Grumman F5F Skyrocket
by Jack McKillop
The Grumman Aircraft Engineering Corporation
See Grumman F3F.
The F5F was a single-seat, all-metal, low-wing, twin-engine, carrier-based monoplane fighter. The wings, fuselage and horizontal and vertical tail structures were aluminum alloy covered while the ailerons, rudder and elevators were fabric covered. The main landing gear retracted into the nacelles while the tail wheel was fixed. The aircraft had twin horizontal stabilizers and the wings folded upward. One of the unique features of this aircraft was the location of the fuselage; it began aft of the leading edge of the wing.
Only one aircraft, the prototype XF5F-1, was built. This twin-engine aircraft was not the first plane designed to operate aboard an aircraft carrier. In July 1925, the Navy ordered three XT2D-1 biplanes from the Douglas Aircraft Company which were to be equipped with pontoons for operating from the sea or a landing gear for carrier or land-based operation. Although designated as a torpedo aircraft, the Douglas aircraft, with a crew of four, was expected to also serve in the level bombing and scouting mission role. It was the Navy’s intention to operate these aircraft from aircraft carriers but it soon became evident that with the unreliable air-cooled engines of the day, the failure of an engine on landing could case a major directional steering problem. In addition, the T2D was a large and heavy aircraft which would reduce the number of aircraft that could be carried in the ship. As a result, the T2D only operated from land with the landing gear and water with the pontoons.
The search for a twin-engine carrier-based fighter began again in the summer of 1935, when the Navy began considering such an aircraft. In a desire to produce aircraft that could reach speeds exceeding 300-mph (483-km/h), on 18 March 1937 the Navy sent out a request to the aviation industry. Six manufacturers, the Brewster Aeronautical Corporation, Chance Vought Aircraft, Curtiss-Wright Corporation, Grumman, Lockheed Aircraft Corporation and the Seversky Aircraft Corporation responded. The Grumman design would have two turbosupercharged Allison V-1710 12-cylinder, two bank, liquid-cooled engines but none of these designs showed sufficient improvements over the single-engine aircraft then in development.
The Navy undertook its own preliminary study to determine the best performance that could be expected from carrier-based fighters powered by:
1. One turbosupercharged Allison V-1710 liquid-cooled engine,
2. Two turbosupercharged Pratt & Whitney R-1535 14-cylinder, two bank, air-cooled engines, or
3. Two turbosupercharged Pratt & Whitney R-1830 14-cylinder, two bank, air-cooled engines.
Based on their study, the Navy sent a request for designs and informal proposals for (1) a single-engine fighter powered by the Allison V-1710 and (2) a twin-engine fighter weighing less than 9,000 pounds (4,082 kilograms). The aircraft armament should be two 20-mm cannon, two 0.30-caliber (7.62-mm) machine guns and 52-pounds (23.6 kilograms) of anti-aircraft bombs.
On 11 April 1938, five companies, the Bell Aircraft Corp., Brewster Aeronautical Corporation, Chance Vought Aircraft, Curtiss-Wright Corporation and Grumman, submitted proposals for either or both single-engine and two-engine with the specific powerplants. Chance Vought also proposed a fighter with a Pratt & Whitney R-2800 18-cylinder, twin-row, air-cooled engine. Based on these proposals, the Navy awarded three contracts in 1938, to Bell Aircraft for the XFL-1 equipped with the 1,150-horsepower Allison V-1710-6, the Chance Vought XF4U-1 with a 1,850-horsepower Pratt & Whitney XR-2800-4 radial engine and Grumman for the XF5F-1 twin-engine aircraft powered by two Pratt & Whitney R-1535-96 radial engines.
In the late 1930s, the Navy's Bureau of Ordnance (BuOrd) developed a tactic to deal with large, heavily defended bomber formations. The fighters would fly above them and drop anti-aircraft bombs. These were small 5.2-pound (2.36-kilogram) bombs with a light case containing 2-pounds (907-grams) of TNT, but would cause considerably more damage than a bullet. BuOrd designed small containers housing two bombs each for installation within the wings, five containers to a side. Twenty bombs were to be dropped at one time, covering an area 150-by-50-yards (137-by-46-meters). The pilot was to be provided with a downward vision window for aiming.
