 The following year, the Defense Advanced Research Projects Agency (DARPA) issued Lockheed Skunk Works a contract to build and test two Stealth Strike Fighters, under the code name ""Have Blue"".These subscale aircraft incorporated jet engines of the Northrop T-38A, fly-by-wire systems of the F-16, landing gear of the A-10, and environmental systems of the C-130.By bringing together existing technology and components, Lockheed built two demonstrators under budget, at $35 million for both aircraft, and in record time.