Seven seconds remained in the countdown to launch a conventional hypersonic glide vehicle from the Kauai Test Facility (KTF) in Hawaii, when a technical issue stopped the count. The Sandia launch team scrambled to find the offending software script error and craft a solution to keep the first test flight of the US Army’s Advanced Hypersonic Weapon (AHW) on track.
The US Army’s Advanced Hypersonic Weapon on a non-ballistic flight path after launch from Sandia’s Kauai Test Facility. (Illustration courtesy of Sandia National Laboratories)
“It was very nerve-wracking,” says David Keese, director of Integrated Military Systems Development Center 5400, who was at KTF’s Launch Operations Building to view the flight in the early morning hours of Nov. 17. “We had to hold the countdown, examine what the problem was, define a solution to the problem, coordinate the solution with the flight test director, and implement that solution, which we did in about 30 minutes.”
Problem solved, the countdown resumed, and the US Army Space and Missile Defense Command/Army Forces Strategic Command (USASMDC/ARSTRAT) AHW flew a non-ballistic glide trajectory at hypersonic speed in its successful first test flight.
The three-stage booster system and glide vehicle were developed by Sandia under the direction of the USASMDC/ARSTRAT. Thermal protection system development for the glide body was the responsibility of the US Army Aviation and Missile Research Development and Engineering Center in Huntsville, Ala. The test flight was launched from Sandia’s Kauai Test Facility.
The AHW program is part of DoD’s Conventional Prompt Global Strike effort to develop conventional weapon systems that can deliver a precision strike anywhere in the world within an hour. Success would mean the US would have an alternative to nuclear weapons to prevent a crisis and it would decrease the conventional military response time significantly, David says.
The test flight represented about four years of work for up to 200 Sandia employees across the Labs. It came from a foundation of work on projects from as long as 25 years ago, David says, including the Sandia Winged Energetic Reentry Vehicle Experiment (SWERVE), the Strategic Target System (STARS), and the Tactical Missile System-Penetrator (TACMS-P).
A flight of many firsts
About 50 Sandia employees, including Defense Systems & Assessments Div. 5000 VP Jeff Isaacson, viewed the test in Kauai. Eric Schindwolf, deputy director of Strike and Aerospace Systems 5420, says large screens projected digital animation driven by the actual data coming from the AHW in real-time along with displays of the vehicle’s condition as it reached certain milestones.
The historic flight had many firsts, David says. It was the first time a Sandia-developed booster had flown a low-altitude, long-range horizontal flight path at the edge of the Earth’s atmosphere; the first time eight grid fins (designed by Sandia and Huntsville, Ala.-based Dynetics Corp.) were used to stabilize a US missile system; and the first time a glide vehicle flew at hypersonic speeds at such altitude and range. This flight test incorporated lessons and data from previous DARPA flight tests conducted as part of the Defense Department’s Prompt Global Strike Program.
“You could almost feel the tension change to jubilation as the launch occurred and the booster performed well and the grid fins deployed,” David says. “At each milestone along the way, Sandia employees were becoming more excited about the success because you could see how the missile was flying. . . . Cheers would go up every time we would meet one more mission milestone.”
The flight path took the vehicle up hundreds of thousands of feet and then it flew toward the Earth’s surface before pulling up slightly to fly horizontally within the atmosphere to the target, Eric says.
“We always knew the pull-up would be the most difficult part of this. We knew that success was going to be historic,” Eric says. “So as we watched this actually happen, the anticipation was really high. Once we saw the vehicle was climbing and leveled out at its glide altitude, we knew we had gotten through the hardest part. You could feel the relief as the team immediately sensed that the rest of the way would be comparatively easier.”
The success was praised by Sandia’s leaders, who flooded employee inboxes with congratulatory emails the next day.
Jeff called the flight a “stunning success” and a “real engineering achievement.”
At a team celebration after the mission, Jeff told the attendees, “This success could not have been achieved without exceptional teamwork, which was evident to anyone in the Launch Operations Building that night.”
Sandia President and Labs Director Paul Hommert, who says he couldn’t have been more proud to be a Sandian as he listened to the test from Washington, D.C., wrote: “Once again today our Laboratory rendered exceptional service in the national interest. For your dedication, excellence, and professionalism thank you and congratulations!"
Eric shared the general scope of Sandia’s work on the AHW. The technical challenges that faced Sandia were aerodynamic stability, aerodynamic heating, and control of the missile and glide vehicle, he says.
Typically, boosters fly missiles to heights of millions of feet above Earth, but the AHW flew only to a peak of hundreds of thousands of feet above the Earth’s surface, before descending to a lower altitude for the remainder of the flight. The modified STARS booster, which was about 40 feet long and 54 inches in diameter, powered maneuvers that had never been done before, Eric says.
The lower a missile flies in the atmosphere, the more it tends to tumble end over end, he says, so Sandia helped develop the eight grid fins to improve stability, which had never been used before on a US missile.
