What Made the X-15 Special? As militaries around the world track and analyze the fast-moving, multi-national race to develop and deploy hypersonic weapons, some are likely to overlook the decades-long and complex history informing the U.S. militaries’ effort to mature the technology.
After publicly calling itself number 3 in the global hypersonic arms race several years ago, the U.S. military has been quickly closing the gap with Russia and China with successful testing and development of its own land-air-and-surface launched hypersonic weapons.
The X-15 Is Born
Beneath the radar aperture of the intense current focus on hypersonics, there are highly impactful and lesser-recognized historical accomplishments, such as NASA’s X-15.
The North American X-15 is a U.S. Air Force-NASA hypersonic rocket-powered aircraft that set speed records as far back as the 1960s.
The aircraft reached speeds of Mach 6 and reached altitudes of 250,000 feet along the “edge of outer space,”as described by aerospaceweb.org
The aerospaceweb.org article says that in 1967, the X-15 reached what was at the time a world record speed of 4,520 miles per hour, making it the highest speed ever recorded by a crewed, powered aircraft.
“The basic X-15 was a single-seat, mid-wing monoplane designed to explore the areas of high aerodynamic heating rates, stability and control, physiological phenomena, and other problems relating to hypersonic flight (above Mach 5),” a 2014 NASA fact sheet on the X-15 states.
The aircraft was primarily a research and reconnaissance plane intended to explore the parameters, possibilities, and limitations of hypersonic flight and the mix of variables involved in making it possible.
Critical data were likely gathered during these early years of experiment, quite likely responsible for informing some of today’s current progress in the realm of hypersonic weapons.
For instance, early information of relevance to hypersonic flight was likely obtained all these decades ago during the X-15’s early years.
Did X-15 Influence Modern Hypersonic Flight?
Such analysis likely helped contribute to current breakthroughs in challenging areas related to achieving hypersonic flight such as thermal management, aerodynamic configurations, and airflow dynamics.
Managing the airflow surrounding hypersonic projectiles is extremely important as it can determine the relative stability of a hypersonic vehicle “in flight.”
Laminar or “smooth” airflow is sought after as the surface can prevent the hypersonic system’s glide path and targeting slope from being thrust off-course.
Also of great relevance, the materials used for the fuselage and platform itself were likely chosen quite carefully, as certain substances perform better or remain stable in the heat of hypersonic flight.
In contrast, other materials cannot sustain temperatures associated with hypersonic speed. This basic research framework still applies today as both the Army and Air Force Research Laboratories consistently work on uncovering optimal combinations of composite materials capable of flying successfully at hypersonic speeds.
Powered by a rocket, the X-15 was air launched from a B-52 to accommodate the large fuel consumption of its rocket engine. Launching from the B-52 at speeds more than 500 miles per hour, the X-15’s rocket engine provided thrust for 80-to-120 seconds of flight, before gliding into landing at speeds of 200mph.
Author Expertise and Experience
Kris Osborn is the Military Affairs Editor of 19FortyFive and President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.