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Lab News -- December 16, 2011

December 16, 2011

LabNews - December 16, 2011PDF (1.8 Mb)

Riding the bullet: Self-guided bullet prototype developed at Sandia can hit target a mile away

By Heather Clark

Take two Sandia engineers who also are hunters, get them talking about the sport, and it shouldn’t be surprising when the conversation leads to a patented design for a self-guided bullet they think could help war fighters.

A tiny light-emitting diode, or LED, attached to a bullet shows a bright path during a nighttime field test that proved the battery and electronics could survive the bulletís launch. (Photo by Scott Rose)

Sandia researchers Red Jones and Brian Kast (both 6531) and other colleagues have invented a self-guided bullet for small-caliber, smooth-bore firearms that could hit laser-designated targets at distances of more than a mile (about 2,000 meters).

“We have a very promising technology to guide small projectiles that could be fully developed inexpensively and rapidly compared to other proposals,” Red says.

Sandia hopes to partner with a private company to complete testing of the prototype and bring a guided bullet to the marketplace.

Researchers have had initial success testing the design in computer simulations and conducting field tests of prototypes, which can be built relatively inexpensively using commercially available parts, Red says. The project was started with funding from the Laboratory Directed Research & Development program.

While engineering issues remain, “we’re confident in our science base and we’re confident the engineering-technology base is there to solve the problems,” he says.

Sandia’s design for the 4-inch-long bullet includes an optical sensor in the nose to detect a laser beam on a target. The sensor sends information to guidance and control electronics that use an algorithm in an eight-bit central processing unit to command electromagnetic actuators. These actuators steer tiny fins that guide the bullet to the target.

Like a well-thrown pass in football

Most bullets shot from rifles have grooves, called rifling, that cause them to spin in order to fly straight, like a football thrown in a long NFL pass. To enable a bullet to turn in flight toward a target and to simplify the design, the spin had to go, Red says.

The bullet flies straight due to its aerodynamically stable design, which consists of a center of gravity that sits forward in the projectile and tiny fins that enable it to fly without spin, just as a dart does, he says.

Computer aerodynamic modeling showed that the concept would result in “dramatic improvements” in the bullet’s accuracy, Red says. Computer simulations showed an unguided bullet under real-world conditions could miss a target more than a half mile away (1,000 meters away) by 9.8 yards (9 meters), but a guided bullet would get much closer, to within 8 inches (0.2 meters), according to the patent.

Plastic sabots provide a gas seal in the cartridge and protect the delicate fins until they drop off after the bullet emerges from the firearm’s barrel.

The prototype does not require a device found in guided missiles called an inertial measuring unit, which would have added a lot to its cost. Instead, the researchers found that the bullet’s relatively small size when compared to guided missiles “is helping us all around. It’s kind of a fortuitous thing that none of us saw when we started,” Red says.

Actuator performance promising

As the bullet flies through the air, it pitches and yaws at a set rate based on its mass and size. In larger guided missiles, the rate of flight-path corrections is relatively slow, so each correction needs to be very precise because fewer corrections are possible during flight. But “the natural body frequency of this is 30 hertz, so that means we can make corrections about 30 times per second. That means we can overcorrect, so we don’t have to be as precise each time,” Red says.

Testing has shown the actuator performance is promising and the bullet can reach speeds of 2,400 feet per second, or Mach 2.1, using commercially available gunpowder. The researchers are confident it could reach standard military speeds using customized gunpowder.

A nighttime field test using a tiny light-emitting diode, or LED, attached to the bullet showed the battery and electronics can survive flight, Red says.

Researchers also filmed high-speed video of the bullet radically pitching as it exited the barrel. The bullet pitches less as it flies down range, a phenomenon known to long-range firearms experts as “going to sleep.” Because the bullet’s motions settle the longer it is in flight, the rate of inaccuracy is less at longer ranges, Red says.

“Nobody had ever seen that, but we’ve got high-speed video photography that shows that it’s true,” he says.

The bullet could have uses for the military, law enforcement, and recreational shooters.

Sandia researchers who helped Red and Brian develop the technology are: engineer Brandon R. Rohrer (6533), aerodynamics expert Marc Kniskern (5422), mechanical designer Scott Rose (6531), firearms expert James Woods (6531) and Ronald Greene (5416), a guidance, control and simulation engineer.

“It was one of the coolest things I’ve ever worked on,” Red says. “I worked with a great bunch of people who are incredibly bright, incredibly motivated, and who solved a great array of problems. It was awesome.” - Heather Clark

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NNSA/DP Employee of Quarter Award recognizes Rita Gonzales for strategy to be used in future

By Sue Major Holmes

The development and production strategy Rita Gonzales (1750) and her team used in the B61 Life Extension Program (LEP) grew naturally from the way she has organized work throughout her Sandia career.

