| XF15C | |
|---|---|
 A XF15C in flight | |
| General information | |
| Type | Fighter |
| National origin | United States |
| Manufacturer | Curtiss Aeroplane and Motor Company |
| Number built | 3prototypes |
| History | |
| First flight | 27 February 1945 |
TheCurtiss XF15C-1 is a mixed-propulsion (piston andjet-powered)fighter aircraft prototype of the 1940s. Designed and built by theCurtiss Aeroplane and Motor Company, it was one of two similar designs ordered by theUnited States Navy (USN) before pure-jet aircraft had demonstrated their ability to operate fromaircraft carriers and the mixed-propulsion designs were abandoned. Only three prototypes were constructed, the first one having crashed in testing while the second was scrapped and the last survives to this day.
By 1943 theUnited States Navy became interested in the mixed-power concept for its shipborne fighters. Jet engines of that era had very slowthrottle response, which presented a safety concern in the case of amissed approach on anaircraft carrier as the aircraft might not be able to throttle up quickly enough to keep flying after leaving the end of the deck. In addition the jet engine consumed a lot of fuel so a piston engine could provide power while cruising and extend the aircraft's range, while using the turbojet for combat.[1] This led to orders for two mixed-propulsion fighters, the XF15C and theRyan FR Fireball. The latter aircraft came first and was designed around a 1,425-horsepower (1,063 kW)Wright R-1820 Cyclone piston engine and a 1,600pounds-force (7,100 N)General Electric J31 turbojet and was intended for use onescort carriers. The XF15C was a much larger aircraft intended to equip theMidway-class aircraft carriers for longer-range missions.[2][3]
During this time, the Curtiss design team was focused on developing the XF14C, a high-altitude fighter intended to use the liquid-cooled,Lycoming XH-2470 Hyper engine or theWright R-3350 Duplex-Cycloneradial engine, both of which were still under development. The Lycoming engine proved to be a failure and the high-priorityBoeing B-29 Superfortress bomber absorbed the bulk of the Wright engines. By late 1943 Curtiss was convinced that investing more resources into the XF14C would be a waste of time and began to search for alternatives. They decided to compete for the mixed-power fighter role instead and began preliminary design work on a high-performance aircraft that could compete with theGrumman F6F Hellcat and theVought F4U Corsair using aPratt & Whitney R-2800 Double Wasp piston engine, and a 2,700-pound-force (12,000 N)Allis-Chalmers J36turbojet. TheBureau of Aeronautics knew the XF14C program was at a dead end and was amenable to the idea. Curtiss submitted a preliminary proposal in December that was accepted. The bureau was willing to transfer the design team and assets from the XF14C program on that basis and would award a new contract for the XF15C if the final design was acceptable.[3][4]
Curtiss delivered its final proposal on 1 February 1944; the aircraft's maximum speed with both engines operating was estimated as 485 miles per hour (781 km/h) and asea-levelrate of climb of 4,890 feet per minute (1,490 m/min). Both figures exceeded any aircraft already in service and the bureau issued a procurement directive for three prototypes and an additionalairframe forstatic-load testing on 24 February. Formal contracts for the aircraft followed on 7 April.[5]
The XF15C-1 was a single-seat, low-wingmonoplane withtricycle landing gear. A 2,100-horsepower (1,600 kW) R-2800-34W radial was mounted in the fighter's nose while a 2,700 lbf (12,000 N) J36 turbojet was mounted in the rearfuselage. It was fed by ducts in eachwing root which meant that the wing had to be relatively thick to house the ducts and the inward-retracting main landing gear. To simplify the fuel system, both engines used the same grade ofavgas. Twoself-sealing fuel tanks were housed in the fuselage, one of 165 US gallons (620 L; 137 imp gal) and the other of 211 US gallons (800 L; 176 imp gal). Thecockpit was positioned just forward of the leading edge of the wing and the pilot was provided with abubble canopy which gave him excellent visibility. The XF15C used alaminar flowairfoil as did the Ryan Fireball. The two-spar wings folded upwards for storage.[6]
The Curtiss aircraft was intended to be armed with four 20-millimeter (0.8 in)autocannon with 200rounds per gun. They would have been mounted in the center section of the wing, immediately outboard of theair intakes for the jet engine, but no guns were ever fitted to any of the three prototypes. Four 5-inch (127 mm) rockets could be carried under each outer wing panel and twohardpoints were provided under the center section for 1,000 lb (454 kg) bombs; only the right hardpoint was plumbed for a 150 US gal (570 L; 120 imp gal)drop tank. An armor plate was provided behind the pilot's seat and the forward portion of the canopy was made frombulletproof glass.[7]
The first prototype made its maiden flight on 28 February 1945 without the turbojet; the first flight with the jet installed was on 3 May. The aircraft made several trial flights to evaluate handling without the jet running, but it crashed on 8 May while on a landing approach, killing the pilot. The subsequent investigate determined that the XF15C had run out of fuel due to a stuckfuel gauge and a hard-to-see low fuel warning light. The second prototype flew for the first time on 9 July, and was followed by a third prototype in November.[8]
A Curtiss engineer proposed installing aT-tail in June to allow aircraft to be parked closer together and to improve the aircraft's handling and aerodynamics, but both aircraft were completed in the original configuration, albeit fully equipped for carrier operations. The second prototype was transferred to the Naval Air Testing Center atNaval Air Station Patuxent River in October for preliminary evaluation. These revealed seriouslongitudinal,directional and lateral stability problems. The aircraft returned to the factory in December for further testing and the nose gear could not be lowered during a flight on 18 January 1946 which caused the prototype to make acrash landing that wrecked thepropeller and lightly damaged the lowerfuselage. Repairs took until 10 April.[9][10]
However, by October 1946, the Navy had lost interest in the mixed-power concept and cancelled further development.
Data fromCurtiss Aircraft 1907–1947;[15]Curtiss XF15C-1 "Stingaree"[16]
General characteristics
Performance
Armament
Aircraft of comparable role, configuration, and era
