Cold War

A2D Skyshark – Unfulfilled Promise of a Revolutionary Aircraft

Aviation enthusiasts and military history aficionados alike can agree that the A2D Skyshark is one of the more intriguing aircraft of the mid-20th century.

Its tumultuous development process, unique design features, and unfortunate cancellation make it a captivating case study in military aviation design and policy.

While the Skyshark ultimately failed to achieve significant operational deployment, its unique concept and the impact it had on subsequent aircraft designs ensure its importance in aviation history.

Contents

Origins

Born out of the rapidly developing field of aviation technology following the Second World War, the A2D Skyshark was a product of the Douglas Aircraft Company, one of the United States’ most prolific military aviation manufacturers.

An A2D with the wings folded.
A Skyshark with the wings folded.

In the post-war period, the U.S. Navy identified a requirement for a high-performance turboprop attack aircraft to replace its existing fleet of propeller-driven attack aircraft.

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The Skyshark was developed from the A-1 Skyraider, another product of the Douglas Aircraft Company and shares a common lineage, but they also represented two different approaches to military aviation during the immediate post-World War II period.

The Douglas A-1 Skyraider, originally designated AD, was a highly successful single-seat attack aircraft that first flew in 1945.

Powered by a single Wright R-3350 radial engine, the Skyraider was characterized by its large, low-mounted wings and its ability to carry a significant payload.

This aircraft was an evolution of World War II piston-engine technology and is considered one of the most effective propeller-driven attack aircraft ever made.

Douglas A-1H Skyraider.
Douglas A-1H Skyraider.

The Skyraider saw extensive service in both the Korean and Vietnam Wars, where its durability, long loiter time, and hefty load-carrying ability made it a valuable asset.

The A2D Skyshark, on the other hand, was an attempt by Douglas to incorporate new and innovative technology into an attack aircraft design.

Rather than relying on the proven piston-engine technology used in the Skyraider, the Skyshark was powered by twin Allison T40 turboprop engines.

This made the Skyshark a considerably more complex and ambitious aircraft than the Skyraider.

While the Skyraider and Skyshark were developed around the same period and had similar roles, they represented different visions for the future of aviation.

The Skyraider was a practical, reliable continuation of proven technology, while the Skyshark was a bold leap forward that ultimately failed to achieve operational service due to its complexity and reliability issues.

The Skyraider had many variants and was renown for its ground attack capabilities.
The Skyraider had many variants and was renowned for its ground attack capabilities.

In a sense, the success of the Skyraider and the failure of the Skyshark mirrored the larger trends in aviation at the time.

While jet and turboprop technology were exciting new frontiers, they also presented significant technical and operational challenges.

Conversely, piston-engine aircraft, though technologically mature and less innovative, provided proven, reliable performance.

As such, the A-1 Skyraider remained in service for decades, while the A2D Skyshark was cancelled after only a limited number of prototypes were built.

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Douglas’s initial response to the Navy’s requirement was a design proposal known internally as the Douglas Model 593. Accepted by the Navy in 1947, the design was given the designation XA2D-1 and eventually named the “Skyshark.”

The Skyshark

The A2D Skyshark was a single-seat aircraft with a low-mounted, straight wing. It was 39 feet 7 inches long with a wingspan of 50 feet, and it stood 15 feet 11 inches tall.

Despite being based on a platform introduced during the Second World War, it was capable of carrying an impressive array of weaponry, including up to 50 fifty-pound rockets or 4,000 pounds of bombs.

However, the most impressive thing about the aircraft was the powerplant which comprised two Allison XT40-A-2 turboprop engines.

The block of an XT40 turboprop.
The block of an XT40 turboprop.

It was developed by the Allison Engine Company, a division of General Motors, and was intended to provide a significant power boost for new generations of military aircraft.

The XT40 was a “twin-pac” engine, meaning it essentially coupled two turbine engines together to drive a common gearbox and, ultimately, a pair of contra-rotating propellers.

Each engine, known as an “Allison T38,” was a turbine engine that drove a single-stage power turbine.

The combined output of the two T38s drove the gearbox and the propellers.

This twin-pac design was intended to give the XT40 superior performance characteristics.

At full power, the XT40-A-2 was rated at 5,100 shaft horsepower, making it one of the most potent turboprops of its era.

The Allison XT40 was selected as the powerplant for several high-performance aircraft, including the Douglas A2D Skyshark and the Convair XFY Pogo.

The Convair XFY-1 Pogo.
The T-40 engine was used in the XFY-1 Pogo.

However, the engine proved to be problematic during development and service. It was plagued with reliability issues, largely due to the complexity of the twin-pac design.

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Although the XT40 did not see extensive service, its development represented a bold attempt to push the boundaries of turboprop technology.

It was one of the first twin-pac turboprops and one of the most powerful turboprop engines of its time.