Rita GONZALES (1750) has been named as an NNSA Defense Programs Employee of the Quarter. (Photo by Randy Montoya)

Rita has been named as an NNSA Defense Programs Employee of the Quarter for Sandia, an award that recognizes people for going beyond the call of duty in supporting NNSA missions. She says she was both honored and humbled to have received it.

“It wasn’t all me; it’s a team,” Rita says. She says she hopes she “helped with the vision and set the standard, but the people that I work with are really the folks who get a lot of credit.”

As manager of Mixed Signal Application-Specific Integrated Circuits (ASICs) and System-on-Chip Products, Rita led a multidepartment effort to develop and deliver ASICs for the B61 program.

Senior Manager Dave Sandison (1740), who nominated her, says she coordinated with weapons systems groups, radar and fireset owners, and seven departments to develop a plan for delivering packaged components.

A development and production strategy

The B61 became part of the US stockpile in the 1960s, and a number of its components are nearing the end of their design life. Modifications also are required to conform to modern Air Force equipment and aircraft.

Dave says Rita’s efforts “resulted in a clear development and production strategy that is now baselined in the B61 phase 6.2/6.2a study.”

“I don’t know that we had a real cohesive strategy before,” says Rita, who has been with Sandia for 20 years. Dave says her demonstrated ability led to her recent promotion to senior manager for the Microsystem Design/MESA Products group.

“She’s one of our very best,” he says.

Rita sums up the strategy in three parts: ensuring that goals, objectives, and requirements are aligned with those of the customer; making sure all the organizations involved understand the responsibilities and commitments so “we’re all moving to those same goals and objectives”; and setting down an efficient way to implement the strategy.

It’s a plan that will be used in the future.

“We’ve developed a common strategy so that everybody doesn’t have to invent the wheel every single time, and use a well-defined common flow” that ensures a quality product in the end, Rita says.

She came up with the strategy and flow over several years.

“There are challenges with getting people to buy in and believe in the vision and then to use it,” she says.

Now, she says, those involved challenge each other to stay on the path.

“It’s not me preaching it anymore. It’s not actually me doing anything other than making sure the vision is appropriate. … So I can sit back and watch it go, which is really nice,” she says.

A multi-organizational effort

An ASIC by its nature is a multi-organizational effort that brings input from many customers, program management, design, packaging, fabricating, testing, and quality control into development and delivery at various stages, with the ASICs produced in Sandia’s in-house MESA fab, Rita says.

“So it’s like all these different customers are coming to us,” she says. “For example, in the B61, all those are folks who are going to be getting ASICs from us; we had to work with each one individually to gather all their different requirements and expectations and schedules. Trying to coordinate all that is obviously challenging.”

Rita says she led teams before becoming a manager, and put a structure in place for the first program she ever led.

“I just worked in a little bit more organized fashion, so I started by leading programs myself,” she says. She modified her organizational structure as her responsibilities grew to require more coordination of people and efforts.

“When I became a manager, that strategy just grew to be a much bigger picture and affected multiple programs,” Rita says. “And in all honesty, when I became a manager and the staff working under me took it over, they improved it. They made it way better.” -- Sue Major Holmes

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Sandia monitors nuclear safety of mission to Mars

By Stephanie Hobby

The Mars Science Laboratory is just beginning its eight-month journey to Earth’s neighbor after a successful launch Friday, Nov. 26, but for the past five years, a team of Sandia engineers has been working behind the scenes to ensure its smooth launch.

NASAís Mars Science Laboratory spacecraft, sealed inside its payload fairing atop a United Launch Alliance Atlas V rocket, clears the tower at Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. (Photo courtesy of United Launch Alliance)

NASA’s $2.5 billion MSL rover, the largest and most sophisticated vehicle to visit the Red Planet, is powered by a multi-mission radioisotope thermoelectric generator, or MMRTG. The generator turns heat from the decay of 10.6 pounds of plutonium dioxide into 110 watts of electricity to move the rover and run a suite of 10 instruments, which can do things like find water 32 feet below the surface and analyze chemical composition of rocks three car-lengths away.

While the MMRTG significantly increases the rover’s range and lifetime from previous rovers, which relied on solar panels, launching nuclear material requires diligent attention to safety, and Sandia has been tasked with the tremendous responsibility of conducting the safety analysis report. Since 2006, Sandia engineers have analyzed millions of combinations of potential scenarios to ensure risks to people, animals, and the environment were minimal as the Atlas V rocketed out of Earth’s atmosphere.

The first time the US launched a nuclear battery was on a satellite in 1961, less than eight weeks after Alan Shepard became the first American in space. Every launch of nuclear material since requires DOE to perform and write up a rigorous safety analysis, which is then sent to the Office of the President for final launch approval. Sandia was selected by DOE in 2006 to conduct the safety analysis for MSL and all future nuclear missions.

