Editing Northrop F-5 (section)

===Derivatives===

====F-20 Tigershark====
{{main|Northrop F-20 Tigershark}}

In comparison to later fighters, the improved F-5E had some weaknesses; these included marginal acceleration, rearward visibility, and [[fuel fraction]], and a lack of Beyond Visual Range (BVR) weapons once such radar–guided missiles became reliable during the 1980s.<ref name="Sprey, p. 145">Sprey 1982, p. 145.</ref> The F-5G, later renamed the F-20 Tigershark, aimed to correct these weaknesses while maintaining a small size and low cost to produce a competitive fighter. Compared to the F-5E, it had 60% more power, a higher climb rate and acceleration, better cockpit visibility, more modern radar and BVR capability, and competitive performance with fourth generation fighters. Like the F-5, it had better cost–effectiveness as it had the minimum necessary features relative to its competition to perform its air superiority mission. As an example, in the 1960s and early 1970s, the F-5's lack of BVR missiles was not a significant disadvantage as the kill rate of such missiles was approximately 8% to 10%,<ref>Sprey 1982, p. 118.</ref> and the performance and loss of surprise (radar warning to the enemy) cost of carrying them was not practically justified. By the early 1980s, the American [[AIM-7 Sparrow]] radar-guided missile in its "M" version was realistically exceeding a 60% kill rate, and was integrated onto the F-20. Brigadier General [[Chuck Yeager]], test pilot and the first man to break the sound barrier, referred to the F-20 as "the finest fighter".<ref>Yeager and Janos 1985, pp. 248–249.</ref> Despite its performance and affordable cost, the F-20 lost out for foreign sales against the similarly capable but more expensive F-16, which was being procured in large numbers by the US Air Force and was viewed as having greater support.<ref>Hammond 2001, p. 99.</ref>

====Northrop YF-17====
{{main|Northrop YF-17}}

The Northrop YF-17's main design elements date from the F-5 based internal Northrop project N-300. The N-300 featured a longer fuselage, small leading-edge root extensions (LERX), and more powerful GE15-J1A1 turbojets. The wing was moved higher on the fuselage to increase ordnance flexibility. The N-300 further evolved into the P-530 Cobra. The P-530's wing planform and nose section was similar to the F-5, with a trapezoidal shape formed by a sweep of 20° at the quarter-chord line, and an unswept trailing edge, but was over double the area. While the YF-17 lost its bid for the USAF lightweight fighter, it would be developed into the larger [[McDonnell Douglas F/A-18 Hornet]].

====Shaped Sonic Boom Demonstration====
{{main|Shaped Sonic Boom Demonstration}}

A single ex-USN F-5E was modified to carry out research into reducing noise from supersonic flight by shaping the shock waves produced by the aircraft.