Northrop YA-9A
The extremely high losses to ground fire during the Vietnam War convinced the United States that any future attack/close air support aircraft would need to be heavily armored. This was doubly true for the war that everyone anticipated in Central Europe: Soviet forces could be expected to bring the same defenses the North Vietnamese did, perhaps worse. When it came to CAS, as it was known, the USAF was dependent on using aircraft that were never designed for it, from the B-57 Canberra to the F-105 Thunderchief, both of which were designed for tactical nuclear delivery. Finally, the US Army accused the USAF of not taking CAS seriously--there was no dedicated CAS aircraft--and threatened to convince Congress to allow the Army back into the fixed-wing aircraft business. This was the boogeyman of the independent USAF, so work began on the A-X program in 1966.
For the A-X requirement, survival was the dominant factor: the aircraft had to be able to take damage. Added later was that the A-X's main focus would be antiarmor: whereas tanks were rarely a factor in the Vietnam War, a World War III scenario would be different, with NATO forces facing a horde of Soviet tanks. The A-X would then need a heavy cannon capable of destroying a tank in a single pass, preferably something in the 30mm range. In 1970, Northrop and Fairchild-Republic were selected to build A-X prototypes, the YA-9 and YA-10, respectively.
Both aircraft turned out to be similar in design: low-winged aircraft with plenty of underwing hardpoints for bombs, rockets and missiles (a legacy of the A-1 Skyraider), designed around the General Electric GAU-8 Avenger 30mm gatling cannon, which was so huge that the drum was behind the cockpit, with the gun sticking out of the nose. Both aircraft emphasized survivability: there were redundant hydraulic systems, self-sealing fuel tanks, the ability to operate from austere airfields, and a titanium "bathtub" surrounding the pilot, proof against 23mm cannon shells--the type used by the deadly Soviet ZSU-23-4 Shilka.
Where the YA-9A differed from the YA-10A was one of the factors that led to Northrop's entry losing the competition: the engines were buried in the wingroots rather than set high and behind the wing as in the YA-10. While this was not necessarily a game changer, it did make the engines more vulnerable to ground fire. Worse, Northrop had chosen to go with the Lycoming YF102 engine, a heavily modified version of the engine that powered the CH-47 Chinook helicopter. Fairchild chose the TF34 turbofan, which was a proven aircraft engine. The YA-9A also used a single tail, while the YA-10A used a spilt tail, which was considered somewhat more survivable.
The flyoff between both aircraft commenced in 1972, and it was a close one, with both aircraft fulfilling the USAF's requirements. In the end, however, it would be the YA-10 that was chosen: the engines were a deciding factor (though Northrop claimed the TF34 could be fitted in the YA-9 as well), as was the fact that Fairchild's YA-10 was the company's last attempt at staying solvent. While Northrop had several aircraft it was either producing (like the F-5E Tiger II) or planning (the YF-17 Cobra, for the lightweight fighter competition), Fairchild had nothing, and the YA-10 would keep the company from going out of business.
The YA-10 would go on to immortal fame as the A-10 Thunderbolt II--better known as the Warthog--while the YA-9A was destined for obscurity. The two prototypes were used for testing by NASA for a few years before both ended up in museums. In the mid-1980s, the West was made aware of the Sukhoi Su-25 Frogfoot, which strongly resembled the YA-9A and had the same purpose. Northrop may have been paid the highest compliment by the very foe the YA-9A was designed to destroy.
Both YA-9A prototypes are in California--one at the Air Force Flight Test Museum at Edwards AFB, and this aircraft, the second prototype, 71-1368. It is maintained in the prototype's color scheme during testing, with dummy Mk 83 1000-pound bombs on the hardpoints. This was one of my "must-sees" when we went to California in May 2021.
Northrop YA-9A
The extremely high losses to ground fire during the Vietnam War convinced the United States that any future attack/close air support aircraft would need to be heavily armored. This was doubly true for the war that everyone anticipated in Central Europe: Soviet forces could be expected to bring the same defenses the North Vietnamese did, perhaps worse. When it came to CAS, as it was known, the USAF was dependent on using aircraft that were never designed for it, from the B-57 Canberra to the F-105 Thunderchief, both of which were designed for tactical nuclear delivery. Finally, the US Army accused the USAF of not taking CAS seriously--there was no dedicated CAS aircraft--and threatened to convince Congress to allow the Army back into the fixed-wing aircraft business. This was the boogeyman of the independent USAF, so work began on the A-X program in 1966.
For the A-X requirement, survival was the dominant factor: the aircraft had to be able to take damage. Added later was that the A-X's main focus would be antiarmor: whereas tanks were rarely a factor in the Vietnam War, a World War III scenario would be different, with NATO forces facing a horde of Soviet tanks. The A-X would then need a heavy cannon capable of destroying a tank in a single pass, preferably something in the 30mm range. In 1970, Northrop and Fairchild-Republic were selected to build A-X prototypes, the YA-9 and YA-10, respectively.
Both aircraft turned out to be similar in design: low-winged aircraft with plenty of underwing hardpoints for bombs, rockets and missiles (a legacy of the A-1 Skyraider), designed around the General Electric GAU-8 Avenger 30mm gatling cannon, which was so huge that the drum was behind the cockpit, with the gun sticking out of the nose. Both aircraft emphasized survivability: there were redundant hydraulic systems, self-sealing fuel tanks, the ability to operate from austere airfields, and a titanium "bathtub" surrounding the pilot, proof against 23mm cannon shells--the type used by the deadly Soviet ZSU-23-4 Shilka.
Where the YA-9A differed from the YA-10A was one of the factors that led to Northrop's entry losing the competition: the engines were buried in the wingroots rather than set high and behind the wing as in the YA-10. While this was not necessarily a game changer, it did make the engines more vulnerable to ground fire. Worse, Northrop had chosen to go with the Lycoming YF102 engine, a heavily modified version of the engine that powered the CH-47 Chinook helicopter. Fairchild chose the TF34 turbofan, which was a proven aircraft engine. The YA-9A also used a single tail, while the YA-10A used a spilt tail, which was considered somewhat more survivable.
The flyoff between both aircraft commenced in 1972, and it was a close one, with both aircraft fulfilling the USAF's requirements. In the end, however, it would be the YA-10 that was chosen: the engines were a deciding factor (though Northrop claimed the TF34 could be fitted in the YA-9 as well), as was the fact that Fairchild's YA-10 was the company's last attempt at staying solvent. While Northrop had several aircraft it was either producing (like the F-5E Tiger II) or planning (the YF-17 Cobra, for the lightweight fighter competition), Fairchild had nothing, and the YA-10 would keep the company from going out of business.
The YA-10 would go on to immortal fame as the A-10 Thunderbolt II--better known as the Warthog--while the YA-9A was destined for obscurity. The two prototypes were used for testing by NASA for a few years before both ended up in museums. In the mid-1980s, the West was made aware of the Sukhoi Su-25 Frogfoot, which strongly resembled the YA-9A and had the same purpose. Northrop may have been paid the highest compliment by the very foe the YA-9A was designed to destroy.
Both YA-9A prototypes are in California--one at the Air Force Flight Test Museum at Edwards AFB, and this aircraft, the second prototype, 71-1368. It is maintained in the prototype's color scheme during testing, with dummy Mk 83 1000-pound bombs on the hardpoints. This was one of my "must-sees" when we went to California in May 2021.