By Lindsay Emery
CENTRA Technology Senior Technical Advisor Walter Rutledge, Ph.D., compares hypersonic boost-glide to a baseball if it were able to change direction in mid-air.
"The baseball can go a long way and your arm is the booster," Rutledge said. "Unlike a football or a baseball, the hypersonic boost-glide system has the ability to change direction as it flies. It's a very useful military vehicle and it can avoid many of the traditional ballistic flight challenges and provide for a more effective weapons system."
More than 20 years ago, Rutledge and his colleagues at Sandia National Laboratories realized that understanding boost-glide flight, then a relatively new area of hypersonics research, would be important for the United States as it expands its high-speed aerospace capabilities.
The significance of his research wasn't lost on the American Institute of Aeronautics and Astronautics when it recently awarded Rutledge with the prestigious Wright Brothers Lecture in Aeronautics Award. The recognition provided him the opportunity to share his experiences with his aerospace peers at a classified AIAA forum this month with his lecture on "Hypersonics for National Security: Conventional Prompt Strike."
"I'm very humbled by this award," Rutledge said. "My colleagues were very nice to put my name in for this and I feel like I'm a spokesperson for the national effort. I was just in a leadership position at the right time to make that happen. This was very much a team effort."
How did Rutledge apply the idea of a baseball changing its path mid-air to solutions for national security that earned him this recognition? It's all about science.
Hypersonic flight occurs when an aerospace vehicle flies greater than Mach 5, or five times the speed of sound. Boost-glide is one type of hypersonic flight vehicle along with ballistic and air-breathing systems.
"Boost-glide refers to a concept of boosting a glider to hypersonic speeds within the atmosphere and releasing it and allowing it to glide to its destination, constantly slowing down along the way like a very fast baseball," Rutledge explained. "These hypersonic systems typically fly in the upper part of the atmosphere in an area called near-space – the area between where aircraft fly and satellites orbit the earth."
With their high maneuverability and ability to operate at varying altitudes, hypersonic boost-glide flight systems can engage targets thousands of miles away in just minutes, something Rutledge confirmed while working at Sandia National Laboratories in Albuquerque, New Mexico. From there, he went on special assignment to join a team at the Pentagon working on the Conventional Prompt Global Strike Program, or CPS.
"Through flight test demonstrations, we were able to prove that the concept of boost-glide was feasible and something that would be very valuable to the warfighter," Rutledge said.
Rutledge has more than 40 years of experience in aerospace technology. He was the program manager for early boost-glide concept studies, conducted by Sandia for the U.S. Department of Defense, which included modeling, simulation, ground tests, experiments and flight testing. These early studies laid the groundwork for the Pentagon to begin investing in hypersonic boost-glide weapon systems.
Dennis Helmich, director of the Integrated Military Systems Center at Sandia, has known Rutledge for nearly three decades. Four years ago, Helmich became Rutledge's director while he was on assignment in Washington, D.C. When asked why Rutledge was worthy of the award, Helmich commended his ability to communicate.
"He works well at that technical level and at higher levels with decision-makers—whether those are general officers or others," Helmich said. "He's able to interact well and translate sometimes the really technical stuff to maybe the not-so technical decision-maker and then he has the political understanding to know who's important and how they need to be influenced one way or another so that's really what makes Walt phenomenal."
At CENTRA Technology, a PAE company, Rutledge has helped manage hypersonic development and prototyping activities in his role as senior technical advisor. The Department of Defense conducted a flight experiment with a hypersonic glide body from the U.S. Navy Pacific Missile Range facility in Kauai, Hawaii, in March 2020. Rutledge helped organize and plan that flight test system before the experiment.
"I look at his career-long contributions in hypersonics and Walt is one of only a handful of people in the nation who I would call 'Keepers of the Flame'," said OUSD R&E Principal Director for Hypersonics Michael White, who has worked with Rutledge over the past three years. "Without them, we simply wouldn't be where we are as a nation in hypersonics."
As senior technical advisor for U.S. Army and Navy hypersonic programs, Len Zentz's long career overlaps several of Rutledge's projects. Zentz remembers sitting down with Rutledge and his wife, Karen, at an Albuquerque restaurant to ask if he would come back to Washington to help lead the CPS project at the Pentagon.
"They needed a champion and a technical person behind it and Walt and his wife thought about it and decided it was a good thing and it turned out to be a great thing for the country," Zentz said. "And looking back on it, I think it was one of the most important conversations I've ever had in my life and how it's turned out for Walt and all of us."
Image courtesy of Sandia National Laboratories