As Sweet as a Warthog! The Northrop YA-9A

August 20, 2021

The Fairchild A-10 is an aircraft that enjoys a great reputation. Though its official name is “Thunderbolt II”, I don’t think hardly anyone calls it that. If they are being polite, they call it the “Tankbuster”.

But for the vast majority, it’s the “Warthog”.


Utterly distinctive in appearance, the A-10 has carved through enemy forces in a host of campaigns over many decades, and apparently will continue to do so for some years still to come. But the “Warthog” had to win its place in the lineup, and there was another aircraft that was built to compete against it.

The Northrop YA-9.

So, a bit of history.

There was long something of a disconnect between the United States Army and Air Force about the sort of support that the latter should provide the former. For close air support – otherwise known as “CAS” – the Air Force had generally relied upon hanging bombs or rockets off existing high performance fighter aircraft.

This proved broadly sufficient during the era of the propellor aircraft and the Second World War, but once the USAF transitioned to jets, CAS was no longer of any great interest. Instead, it was all about speed – preferably supersonic.

The USAF got really focused on nuclear delivery and, if they were called on for “ground-pounding” duties, they had the F-100 Super Sabre – another fighter converted for ground attack – and the F-105. But these were both designed as supersonic aircraft and as a result nothing in the USAF inventory was particularly suitable for close air support.

This became extremely apparent during the Vietnam War. In 1964 the USAF actually resorted to taking hand-me-down A-1 Skyraiders from the US Navy. This did sterling work supporting US troops, but the Skyraider was essentially a Second World War aircraft and the USAF wanted something better.

They were also concerned that the US Army was beginning to experiment with dedicated attack helicopters. An agreement reached in April 1966 between the US Army and Air Force meant that the Army would give up its fixed wing transport assets -mainly the C7 Caribous – and in return the Air Force would not be involved in front line rotary winged operations.

Naturally, the USAF was then concerned that they might lose budget to the Army if the new attack helicopters could do a better job of supporting troops than high-speed aircraft. So, in mid-1966 the Air Force commissioned the A-X program, intended to develop a new ground attack aircraft.

In sharp contrast to the USAF’s usual designs, this was to focus on operating low-and-slow, right above the treetops and with the pilot able to loiter in support of forces on the ground. The proposed aircraft would need to have massive firepower and payload abilities and it would need to be well armoured.

In 1970, the focus switched from attacking insurgents in jungles to fighting a conventional armoured conflict against the Soviet Union in Germany. The USAF tweaked its requirements and posted a request for proposals that called for what was essentially a modern-day version of the Soviet’s World War Two Shturmovik, the IL-2.

The new aircraft needed to be able to assist in breaking up enemy armoured formations and to be able to provide close air support with a range of ordnance to friendly ground troops as close as possible. To do this the new support plane would only have a maximum speed of 460 mph (740 km/h) and an external payload of 16,000 pounds (7,300 kg). The new AGM-65 Maverick fire-and-forget missile, then in development, would be the main anti-armour ordnance.

But the primary weapon, which the aircraft would be built around, would be a rotary 30mm cannon that would be able to tear up lighter armoured vehicles.

The USAF expected to purchase six hundred of the new attack aircraft and stipulated that the fly away cost should be no more than $1.4 million – which would be about $9.5 million today. Six companies entered submissions, but only two, the Fairchild YA-10 and the Northrop YA-9 were awarded development contracts.

Northrop built two YA-9A prototypes, these both flying in 1972.

In contrast to the A-10, the A-9 had a more conventional appearance. A shoulder-winged monoplane of all-riveted aluminum alloy construction, the A-9 differs from its rival in having its two turbofan engines mounted under the wing roots. These were Lycoming YF102, a derivation of the T55 turboshaft that was used on the US Army’s Chinook helicopters.


