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Fifty-seven years ago this week, the USN/Convair YF2Y-1 Sea Dart became the first and only seaplane ever to exceed the speed of sound.  Convair test pilot Charles E. Richbourg was at the controls of the experimental sea-based fighter.

In 1948, the United States was looking to develop a sea-based supersonic fighter as a means projecting naval airpower.  However, few in the Navy at that time believed that such as aircraft could be operated successfully from an aircraft carrier.  Thus, the new aircraft would need to be a seaplane   That is, it would take-off and land in the ocean.

Consolidated Vultee Aircraft (Convair) won a competition for a Navy contract to build and flight test a pair of supersonic seaplane prototypes.  Convair’s winning airframe featured a delta wing, a large triangular vertical tail, twin afterburning turbojets and dual retractable hydro-skis.  Known as the XFY2-1 Sea Dart, the two protoype aircraft were assigned BuAer tail numbers 137634 and 137635, respectively.

The Sea Dart’s nominal specifications included a length of 52.5 ft, a wingspan of 33.7 ft and an empty weight of 12,625 lbs.  The single-place aircraft was initially powered by twin Westinghouse J46-WE-2 turbojets.  Each of these non-afterburning powerplants produced a meager 3,400 lbs of sea level thrust.  This led to the aircraft being significantly underpowered.

The XF2Y-1 design maximum speed was 825 mph, a rate of climb of 17,000 ft/min and a service ceiling of nearly 55,000 ft.  The type’s take-off speed from the water was approximately 145 mph.  Although the prototypes were never outfitted with armament, an operational Sea Dart reportdely would have had a mix of 4 x 20mm cannon, a bevy of 2.75-inch unguided rockets and a pair of air-to-air missiles.

Convair test pilot Ellis D. Shannon made the official first flight of XF2Y-1 Ship No. 1 (BuAer 137634) on Thursday, 09 April 1953.  San Diego Bay served as the take-off and landing site.  Shannon quickly determined that the XF2Y-1 was indeed underpowered.  The aircraft’s hydro-skis also vibrated badly during ocean take-off and landing.  The result was that the XF2Y-1 was quite challenging to control during high-speed ocean surface operations.

The second Sea Dart to fly was the first YF2Y-1 (BuAer 135762)aircraft.  The main difference between the YF2Y-1 and XF2Y-1 was the propulsion system.  Specifically, the YF2Y-1 was powered by afterburning J46 turbojets and its air induction and exhaust systems were configured differently.  With the introduction of the YF2Y-1, the XF2Y-1 was cancelled by the Navy.

Flight testing of the YF2Y-1 Sea Dart began in early 1954.  Convair test pilot Charles E. Richbourg was assigned to make the initial flights in Ship No. 1.  The zenith of the YF2Y-1’s flight test program occurred on Tuesday, 03 August 1954 when Richbourg flew the seaplane faster than the speed of sound while passing through 34,000 feet in a shallow dive.  This event marked the first and only time in aviation history that a seaplane exceeded Mach 1.

The Sea Dart’s bright moment of achievement was followed several months later by the program’s darkest day.  On Thursday, 04 November 1954, Richbourg was performing a XF2Y-1 flight demonstration for Navy leadership and members of the press over San Diego Bay when structural failure of the aircraft’s left wing caused it to distintegrate in flight.  Rescue forces quickly found Richbourg and pulled him out of the water.  However, the 31 year-old pilot did not survive.

The loss of the first YF2Y-1 came at a time when the Navy was already losing interest in the Sea Dart Program.  The service had rethought the notion of operating a high-performance aircraft from its carrier force and now reckoned that such operations were indeed possible.  These realities, coupled with the Sea Dart’s seemingly unsolvable hydro-ski vibration problems, effectively sounded the death knell of Convair’s supersonic seaplane concept.

Notwithstanding the above, it would not be until the fall of 1957 that the Sea Dart Program would officially come to an end.  Actually, three (3) more YF2Y-1 airframes were manufactured.  Sea Dart Ship No. 3 (BuAer 13563) flew for the first time on Friday, 04 March 1955.  This aircraft was used mainly for flight testing various hydro-ski arrangements.  Sea Dart Ship No. 4 (BuAer 135764) and Ship No. 5 (BuAer 135765) never flew.

Posted in Aerospace, History


travelforaircraft August 7, 2011

Very nice summary that you’ve written. The Sea Dart was part of the Navy’s Sea Strike Force (SSF) which bore an enormous cost and included ships and the P6M Seamaster development. Though the SSF faded away and aircraft carriers as well as submarines now do what the SSF was intended to accomplish both the Sea Dart and Seamaster were aeronautical supererlatives that were overtaken by events.

Mike Folks August 8, 2011

There is one of the last remaining Convair Sea Darts on display outside the San Diego Aerospace Museum, next to one of the Lockheed “Black Bird”aircraft,which I believe it’s YF-12 prototype.

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