The Air Force has been working on airborne laser weapons for more than 40 years, but a fielded system remains elusive. Experts also warn that the US does not enjoy a commanding lead in laser research. And the Air Force’s flagship laser weapon program, the Airborne Laser (later called the Airborne Laser Testbed) was terminated late last year and is now being dismantled.
Still, service and industry experts predict there is plenty of reason for realistic optimism. Operational laser systems that can perform a variety of destructive missions are not too far off, these experts insist, but they will likely be complementary to USAF’s kinetic weapon inventory, not a substitute for it.
The Airborne Laser was to be the prototype for a small fleet of aircraft that would fly outside enemy borders, ready to shoot down any boosting ballistic missiles.
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(AFRL photo) |
The ABL project lasted 16 years and cost more than $5 billion. In the end, a series of tests proved the 747-based system could, in fact, spot, track, lase, and destroy a ballistic missile target at beyond visual range, but it was deemed by Pentagon leaders too expensive and impractical to progress to an operational system.
Another program, the Advanced Tactical Laser, mounted on a C-130 transport, proved a laser system could be effective against certain ground targets, such as antennae and light vehicles. It too has been shelved.
Both the ABL and ATL used chemical lasers, which, though able to produce high power in the megawatt class, proved cumbersome to operate because of the large quantities of chemicals consumed and the extensive and heavy plumbing they required.
The developers are well aware of a perception that laser weapons are science projects and point to significant developments and new approaches. For airborne applications, the Air Force has shifted its attention to solid-state, electric, or fiber lasers, depending only on electricity that can be generated from an aircraft’s engines.
However, unlike the megawatt-class chemical lasers, the other types are currently limited to a lesser punch, having produced up to 150 kilowatts’ worth of laser power. These levels are considered tactically relevant, though, and prospects are good that power can be increased in the future.
The ABL was not a dead end with no payoff, according to Lt. Gen. Ellen M. Pawlikowski, commander of USAF’s Space and Missile Systems Center at Los Angeles AFB, Calif. Pawlikowski was previously the ABL program director for five years and later oversaw the program as commander of the Air Force Research Laboratory.
“We learned a lot” with the ABL, Pawlikowski observed, particularly with regard to pointing and directing lasers and handling them safely. The ABL was also a hothouse of development that encompassed everything from thermal management to packaging to software. None of that will go to waste, she said.
“The whole ability to keep the laser beam on the spot that you want to fire at was nontrivial,” Pawlikowski asserted, noting that the front end of the ABL involved “over a hundred different optics pieces that all were unique.”
Other key enabling results from ABL included learning “the effects of the atmosphere, the turbulence, and … the effect that had on the laser beam.” The ABL demonstrated it could gauge and compensate for atmospheric turbulence so that the beam would remain coherent and focused over long distances.
Another ABL by-product was “lethality measurements,” Pawlikowski said.
“We explored the effect of the [chemical oxygen-iodine laser] on lots of different materials, so that we could understand just how effective that laser could be,” she said. Studies were done on reflective and nonreflective surfaces of various thicknesses and materials to calculate their vulnerability to laser fire.
The various disciplines necessary to get the ABL to successfully shoot down ballistic missiles will be applied to the next generation of laser weapons, she said.
“Directed energy and laser weapons will have game-changing capability in the future of combat operations,” said Col. Joseph M. Skaja Jr., head of electronic warfare and directed energy requirements for Air Combat Command. “Unfortunately, they aren’t ready for prime time yet.”
ACC’s priorities for lasers will be in their applications to “survivability, our situational awareness, and our lethality,” Skaja said. The command is also looking for various effects on the sensors of the munitions that would be launched against Air Force aircraft, he added, entailing “blinding” sensors or otherwise affecting them to make weapons ineffective.
Lasers will be able to enhance situational awareness by providing information about other aircraft, Skaja said, offering an ability to scan an enemy and determine an aircraft type at a distance. Eventually, USAF will field a radar-type laser, which will allow for ground mapping and targeting without emitting radio frequency energy—a plus for remaining stealthy.
