The Ryan FR Fireball was an American mixed-power, piston and jet-powered, fighter aircraft designed for the United States Navy during World War II.
It was the Navy’s first aircraft with a jet engine.
Only 66 aircraft were built before Japan surrendered in August 1945.
Design of the FR-1 began in 1943 to a proposal instigated by Admiral John S. McCain Sr. for a mixed-powered fighter because early jet engines had sluggish acceleration that was considered unsafe and unsuitable for carrier operations.
Ryan received a contract for three XFR-1 prototypes and one static test airframe on 11 February 1943 with the first two prototypes delivered in 14 months.
Another contract was placed for 100 aircraft on 2 December 1943 and a later contract on 31 January 1945 increased the total of FR-1s on order to 700.
The XFR-1 was a single-seat, low-wing monoplane with tricycle landing gear.
A 1,350-horsepower (1,010 kW) Wright R-1820-72W Cyclone radial engine was mounted in the fighter’s nose while a 1,600 lbf (7,100 N) General Electric I-16 (later redesignated as the J-31) turbojet was mounted in the rear fuselage.
It was fed by ducts in each wing root which meant that the wing had to be relatively thick to house the ducts and the outward-retracting main landing gear. To simplify the fuel system, both engines used the same grade of avgas.
Two self-sealing fuel tanks were housed in the fuselage, one of 130 US gallons (490 l; 110 imp gal) and the other of 50 US gallons (190 l; 42 imp gal).
The cockpit was positioned just forward of the leading edge of the wing and the pilot was provided with a bubble canopy which gave him excellent visibility.
The XFR-1 had the first laminar flow airfoil in a navy carrier aircraft.
The Fireball was armed with four .50 in (12.7 mm) M2 Browning machine guns with 300 rounds per gun.
They were mounted in the centre section of the wing, immediately outboard of the air intakes for the jet engine.
Four 5-inch (127 mm) rockets could be carried under each outer wing panel and two hardpoints were provided under the centre section for 1,000 lb (454 kg) bombs or 100 US gal (380 l; 83 imp gal) drop tanks.
Armor plates were provided in front and behind the pilot’s seat and for the oil cooler.
The first XFR-1 made its first flight on 25 June 1944 without its jet engine, but this was installed shortly afterward.
The second prototype first flew on 20 September 1944.
Test flights confirmed wind tunnel tests that revealed a lack of longitudinal stability because the centre of gravity had been miscalculated.
In addition, the circular rear fuselage of the FR-1 gave less stability than the slab-style fuselage of the Grumman F4F Wildcat that was used as a model for the stability calculations.
A new tail with enlarged vertical and horizontal stabilizers was designed and retrofitted to the prototypes.
The original Douglas double-slotted flaps proved to be unsatisfactory during flight testing, but all three prototypes and the first 14 production aircraft were built with them before they were replaced with a single-slotted flap.
The first prototype was lost in a crash at NAS China Lake on 13 October 1944.
Investigation showed that the wing structure was not strong enough to resist compressibility effects.
This was cured by doubling the number of rivets in the outer wing panels.
The second prototype crashed on 25 March 1945 when the pilot failed to recover from a dive from 35,000 feet (10,670 m), probably also due to compressibility effects.
The third prototype crashed on 5 April when the canopy blew off during a high-speed pass over Lindbergh Field.
Operational testing by the Naval Air Test Center at Naval Air Station Patuxent River that included carrier acceptability tests revealed additional problems:
The piston engine tended to overheat until electrically operated cowl flaps were installed, the catapult hooks had to be moved, and the nosewheel oleo shock strut had to be lengthened by 3 inches (76 mm).
Carrier suitability tests began aboard the escort carrier Charger in early January 1945.
The aircraft successfully made five catapult take-offs using the piston engine as well as three take-offs using both engines.
No problems were reported when landing aboard the carrier.
The FR-1 Fireball was further developed into the XFR-2 which utilized a 1,425 hp (1,063 kW) Wright R-1820-74W in place of the -72W.
One single airframe was converted to this configuration.
No prototypes were built for the next proposed variant, the FR-3, which would have used a General Electric I-20 turbojet.
Both of these projects were cancelled with the end of the war.
The fastest Fireball was the XFR-4, which had a Westinghouse J34 turbojet and was approximately 100 mph (160 km/h) faster than the FR-1.
The turbojet’s air intakes were moved from the wing roots to the fuselage in front of the wing; they were covered by electrically powered doors to lessen drag when the aircraft was flying only on its piston engine.
The Fireball’s fuselage was lengthened by 8 inches (203 mm) to accommodate the larger engine and the leading-edge extension of the wing root that housed the air intakes was also removed.
The XFR-4 was intended to serve as a testbed for the turbojet installation on the XF2R-1 Dark Shark.
This was the final variant; the piston engine was replaced with a General Electric XT31-GE-2 turboprop, but only one prototype was built.
On 2 December 1943, orders for 100 production FR-1s were placed, with a follow-up order of 1,000 additional fighters in January 1945.
All of the contracts were contingent on the aircraft successfully completing carrier trials.
Only 66 Fireballs were completed by November 1945 as orders for 1,044 FR-1s were cancelled on VJ Day.
Military designation of the prototype Model 28 aircraft,
Single-seat fighter aircraft,
Conversion with a Wright R-1820-74W replacing earlier piston engine,
One aircraft modified.
Proposed variant with a General Electric I-20 replacing earlier jet engine.
Variant with Westinghouse J34
32 ft 4 in (9.86 m)
40 ft 0 in (12.19 m)
13 ft 11 in (4.24 m)
275 sq ft (25.5 m2)
Root: NACA 65-117 a=1.
Tip: NACA 65-115 a=.5
7,689 lb (3,488 kg)
11,652 lb (5,285 kg)
1 × Wright R-1820-72W Cyclone,
9-cylinder air-cooled radial piston engine,
1,350 hp (1,010 kW)
1 × General Electric J31-GE-3 centrifugal-flow turbojet engine,