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Learn more - CREATE AN ACCOUNTSIGN IN JOIN IEEESIGN IN Close Access Thousands of Articles -- Completely Free Create an account and get exclusive content and features: Save articles, download collections, and talk to tech insiders -- all free! For full access and benefits, join IEEE as a paying member. CREATE AN ACCOUNTSIGN IN Topic Aerospace Type News DARPA Wants a Better, Badder Caspian Sea Monster Liberty Lifter X-plane will leverage ground effect Evan Ackerman 19 May 2022 4 min read A rendering of a grey seaplane with twin fuselages and backwards-facing propellers DARPA darpa x-plane aircraft Arguably, the primary job of any military organization is moving enormous amounts of stuff from one place to another as quickly and efficiently as possible. Some of that stuff is weaponry, but the vast majority are things that support that weaponry--fuel, spare parts, personnel, and so on. At the moment, the U.S. military has two options when it comes to transporting large amounts of payload. Option one is boats (a sealift), which are efficient, but also slow and require ports. Option two is planes (an airlift), which are faster by a couple of orders of magnitude, but also expensive and require runways. To solve this, the Defense Advanced Research Projects Agency (DARPA) wants to combine traditional sealift and airlift with the Liberty Lifter program , which aims to "design, build, and flight test an affordable, innovative, and disruptive seaplane" that "enables efficient theater-range transport of large payloads at speeds far exceeding existing sea lift platforms." DARPA DARPA is asking for a design like this to take advantage of ground effect, which occurs when an aircraft's wing deflects air downward and proximity to the ground generates a cushioning effect due to the compression of air between the bottom of the wing and the ground. This boosts lift and lowers drag to yield a substantial overall improvement in efficiency. Ground effect works on both water and land, but you can take advantage of it for only so long on land before your aircraft runs into something. Which is why oceans are the ideal place for these aircraft--or ships, depending on your perspective. During the late 1980s, the Soviets (and later the Russians) leveraged ground effect in the design of a handful of awesomely bizarre ships and aircraft. There's the VVA-14, which was also an airplane, along with the vehicle shown in DARPA's video above, the Lun-class ekranoplan, which operated until the late 1990s. The video clip really does not do this thing justice, so here's a better picture, taken a couple of years ago: Oblique overhead view of a huge grey seaplane on the water Instagram The Lun (only one was ever made) had a wingspan of 44 meters and was powered by eight turbojet engines. It flew about 4 meters above the water at speeds of up to 550 kilometers per hour, and could transport almost 100,000 kilograms of cargo for 2,000 km. It was based on an earlier, even larger prototype (the largest aircraft in the world at the time) that the CIA spotted in satellite images in 1967 and which seems to have seriously freaked them out. It was nicknamed the Caspian Sea Monster, and it wasn't until the 1980s that the West understood what it was and how it worked. In the mid 1990s, DARPA itself took a serious look at a stupendously large ground-effect vehicle of its own, the Aerocon Dash 1.6 wingship . The concept image below is of a 4.5-million-kg vehicle, 175 meters long with a 100-meter wingspan, powered by 20 (!) jet engines: A black and white wireframe drawing of a huge streamlined aircraft Wikipedia With a range of almost 20,000 km at over 700 km/h, the wingship could have carried 3,000 passengers or 1.4 million kg of cargo. By 1994, though, DARPA had decided that the potential billion-dollar project to build a wingship like this was too risky, and canceled the whole thing. A concept image of a massive grey seaplane skimming over the ocean Less than 10 years later, Boeing's Phantom Works started exploring an enormous ground-effect aircraft, the Pelican Ultra Large Transport Aircraft. The Pelican would have been even larger than the Aerocon wingship, with a wingspan of 152 meters and a payload of 1.2 million kg--that's about 178 shipping containers' worth. Unlike the wingship, the Pelican would take advantage of ground effect to boost efficiency only in transit above water, but would otherwise use runways like a normal aircraft and be able to reach flight altitudes of 7,500 meters. Operating as a traditional aircraft and with an optimal payload, the Pelican would have a range