Eric says Sandia’s researchers did not want to risk having the fins interact with the missile exhaust near the ground, so four opened right after clearing the launch tower and four more deployed when the first stage burned out nearly 60 seconds later.
“They provided the margins of aerostability and control needed to prevent the missile from tumbling,” Eric says.
‘String of pearls’
Because the 2,485-mile (4,000-kilometer) flight from Kauai to the Army’s Reagan Test Site on the Kwajalein Atoll was so low, the curvature of the Earth prevented continuous monitoring from the takeoff and landing sites alone, he says.
Space, air, sea, and ground platforms collected vehicle performance data during all phases of the flight, according to a Pentagon news release. The Sandia booster and glide vehicle transmitted data to this network, called the “string of pearls,” Eric says.
Sandia also led the design and development of the glide vehicle, including improved navigation, guidance, and control technologies and teaming with AMRDEC to use advanced thermal protection materials to protect it on the long flight in the atmosphere.
Sandia researchers also successfully designed and tested the Flight Termination System for the AHW. This system protects public safety by destroying the vehicle if it should fly off-course during a test flight, he says.
The test’s objective was to collect data on the technologies and test range performance for long-range atmospheric flight. The mission emphasized aerodynamics; navigation, guidance, and control; and thermal-protection technologies, according to the Pentagon news release.
Eric says Sandia employees are analyzing the data from the test flight, which will be used by DoD to model and develop future hypersonic boost-glide capabilities.
“This was only a very first demonstration,” Eric says. “This is not a weapon by any stretch of the imagination. There’s quite a bit of work that needs to be done.”
David says the information gathered also will be used to validate Sandia’s computational models so they can be used with more confidence in the future.
David had nothing but praise for the people who spent nights, weekends, and many long hours working at KTF and the Labs.
“All the credit for the success of this effort goes to the team and its tremendous commitment and dedication that produced these extraordinary accomplishments that enhance our country’s national security,” he says. - Heather Clark
Steve Dai (1832) jokes that his approach to creating materials whose properties won’t degenerate when temperatures swing is a lot like cooking — mixing ingredients and fusing them together in an oven.
MATERIALS SCIENCE RESEARCHER Steve Dai (1832) has come up with a unique approach to creating materials whose properties won’t degenerate when temperatures swing. (Photo by Randy Montoya)
Sandia filed a patent last September for a unique materials approach in multilayered, ceramic-based, 3-D microelectronics circuits, such as those used in cell phones. The approach compensates for the effects of how something called the temperature coefficient of resonant frequency, which is one critical property of materials aimed at radio and microwave frequency applications, changes due to temperature fluctuations. The work was the subject of a two-year Early Career Laboratory Directed Research and Development (LDRD) project that wrapped up in March.
The LDRD team focused on developing fundamental understanding of why certain materials behave as they do. That knowledge could help manufacturers design and build better products.
Steve, who spent 14 years with Motorola before joining the Labs in 2009, says Sandia was interested in the research for its own programs, but the work also has potential commercial applications. He says, however, no exact projects have been pinpointed.
“At this point we’re just demonstrating the technology,” he says. “We have to demonstrate that it’s practical, that we can design a device with it, that we can design it over and over again, and can design it reliably.”
Wasting potential bandwidth
The familiar cell phone illustrates how the development might be used.
The Federal Communications Commission allocates bandwidth to various uses — aviation, the military, cell phones, and so on. Each must operate within an assigned bandwidth which, like a pipeline, has finite capacity. But temperature variations in operating a cell phone cause the properties of the materials inside to change, and that causes a shift in resonant frequency at which a signal is sent or received.
Because of that shift, cell phones tend to operate in the middle of the bandwidth, avoiding the edges so as not to break the law by drifting outside the assigned frequency range. That necessary caution wastes potential bandwidth and sacrifices the rate at which data can move.
Under the LDRD, Steve worked on low temperature co-fired ceramic (LTCC), a multilayer 3-D packaging and interconnection technology that can integrate passive components. Most mainstream LTCC dielectrics now on the market have a temperature coefficient of resonant frequency in a range as wide as that between northern Alaska in the winter and southern Arizona in the summer. A dielectric is a material, such as glass, that does not conduct electricity but can sustain an electric field.
Steve’s research achieved a near-zero temperature coefficient by incorporating compensating materials into the multilayer LTCC structure.
A graph shows the differences. Resonant frequencies used in various LTCC base dielectrics today appear as slanted lines on the graph as temperatures change. Steve’s approach to an LTCC leaves the line essentially flat — indicating radio and microwave resonator frequency functions that remain stable as temperatures change.
“The critical kind of understanding about the science here is required to design the material right to achieve properties that complement each other,” Steve says.
He presented the results of the approach in a paper published in January in the Journal of Microelectronics and Electronic Packaging.
“We can actually make adjustments in the materials property to make sure the resonance frequency doesn’t drift,” Steve says.
And, he says, “if your materials property doesn’t drift with the temperature, you can fully utilize whatever the bandwidth is.”