Despite the difficulties it encountered, the XT40 program contributed to the broader development of turboprop technology and offered lessons for subsequent engine designs.

This incredible new engine was expected to propel the Skyshark to speeds in excess of 500 miles per hour.

A closeup of the contra rotating propeller.
A closeup of the contra-rotating propeller. Photo credit – Alan Wilson CC BY-SA 2.0.

The turboprop engines offered a favourable balance between the raw power of jet engines and the fuel efficiency and operational versatility of piston-engine propeller aircraft.

The contra-rotating propellers would cancel out the torque effects usually experienced with single propeller configurations, enhancing stability and manoeuvrability.

Cancellation

The A2D Skyshark’s cancellation was the culmination of a series of significant technical, operational, and contextual challenges that overshadowed its development process.

One of the main culprits behind the Skyshark’s cancellation was the technical and reliability issues associated with its Allison T40 turboprop engine.

The A2D in flight.
The A2D in flight.

It suffered from numerous mechanical and operational problems throughout its development, leading to several in-flight engine failures during testing.

The Skyshark program was also dealt a significant blow when one of the prototypes crashed during a test flight in 1950, killing Douglas test pilot Charles E. Richbourg. This tragic event underscored the risks associated with the Skyshark’s innovative, yet complex design.

Furthermore, during the Skyshark’s prolonged development period, advances in jet technology had started to eclipse turboprop designs.

Jet engines were proving to be more reliable, efficient, and able to deliver higher speeds, leading to a shift in military aviation towards pure jet designs.

Successful jet aircraft, like the Douglas A-4 Skyhawk and the Grumman A-6 Intruder, began to emerge, making the Skyshark seem increasingly obsolete.

Finally, there were fiscal concerns. The cost of maintaining and troubleshooting the complex T40 engine and the continued developmental delays made the Skyshark an expensive project.

The engine's exhausts ran down each side of the aircraft, exiting behind the cockpit. Photo credit - Alan Wilson CC BY-SA 2.0.
The engine’s exhausts ran down each side of the aircraft, exiting behind the cockpit. Photo credit – Alan Wilson CC BY-SA 2.0.

With other viable options emerging and budgets to consider, the U.S. Navy grew increasingly disinclined to continue supporting the troubled Skyshark program.

In 1954, after seven years of development and the production of only twelve aircraft, the U.S. Navy officially cancelled the A2D Skyshark program.

It was a disappointing end to an aircraft that had promised much but was ultimately undone by a combination of technological issues, operational risks, shifting military priorities, and financial constraints.

Conclusion

The story of the A2D Skyshark is a compelling example of the risks and challenges associated with the introduction of new technologies and design concepts in aviation.

The A2D had promise, but technical issues were its demise. Photo credit - Tomas Del Coro CC BY-SA 2.0.
The A2D had promise, but technical issues were its demise. Photo credit – Tomas Del Coro CC BY-SA 2.0.

The Skyshark’s bold design and innovative features, which held so much promise, ultimately led to its downfall.

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However, the Skyshark’s legacy should not be viewed merely as a failure. Its development and the lessons learned from it undoubtedly influenced the subsequent evolution of military aviation.

The experience gained from the Skyshark’s turboprop propulsion technology helped refine future designs. And although the Skyshark never saw operational service, it stands as a testament to the bold innovation and technological ambition that characterized mid-20th-century aviation design.

Though the A2D Skyshark’s life was short and marred by difficulties, its contribution to aviation history and technology is undeniable. Despite its eventual cancellation, the Skyshark inspires aviation enthusiasts and scholars alike, reminding us of the audacious spirit that drives progress in aviation technology.

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Specifications

  • Crew: 1
  • Length: 41 ft 2 in (12.55 m)
  • Wingspan: 50 ft 0 in (15.24 m)
  • Height: 17 ft 1 in (5.21 m)
  • Empty weight: 12,944 lb (5,871 kg)
  • Gross weight: 18,720 lb (8,491 kg)
  • Max takeoff weight: 22,966 lb (10,417 kg)
  • Powerplant: 1 × Allison XT40-A-2 turboprop, 5,500 shp (4,100 kW) equivalent – (5,100 shp (3,800 kW) + 830 lbf (3.7 kN) residual thrust)
  • Maximum speed: 492 mph (792 km/h, 428 kn) at 17,592 lb (7,980 kg) at 40,000 ft (12,000 m)
  • Combat range: 512 mi (824 km, 445 nmi) at 17,592 lb (7,980 kg) at 338 mph (294 kn; 544 km/h)
  • Service ceiling: 48,300 ft (14,700 m) at 17,592 lb (7,980 kg)
  • Rate of climb: 7,960 ft/min (40.4 m/s) at 17,592 lb (7,980 kg)
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