(military or political requirements). The need Division Air Defense didn't go away with the Sgt. York, which didn't enter service. Instead, they came up with a missile based system to meet the requirement.

The Sgt. York was fatally flawed from the beginning. It was built from off-the-shelf components, including an M-48 tank chassis, twin 40mm Bofors cannon, and a radar/fire control system adapted from the F-16. They never could get the system to work properly. At first, the requirement was to shoot down supersonic fighters flying on the deck. It couldn't do that. Then, the requirement was to take out attack helicopters flying nap of the Earth attack profiles. It couldn't do that. Finally, the requirement was reduced to being able to shoot down hovering helicopters. It couldn't do that, either. They finally cancelled the program after it was proven that the tests were being rigged to make it appear the system was working.

The fatal flaw in the Sgt York was the 40mm cannon. That weapon is only effective out to about 2KM, while attacking helicopters carry missiles with much greater range. They could've hung outside the Sgt York's range and blew them to pieces.

Weapons systems get old over time, making them more difficult to maintain and operate. New technologies come along that allow new weapons to be more capable than the old ones. That's why we don't operate P-51 Mustangs or F-86 Sabers anymore despite the fact that those were top fighters in their day.

The JSF is designed to replace several old designs with three variations on a single design. The Air Force plans to replace the F-16 and A-10 with the JSF. Both of those planes are early 1970s designs. The Navy will use the JSF to replace the A-6 (1950s design that has already been retired except for the EA-6B version) and F-18A/B models (1970s design). The Marines also will replace their F/A-18s and AV-8B Harriers with the STOVL version of the JSF. The Harriers are getting old, they're hard and dangerous to fly, and have limited capabilities compared to the JSF.

The goal is to increase capabilities of individual aircraft to the point where you don't need so many planes to do the same mission. Stealth is a technology that helps accomplish that goal. One or two planes going in undetected might be able to accomplish the same mission that takes a squadron today, especially against heavily defended targets.