- Convair XF2Y-1 Sea Dart (BuNo 137634) landing on shore. | Photo: US Navy

Flightline: 128 - Convair F2Y-1 Sea Dart

Designed after WWII, the Sea Dart was the US Navy's first and only supersonic seaplane fighter, though it never saw production.

In the wake of WWII, the US Navy sought a supersonic interceptor aircraft, but doubts about operating jet aircraft, especially supersonic jets, from carriers led to the request for a seaplane interceptor. Convair's design team under Ernest Stout proposed a plane based on the F-102 Delta Dagger, modified with retractable skis.

Orthograph of the Sea Dart. | Illustration: Convair

Orthograph of the Sea Dart. | Illustration: Convair

In order to reduce the chances of water ingestion, the intakes were moved behind the cockpit, high on the fuselage. The aircraft would sit level in the water, with the wingtips providing floatation for some measure of stability. At 10mph, the skis would extend to an intermediate position, pushing the fuselage out of the water. Between forty-five and fifty-five mph the skis would be fully extended; take off speed would be 145mph. Production aircraft were expected to be fitted with a pair of Westinghouse J46 turbojets, though the prototypes were equipped with J34s instead, as the former were not available. The prototypes were unarmed, but operational F2Ys were to be fitted with four Colt Mk12 20mm cannon and an unspecified number of folding fin aerial rockets; a similar weapons loadout was carried by the F-89 Scorpion and F-94 Starfire.

Line drawing of the XF2Y-1 prototype with its single ski. | Illustration: blueprints.com

Line drawing of the XF2Y-1 prototype with its single ski. | Illustration: blueprints.com

During construction of the XF2Y-1, the contract was altered, eliminating the second prototype and adding 4 service test aircraft (YF2Y) and eight production F2Y models. The prototype was also fitted with a single larger ski compared to the test types. In December 1952 the XF2Y was transported from Convair's San Diego factory to San Diego Bay for testing. On 14 January 1953 it achieved a short flight during taxi testing, with the first official flight occurring on 9 April.

The XF2Y with a trailer and access ladder. | Photo: US Navy

The XF2Y with a trailer and access ladder. | Photo: US Navy

The XF2Y in flight over San Diego. The yellow markings against the dark blue provided a reference of the aircraft's attitude for engineers. | Photo: US Navy

The XF2Y in flight over San Diego. The yellow markings against the dark blue provided a reference of the aircraft's attitude for engineers. | Photo: US Navy

Flight testing on the XF2Y showed that the plane was (as expected) underpowered with the J34 engines, and was unable to exceed Mach 1. The design, based on the pre-area rulled F-102 fuselage, generated excessive drag, which only exacerbated the issue. In addition, the hydroskis proved to be less effective than hoped, and even with the shock-absorbing oleo legs the aircraft experienced jarring vibrations during takeoffs and landings. Engineers attempted to correct the flaws by refining the ski design, switching to two skis, removing the beaching wheels, and changing the oleo legs, but the vibration issue was never fully solved.

With the cancellation of the second XF2Y, the first two YF2Y test types were fitted with J46s engines and began their test program in 1954. Unfortunately, the J46 proved to also be underpowered, and the Sea Dart was still unable to exceed Mach 1 in level flight. That said, the aircraft did go supersonic on several flights by executing a shallow dive, making it the sole seaplane to break the sound barrier. Tragedy struck on 4 November 1954, when Convair test pilot Charles Richbourg was killed during a demonstration flight. YF2Y-1 BuNo 135762 broke apart in mid-air when the aircraft's structural limitations were exceeded. This accident, combined with lingering issues with the hydroski design and advancing technology allowing supersonic jets to fly from carriers saw the Sea Dart project relegated to experimental status, with the eight production aircraft cancelled and the last two test aircraft completed without engines.

One of the last photos of Convair pilot Charles Richbourg and the F2Y prior to their ill-fated flight. Photo: US Navy

One of the last photos of Convair pilot Charles Richbourg and the F2Y prior to their ill-fated flight. Photo: US Navy

Flights of the remaining Sea Darts continued, at a reduced tempo, until 1957 after which the aircraft were placed into storage. For this reason, the aircraft were still technically "on the books" in 1962 and were thus redesignated the YF-7A under the Tri-Service scheme, even though they had not flown for some 5 years. One XF2Y prototype and three YF2Y test aircraft survive, on display across the US:

XF2Y-1 Sea Dart, Bureau Number 137634, is in bad shape due to a mistake with a crane and is awaiting restoration for the Smithsonian Institution in Washington D.C..

XF2Y-1 Sea Dart, Bureau Number 137634, is in bad shape due to a mistake with a crane and is awaiting restoration for the Smithsonian Institution in Washington D.C..

YF2Y-1 Sea Dart, Bureau Number 135763, is on display at the San Diego Air & Space Museum in Balboa Park.

YF2Y-1 Sea Dart, Bureau Number 135763, is on display at the San Diego Air & Space Museum in Balboa Park.

YF2Y-1 Sea Dart, Bureau Number 135764, is on display at the Wings of Freedom Aviation Museum at NAS Willow Grove, Pennsylvania.

YF2Y-1 Sea Dart, Bureau Number 135764, is on display at the Wings of Freedom Aviation Museum at NAS Willow Grove, Pennsylvania.

YF2Y-1 Sea Dart, Bureau Number 135765, is on display at the Florida Air Museum

YF2Y-1 Sea Dart, Bureau Number 135765, is on display at the Florida Air Museum

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