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Curtiss XP-40Q (Warhawk)

Single-Seat Monoplane Fighter Prototype Aircraft

The Curtiss XP-40Q became the fastest of the Warhawk fighter line but still could not match the capabilities of competitors during World War 2.
Authored By: Staff Writer | Edited: 7/13/2018
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Year: 1943
Status: Cancelled
Manufacturer(s): Curtiss Aeroplane Company - USA
Production: 3
Capabilities: Fighter; X-Plane;
Crew: 1
Length: 35.27 ft (10.75 m)
Width: 35.20 ft (10.73 m)
Weight (Empty): 6,173 lb (2,800 kg)
Weight (MTOW): 8,999 lb (4,082 kg)
Power: 1 x Allison V-1710-121 liquid-cooled inline piston engine developing 1,425 horsepower and driving four-bladed propelled unit at the nose.
Speed: 423 mph (680 kph; 367 kts)
Ceiling: 39,009 feet (11,890 m; 7.39 miles)
Range: 994 miles (1,600 km; 864 nm)
Rate-of-Climb: 2,000 ft/min (610 m/min)
Operators: United States (cancelled)
As important as the Curtiss P-40 Warhawk fighter series was to the Allied cause in the early-going of World War 2 (1939-1945), it nonetheless held roots in the pre-war period. As such, it was quickly becoming outpaced by more modern wartime developments that were driven by practical combat experience. Curtiss attempted several programs to evolve their P-40 product along but all failed in the end. The XP-40Q was one such attempt and this work was intended as an ultimate incarnation of the P-40 but it, too, failed to see adoption as it was still an outmoded design when compared to contemporaries like the Republic P-47 Thunderbolt and North American P-51 Mustang fighters.

The XP-40Q began in offshoot projects like the Model 87X and the XP-40N of 1943 and each incorporated several modern changes to keep the machine a viable gunnery platform for the foreseeable future. The Model 87X evolved to become the XP-40Q and this endeavor involved a pair of P-40K airframes and a single P-40N.

The first P-40K aircraft was outfitted with an Allison V-1710-121 rated at 1,425 horsepower output and held its cooling intakes at the wings. The engine cowling was redesigned as a much closer-fitting cover to encourage aerodynamic efficiency. All other qualities of the fighter were still rooted in the original P-40 which only worked against the design. This prototype was designated simply as "XP-40Q".

The second P-40K had the cooling intakes replaced by a more traditional, small-area chin scoop and was completed with a more useful bubble-style canopy. The bubble canopy allowed the rear dorsal section of the fuselage to be cut-down for streamlining and as a weight-savings measure. A section of bulletproof glass was mounted inside the curved windscreen for pilot protection. The supercharged engine featured water injection for additional war power output and drove a four-bladed propeller unit over the original's three-bladed unit. This prototype became "XP-40Q-1" in the lineup.

Then followed the third prototype - "XP-40Q-2" - whose only major feature was clipped wing tips to add a slight bump in speed. This quality was also later added to the first prototype.

With the changes in place, the Q-series became the fastest Warhawks of the Curtiss family of fighters, netting speeds over 420 miles per hour (422 mph officially). Earlier marks did not even exceed 400mph. However, this was not enough to compete with the numbers of P-47 and P-51 fighters coming off production lines and were more than ready to tackle a variety of over-battlefield roles. This inevitably led the Q-series to find its end before 1945.

In the post-war period, two prototypes were scrapped. XP-40Q-1 found a slightly extended life as it was purchased for competition flying in the Cleveland Air Races. During the 1947 Thompson Trophy Race, its engine caught fire and the pilot baled - the aircraft becoming a total loss as it crashed in flames.

As finalized, the XP-40Q showcased a wingspan of 35.2 feet and a length of 35.3 feet. It's loaded weight was 9,000lb. Maximum speed was 422 miles per hour with a service ceiling of 39,000 feet. Power stemmed from a single Allison V-1710-121 outputting 1,425 horsepower. The design was never outfitted with armament - its suite proposed as 4 x 0.50 caliber Browning heavy machine guns. This was another limiting weight-savings measure that ultimately would have lacked the punch of its competitors.


4 x 0.50 caliber heavy machine guns in wings (two per wing).

Graphical image of an aircraft medium machine gun
Graphical image of an aircraft heavy machine gun

Variants / Models

• XP-40Q - Base Series Designation; three conversion models used in testing.
• XP-40Q-1 - Single example with Allison V-1710-121 engine driving four-bladed propeller unit.
• XP-40Q-2 - Two examples completed with cut-down fuselage, bubble canopy and clipped wing tips.
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