F2Y Sea Dart Design
These aircraft were designed, built, and flown before the supersonic "area rule" was first incorporated in aircraft designs. The area rule revealed that streamlining the aircraft fuselage into an hourglass shape, to compensate for the wing area, reduced aerodynamic drag-the unseen forces that slow aircraft down and increase thrust requirements. Compounding the issue, high-thrust engines were not available at that time.
The Sea Dart had a vee-shaped hull, and its internal spaces were organized as multiple watertight compartments to keep it afloat if battle damaged. It had twin dive brakes on the lower rear fuselage that could be also be used as water brakes or rudders. Flight controls were hydraulic. The Sea Dart could not take off or land on a runway, but each of the hydro-skis had a small wheel at the end, and a third small wheel was mounted near the rear of the aircraft to allow it taxi onto or off of a seaplane ramp. The cockpit canopy pivoted up as a single unit, and featured a rather antique-looking windscreen with twin oval glass panels in a metal frame. Apparently pilot visibility was not very good.
The aircraft was to be armed with four 20 millimeter cannon and a pack of 70 millimeter (2.75 inch) folding-fin air rockets (FFARs), though in fact no Sea Dart would ever be armed.
The design called for the aircraft to be equipped with twin hydroskis. Tthe twin hydroskis were "planing" skis and derived lift the same as a person using water skis. They were not skis that provided lift in the same manner as hydrofoils. The YF2Y-1 was similar in appearance to the XF2Y-1 but had a longer, redesigned exhaust, and the little beaching wheels were removed from the hydro-skis and the fuselage, meaning it had to be fitted with external beaching gear to be brought up on shore.
The aircraft "taxied" up the seaplane ramp after its first test run. Small wheels at the aft end of the skis plus a small tail wheel provided this land taxi capability. The airplane entered the water the same way. Taxi down the ramp was made with the ski oleos in the beach position for attitude purposes. Upon attaining flotation, the main wheels on the ski afterbodies were rotated 90 degrees by electrical switch and hydraulic action to place the tapered afterbody of the ski in the proper hydrodynamic position.
Takeoff was accomplished by a combination of ski extension, retraction, afterburner thrust, and a rapid rotation at take off speed. Two Westinghouse J46 engines producing 4,000 lb. of thrust (augmented to 6,000 lb. with afterburner operating) powered the Seadart during most of its testing. The characteristic sharp rotation and liftoff was necessary to achieve positive separation from the water allowing rapid acceleration. The skis could be retracted immediately as with any retractable landing gear.
Normal landing and takeoff procedures for both the twin-ski and single-ski configuration were to maintain a heading parallel to the major wave or swell condition and into the wind as much as possible. Usually, this involved a crosswind component of 30 to 60 degrees. Landing or takeoff directly into any sizeable wave pattern or swells was unacceptable and not attempted. A smoke float deployed during operations indicated wind conditions. Except for being underpowered, the open-sea handling characteristics were considered excellent by the test pilots. This was despite the 120-knot takeoff speed and 125-knot landing speed.
The Sea Dart was originally planned to be powered by twin Westinghouse XJ46-WE-02 engines with 26.68 kN (2,720 kgp / 6,000 lbf) afterburning thrust each. The XJ46 engine, an afterburning derivative of the Westinghouse J34 axial-flow turbojet, was expected to give the aircraft a top speed well in excess of Mach 1.
As the first Sea Dart prototype was finished before the XJ46 engines were available, it was fitted with twin Westinghouse J34-WE-32 engines with 15.11 kN (1,540 kgp / 3,400 lbf) maximum takeoff thrust each. The Sea Dart was, to nobody's surprise, badly underpowered with its J34 engines and remained solidly subsonic. The hydro-skis turned out to give an extremely rough ride on takeoff and landing, though a redesign effort helped reduce this problem.
The XJ46 engines were installed in the prototype later that year, but they failed to meet their designed thrust levels. The detestable Vought F7U Cutlass carrier would use production J46 engines, and the lack of engine power and poor fuel economy would be high on the list of pilot complaints against the "Gutless", as it was known.
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