The Air Force is thinking about lasers that could deliver destructive force on enemy aircraft or even on ground targets, but Skaja said those capabilities are not near-term.
Crawl, Walk, Run
With the demise of the ABL, the new Air Force flagship laser program is called the Demonstrator Laser Weapon System, or DLWS. It is a collaborative effort of the AFRL and DARPA, the Defense Advanced Research Projects Agency. The demonstrator will be “a lead-in to future laser applications on aircraft,” Skaja said.
The DLWS is “just the laser,” not a packaging concept, which will come later, he said. It is a solid-state laser in the 150 kw class.
“Once we get the laser capabilities where we want, we’ll have to get the size, weight, and power issues to determine which aircraft it will fit. Obviously, it’s easier on a large aircraft, than to miniaturize everything and put it on a smaller aircraft.” That is the sequence the development process will take. After ground testing, the DLWS will be packaged and mounted on a B-1 bomber, though it is not the objective platform for the capability.
Long term, the Air Force is eyeing a system that could be mounted in a pod, then hung on a variety of platforms ranging from small remotely piloted aircraft all the way up to bombers. However, no provision is being made in any USAF airplanes for this goal.
“There are currently no plans to plumb a laser system onto the F-35” fighter, for example, Skaja said. “We are still very much in the ‘crawl’ stage of the ‘crawl, walk, run’ profile laser path. … We have to put a laser on an aircraft to make it work before we could even hope to miniaturize it to put it on a fighter-size aircraft.”
Northrop Grumman, however, has suggested that the F-35B version could be adapted to a laser weapon platform, according to Dan Wildt, vice president of the company’s directed energy systems division.
Wildt said the space behind the cockpit occupied by the F-35B’s lift fan—which allows for short takeoffs and vertical landings—could be filled with a laser.
Considerable power could be supplied by the aircraft’s F135 engine, he said. The engine generates more than 40,000 pounds of thrust and power would be supplied “off the drive shaft,” which normally connects the F135 to the lift fan, making for a ready-made laser platform, Wildt said. The proposal is, for now, company-funded.
Fiber lasers would be a natural for a fighter application, he added. They generate low-wattage power but can be bundled to deliver more power. Given that fiber lasers are lighter, smaller, and give off far less heat than most other types, “that’s probably where fiber lasers will find their niche,” he predicted.
The big technology push with fiber lasers is to get them to function “coherently,” Wildt said, meaning they all produce at the same wavelength and in a way that multiplies their power. Conceptually, this can be seen in how a single powerful flashlight generates more intense illumination than a dozen weak flashlights all focused on the same spot.
Skaja said the B-1 demonstration should take place in the next few years, and USAF doesn’t have a definitive timeline.
Although the Air Force has not “ruled out” the use of chemical lasers in a future airborne system, the technology’s current cost, weight, and complexity make it a low priority for the near future, Skaja said.
That’s not to say that chemical lasers won’t have significant possibilities within the next decade. Pawlikowski noted that in a ground-based application, where weight and size are far less of an issue than they are on aircraft, megawatt-class chemical lasers could be highly useful in a ballistic missile defense system or for air base defense.
Air Force budgets for operational laser weapons will be small for a while, Skaja said, as technologies shake out and the art of the possible is determined.
“We are heavily involved in developing the right programs with our science and technology partners to make sure that our priorities are being pursued by the research labs,” he said. Not a lot is budgeted in programs of record, but ACC is ensuring its priorities are known by AFRL and DARPA, so “they can invest their research money appropriately,” he added.
A snide joke circulates through the laser weapon community: Laser weapons are only five years away—and always will be.
Skaja chuckled at the joke and admitted in the past, there have been some promises on laser capability, notably with the ABL and its probable service dates that “kept slipping and slipping,” and as a result, skepticism mounted.
“One of my jobs” at ACC, he said, “is to make sure we temper the laser zealots with the reality of when a laser will be applicable on an airplane. There is a huge difference between making a laser work and making a laser work on an airplane.”
