The Forgotten F-20 Tigershark
When looking back upon noteworthy aircraft in the 1970s, we may remember it as the era of the F-16 and F-15. However, many other western concepts emerged during this era, some with great potential. Few of these concepts would be employed, and naturally have largely been forgotten.
One such design - which was designed in competition with the F-16 - was the F-20 Tigershark, an aircraft in which its development was marred with controversy and uncertainties, but arguably, could have become a great fighter.
HISTORY
Beginning in the early 1960s, the United States was looking for a small and affordable fighter aircraft for both domestic use and sale on the international market. Several existing aircraft were considered for modification, including the Starfighter, however, a new concept by Northrop was chosen. This aircraft would be the F-5 Freedom Fighter. A small and nimble aircraft, it possessed certain qualities not found in larger aircraft like the F-4. Over 800 would be produced, and the small platform was both easy to operate and affordable.
With comparable agility to the revered MiG-21 - these aircraft would be sent to Vietnam in the mid 60s, filling a variety of roles. Although they had their faults, these early models, from the Alpha through to Charlie, were still deadly in the right hands, and despite their short range were considered the best adversary against the MiG.
At the same time, back in the US, the F-5s were chosen to fill what would ironically become their most iconic tasking; aggressor aircraft to simulate MiGs. They would fill this role for many years, famously taking part in the Air Combat Evaluation trials against the F-14 and F-15. While these newer aircraft held the advantage in beyond-visual-range, pilots remember that the F-5 remained an equal match once within visual range.
Considering the benefits of the Freedom Fighter, the US military green-lit an upgrade program in 1970, which would see the aircraft further modernised with a new radar, and improved internals for better air-to-air capabilities. The result was the F-5E Tiger II, which has become what most people today associate with the designation F-5.
F-5Es still operate to this day in various locations, but in the mid 1970s a further upgrade program was on the table, which would allow this versatile aircraft to be bought up to fourth-gen standards. This would become known as the F-20.
F-20 PROGRAM
During the 1970s, the rapidly evolving Cold War led to changes in policy related to advanced weapons sales abroad. In the 60s, when Kennedy had ordered the F-5 program to begin, this was far less of an issue, but by the 1970s the international situation was far less black-and-white. President Nixon had been attempting to normalise relations with Russia and China, and part of this process involved the denial of advanced weapons sales to certain countries that could be seen as proxies. Notably, Taiwan had been asking for F-5Gs, and this was denied to prevent the wrong message being sent to China.
Some exceptions were made – for example Iran received F-14s, and Israel received F-15s - however broadly speaking, US aircraft sales during this period were under increased scrutiny. This would ironically lead to a vacuum in the market, which was filled by European and Soviet manufacturers, and at one point it was noted that weapons sales had increased globally during this time. The Soviets were not afraid to send new aircraft to their allies, including the latest Sukhoi and MiG designs, as well as others.
President Carter had lobbied against international weapons sales, however by 1980 the military was seriously reconsidering this. A proposal was put forward, returning to Kennedy’s initial vision; something akin to a modernised F-5 should be built, which would outperform the original F-5 and be deadly in the skies - but with careful considerations so that the US could mitigate its threat if turned against the US by foreign buyers. The answer was “FX” - a program to produce such an aircraft for export.
It would be an entirely privately funded venture, and manufacturers could not advertise the aircraft, rather everything would be handled by the Department of Defence. General Dynamics answered with the F-16/79, which as the name suggests, was an F-16A with the F100 engine replaced by the classic J79 used in the F4 Phantom, a far cheaper engine. Northrop answered with an upgraded model of the F-5G. However, by 1982 the situation had changed yet again; Taiwan was once again denied the F-5G and so announced they would build their own fighter - the F-CK-1 – and at the same time the sale of F-16s to Pakistan was offered.
In response, Northrop was given the go-ahead to produce an aircraft which was far more capable than initially intended; it would basically need to compete with the F-16A - the most agile of the Viper variants to be produced - and would require a new engine, better avionics, and perhaps an altered airframe.
DESIGNING THE F-20
The F-5G name was dropped, and in late 1982 the US Air Force approved the newly named ‘F-20 Tigershark’. Design and construction would begin immediately. During construction, to lower weight, parts of the aircraft were replaced with fiberglass and other composites.
