Curtiss F6C-2 Hawk on USS Langley (CV-2) for trials, 1926-7
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The Curtiss F6C Hawk was the first version of the US Army's P-1/ P-6 Hawk fighter to see service with the US Navy and evolved from a standard land-based fighter into a dedicated Naval aircraft.
Despite its high designation the F6C was only the second Curtiss fighter to be produced for the US Navy. FC, F2C and F3C had been skipped because those ( or similar) designations had been issued to three Curtiss racers. The F4C was the first fighter Curtiss produced for the Navy, but it wasn't related to the Hawk family. F5C was skipped because many Curtiss F-5L Flying Boats (based on a British original) were still in service in the mid-1920s.
The Navy ordered nine F6C-1s in March 1925, the same month as the Army ordered the P-1. Five of these aircraft were delivered as F6C-1s, and the remaining four as F6C-2s. At this stage the F6C was very similar to the P-1, and was intended for use by the US Marines as a land fighter. It was thus a standard biplane fighter with staggered tapered single bay wings, a welded steel tube fuselage, wooden wings and a fabric covering and powered by the Curtiss D-12 (V-1150 engine).
The -1s and -2s were followed by thirty-five F6C-3s that were ordered in 1927. These were generally similar, but with a number of changes of detail. A more dramatic change came with the thirty-one F6C-4s that were ordered in 1931. In these aircraft the Curtiss inline engine used in the early Naval aircraft and the Army's P-1 was replaced by a Pratt & Whitney Wasp radial air-cooled engine. All later Naval Hawks would use air cooled engines, after the Navy decided that they were easier to maintain at sea.
Service
Only a handful of F6C-1s actually entered squadron service. After a brief period with VF-1 and VF-2 they were transferred to Marine Squadron VF-9M.
The small number of F6C-2s did see service at sea, with some going to VF-2 on the USS Langley while others served on the Lexington. They remained in service until 1928 when the US Navy decided to only use air cooled radial engines on its carriers.
The F6C-3 was produced in larger numbers. Most served as normal land planes, some on land with the Marines and others on-board carriers. The F6C-3 was also the only version to see service as a floatplane. During 1928 VF-5S (which became VB-1B) received a number of -3s that had served on the USS Lexington. VF-5 used them as floatplanes, but only for a short period.
The F6C-4 was used by VF-2B on the Lexington from 1929-30. The remaining aircraft then became trainers. The Marine Corps used the type for longer. It received four in 1927 and had twelve by 1931. Most of them were used by Marine Squadron VMF-10 which was based at San Diego.
Variants
F6C-1
Nine F6C-1s were ordered for the navy in March 1925. They were similar to the Army's P-1 but could be fitted with twin floats. Five were delivered as F6C-1s, starting in August 1925. The remaining four were delivered as the F6C-2.
Of the five -1s one became the prototype for the F6C-4 then the XF6C-5, while two were converted into F6C-3s.
F6C-2
The last four aircraft in the first F6C order were completed as the F6C-2. This was similar to the -1, but was equipped with arrestor hooks to make it suitable for carrier operations. They also had stronger fuselages and a high-impact undercarriage. They were delivered in November 1925 and remained in service until 1928 (operating on the USS Langley for much of that period).
F6C-3
The F6C-3 was the designation given to thirty-five aircraft based on the P-1A airframe (3in longer than the P-1). They were delivered from January 1927 and originally used the standard reinforced -2 undercarriage. During 1928 they were given the spreader-bar type undercarriage used on the -4, but when operated by the US Marines the earlier -1 undercarriage was installed instead (reducing weight on aircraft that didn’t need the extra strength required for carrier operations).
Two of the -1s were later converted to the -3 standard.
In 1930 F6C-3 A7147 was given an aerodynamic clean and won the Curtiss Marine Trophy.
The F6C-3 was the last of the F6C family that could be equipped with twin floats instead of the standard undercarriage. In 1928 Navy Squadron VB-1 became the only unit to use the F6C in its float configuration.
XF6C-3
This designation was given to F6C-3 A7136 while it was being used for test work.
F6C-4
The F6C-4 marked a major change in the design of the F6C. In 1926 Curtiss produced a prototype F6C powered by a Pratt & Whitney Wasp radial air-cooled engine. The US Navy decided to adopt the air-cooled engine for all of its carrier-borne aircraft, finding them easier to maintain at sea than liquid cooled engines. The Army carried out a similar experiment with the Curtiss P-3, but decided to stick with its inline engines.
An order was placed for thirty-one F6C-4s. The first was delivered in February 1927 and was used for tests, with the designation XF6C-4. It has a new spreader bar main undercarriage and a spinner. The remaining thirty were delivered nearly a year later with the new undercarriage but without the spinner. They had a fairly short front line career and became training aircraft in 1930.
XF6C-5
The first F6C-1 was used as the prototype for the F6C-4 and was later given a 525hp Pratt & Whitney R-1690 Hornet engine and re-designated as the XF6C-5. It was also given the -4 spreader bar undercarriage.
F6C-6
The F6C-6 was a single production F6C-3 that was modified for the 1927 racing season, with a rounded-out rear fuselage. It came fourth in the unlimited free-for-all race and was then converted back for squadron service, retaining the new rear fuselage, gaining the -4 undercarriage but otherwise resembling a standard -3.
XF6C-6
After winning the 1930 Curtiss Marine Trophy F6C-3 A7147 was returned to Curtiss for a very dramatic re-build, with the 1930 Thompson Trophy race in mind. The lower wing was removed completely, turning the aircraft into a parasol wing monoplane. The upper wing was moved back several inches to restore the balance of the aircraft. A single strut was installing, running from the undercarriage root to the remaining wing. The tunnel radiator was removed and the type of surface radiators used on early Curtiss races and the PW-8 fighter were installed. The aircraft was given a single-strut main undercarriage, as used on the Army's P-6E.
Curtiss hoped that the modified aircraft could reach 250mph. It performed well in the early laps of the Thompson Trophy Race, and Marine Corps Captain Arthur Page was leading the race with a best lap speed of 219.6mph when he was overcome by exhaust fumes. Sadly Captain Page, who was a successful racer, died of his injuries on the day after the race.
XF6C-7
The XF6C-7 was a single F6C-4 that was given a 350hp inverted air-cooled Ranger SGV-770 engine at the Naval Aircraft Factory during 1932.
F6C-3
Engine: Curtiss V-1150-1 12-cylinder water-cooled engine
Power: 435hp
Crew: 1
Span: 31ft 6in
Length: 22ft 10in
Height: 10ft 8in
Empty weight: 2,161lb
Loaded weight: 2,963lb
Max speed: 154mph at sea level
Climb Rate: 3.5 mins to 5,000ft
Range: 655 miles
Armament: Two .30in machine guns
F6C-4
Engine: Pratt & Whitney R-1340 radial engine
Power: 410hp
Crew: 1
Span: 31ft 6in (37ft 6in in part work)
Length: 22ft 6in
Height: 10ft 11in
Empty weight: 1,980lb
Loaded weight: 2,785lb
Maximum take-off weight: 3,171lb
Max speed: 155mph at sea level
Climb Rate: 2.5 mines to 5,000ft
Service ceiling: 22,900ft
Range: 361 miles
Armament: Two fixed forward firing .3in machine guns
Bomb load: light bombs on underwing racks
