Military


F6U Pirate

The F6U Pirate, a straight-wing jet fighter, was a somewhat ugly and rather unsuccessful aircraft. The design was conventional-- a straightforward "flying stovepipe" with intake in the nose and exhaust in the tail, with straight wings, a blunt nose, small wing root jet intakes, and small additional fins at the tips of the tailplane. The construction was innovative, with use of glassfibre and balsa wood - the skin was Vought's patented Metalite, a core of balsa wood sandwiched between two thin layers of aluminium alloy. The F6U was underpowered, and was modified to become the first operational jet fighter with an afterburner.

As more German jets appeared in combat, it became a foregone conclusion that Japan would be producing them too. This prompted the Navy to issue a requirement for carrier jet fighters. In late 1944 BuAer sent requests to several manufacturers for jet proposals. From all the proposals submitted, BuAer technical desk chose three designs to be developed, including the Chance Vought F6U Pirate.

The company Chance Vought dealt with the development of the jet fighter model V-340 at the end World War II. With its F4U firmly established in production and service, Vought was well placed to respond to the US Navy's request for an interceptor powered by a single 3,000 lb thrust Westinghouse turbojet. The company obtained an order for three experiment aircraft Xf6U-1. The all-metal airframe of the aircraft had a low wing, and the horizontal tail assembly was located on the keel above the fuselage. The aircraft had a three-strut retractable landing gear and additional wingtip fuel tanks with a capacity of 530 liters (140 US gallons) each. The highly placed cockpit was located almost in the very tip of the nose of the figher.

The first turbojet powered aircraft designed by Chance Vought was awarded a contract from the US Navy for three prototypes on December 29, 1944. The first of three experiment aircraft rose into air on 2 October 1946. It had a Westinghouse J34-WF 22 turbojet engine with a thrust of 1361 kg (3,000 pounds), located in the tail end of the fuselage. The aircraft was found to be under powered as well as having very bad handling properties. To help improve the aircraft's performance, the third prototype, which first flew on 10 November 1947, was fitted with an afterburning engine, the first US Navy fighter to have such a powerplant. During trials, the XF6U was subjected to five different tail arrangement modifications. These were required to remedy a lateral stability problem, especially after the installation in a lengthened rear fuselage of the afterburner required to boost performance to acceptable levels. Various changes were implemented during the flight test program in hopes of improving the handling characteristics, most visibly the addition of small "finlets" near the ends of the horizontal tailplane.

Improvements were made and the airframe was modified so a new engine with an afterburner could be fitted the Westinghouse J-34-33, this aircraft was known as the F6U-1. The afterburner (Solar Model A-103B) produced approximately 30% boost by adding fuel to burn residual oxygen. The powerplant consisted of an 11-stage axial flow compressor, a double annular engine combustion chamber, and a two-stage turbine, plus the afterburner combustion chamber, two-position nozzle, cooling shroud and controls. Engine-driven accessories consisted of an all-speed governor, main and emergency (automatic) fuel pumps, lubricating system pump, hydraulic pump and generator. The engine compartment was cooled by air taken in by boundary layer ducts at the wing roots and exhausted at a gill forward of a firewall on the bottom centerline. The afterburner compartment was cooled by air entering through two flush scoops on the lower fuselage aft of the firewall and out by nozzle shroud ejector action.

The hydraulically-actuated speed brakes limited the maximum Mach number of the airplane in a dive so that during normal fighter operations, the transonic region of high buffet and/or trim change would not be reached. Mild buffet was encountered at a Mach number of 0.79 in level flight.

The production aircraft F6U-1, the first of which rose into air during July of 1949, began to enter into service by US Navy already in the following month. Development was so slow that the type was obsolete even as the first production aircraft were being delivered.

Even with modifications the performance was described as "sub-marginal", and they were assigned to development tasks and training. A total of 65 had been ordered but after 30 had been delivered, the remainder were cancelled. On 30 October 1950, the BuAer informed Vought of the Navy's opinion of the Pirate in terms both bureaucratic and scathing: "The F6U-1 had proven so sub-marginal in performance that combat utilization is not feasible." Inferior in performance to the FJ-1 Fury and the F9F-2 Panther, the Pirate was doomed.

The F6U-1P was one of the production F6U-1s following the installation of cameras for evaluation in a reconnaissance role.



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