While the airframe would remain largely the same, some important modernisations were done - likely inspired by the ingenuity of the F-16. Firstly, leading edge extensions were added to the wings, improving the lift coefficient without overly impacting weight or size. A new horizontal stabiliser - 30% larger than its predecessor - was added. The aircraft was now somewhat unstable - just like the F-16 - giving it better turn performance. In fact, at Mach 0.8 at altitude, it could achieve a turn rate of 11.5 degrees per second, close to the F-16s 12.8 at the same altitude and speed.
The twin J85s used on the F-5E would be replaced by a single General Electric F404. This single engine alone would produce 70% more thrust than the twin engines combined on the older aircraft. It was also claimed that this was the most reliable engine in a fighter at the time, in one video it is stated that the F-20 could achieve an idle power to full afterburner acceleration from just 47 knots at 45000 feet, without compressors stalls or any sort of engine cut-off.
In terms of general performance, the Tigershark - thanks to its engine - would be capable of speeds beyond Mach 2.0, at altitudes up to 55,000 feet. It also boasted a long range given its small size; in one test flight from Edwards Air Force Base in California to Andrews Air Force Base in Maryland, without refuel, a range of over 2,000 miles or 3,200 kilometres was achieved.
In the cockpit, everything was upgraded. A fly-by-wire flight control system replaced the older system from the Tiger, whilst an electronic navigation system replaced the older analogue electro-mechanical system. The new AN/APG-67 allowed for far better air-to-air and air-to-ground performance and could be operated in a variety of modes like the F-16. For the pilot, a new, large heads-up display would provide important information. Below it lay a simple data entry display, and below that - on the left and right - were two multi-function displays capable of operating in several modes. The Tigershark would also offer a more complex HOTAS to allow for better systems employment without cluttering up the cockpit with further panels.
The cockpits general layout was not dissimilar to the F-16, with the twin MFD setup, plus the basic DED, however on a technical level, the F-20 appeared to borrow components from the Hornet. The MFD visualisation of air-to-air and air-to-ground modes, as well as other MFD pages like the stores display and digital RWR compass looked very similar to those displayed on the Hornets DDI’s. It also seemed to have used a Hornet stick. It is possible that pre-existing components were used to achieve a working mock-up for the promotional videos, and that a finalised production model would use more unique components.
The F-20 was promoted as compatible with a variety of common weapons for very flexible performance; Maverick air-to-ground missiles, Mark 80 bombs of all kinds, Sidewinders, Sparrows, and in the nose a twin cannon. It could even be set up for air-to-sea missions, using the Harpoon missiles and laser guided bombs, then directed to target using an air-to-ground radar mode similar to that in the Hornet. Northrop also intended the aircraft to carry AMRAAM missiles once they were available.
Northrop also claimed that the Tigershark had the fastest scramble time of any modern aircraft, using an internal cartridge start, the engine could be up to speed in 19 seconds, while the laser INS would be ready in 22, and the aircraft airborne in less than 1 minute from a cold start.
However, there were some drawbacks. The airframe - while providing good agility in a fight - lacked lift performance in standard flight, limiting its range and payload ability. Weapons had to be mounted further out on the wings, on hardpoints only rated for 1,000 pounds of stores. It did however hold one crucial air-to-air advantage over the Vipers of the time; the F-20 could field the AIM-7 Sparrow, allowing it to engage in beyond visual range combat, a feature the F-16 wasn’t widely capable of until the late 80s.
In terms of price the F-20 would cost significantly more than an older F-5E, yet cheaper than its competition; an F-15 at the time was around $30 million, the latest F-16s were $15 million, and an older F-16A was around $13 million. The F-20, in contrast, would only cost $10.7 million. However, there were drawbacks; one estimate put the F-20s lifespan at half that of an F-16, yet another presumed that the Tigershark would cost 60% less than the F-16, and require only half the maintenance.
Flying in its more archaic F-5G form since August 1982, testing of the F-20 had been continuous during the design process due to its close similarities to the F-5. Thus allowing for easy modification and flight testing. Initially testing was done by simply swapping out the engine of an F-5G with the F404, but by 1983 a better prepared testbed was available. The aircraft proved powerful in the air. 9G capable, it was boasted in promotional footage as having practically no agility limits imposed, allowing for incredible angles of attack, high G and low speed manoeuvres.
During its several years of testing, the Tigershark in various iterations of development successfully fired all of its intended weapons, such as the Maverick, Sparrow, Sidewinder, and so on. Customers were already lining up; Bahrain wished to order the aircraft, and South Korea was also considering its purchase. Chuck Yeager - who was working with Northrop at the time - said that the aircraft was ‘magnificent’.
