Grumman FF-1 from the right |
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The Grumman FF was a two-man fighter that was the first in the series of Grumman fighters to serve with the US Navy, and that featured retractable landing gear and an enclosed cockpit, making it an advanced design for the time.
The Grumman Engineering Corporation was formed in December 1929, and the FF would be its first aircraft design to actually be built. It very quickly gained a US Navy Contract, for floats to convert landplanes into seaplanes. These were internally designated as the Grumman G-1 and G-2, and in the navy as the Model A (eight purchased) and Model B (fifteen ordered). These were of monocoque aluminium construction, with retractable landing gear built in, and were installed on Vought O2Us and O3Us. The company then produced designs for a twin engined amphibious monoplane (the G-3) and an amphibious single engine biplane (the G-4), neither of which was built.
XFF-1
The idea of fitting the landing gear from these floats to existing aircraft came up in February 1930, during the contract negotiations for the purchase of the Modal A floats. The Navy wanted Grumman to adapt the gear to use on existing fighters such as the Boeing F4B, but Grumman preferred to design their own aircraft. On 10 March 1930 they submitted a design for a two-seat ship-board fighter to the Bureau of Aeronautics, with the internal designation G-5.
The G-5 was an advanced design for the period. It was to use the retractable undercarriage from the floats, which saw the main wheels pulled up into the side of the fuselage, sitting flush against the fuselage just in front of the wings, giving the aircraft a rather squat appearance. It was of all metal construction, with a semi-monocoque aluminium alloy fuselage, and an aluminium wing structure with fabric covering. It was to be powered by a 575hp Wright W-1820-E Cyclone air cooled radial engine. The upper wing was level, and contained flotation bags, while the lower wing had a slight dihedral. It was armed with a fixed forward firing 0.30in machine gun and two Browning machine guns in the rear cockpit. The two man cockpit was covered by two sliding canopies. Grumman estimated that it would out-perform every fighter in US Naval Service.
The Bureau requested a set of drawings what was then known as the High Performance Two Seat Fighter, from which they planned to build a wind tunnel model. Just over a year later, on 28 March 1931, the Navy ordered a single prototype of the G-5, as the XFF-1. The original plan was for the prototype to be delivered in October 1931, but this was delayed to December after the company moved from its small factory at Baldwin, Long Island to a new larger site at nearby Curtiss Field at Valley Stream.
The XFF-1 made its maiden flight on 29 December 1931, and was then delivered to Naval Air Station Anacostia on the same day (presumable flown there). With its original 575hp engine the XFF-1 reached a top speed of 195mph, seven mph faster than the Boeing F4B-2, which was then the Navy’s fastest fighter.
After tests by the Board of Inspection and Survey a number of minor changes were made, including a reduction in the number of struts in the canopy and the number of cooling vents on the engine cover and stronger landing gear struts. The old canopy had flat glass panels with struts running length ways either side of the top panel, the new canopy used curved glass to eliminate these struts. In May 1932 the prototype returned to Grumman to be given a 750hp Wright R-1820-78 radial engine, which lifted its top speed to 201mph.
After tests of the modified aircraft the Navy ordered twenty-seven FF-1s on 19 December 1932.
The prototype returned to Grumman to be brought up to production standards, and then sent to the West Coast, where it served with VF-5S then with VF-5B (the FF-1 squadron on Lexington). In January 1934 it returned to Anacostia, where it was used for experimental work before being struck off on 31 March 1937. One of the experiments was Project YEHUDI, in which twelve 600 candle power landing lights were attached to it to be used as a form of camouflage. Trials in October 1936 weren’t a success.
FF-1
The FF-1 was very similar to the later version of the prototype. External mass balances were added to the ailerons, and the tail hook and wheel were moved back almost to the tip of the tail. The engine used a Townend ring with individual exhausts for each cylinder.
Deliveries of the FF-1 began in April 1933 and were completed by November 1933. Twenty five of them went to squadron VF-5B, one to VF-1B and one to NAS Anacostia.
During 1933 and most of 1934 VF-5B operated its FF-1s on the USS Lexington (CV-2). In the autumn of 1935 the squadron moved to the Ranger (CV-4). In November 1935 nine of the FF-1s were replaced with F2F-1s, and in March-April 1936 both types were replaced by the F3F-1.
FF-2
By the time the FF-1 was withdrawn from the fleet twenty five aircraft were still intact. Of these twenty-two were sent to the Naval Aircraft Factory, Philadelphia, to be converted into the FF-2. The FF-2 was to be used as a land based fighter trainer, so dual controls were installed and the tailhook removed. An engine exhaust collector ring replaced the individual exhaust stacks on the FF-1. A direction finding HF/ RDF radio was installed with a loop antenna between the starboard wings. The FF-2 kept the full three gun armament.
The FF-2s were initially distributed to six Naval Reserve Air Bases, with Kansas getting 6, Glenview 5, Grosse Isle 4, Minneapolis and Robertson, MO 3 each and Philadelphia a single aircraft. By June 1940 fifteen were still in use, with Kansas, Chicago, Detroit, Minneapolis and St. Louis each having three. The last FF-2 was finally struck off at Quantico in July 1942.
SF-1
A second prototype was completed as the XSF-1, a two-man scout plane. This was also ordered into production, as the Grumman SF-1. Thirty three of these were ordered, making it the more numerous of the type, and they served with VS-3B on the Lexington.
XF2F-1
The success of the trials of the XFF-1 interested the Navy in a single seat version, and a prototype was ordered as the XF2F-1. This was soon followed into production by the F2F and later the F3F, the final Grumman biplane fighter.
FF-2
Engine: Wright R-1820-78
Power: 700hp
Crew: 2 (pilot and observer/ gunner)
Span: 34ft 6in
Length: 24ft 6in
Height: 11ft 1in
Empty weight: 3,250lb
Gross weight: 4,828lb
Max speed: 207mph at 4,000ft
Climb Rate: 2.9min to 5,000ft
Service ceiling: 21,000ft
Range: 921 miles
Armament: One fixed forward firing 0.3in gun and two flexibly mounted 0.3in guns