By Kris Osborn, President, Center for Military Modernization
(Washington D.C.) The Air Force had successfully fired its breakthrough hypersonic Air Launched Rapid Response Weapon from a B-52 with initial success, an auspicious development suggesting rapid weapons development for the service as it seeks to close the gap with China and Russia.
However, although the first test firing indicated an initial measure of success, the service is now canceling the ARRW. Air Force acquisition executive Andrew Hunter told Congress of the Air Force’s but did say there was value in continued research and development.
The service “does not currently intend to pursue follow-on procurement of the ARRW once the prototyping program concludes,” Air Force acquisition chief Andrew Hunter said in a written statement to the House Armed Services tactical air and land forces subcommittee, according to an essay published in Breaking Defense.
The article in Breaking Defense cited senior service officials explaining that a recent test of the ARRW simply did not go well, however not many details are provided.
What is significant about the ARRW is that developmental progress in the realm of hypersonic weapons has likely been advanced to a very substantial degree, as the ability to launch and then sustain hypersonic speeds has been a longstanding challenge for the Pentagon. While Hunter did not definitely say that the service would “never” buy the weapon, he did clearly indicate that progress toward production following the prototype phase will come to a halt.
Last year, the ARRW did fire successfully from a B-52 and, according to Air Force reports. “Following separation from the aircraft, the ARRW’s booster ignited and burned for expected duration, achieving hypersonic speeds five times greater than the speed of sound,” an Air Force statement from last year stated.
Much was likely learned from this experiment, at which point the ARRW looked promising, however a more recent test has cast a shadow of doubt upon the weapon’s future. The technical reasons for the failed test and cancellation are not available, likely for security reasons, yet the failure or challenge calls to mind some of the difficulties when it comes to hypersonic flight.
Several key areas need to be successfully addressed in order for an air-launched weapon to achieve and then sustain hypersonic speeds. Thermal management is critical, as materials simply cannot withstand the heat generated at hypersonic speed, unless they are promising new composites able to sustain flight at unprecedented temperatures. This is a huge focus for the Pentagon, as the Army and likely the Air Force and Navy as well now experimenting with and testing new combinations of composite materials able to withstand sustained hypersonic flight. Experiments are now ongoing at the Army Research Laboratory with the specific aim of discovering new materials capable of hypersonic flight.
The other primary challenge with hypersonic flight, apart from guidance and targeting technology, is the question of air flow and what’s called boundary layer. Hypersonic weapons, projectiles or someday even hypersonic drones will need to be designed to maintain flight course and trajectory with a smooth or “laminar” air flow to prevent disruption. A turbulent air flow, by contrast, can lead to shifting molecules and particles surrounding the hypersonic projectile which disrupt the equilibrium and throw the weapon off course.
Addressing this successfully pertains to advanced evaluation of the aerodynamics surrounding hypersonic flight, something which relates to the materials, shape and configuration of the projectile itself. The specific way in which shapes are configured is designed with a specific mind to air flow and aerodynamic phenomena related to the surrounding air flow. Similar aerodynamic principles are factored in when it comes to designing fighter jets to optimize vectoring through air flow management, enable effective air maneuvering and reduce drag.
The Air Force has been attempting and testing hypersonic flight for many years, going back to the Waverider X-51A which achieved but did not sustain hypersonic speeds of Mach 5. Using scramjet propulsion, the Waverider was able to achieve but not fully sustained hypersonic speeds. However, a record was set and in 2013 the X-51 was able to achieve Mach 5 for 210 seconds, a breakthrough which inspired further development.
With this history, and the initial progress with ARRW, the Air Force likely plans to surge forward quickly with additional hypersonic weapons development. There are other promising hypersonic weapons programs as well, and it is a near certainty that the Pentagon is continuing to prioritize and accelerate their development.
Kris Osborn is the Military Affairs Editor of 19 FortyFive 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.
