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Curtiss P-304

Single-Seat, Single-Engine Jet-Powered Fighter Proposal [ 1945 ]

The Curtiss P-304 existed in two proposed forms - both jet-powered - and borrowed heavily from the abandoned XP-55 Ascender program.

Authored By: Staff Writer | Last Edited: 05/16/2022 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

The Curtiss had one of the classic fighters of the World War 2 (1939-1945) era in the P-40 "Warhawk" (detailed elsewhere on this site) but this design was soon superseded by those of greater performance and firepower. Even so, the company attempted to stay relevant before the end of the war arrived in 1945, putting forth several imaginative fighter concepts of both prop- and jet-driven design. One of the latter was actually a dual-proposal under the "P-304" project designation and centered on a design study for a new single-seat, jet-powered fighter form utilizing data collected from Curtiss' earlier XP-55 "Ascender" fighter prototype (detailed elsewhere on this site). The P-304 attempted to better the XP-55 design by implementing a jet powerplant while retaining much of the unique features of the prop-driven Ascender fighter.

The single-seat, single-engine XP-55's arrangement is its best-remembered quality as it seated the engine at the rear of the fuselage, had swept-back wing mainplanes and nose-mounted canards (smaller, forward wings). The pilot's cockpit was situated just forward of midships with the engine to his immediate rear which cleared the nose assembly to hold all of the intended armament - 4 x 0.50 heavy machine guns. A modern tricycle undercarriage was fitted for ground-running and power originated from an Allison inline engine driving a three-bladed propeller in a "pusher" configuration. The wing mainplanes were given vertical planes at their tips for stability and control. Compared to other fighters of the period, the XP-55 certainly may have appeared as the future of combat flying. A first-flight was held on July 19th, 1943.

In the end, however, only three examples came to be and two were lost in crashes. Despite its arrangement, the aircraft could not best the latest prop-driven designs in terms of performance and added little to the mix despite its uniqueness. Jet-powered forms were also beginning to take center stage which further doomed the XP-55 project to history.

From this experience, Curtiss forged ahead with its P-304 beginning in March of 1945. Again a single-seat, single-engine format was used and canards were once again fitted at the nose. The aircraft would retain nose-mounted armament and feature its engine in the aft section of the fuselage behind the pilot. The wing mainplanes were swept-back to promote high- speed flying. The primary difference between the preceding XP-55 and the P-304 was the relocation of the vertical fins from the wingtips to the tail, this now as a single fin.©MilitaryFactory.com
For all this, the P-304 proposal was nothing more than the XP-55 fitted with a jet engine with a few changes to suit the new approach. The intended engine was to be the General Electric TG-180 turbojet outputting 4,000lb of thrust.

To improve upon the lackadaisical performance figures encountered when flying the XP-55, the P-304 was drawn up with a turbojet engine powerplant from the beginning but this soon led to the two distinct forms being proposed: the P-304-4, with a nose-mounted intake used to aspirate the engine within the fuselage, and the P-304-5, with side-mounted, underwing intakes. Both designs saw the engine exhaust through a single port at the rear of the fuselage, located just under the vertical tail plane. In addition to this, the swept-back wing mainplanes, which promoted high-speed flight, were shoulder-mounted and set near midships. A tricycle undercarriage would be retained from the XP-55 design and aluminum alloy would be used throughout the construction of both aircraft.

With their new P-304, Curtiss engineers hoped to solve various issues encountered with the XP-55 - namely performance (including operational range) and stability / control. Range would be augmented by the use of wingtip fuel tanks, a common fixture in early jet-powered fighters.

Curtiss engineers estimated a maximum speed between 600 and 622 miles-per-hour depending on altitude with a rate-of-climb of 5,530 feet-per-minute possible. Combat radius was listed at 500 miles. Both aircraft had an overall length of around 33 feet with the P-304-5 being slightly longer by a few inches and the P-304-4 was the heavier of the two by a few hundred pounds due to its longer duct work assembly and strengthened undercarriage required for the special configuration. The P-304-4 would also feature more internal fuel stores to achieve the desired range and offset its weight gains.

Neither the P-304-4 nor the P-304-5 were furthered beyond paperwork and concept art. The end of the war in 1945 and the military drawdown that followed doomed such outlying projects like the P-304 in full - leaving their potential and ultimate influence to the imagination of the reader.©MilitaryFactory.com
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Curtiss-Wright - USA
United States (cancelled)
Operators National flag of the United States
Service Year
United States
National Origin
Project Status

General ability to actively engage other aircraft of similar form and function, typically through guns, missiles, and/or aerial rockets.
Aircraft developed for the role of prototyping, technology demonstration, or research / data collection.

33.8 ft
(10.31 meters)
40.0 ft
(12.20 meters)
9,921 lb
(4,500 kilograms)
Empty Weight
14,473 lb
(6,565 kilograms)
Maximum Take-Off Weight
+4,553 lb
(+2,065 kg)
Weight Difference

1 x General Electric TG-180 turbojet engine developing 4,000lb of thrust.
621 mph
(1,000 kph | 540 knots)
Max Speed
36,089 ft
(11,000 m | 7 miles)
500 miles
(805 km | 435 nm)
5,530 ft/min
(1,686 m/min)

MACH Regime (Sonic)
RANGES (MPH) Subsonic: <614mph | Transonic: 614-921 | Supersonic: 921-3836 | Hypersonic: 3836-7673 | Hi-Hypersonic: 7673-19180 | Reentry: >19030

4 x 0.50 caliber (12.7mm) heavy machine gun.


P-304 - Base Series Designation
P-304-4 (Type I) - First proposal with nose-mounted intake; heavier design with reinforced undercarriage and additional internal fuel stores.
P-304-5 (Type II) - Second proposal with side-mounted intakes.

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