of about 12,000 km. In ground effect, however, the range would have increased to 18,500 km, illustrating the appeal of designs like these. But Boeing dropped the project in 2005 to focus on lower cost, less risky options. We'd be remiss if we didn't at least briefly mention two other massive aircraft: the H-4 Hercules, the cargo seaplane built by Hughes Aircraft Co. in the 1940s, and the Stratolaunch carrier aircraft, which features a twin-fuselage configuration that DARPA seems to be favoring in its concept video for some reason. From the sound of DARPA's announcement, they're looking for something a bit more like the Pelican than the Aerocon Dash or the Lun. DARPA wants the Liberty Lifter to be able to sustain flight out of ground effect if necessary, although it's expected to spend most of its time over water for efficiency. It won't use runways on land at all, though, and should be able to stay out on the water for 4 to 6 weeks at a time, operating even in rough seas--a significant challenge for ground-effect aircraft. DARPA is looking for an operational range of 7,500 km, with a maximum payload of at least 90,000 kg, including the ability to launch and recover amphibious vehicles. The hardest thing DARPA is asking for could be that, unlike most other X-planes, the Liberty Lifter should incorporate a "low cost design and construction philosophy" inspired by the mass-produced Liberty ships of World War II. With US $15 million to be awarded to up to two Liberty Lifter concepts, DARPA is hoping that at least one of those concepts will pass a system-level critical design review in 2025. If everything goes well after that, the first flight of a full-scale prototype vehicle could happen as early as 2027. From Your Site Articles * Advanced Research Projects from DARPA's Pentagon Demo Day ... > * DARPA's Newest X-Plane Concepts Are All Robots - IEEE Spectrum > Related Articles Around the Web * DARPA sets goals for Liberty Lifter heavy-lift seaplane > darpa x-plane aircraft {"imageShortcodeIds":["29824201"]} Evan Ackerman Evan Ackerman is a senior editor at IEEE Spectrum. Since 2007, he has written over 6,000 articles on robotics and technology. He has a degree in Martian geology and is excellent at playing bagpipes. The Conversation (1) [defa] Harry Solomon 23 May, 2022 LS The ocean is not empty. I would not want to be in a fishing boat when this guy comes barreling over the horizon directly towards me at 700 km/h. Is DARPA considering the safety and environmental aspects of such a plane? What collision avoidance technologies are needed? What is the effect of a sudden rise in pressure caused by overflight on sea life, both microfauna (plankton) and megafauna (seals, whales), at the surface or in the upper few meters of the water? What are the risks of bird strikes due to a flock of seabirds suddenly taking flight due to the noise of the approaching aircraft? 0 Replies Hide replies Show More Replies A rendering of a lunar base. In the foreground are rows of solar panels and behind them are two astronauts standing in front of a glass dome with plants inside. Topic News Type Energy Engineers Are Working on a Solar Microgrid To Outlast Lunar Nights 4h 4 min read Black and white image showing different white box shapes in rows Topic News Type Sensors Trilobite-Inspired Camera Boasts Huge Depth of Field 6h 3 min read Light and dark pink sections of a microscopic view of heart tissue Topic News Type Biomedical Damaged Hearts Next in Line for Powerful mRNA Therapies 9h 3 min read Related Stories Topic Magazine Robotics Type Feature Inside DARPA's Subterranean Challenge Topic Type Robotics News DARPA's RACER Program Sends High-Speed Autonomous Vehicles Off-Road Topic News Type Sensors Physicists Spin Up Quantum Tornadoes Topic Magazine Energy Type Feature Practical Power Beaming Gets Real A century later, Nikola Tesla's dream comes true Paul Jaffe 21 May 2022 8 min read This nighttime outdoor image, with city lights in the background, shows a narrow beam of light shining on a circular receiver that is positioned on the top of a pole. A power-beaming system developed by PowerLight Technologies conveyed hundreds of watts of power during a 2019 demonstration at the Port of Seattle. PowerLight Technologies Yellow Wires have a lot going for them when it comes to moving electric power around, but they have their drawbacks too. Who, after all, hasn't tired of having to plug in and unplug their phone and other rechargeable gizmos? It's a nuisance. Wires also challenge electric utilities: These companies must take pains to boost the voltage they apply to their transmission cables to very high values to