Meet The X-24C: A Mach 6 ‘Scramjet’ The Air Force Said ‘No’ To
BySandboxx NewsPublished53 seconds ago
X-24CX-24C. Image Credit: Creative Commons.
The X-24C had a tremendous amount of potential. However, hypersonic speeds don’t always mean the US Air Force will go all in – Today scramjet propulsion is the subject of continued study, as it appears to be one of the most promising methods of powering hypersonic weapons and aircraft. So, you may be surprised to learn that Lockheed was actually pursuing the idea of scramjet-powered hypersonic aircraft more than four decades ago.
Hypersonic is a term used to refer to vehicles that travel at speeds in excess of Mach 5.
By the end of 1968, the rocket-powered X-15 program had run its course, leaving the U.S. Air Force without any hypersonic aircraft in testing or development. That’s where Kelly Johnson’s team at the legendary Lockheed Skunk Works entered the picture.
Taking on the role of lead contractor, Lockheed worked side by side with the Air Force’s National Hypersonic Flight Research Facility and NASA to develop and field two hypersonic test aircraft, with each vehicle slated for 100 flights. The decision was made to equip this new “L-301” program’s aircraft, unofficially dubbed the X-24C, with a new LR-105 rocket engine found at the time in the Atlas series of rockets. The LR-105 would launch and accelerate the X-24C to hypersonic speeds, not unlike the rocket engine in the X-15. From there, a second hydrogen-fueled, air-breathing ram/scramjet (supersonic-combustion ramjet) engine mounted on its belly would take over.
Scramjet propulsion and hypersonic velocities
The scramjet engine would propel the X-24C at sustained speeds in excess of Mach 6, reaching intended peak speeds that were higher than Mach 8, or more than 6,130 miles per hour. The aircraft itself resembled the lifting body design leveraged by the Martin Marietta X-24A and B programs that tested unpowered reentry flight characteristics.
That scramjet propulsion concept is still widely considered to be the most likely candidate for hypersonic aircraft to this day. A normal jet engine uses a compressor section (fan blades) to compress air to be mixed with fuel and ignited, but at hypersonic velocities, that compressor becomes a hindrance, slowing airflow to subsonic speeds as it passes through.
https://www.19fortyfive.com/2022/02/meet-the-x-24c-a-mach-6-scramjet-the-air-force-said-no-to/
