The Close Call of the Northrop YA-9A Prototype

The close air support YA-9A had intriguing design features despite losing a pivotal contract to replace the aging Douglas A-1 Skyraider.

Jason McDowell

Tuesday, July 11, 2023 at 10:51 AM ET

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With a high-wing configuration, the low-slung Northrop A-9A has a very different appearance than its competitor, the A-10. [Credit: USAF]

Key Takeaways:

The U.S. Air Force initiated a competition in the mid-1960s for a new close air support (CAS) aircraft, prioritizing cost, survivability, and low-speed maneuverability, which ultimately led to the development of prototypes for the A-10 Thunderbolt II and its competitor, the Northrop YA-9A.
The YA-9A featured a high wing for easier engine maintenance and shorter landing gear, a conventional cruciform tail, and less common, less reliable geared turbofan engines compared to the A-10.
It incorporated an innovative but complex "Side Force Control" (SFC) system for precise, bank-free targeting by blending rudder and asymmetric speed brake inputs, a feature contrasting with the A-10's simpler design philosophy.
Despite demonstrating competitive flight performance, including impressive short takeoff and landing distances, the YA-9A ultimately lost the contract to the A-10, with its two prototypes later preserved in museums.

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In the mid-1960s, the U.S. Air Force presented aircraft manufacturers with an interesting challenge—design a clean-sheet close air support (CAS) aircraft to replace the aging Douglas A-1 Skyraider. Accustomed to developing sleek fighters and bombers that ventured into supersonic speeds, this new request challenged them to instead prioritize cost, survivability, and low-speed maneuverability. It was a new set of requirements that required new thinking.

Just as the design requirements were unconventional for the time, so too was the appearance of each proposed contender. A total of six manufacturers submitted a wide variety of proposals, ranging from multiengine jets to a single-engine V-tail pusher turboprop. In each case, the manufacturers prioritized function over form, with most concepts utilizing straight wings, bulbous canopies, and a multitude of external hard points on their wings.