“We look at the probabilities of all the different accidents that could happen. Because each event can happen at a particular time and a different way, we simulate the trajectory of a launch. There are parameters that represent those times and ways, and we randomly select each of these every time we run the code. We run the code more than a million times, so we build up a large statistical database,” says Ron Lipinski (6223), team leader for Sandia’s safety analysis report. Ultimately, Sandia provides probabilities of risk to decision makers. Sandia does not make the decision to launch.

Built with safety in mind

The MMRTG is built with safety in mind. The marshmallow-sized plutonium pellets are encased in four layers of iridium and graphite, designed to withstand heat from a fire or reentry. Plutonium-238 dioxide was a deliberate choice; the alpha particles it gives off can be stopped by a sheet of paper. In fact, about the only way it could pose a health risk is if it’s ground into fine particles and inhaled. It is manufactured in ceramic form, and if something goes wrong, it is designed to break into large chunks, which would drastically minimize environmental hazards.

While the risk of a launch failure is small, and the chance of any plutonium being released is even smaller, accidents do happen, so the model simulates anomalies in every part of the launch sequence, including rocket trajectory, accident times, explosions and fires, debris impact, and orbital reentry. The team uses the Launch Accident Scenario Evaluation Program (LASEP) to analyze how the plutonium-powered generator would respond to a given incident. Sandia’s experts in blast and impacts, fire and thermal, reentry dynamics, health physics, atmospheric transport, and contamination work together to develop a robust picture of any potential risks.

In the event of an explosion, the blast and subsequent impacts could damage the fuel and its casings, so one team was focused on running hundreds of scenarios over the course of several years to understand how the fuel and fuel containment structures would react.

“We track how much plutonium-238 would be released and what form it would be released in, should there be a blast or impact. We then provide that data to LASEP, which combines many different scenarios to perform its calculations,” says team leader John Bignell (6223), who came to Sandia from NASA’s Jet Propulsion Laboratory, where he did structural analysis for the rover suspension and chassis. “It’s pretty amazing to think that something you had direct contact with ends up on another planet, and I was excited to get the opportunity to continue working on this project when I came to Sandia.”

A long history of testing

Launching something as large as the MSL required tons of rocket fuel, so fire is another hazard, particularly in the first 50 seconds after launch, when the rocket is still relatively close to Earth. Tim Bartel (6223) led a team to analyze the risks of high temperatures on nuclear cargo, either from an explosion or accidental reentry of the rocket.

“Liquid propellant makes a big explosion, but it’s over quickly and doesn’t really do much damage. Solid propellant is different. It’s reliable and provides the extra thrust needed, but it can cause a really hot-burning environment, and the temperature can reach 3,000 Kelvin, which is hot enough to vaporize plutonium and present health hazards,” Tim says. “Sandia has a long history of testing and characterizing burns, and we do thousands of calculations over the course of several years to better understand and mitigate those risks.”

All of those calculations are used to determine the source term analysis, which is how much plutonium could be released to the atmosphere and the particle size distribution. “We are trying to analyze things that rarely happen, and we dig into the details of those rare occurrences. Then we have multiple layers of people looking at those results because of the high level of scrutiny and the possible impacts to the public. So we have to do a good job and show that we do a good job, too,” says Daniel Clayton (6223), team lead for the source term analysis.

Nathan Bixler (6223), who also conducts safety analysis for commercial nuclear reactors, led the team to understand consequences, including how the release could be transported by wind and how it would affect the public. He used Daniel’s analysis and combined that with historical meteorological data, which is considered to be a good indication of future weather patterns.

“The chance of an accident is low; even lower is the chance that plutonium would be released, and the chance that human health could be affected by an accident is fractions of a percent,” Nathan says. “If an accident were to happen, we calculate that a little over a square kilometer would be contaminated which is likely to be confined to Kennedy Space Center and the Cape Canaveral Air Force Station, and could be cleaned up without any impact to the surrounding area.”

A few members of the Sandia team went to Florida for the launch; Ron was part of the Radiological Control Center at Mission Control, which included representatives from NASA, DOE, Lawrence Livermore National Laboratory, and state and local agencies in Florida, to do rapid response in case of an accident.

Sandia will monitor the safety of future missions, and the team is thrilled to be a part of this effort. Greg Lucas (6223) was hired after an internship with the group, and this is his third year with the program. “It’s a great project to be a part of so early in my career,” Greg says. “It’s nice to know that your analysis does help this launch proceed, and you feel that you have a part in making the MSL mission happen.”

 “This is an opportunity to be part of history, and to be a part of this mission is wonderful,” says Ron. “We’ve gotten some tremendous insights into other planets, as well as our own. It’s very exciting.” -- Stephanie Hobby

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