1944.

XP-60 - Model 90/90A - Initial Prototype

The Model 90, also known as the XP-60, was Curtiss’ initial prototype in the P-60 series. It was ordered on October 1, 1940, specifying one of the two XP-53 prototypes to be reused and developed as the XP-60. Two months later, the Army requested the incorporation of a Rolls-Royce Merlin engine, leading to the aircraft’s redesignation as the XP-60. This prototype used the P-40D’s fuselage and tail assembly combined with the laminar-flow wing. It retained the inward-retracting undercarriage from the P-40.

Powering the XP-60 was a 1,300-hp Packard V-1650-1 Merlin engine, a license-built, liquid-cooled engine fitted with a single-stage, two-speed mechanical supercharger. The radiator was relocated farther back under the nose to accommodate this configuration. Planned armament included eight M2 Browning machine guns, each with 250 rounds, with a total of 2,000 rounds. To enhance combat survivability, the aircraft was designed to include armor protection for the pilot and self-sealing fuel tanks.

The preliminary design for the XP-60 was presented to the Army on January 16, 1941, and subsequently approved by the Army. Construction began shortly after, and by September 16, 1941, the aircraft initiated taxi trials with the Merlin engine installed. Just two days later, it made its maiden flight, only 11 days after the first flight of the XP-46. During initial testing, undercarriage failures caused damage, prompting design tweaks like enlarging the vertical tail. These changes led to a redesignation of the Curtiss Model 90A. Self-sealing fuel tanks and a bulletproof windscreen were later installed. By the spring and summer of 1942, the aircraft was sent to the Army Air Forces for further testing.

Despite modifications being made prior to the subsequent testing, the XP-60’s engine underperformed as it failed to deliver the expected power output. Additionally, the aircraft’s wings did not meet manufacturing standards, meaning they failed to provide the full benefits of laminar flow and negatively impacted its flight performance. The XP-60 only achieved a top speed of 387 mph.

With the aircraft falling short of Army expectations, with concerns about a potential shortage of Packard-built Merlin engines, the Army instructed Curtiss to experiment with installing alternative engines in the XP-60 airframe. This led to the development of the XP-60D in August 1942, which was equipped with an uprated V-1650-3 Merlin engine, the same engine used in the P-51 Razorback Mustang. The conversion to the P-60A and P-60D marked the end of the first phase of XP-60 development.


Specifications

Curtiss XP-60 (Model 90/90A)

General Characteristics

  • Crew: 1 (Pilot)
  • Length: 33 ft 7.5 in (10.23 m)
  • Height: 12 ft 4 in (3.75 m)
  • Span: 41 ft 5.25 in (12.62 m)
  • Wing Area: 275 sq ft (25.54 sq m)
  • Propeller Type: 3-bladed Curtiss Electric propeller
  • Propeller Diameter: 11 ft (3.35 m)
  • Powerplant: Packard V-1650-1 Merlin liquid-cooled engine
    → 1,300 hp (956 kW)
  • Internal Fuel: 135 - 228 US gal. (511 - 863 L)
  • Empty Weight: 7,008 lb (3,179 kg)
  • Gross Weight: 9,277 lb (4,208 kg)
  • Max. Takeoff Weight: 9,700 lb (4,400 kg)

Performance

  • Power-to-Weight Ratio: 0.14 hp/lb (0.23 kW/kg)
  • Cruising Speed: 314 mph (505 km/h)
  • Critical Altitude Speed:
    • 380 mph @ 20,000 ft (612 km/h @ 6,096 m)
    • 387 mph @ 22,000 ft (623 km/h @ 6,706 m)
  • Wing Loading: 33.7 lb/sq ft (164.8 kg/sq m)
  • Average Initial Rate of Climb: 2,055 fpm
  • Time to Altitude: 7.3 minutes to 15,000 ft (4,572 m)
  • Service Ceiling: 29,000 ft (8,839 m)
  • Range: 800 - 1,100 miles (1,287 - 1,770 km)

Armament

  • Guns:
    • 6 to 8 x 0.50-cal. M2 Browning machine guns (250 rpg; 2,000 rounds)

Diagrams


Images


Conclusion | Why it should be in the game

   The addition of the Curtiss XP-60 series would bring an interesting variety of “what-could-have-beens” to US aviation in War Thunder, offering a potential successor to the P-40 Warhawk. While the XP-60 could match the P-40F Warhawk in speed, it was heavier but compensated with superior firepower, increasing to eight heavy machine guns. It would excel in Boom-and-Zoom tactics and head-on engagements thanks to its armor protection and combat durability.

   What makes the XP-60 series unique is its flawed but exhaustive development history—a series of prototypes that never fully evolved into a reliable fighter for the US Army Air Forces. Despite its potential, the XP-60 ultimately symbolized Curtiss’ final effort to secure production orders and replace the Warhawk during World War II, an ambition that unfortunately never came to fruition.


See Also - P-60 Family

XP-60D (Model 90B)

XP-60A (Model 95A)

XP-60C (Model 95C)

XP-60E (Model 95D)

YP-60E


Sources

  • Curtiss Aircraft 1907-1947 (1979)
  • The American Fighter The Definitive Guide to American Fighter Aircraft from 1917 to the Present (1987)
  • US Fighters of World War Two (1991)
  • America’s Hundred Thousand US Production Fighters of WWII (1997)
  • US Experimental & Prototype Aircraft Projects: Fighters 1939-1945 (2008)
  • Curtiss Company Profile 1907–1947 (2014)
  • Curtiss P-60
  • Curtiss P-60 - Wikipedia

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

1 Like

A +1 from me! Would be neat to have the base XP-60 in game!

1 Like

Looks boring, all 5 of them. And we already have plenty of boring looking american planes with boat-like fly performance.

You are entitled to your opinion, and I think your opinion is wrong.

There are plenty of interesting American planes, and not all of these have gunboat flight performance. P-38 Lightnings, P-63 Kingacobras, P-51 Mustangs, and F4U Corsairs are fascinating aircraft with DEFINITELY NOT boat-like flight performance. They are energy fighters that require greater discipline and skill to fly.

I can list more that are yet to come to War Thunder. Aircraft such as P-63D Kingacobra, XP-40Q-2A Warhawk, turbo-supercharged FG-3 Corsair, F4U-5 Corsair, XP-67 Moonbat, Republic XP-72 Thunderbolt, and FR-1 Fireball are examples of genuinely fascinating aircraft with overall decent performance.

Anyway, I made P-60 suggestions on behalf of someone else, and I also found these aircraft interesting, given their history as an attempt to supersede the P-40 Warhawk. You can vote whatever you’d like, however.

1 Like