Northrop F-20 Tigershark

The Northrop F-20 Tigershark (initially F-5G) was a privately financed light fighter, designed and built by Northrop. Its development began in 1975 as a further evolution of Northrop's F-5E Tiger II, featuring a new engine that greatly improved overall performance, and a modern avionics suite including a powerful and flexible radar. Compared with the F-5E, the F-20 was much faster, gained beyond-visual-range air-to-air capability, and had a full suite of air-to-ground modes capable of firing most U.S. weapons. With these improved capabilities, the F-20 became competitive with contemporary fighter designs such as the General Dynamics F-16 Fighting Falcon, but was much less expensive to purchase and operate.

Much of the F-20's development was carried out under a US Department of Defense (DoD) project called "FX". FX sought to develop fighters that would be capable in combat with the latest Soviet aircraft but, by excluding sensitive front-line technologies used by the United States Air Force, the FX could be sold to foreign nations without the risk of significant technological advancements falling into Soviet hands. FX was a product of the Carter administration's military export policies. Northrop had high hopes for the F-20 in the international market, but policy changes following Ronald Reagan's election meant the F-20 had to compete for sales against aircraft like the F-16, the USAF's latest fighter design. The development program was abandoned in 1986 after three prototypes had been built and a fourth partially completed.


Northrop F-20 Tigershark
Class Aircraft
Type Fighter
Manufacturer Northrop Corporation
Origin United States of America
Country Name Origin Year
United States of America 1982
ManufacturerName Production From Production To Quantity
Northrop Corporation 3 View

The primary design change between the earlier F-5E and the F-5G was the use of a single General Electric F404 engine that was originally designed for the F/A-18 Hornet. The new engine provided 60% more thrust compared to the combined output of the F-5E's paired General Electric J85s. This improved the aircraft's thrust-to-weight ratio to 1.13 from 1.0. The new engine gave speed of over Mach 2.0, a ceiling over 55,000 ft (16,800 m), an initial climb rate of 52,800 ft per minute (16,100m/min), and overall climb performance to 40,000 ft (12,192 m) that was decreased from 2.2 minutes to 1.1 minutes.

The wing profile remained the same as the F-5E, but had modified leading edge extensions (LEX), which improved the maximum lift coefficient of the wing by about 12% with an increase in wing area of only 1.6%. The original aircraft was fairly sluggish in pitch, so the horizontal stabilizer was increased in size by 30% and a new dual-channel fly-by-wire control system was added. Destabilizing the aircraft in pitch and modifying the LEX improved the instantaneous turn rate by 7% to 20°/sec. Sustained turn rate at Mach 0.8 and 15,000 ft (4,572 m) rose to 11.5°/sec, which compared well with the F-16's 12.8°/sec. Supersonic turn rates were 47% higher than those of the F-5E.

The F-20 would also make greater usage of composite materials in its construction. During its development, several areas using metal were re-designed to use fiberglass, and there were numerous upgrades to various mechanical parts.

The F-20's avionics suite was all-new and greatly improved over the earlier designs. The General Electric AN/APG-67 multi-mode radar was the heart of the sensor suite, offering a wide range of air-to-air and air-to-ground modes. The F-5's electro-mechanical navigation system was replaced with an all-electronic version based on a ring laser gyroscope. Time from power-on to being able to launch was greatly reduced as a result, to about 22 seconds, and Northrop boasted the aircraft had the shortest scramble time of any contemporary aircraft. The cockpit of the F-5 was completely re-worked with a large heads-up display (HUD) and two monochrome multi-function displays set high on the control panel, and the addition of a complete hands-on-throttle-and-stick (HOTAS) control system. Many of the avionics promised to have reliability beyond that of any competing aircraft then in service.

The F-20 would have been able to utilize most of the common weapons in U.S.'s inventory, including the entire range of Mark 80 series bombs, the AGM-65 Maverick air-to-ground missile, and the AIM-9 Sidewinder and AIM-7 Sparrow air-to-air missiles. Like the earlier F-5s, the test F-20s were equipped with two M39 cannon mounted in the nose. Production F-20s may have substituted two Ford Aerospace Tigerclaw cannons instead of the M39s; while the Tigerclaw was based on the M39, it was lighter and had a higher rate of fire than the M39A2.

The F-20 did, however, have several problems inherent to its small size. The low-mounted wing meant that there was limited ground clearance, and the position of the landing gear meant loads had to be positioned towards the outer ends of the wings. This limited hard point weights to 1,000 lb (454 kg) or less. A single hard point under the fuselage could carry more, a single Mk 84 2,000 lbs bomb or up to five Mk 82 500 lbs bombs. Additionally, although the wing profiling improved lift at higher angles of attack (AoA) while maneuvering, it did not improve cruise lift performance at normal AoA. This did not present a problem in the fighter role, but did severely reduce its payload/range figures compared to similar aircraft like the F-16.

Offered as a low-cost option, the F-20 was significantly more expensive than the F-5E, but much less expensive than other designs like the $30 million F-15 Eagle, or $15 million F-16 Fighting Falcon. The F-20 was projected to consume 53% less fuel, require 52% less maintenance manpower, had 63% lower operating and maintenance costs and had four times the reliability of average front-line designs of the era. The F-20 also offer the ability to fire the beyond-visual-range AIM-7 Sparrow missile, a capability that the F-16 lacked at that time, and did not gain until the Block 15 ADF version in February 1989.


