The F-16XL is a derivative of the F-16 Fighting Falcon with beautiful cranked-arrow delta wing. The type entered the USAF Enhanced Tactical Fighter (ETF) competition in 1981 but it sadly lost to the F-15E Strike Eagle. Both prototypes were shelved until being turned over to NASA for additional aeronautical research in 1988. The duo was eventually fully retired in 2009 and stored at Edwards AFB (CA).