HYPERSONIC
As with past programs, including stealth technology and ballistic- missile research, Southern California could be poised to take a leading role in its development.
The Defense Advanced Research Projects Agency, or DARPA, the same agency that helped develop the Internet, and the Air Force are spearheading a program called the Hypersonic Airbreathing Weapon Concept. It has awarded defense firms, including Raytheon Co. and Lockheed Martin Corp., contracts to work on technologies that would enable an “effective and affordable” air- launched hypersonic cruise missile.
Aerospace firm Orbital ATK Inc. also was recently selected to take part in a hypersonic aircraft engine project with DARPA, while military aircraft manufacturers have discussed their own concepts for hypersonic planes.
Nearer term, the Defense Department is prepared to start testing a hypervelocity projectile for gun systems that could reach speeds close to Mach 6, according to reports. The projectile could have implications for
future missile defense.
Reliable hypersonics not only could propel a missile to incredible speeds that make them harder to shoot down but also could allow for greater maneuverability at unusual altitudes — both nearer to the ground and far higher than the range of current missile defense systems, according to a Rand Corp. report released last year.
“There was this old saying that hypersonics was the future and always would be,” said Kevin Bowcutt, senior technical fellow and chief scientist for hypersonics at Boeing, who came up with the original concept design for the X- 51A in 1995. “Now people believe it. It’s real.”
The current technological emphasis in the U.S. on hypersonics is multifold. Historically, the U. S. has been a leader in this field, and the technology is promising. But development is not being driven by a specific mission need, said James Acton, codirector of the Nuclear Policy Program at the Carnegie Endowment for International Peace think tank.
Other analysts have said the current push for hypersonics could be an attempt to discourage other countries from considering hypersonic missile attacks.
But to develop
functional hypersonics technology, the U. S. will need to develop engine systems and materials that can operate at high speeds and temperatures for extended periods of time. That research and development cost alone would be significant, and wouldn’t even include the billions of dollars needed to develop operational vehicles, experts say.
Tens of billions of dollars could be spent on hypersonics contracts between 2020 and 2035 if the research “comes to fruition in real weapons programs,” said Loren Thompson, an aerospace analyst with the Lexington Institute think tank, which receives funding from Lockheed Martin and Boeing.
U.S. development of hypersonics dates to the 1940s, when JPL attached a WAC Corporal rocket in the nose of a German V-2 rocket to create a two- stage rocket as part of the Army’s Bumper program. Launched from New Mexico’s White Sands Missile Range in 1949, the rocket reached 5,150 mph, or about Mach 6.7.
Another major breakthrough came in the 1950s and 1960s with the X-15 program, experimental rocketpropelled aircraft that reached a top speed of Mach 6.7 and were designed to advance
understanding of hypersonic flight.
Data from the test flights helped influence the spacecraft design of the Apollo capsule and the Saturn V rocket that took astronauts to the moon.
The Space Shuttle, which flew from 1981 to 2011, also reached hypersonic speeds as it re- entered the Earth’s atmosphere, leading to developments in heatabsorbing ceramic tiles and large, rounded edges to lower re- entry temperatures.
But despite these incremental developments, hypersonics researchers say there are still big technical hurdles to solve, especially in materials science.
When re-entering the Earth’s atmosphere, the outer surface of the space shuttle orbiter encountered temperatures of nearly 3,000 degrees Fahrenheit. Aircraftgrade aluminum melts at a temperature about three times less than that, and the structure of a plane would fail at even lower temperatures.
One possible solution is materials such as titanium or nickelbased alloys, which can be used at speeds slightly beyond Mach 5. Past that, ceramicmatrix composites, a more exotic blend of strong, lightweight fibers, might be an answer.