Pratt & Whitney X-1800

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X-1800 (XH-2600)
P&W X-1800.jpg
Type 24-cylinder H-engine
National origin United States
Manufacturer Pratt & Whitney
First run 1940
Number built 1

The Pratt & Whitney X-1800 (later enlarged as the XH-2600) was an H-block aircraft engine project developed between 1938 and 1940, which was cancelled with only one example being built.

Design and development[edit]

The X-1800 was a watercooled 24-cylinder H-block of 2,240 in3 displacement;[1] this was later expanded to 2,600 in3 displacement.[2] It was intended to be used in the Vultee XP-54, Curtiss-Wright XP-55 Ascender, Northrop XP-56, and Lockheed XP-49. Projected performance was to be 1,800 to 2,200 hp (1350-1640 kW), with a turbocharger to secure high-altitude performance. The designation came from the intended power rating rather than the more usual cubic inch engine displacement figure.[3]

The target date for series production was 1942. In 1940, however, performance on the test bench did not continue to improve, demonstrating a need for considerable additional development effort. Pratt & Whitney subsequently ended development of the X-1800 in October 1940, with only one built, to concentrate on radial engines.



Specifications (X-1800)[edit]

General characteristics

  • Type: 24 cylinder H-engine
  • Bore: 5.25in (133.35mm)
  • Stroke: 5.00in (127mm)
  • Displacement: 2,597.7 cu in (42.57L)
  • Length: 107in (2.71m)
  • Dry weight: 2,400lb (1,089kg)



  • Power output: 1,800 - 2,000 hp

See also[edit]

Related development
Comparable engines
Related lists



  1. ^ Gunston 2006, p. 163.
  2. ^ Connors, p. 147.
  3. ^ Gunston 2000


External links[edit]