The Northrop YA-9 and the Fairchild Republic YA-10 were the two major competitors in the U.S. Air Force’s 1970s A-X program to find a dedicated close air support aircraft capable of knocking out Soviet tanks and surviving intense ground fire.
Although the YA-9 was a highly capable “flying tank,” the Air Force selected the A-10 Warthog in 1973. An interesting footnote to the story is that the YA-9 may have lived on in another design.
Su-25 Frogfoot in operations in Syria. Image Credit: Creative Commons.
Su-25 Frogfoot. Image Credit: Creative Commons.
The aircraft bears a striking resemblance to the Soviet Sukhoi Su-25 “Frogfoot” ground-attack aircraft, which was adopted shortly after the US competition was announced.
Although the Soviet design had been in the works for some time, the similarity of the two aircraft is striking.
While the YA-9 was an outstanding aircraft in many respects, especially in its “fighter-like” handling and being known as a very good weapons platform, it ultimately lost the competition to what has been arguably characterized as the greatest ground-attack aircraft of all time: the A-10 Thunderbolt.
The Development Of The YA-9 Ground Attack Aircraft
The YA-9 ground attack aircraft was designed by Northrop in the early 1970s, in response to a request by the US Air Force for a low-flying, slow, close air support aircraft capable of destroying the heaviest Soviet tanks and armored vehicles.
The Army and the Air Force were fighting over budgetary funds, and the Army was designing attack helicopters for close air support (CAS), a task the Air Force wasn’t interested in, and many analysts believe they still aren’t.
During the Vietnam War, the CAS mission was largely handled by A-1 Skyraiders, a hand-me-down from the Navy.
A large number of aircraft in the close air support realm were shot down due to intense small arms, anti-aircraft missiles, and concentrated low-level anti-aircraft artillery fire.
P-47 Thunderbolt. Image Credit: Creative Commons.
The Skyraider and the World War II P-47 Thunderbolt were excellent examples of highly survivable, rugged, maneuverable, and heavily armed ground support aircraft.
However, the Army’s rotary-wing development spurred the Air Force forward with CAS designs using turbofan engines.
The aircraft was developed with Short Take-Off and Landing (STOL) capabilities and had excellent maneuverability, much like its competitor.
The YA-9 also possessed the ability to loiter over the target for long periods of time.
The A-9 was designed with low-level flight survivability in mind. The pilot sat in a bubble canopy that afforded excellent 360-degree over-the-nose visibility.
With redundant flight control systems and robust aluminum alloy armor that was 1.25 to 2.5 inches thick, protecting the pilot and key components of the aircraft, the A-9 could withstand multiple direct hits from Soviet 23mm anti-aircraft cannons.
However, if adopted, the plan was to switch the pilot’s armor to a titanium bathtub design.
The YA-9 Specs And Armament
The aircraft was 53’6” long, with a wingspan of 57’, and a height of 17’10”. The aforementioned Soviet Su-25 Frogfoot’s dimensions were remarkably similar, as was its external design.
It would seem like US and Soviet aircraft designers had very similar parameters in what a close-support aircraft should look like and perform.
The YA-9 was constructed with an all-metal riveted aluminum alloy, semi-monocoque with stressed skin. Extensive use was made of honeycomb structure and chemically milled skins.
The wings featured ten weapon pylons that could carry 16,000 pounds of ordnance, depending on the mission.
The aircraft was armed with an M61 Vulcan 20mm Gatling gun because the GAU-8 Avenger 30mm cannon was not yet ready for testing.
The aircraft was equipped with twin turbofans mounted in nacelles under the wing roots.
Northrop selected the Lycoming YF102 engine for the YA-9 rather than the more powerful General Electric TF34 used by the A-10.
Each engine produced 7,200 pounds of thrust each, and it powered the aircraft to a top speed of 520 mph. Maintenance crews could replace the engines in an hour.
A-10 Warthog. 19FortyFive.com image taken in Lakeland, Florida on 4/19/2026.
A-10 Warthog Lakeland Florida Airshow 19FortyFive.com. Taken on 4/19/2026.
A-10 Warthog. Image Credit: 19FortyFive.com Taken on 4/19/2026.
Northrop built only two YA-9A prototypes, serial numbers 71-1367 and 71-1368.
The two YA-9s completed 123 flights, totaling 307.6 flight hours, during the ground attack aircraft competition.
Following the competition, the two YA-9s were transferred to the NASA Dryden Research Center before being retired from service on April 2, 1973.
However, both are currently on display as museum pieces. The March Field Air Museum is home of 71-1368, while Edwards AFB is the home of 71-1367.
Key Differences Between The YA-9 And The A-10 Thunderbolt
While both aircraft were built to fly low, fly slow, and absorb heavy ground fire, they took very different structural approaches:
The YA-9 used two Lycoming YF-102 turbofan engines mounted directly at the wing roots.
In contrast, the A-10 used General Electric TF34 engines mounted high on the rear fuselage to shield them from ground fire and reduce their heat signature.
The engines’ location and power favored the A-10.
The YA-9 featured a more conventional low/mid-mounted wing design.
The A-10 utilized a high-mounted wing that sat closer to the ground, allowing ground crews to re-arm and refuel the aircraft faster and with less equipment.
The YA-9 was originally tested with a 20mm Vulcan cannon, whereas the A-10 was specifically designed and built around the massive, armor-piercing 30mm GAU-8 Avenger rotary cannon, which brings the BRRRT in the A-10.
The Legendary A-10 Won The Competition
Although the YA-9 was an excellent aircraft, many practical considerations during the fly-off tilted the competition in favor of the A-10, which took the Thunderbolt name like the WWII-era P-47. Its pilots nicknamed it “the Warthog” or simply “the Hog.”
Engine reliability was a significant factor.
The Air Force preferred the more developed and reliable engines of the A-10, viewing the YA-9’s engines as somewhat unproven at the time.
Maintenance and ordnance loading were much easier to accomplish on the Thunderbolt.
The A-10’s lower profile and wing configuration made reloading weapons and servicing the aircraft far easier in a rugged, forward-base environment.
The flyaway cost was lower for the A-10. Fairchild’s initial prototype strategy resulted in an airframe closer to a production-ready design, keeping the projected flyaway cost at an estimated $1.4 million per aircraft.
Although the YA-9 was an excellent aircraft and its pilots said it handled like a fighter, it lost the competition to the A-10, which is hard to argue with.
The success of the A-10 has been well documented as arguably the best close-air support aircraft ever, serving in every conflict from Desert Storm to the present conflict in Iran. And its popularity with the troops it supported is legendary.
About the Author: Steve Balestrieri
Steve Balestrieri is a National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing on defense, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in many military publications