On 30 August 1982, the original engine-change-only F-5G (serial 82-0062, c/n GG1001, registered N4416T) made its maiden flight piloted by Russ Scott. During the 40-minute flight, the prototype climbed to 40,000 ft (12,000 m) and reached Mach 1.04. GG1001 demonstrated outstanding reliability; by the end of April 1983 240 flights had been accumulated, including evaluation flights with 10 potential customer nations. The second prototype (serial number 82-0063, registered N3986B, c/n GI1001), featuring the complete avionics suite, made its first flight on 26 August 1983. The F-20 would fly a total of 1,500 flights prior to its termination; although these were exclusively flown in ideal conditions. Note: "...Northrup did not take a prototype approach with the F-20...The First F-20 was intended to be a production quality aircraft..." page 5 Rand Corporation report A Case Study of the F-20 Tigershark June 1987.

During the test program, the F-20 fired the AIM-9 Sidewinder and, in February 1985 the AIM-7 Sparrow. In air-to-ground testing, it fired the AGM-65 Maverick, 2.75 in (70 mm) folding fin aerial rockets, dropped Mk. 82 bombs, and fired rounds from a 30 mm (1.18 in) gun pod (GPU-5/A, four-barrel GAU-13/A) in addition to the two internal 20 mm (.79 in) M39 cannon.[40] One of the F-20's flight characteristics was the ability to fly at only 124 km/h (77 mph) at 35° AoA (angle of attack), while the F-16 was limited to 30°; acceleration from Mach 0.9 to 1.2 in 29 seconds (at 9,150 m); climb to 12,200 m (or 40,000 ft) in 2.3 minutes (including 55 sec for the start and 22 for the INS set-up).

Northrop signed a Memorandum of Agreement with the Air Force in May 1983 that made the Air Force responsible for certifying the F-20's performance, air worthiness and fixed-price program. Aerospace legend Chuck Yeager, employed as a spokesperson for Northrop, touted the aircraft as "magnificent" and was featured in advertising.

In November 1982, Bahrain became the first customer. South Korea also explored local production of the F-20, and in support improvements were implemented. These included avionics upgrades, an expanded fuel tank, and the use of fibreglass composites. The changes were so extensive that a fourth prototype was built to test them. By 1983, Northrop was involved in a number of simultaneous negotiations for the F-20, and its prospects appeared positive.

On 10 October 1984, GG1001 crashed in South Korea on a demonstration flight, killing Northrop pilot Darrell Cornell. An investigation cleared the F-20 of mechanical or design faults; it concluded Cornell had blacked out due to excessive g-forces. GI1001 crashed in May 1985 at Goose Bay, Labrador, killing Northrop pilot Dave Barnes. Again the crash was blamed on G-LOC; Barnes had been practicing his aerobatic routine for the Paris Air Show.

Role Fighter aircraft
National origin United States
Manufacturer Northrop Corporation
First flight 30 August 1982
Status Canceled
Number built 3
Program cost US$1.2 billion
Developed from Northrop F-5


General characteristics

  • Crew: 1 pilot
  • Length: 47 ft 4 in (14.4 m)
  • Wingspan: 27 ft 11.9 in / 8.53 m; with wingtip missiles (26 ft 8 in/ 8.13 m; without wingtip missiles)
  • Height: 13 ft 10 in (4.20 m)
  • Wing area: 200 ft² (18.6 m²)
  • Empty weight: 13,150 lb (5,964 kg)
  • Loaded weight: 15,480 lb (7,021 kg)
  • Max. takeoff weight: 27,500 lb (12,474 kg)
  • Powerplant: 1 × General Electric F404-GE-100 turbofan, 17,000 lbf (76 kN)

Performance

  • Maximum speed: Mach 2
  • Combat radius: 300 nmi (345 mi, 556 km) ; for hi-lo-hi mission with 2 × 330 US gal (1,250 L) drop tanks
  • Ferry range: 1,490 nmi (1715 mi, 2759 km) ; with 3 × 330 US gal (1,250 L) drop tanks
  • Service ceiling: 55,000 ft (16,800 m)
  • Rate of climb: 52,800 ft/min (255 m/s)
  • Wing loading: 81.0 lb/ft² (395 kg/m²)
  • Thrust/weight: 1.1

Armament

  • Guns: 2× 20 mm (0.79 in) Pontiac M39A2 cannons in the nose, 280 rounds each
  • Hardpoints: Five external hardpoints with a capacity of 8,000 lb (3,600 kg) of bombs, missiles, rockets and drop tanks for extended range
  • Rockets: 2× CRV7 rocket pods Or
    2 × LAU-10 rocket pods with 4 × Zuni 5 in (127 mm) rockets each Or
    2 × Matra rocket pods with 18× SNEB 68 mm rockets each
  • Missiles: 2× AIM-9 Sidewinders on wingtip launch rails (similar to F-16 and F/A-18)
    AGM-65 Maverick air-to-surface missiles on hardpoints
  • Bombs: Various air-to-ground ordnance such as Mark 80 series of unguided iron bombs (including 3 kg and 14 kg practice bombs), CBU-24/49/52/58 cluster bomb munitions, M129 Leaflet bomb

Avionics

  • General Electric AN/APG-67

End notes