However, government and corporate business manoeuvres would get in the way.
In 1983 the US government began directly funding the development of the Israeli IAI Lavi. The Lavi would be a direct competitor to the F-20, and one produced by a foreign state. This decision caused serious controversy, specifically harming Northrop, who justly noted that they had been told to fund their own F-20 project - but now the US military, inexplicably, was funding a foreign competitor.
Annoyance did not subside; others in the industry threw their support behind Northrop, but congressional favour towards the Israeli project overruled the complaints of Northrop and others in the industry. To make matters worse, Northrop were bound by their contract; while other manufacturers could market how they pleased, all of Northrop’s marketing ideas and even material had to go through the US government for approval, which would often take months.
The straw that broke the camel’s back, according to Northrop, was the State Department’s complete disinterest in selling the F-20, despite all the work that went into it.
END OF THE PROGRAM
The issue of the F-20 would be dragged before congress. In these hearings, the Under Secretary of State for Security Assistance - William Schneider Jr - stated that the F-20 probably wouldn’t sell. In fact, he then went on to claim that the Tigershark was primarily a foreign policy tool, and its actual commercial success as a jet was secondary. CEO of Northrop Thomas Jones stepped up to voice his complaints; that Northrop should sell its own aircraft if the state has no interest to do so. Finally, Brigadier General Thomas Baker testified in Northrop’s defence; stating that he believed the Air Force was deliberately not marketing the aircraft; he noted that he had seen 100 aircraft sold to foreign nations over the previous four years, and none of them were the FX fighter. Finally, he said this decision was clearly ridiculous, pointing to the French who had proven with their Mirage that there was a big market for a low-cost fighter abroad.
Finally, after the congressional hearings, the Air Force was compelled to promote the aircraft. In internal reviews, the F-20 was acknowledged as a potentially serious threat to adversaries, a deadly aircraft in the right hands. It was also noted that unlike the $60 million General Electric had spent on the F-16/79, Northrop had invested $750 million into the F-20 to perfect the design. Sadly, reviews from some corners claimed no market existed for the aircraft.
In yet another controversial move, after having been directed by Congress to consider a single engine, light weight aircraft for aggressor or training use in 1985 - clearly inferring the F-20 - the Navy responded, saying it had decided on a specifically configured F-16 variant. Behind closed doors, the rumour was that these F-16s had been sold below market price at a loss, deliberately to keep the F-20 out of the market.
The final blow would come not long after, in 1986. One of the prerequisites for several foreign nations, who had shown interest in the F-20, was US adoption of the aircraft; they would purchase if the US was operating and maintaining it. This decision was only logical; it inferred that the US had faith in the design, and thus others too could place their faith in the aircraft. Northrop had hoped in one final bid to appeal to the Air National Guard. Northrop noted the aircraft was the perfect choice; it was affordable, easy to maintain, could field the AIM-7, and best of all had arguably the fastest start-up and scramble time. In a shocking disappointment to Northrop, the National Guard announced they would procure the new F-16C for the role, which once delivered would also field the AIM-7.
Facing one defeat after another, and still unable to sell, in 1986 Northrop executives decided to stop the program. Negotiations with Bahrain and Morocco were ended, and some executives were noted as attempting to bribe South Korea into purchasing the aircraft in a last ditch move, leading to several people stepping down from their positions. By this time, the program had cost $1.2 billion for Northrop. Those within the company wished to escalate with some form of legal action, and wished to publicly call out what they perceived as continual favouritism towards the F-16. This didn’t happen, out of fear of repercussions, specifically due to anxiety that the B-2 Spirit contract could be cancelled.
CONCLUSION
In retrospect, it is easy to sympathise with Northrop. Some commentators have speculated that the entire F-20 ordeal was to produce competition with the F-16, and artificially drive down prices, but this is anyone’s guess.
Nevertheless, we can speculate that the F-20 would have been a great aircraft, highly capable in its role as fighter. Despite the strange hostility to its adoption, the only consistent criticism was lack of customers, in every other avenue the F-20 was admitted as being a dominant aircraft in its intended air-to-air role.
A privately funded aircraft capable of taking on the best aircraft at the time, the F-20 may not be well remembered, but it will nevertheless go down as one of the greatest aircraft that never had the chance to prove itself.