Though he believes the Air Force will get there, “we have to not overpromise either the time frame or the capability. We have to let the technology develop appropriately.”
He added that he doesn’t believe the Pentagon or Air Force leaders are “overexpecting things” in the laser realm. “They want the laser and directed energy capabilities to move forward, and I think we’ve got a good plan and the senior leadership has been involved in the plan we’ve developed.”
Wildt, however, took some minor umbrage with the five-years joke. In the past, there have been a number of laser weapons that could have been deployed, he said, but weren’t, either because of expense or because of the lure of a cheaper, better, or more compact system just over the technological horizon. “Sometimes, ‘better’ is the enemy of ‘good enough,’ ” he asserted.
Northrop Grumman has been involved with programs such as the Tactical High Energy Laser, or THEL, which demonstrated shootdowns of mortars and Katyusha rockets. The program worked in coordination with Israel, which suffers attacks from such weapons. It was never fielded.
Two Broad Tasks
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The Advanced Tactical Laser system aircraft—a modified C-130 transport—proved a laser system could be effective against certain ground targets, but has been shelved. (Boeing photo) |
The company has also demonstrated an ability to shoot lasers from moving ships, against bobbing, “Zodiac”-style assault boats, inflicting damage—and at long range. Such an application would be valuable in the Persian Gulf today, he noted.
“These are not ‘Star Trek’ weapons. These are very real,” Wildt said. “They’re here … and we think lasers offer a cost savings” because they require only the cost of electricity, and in more powerful versions that can be land- or sea-based, can substitute for the development of other projectiles that don’t have to be developed, bought, or replenished.
“The question is, when will a user or operator say, ‘I’m going to pick this one,’ and take it across what is known in our circles as the ‘S&T valley of death’ and deploy this? … We believe the technology is ready.”
Michael Rinn, vice president of Boeing’s directed energy systems group, noted that lasers are not taking an unusually long time to offer practical, operational capability, when compared with other technologies.
“In fairness,” he said, “everybody likes to poke ABL because it took 12 years and in the end it was a demonstrator” that’s now dead.
But Rinn noted the Navy’s Aegis program started in the 1970s and is only now mature, and the F-22 fighter is only now fully delivered, when its genesis can be traced back to 1984.
“So, … directed energy is not really that different from these advancing technologies like stealth” and has been developed “on much smaller budgets.”
Pawlikowski said the five-years joke is probably accurate, at least for now. However, “I think we’re making progress in getting closer to being within that five years.”
She said that two broad tasks remain to be accomplished in the realm of laser weapons. “We still need to explore what are the real applications” for the technology, to define the target set it can most effectively be used against. “We have to be realistic in terms of what kind of damage a laser can do, firing out of an airplane. That has to be married up with how much power you can get out of a laser on an airplane. And I believe that, at best, we are at least five years away from being able to marry those two up,” she added.
She is optimistic about a hybrid laser—specifically, the Diode-Pumped Alkali Laser (DPAL) system, which uses a combination of electrical and chemical laser generation—that can generate 100 kw power levels. There are useful applications at that power, she said. Such a system might just be within five years of operation.
Pawlikowski believes the key breakthrough in laser weapons would be the development of a far more efficient laser. Today’s systems typically generate just 15 percent laser power and 85 percent heat. That means power output is weak relative to input and creates a lot of heat that has to be gotten rid of.
A doubling of efficiency—to 30 or 40 percent—would be “huge,” she said. “That would cut back on my thermal problems. … That’s a critical area that I think we need to continue investing in,” she said.
Asked whether the US is leading the field in laser technology, Pawlikowski warned the US should not assume scientific superiority.
“The rest of the world is catching up, and in some cases, maybe they are … a little bit ahead,” she acknowledged.
The money “hurdle” necessary to leap in order to do groundbreaking work in lasers is “not as extreme as it was.” The US has also trained scientists and engineers from all over the world who have gone back to their own countries, she noted.
Pawlikowski sees more leveling in terms of technological advantages the US has over other countries in the future.
“I don’t think directed energy is less so than any others.”