Lockheed L-301 (sometimes called the X-24C, though this designation was never officially assigned) was an experimental air-breathing hypersonic aircraft project. It was developed by the NASA and United States Air Force (USAF) organization National Hypersonic Flight Research Facility[1] (NHFRF or NHRF[2]), with Skunk Works as the prime contractor. In January 1977, the program was "tentatively scheduled to operate two vehicles for eight years and to conduct 100 flights per vehicle."[3] NASA discontinued work on L-301 and NHRF in September 1977 due to budget constraints and lack of need.[1]