Though these engines produced less power than the TF34s used on the YA-10s -7,200lbfs vs. 9,280lbfs – Northrop believed that they potentially offered a substantial price saving for initial purchase and in lifetime costs. And the lower power doesn’t seem to have affected the YA-9As performance.

Northrop’s test pilots reported that the aircraft handled like a fighter aircraft and the two aircraft demonstrated a top speed of 520 mph (837 km/h). It also had great maneuverability, principally due to the YA-9s having a large rudder and flaps. This allowed the aircraft to slide sideways without yawing or banking, assisting with weapons aiming.


The pilot view was also very good, as expected for an aircraft designed to operate at low levels.

Protection was also substantial. The pilot was ensconced in an armored “bathtub” which on the prototypes was aluminium, but in the production aircraft would have been titanium. The hydraulic flight controls were duplicated, and the wing-mounted fuel tanks were self-sealing and filled with foam to prevent fires and fuel leaks if the aircraft was hit.

Ten hardpoints were mounted under the wings, which could carry the specified 16,000 lbs of ordnance. The cannon was, in contrast to the A-10, mounted under the aircraft belly and not in the nose, with the muzzle under the cockpit.


However, at the time of the A-X competition flyoff, the GAU-8 cannon, the chosen weapon, was still in development and as a result both the YA-9s and YA-10s would carry M61 Vulcan 20mm cannons for testing.

On October 10, 1972, both the YA-9s and YA-10s were handed over to the Air Force for two months of evaluation. In January 1973, the A-10 was declared the winner and Fairchild awarded the production contact.

The YA-9As scored well in the testing, with the two prototypes conducting a total of 123 flights, and the Air Force stated that the aircraft did meet its requirements. However, the Air Force stated that the reason for the selection of the A-10 was that Fairchild had conducted a more thorough testing program of their design.

They also stated that the fact the engines of the A-10 were more developed was an important factor. With that the two YA-9s were retired, though happily not scrapped. Today one resides at Edwards Air Force Base in California, awaiting restoration, whilst the other is on display at the March Field Air Museum, also in California.

There are a couple of other details that we should examine when it comes to the Northrop A-9 before concluding.

The decision to not choose the A-9 as their new attack aircraft, especially as the USAF admitted the aircraft was perfectly adequate, has led to speculation as the exact reasoning behind the decision. The fact that a reason given was the greater testing done by Fairchild on the YA-10 is often attributed to the respective states of the two competitors at the time.

Northrop was in the process of fielding the first of the F-5E Tigers, an aircraft that would prove a great success.

But their main development focus was on the new Northrop YF-17 light fighter that was potentially one of the most successful aircraft the company would ever produce.


As a result, most of Northrop’s efforts – testing, financial and political -were absorbed by the YF-17.

But Fairchild was a company in trouble. They had only one defence contract of any great potential in the pipeline – the YA-10. So, they threw everything they had at it, including making it known amongst their political supporters that failure to win the A-X competition would spell the end of the company.

This has led to speculation that it was primarily for this reason that the A-10 won.

I’d say more research would have to be conducted to determine the truth of this. But if the USAF was happy with either aircraft, it would make sense to please those in Congress making noise about the issue as a bonus to getting a good aircraft.

The other point is one that has been circling for decades.

In 1975 the Soviets flew the Su-25, their own armored ground attack aircraft. This aircraft was built to the same sort of doctrine as the A9 and A-10 and its similarity to the A-9 has long caused speculation.

Did the Soviets rip off Northrop’s aircraft?

Personally, I think it is largely a case of similar design parameters resulting in similar designs. In fact, the sketches for what became the Su-25 were down on paper in 1968. But development of the prototypes didn’t start until 1972, the same year that pictures of the two A-X competitors were appearing in the press.

And interestingly, in 1972 and ’73 articles appeared in the Soviet military press discussing the A-9 and talking about its maneuverability and armour layouts in very favorable terms.

So, while I don’t think the Su-25 is a rip off of the A-9, it is entirely possible that it was influenced by it.


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