Another advantage: Manufacturers could eliminate additional mechanical and electrical circuits now built into a device to compensate for temperature variations, he says. That would reduce costs.
One basic challenge of the project was choosing different materials that don’t fall apart when co-fired together, Steve says. Glass ceramic materials used are both fragile and rigid, but they’re also very solid with minimal porosity. Researchers experimented with different materials, changing a parameter, adjusting the composition, and seeing what worked compatibly.
“It’s in a sense like cooking, you mix all these things together — it’s cooking. You have these ingredients, certain things you do in certain ways, just making sure it works together. Even the equipment is very similar; we have furnaces, ovens, mixers. . . . Each step is very much like making bread or something,” he says.
Steve had to consider both physical and chemical compatibility. Physical compatibility means that as materials shrink when they’re fired, they shrink in the same way so they don’t warp or buckle. Chemical compatibility means each material retains its unique properties rather than diffusing into the whole.
Looked at variables to boost performance
The LDRD created a new set of materials to solve the problem of resonant frequency drift but also developed “more of an understanding of why this works this way,” Steve says. “Why select material A and not B, what’s the rationale? Once you have A in place, what’s the behavior when you make a formulation change, a composition change, do little things?”
Researchers looked at variables to boost performance. For example, the functional material within the composite carries the electrical signal, and researchers experimented with placing that material in different areas within the composite until they came up with what worked best and understood why.
“That’s really important, the why,” Steve says.
The team also constructed a computational model to analyze what happens when materials with different properties are placed together, and what happens if you change their order in the stacked layers or the dimensions of one material versus another.
“We study all these different facets, the placement of materials, the thickness, to try to hit the sweet spot of the commercial process,” he says. That’s where computer modeling helps.
“Modeling can calculate all these things,” Steve says. “Modeling’s important. You cannot do exhaustive experiments. Modeling can change whatever you want, once you have the basic experiment.”
Manufacturing can be done as a simple screen printing process, a low-cost, standard commercial process much like printing an image on a T-shirt. Steve says the idea was to avoid special requirements that would make the process more expensive or difficult.
“That’s kind of the approach you try to take, make it simple to use with solid understanding of the fundamentals of materials science,” he says. -- Sue Major Holmes
A former DARPA robot developed at Sandia is now serving an educational purpose at New Mexico Highlands University (NMHU).
About a decade ago, Sandia developed the Multi-function Utility Logistics Equipment Vehicle, or MULE, robot. The project was sponsored by DARPA — the Defense Advanced Research Projects Agency — Lockheed Martin, and Sandia to help troops haul heavy equipment across a variety of terrains, and could negotiate one-meter steps. But once the MULE had served its purpose, it was parked in a garage at Sandia’s Robotic Vehicle Range and left alone until the summers.
SANDIA PROGRAM MANAGER Jake Deuel (6532) joins Logan Herrera, a senior undergraduate computer science major at NMHU, Sandia senior staff scientist Wendy Amai (6532), NMHU computer science graduate student Miguel Maestas, and chair of NMHU’s computer and mathematical sciences department Gil Gallegos. (Photo by Rick Loffredo/NMHU)
For the past two summers, students and Gil Gallegos, chair of the computer and mathematical sciences department at Highlands, worked with the MULE as part of DOE’s FAST, or faculty/student program, which pairs students with professors for research projects.
Gallegos and NMHU students added hardware and software to expand the MULE’s capabilities.
“Every summer, we’d dust this off, and students would get very excited to work on it for the summer,” says Jake Deuel (6532), manager of the Robotic and Security Systems group. “We realized we weren’t doing anything with it, and found a way to donate it to NMHU for two years.”
Gallegos says the goal of having the MULE at the university’s lab is to help generate thesis topics for graduate students in the computer science department and for undergraduate senior capstone projects. He adds that it will be a valuable recruiting tool to encourage students to pursue STEM careers.
“We’re very appreciative of Sandia allowing us to use this. It really does improve our program, and it’s very exciting to have the robot in the lab and to have students excited about it,” Gallegos says.
Miguel Maestas earned his bachelor’s degree in computational engineering from NMHU two years ago and is now in his second semester as a master’s student. He says the MULE will be instrumental to his thesis work, and is anxious to start working with it. He will first run diagnostics to ensure all electronic parts are intact, and has plans to integrate a 3-D image capture function. Eventually, this would help with object and possibly facial recognition to enhance the robot’s navigational capabilities.
Currently, four undergraduate and three graduate students are signed up to work with the MULE, but Gallegos expects that having the robot on campus will continue to generate interest. Other projects in the works include software development to communicate with motors that control the MULE’s six wheels and shoulders and installing microcontrollers for individual joints, shoulders, and wheels.
“I’m hopeful that this will help recruit other students into the computer sciences department. It’s very exciting to be able to work with the MULE and to know that it has been used to help develop other projects that are state-of-the-art,” Maestas says. -- Stephanie Hobby