This was a requirement in the Navy's 1938 fighter procurement, so the Bell XFL-1, Chance Vought XF4U-1 and Grumman XF5F-1 were all built with the small bomb bays to house the BuOrd containers and downward vision windows. According to a BuOrd history published in 1953: "Although anti-aircraft bombs gained a group of staunch advocates, their admirers were more numerous on the higher level of planning than on the lower one of actual combat." The bomb bays were deleted from the production F4Us by the Bureau of Aeronautics (BuAer). Although BuOrd bought 200,000 of the bombs, they were apparently only used as antipersonnel weapons.
As work progressed on the XF5F-1, it was learned that Pratt & Whitney was no longer offering the R-1535-96 engine with two-speed superchargers and this forced Grumman to use the Wright R-1820-40 and -42 nine-cylinder, single row, air-cooled engine driving three-blade propellers which rotated in opposite directions. The one problem with the Wright engine was that it had a greater diameter than the engine specified by the Navy thus reducing pilot visibility forward and downward.
Initially, the armament of this aircraft was to be four Madsen 23-mm cannons mounted in the nose however, Madsen was a Dutch company and when The Netherlands fell to the Germans on 15 May 1940, the plans had to be changed. The revised plan called for four 0.50-caliber (12.7-mm) machine guns in the nose but these were never installed.
The first flight occurred on 1 April 1940 and a number of minor problems were corrected before the aircraft was delivered to Naval Air Station (NAS) Anacostia, District of Columbia on 22 February 1941 for testing. Meanwhile, Chance Vought (which had been renamed the Vought-Sikorsky Division of United Aircraft) had completed their design and built the XF4U-1 which made it’s first flight on 29 May 1940 and by the end of 1940, the aircraft had reached a speed of 404-mph (650-km/h), the first aircraft to ever reach that speed. As a result, the Navy ordered 584 production F4U-1 Corsairs on 30 June 1941. Because the top speed of the XF5F-1 was 383-mph (616-km/h), it was evident that there would be no production orders for the aircraft. The only category that the XF5F-1 bested the XF4U-1 was in rate of climb. The rate of climb of the XF5F-1 was 4,000-feet-per-minute (1,219-meters-per-minute) which was superior to the Corsair at 2,660-feet-per-minute (811-meters-per-minute). In all other categories, the Corsair was superior.
The aircraft was returned to Grumman to have several major changes made in attempt to increase its speed. The most obvious change was lengthening the nose to the leading edge of the wing but all of these changes were ineffective in increasing the speed.
After suffering three landing gear failures, the XF5F-1 was struck off the inventory at NAS New York, New York on 11 December 1944 after 211 flights totaling 155.7 hours on the airframe.
Wingspan: 42-feet (12.80-meters)
Wing Area: 303.5-square-feet (28.19-square-meters)
Length: 28-feet 8.5-inches (8.73-meters)
Height: 11-feet 4-inches (3.45-meters)
Empty Weight: 7,990 pounds (3,624 kilograms)
Maximum Speed: 383-mph at sea level (616-km/h at sea level)
Service ceiling: 33,000-feet (10,058-meters)
Range: 1,200-miles (1,931-kilometers)
One hundred one of the these aircraft were based at three training bases, NAS Corpus Christi, Texas, NAS Miami, Florida and NAS Norfolk, Virginia. They were:
Battle Force, Pacific Fleet, NAS San Diego, California: 10 F3F-2s
Marine Base Air Detachment 2, NAS San Diego, California: 4 F3F-2s
NAS Corpus Christi, Texas: 14 F3F-2s, 1 XF3F-3 and 16 F3F-3s
NAS Miami, Florida: 28 F3F-1s, 18 F3F-2s and 4 F3F-3s
NAS Norfolk, Virginia: 1 XF3F-1, 11 F3F-1s; 7 F3F-2s and 1 F3F-3
NAS Pearl Harbor, Territory of Hawaii: 1 F3F-2
NAS Seattle, Washington: 1 F3F-3