avoid dissipating most of the power along the way. And when it comes to powering public transportation, including electric trains and trams, wires need to be used in tandem with rolling or sliding contacts, which are troublesome to maintain, can spark, and in some settings will generate problematic contaminants. Many people are hungry for solutions to these issues--witness the widespread adoption over the past decade of wireless charging, mostly for portable consumer electronics but also for vehicles. While a wireless charger saves you from having to connect and disconnect cables repeatedly, the distance over which energy can be delivered this way is quite short. Indeed, it's hard to recharge or power a device when the air gap is just a few centimeters, much less a few meters. Is there really no practical way to send power over greater distances without wires? To some, the whole notion of wireless power transmission evokes images of Nikola Tesla with high-voltage coils spewing miniature bolts of lightning. This wouldn't be such a silly connection to make. Tesla had indeed pursued the idea of somehow using the ground and atmosphere as a conduit for long-distance power transmission, a plan that went nowhere. But his dream of sending electric power over great distances without wires has persisted. To underscore how safe the system was, the host of the BBC science program "Bang Goes the Theory" stuck his face fully into a power beam. Guglielmo Marconi, who was Tesla's contemporary, figured out how to use "Hertzian waves," or electromagnetic waves, as we call them today, to send signals over long distances. And that advance brought with it the possibility of using the same kind of waves to carry energy from one place to another. This is, after all, how all the energy stored in wood, coal, oil, and natural gas originally got here: It was transmitted 150 million kilometers through space as electromagnetic waves--sunlight--most of it millions of years ago. Can the same basic physics be harnessed to replace wires today? My colleagues and I at the U.S. Naval Research Laboratory, in Washington, D.C., think so, and here are some of the reasons why. There have been sporadic efforts over the past century to use electromagnetic waves as a means of wireless power transmission, but these attempts produced mixed results. Perhaps the golden year for research on wireless power transmission was 1975, when William Brown, who worked for Raytheon, and Richard Dickinson of NASA's Jet Propulsion Laboratory (now retired) used microwaves to beam power across a lab with greater than 50 percent end-to-end efficiency. In a separate demonstration, they were able to deliver more than 30 kilowatts over a distance of about a mile (1.6 kilometers). These demonstrations were part of a larger NASA and U.S. Department of Energy campaign to explore the feasibility of solar-power satellites, which, it was proposed, would one day harvest sunlight in space and beam the energy down to Earth as microwaves. But because this line of research was motivated in large part by the energy crisis of the 1970s, interest in solar-power satellites waned in the following decades, at least in the United States. Although researchers revisit the idea of solar-power satellites with some regularity, those performing actual demonstrations of power beaming have struggled to surpass the high-water mark for efficiency, distance, and power level reached in 1975. But that situation is starting to change, thanks to various recent advances in transmission and reception technologies. In this image, a narrow purple beam shines across a darkened room. During a 2019 demonstration at the Naval Surface Warfare Center in Bethesda, Md., this laser beam safely conveyed 400 watts over a distance of 325 meters.U.S. Naval Research Laboratory Most early efforts to beam power were confined to microwave frequencies, the same part of the electromagnetic spectrum that today teems with Wi-Fi, Bluetooth, and various other wireless signals. That choice was, in part, driven by the simple fact that efficient microwave transmitting and receiving equipment was readily available. But there have been improvements in efficiency and increased availability of devices that operate at much higher frequencies. Because of limitations imposed by the atmosphere on the effective transmission of energy within certain sections of the electromagnetic spectrum, researchers have focused on microwave, millimeter-wave, and optical frequencies. While microwave frequencies have a slight edge when it comes to efficiency, they require larger antennas. So, for many applications, millimeter-wave or optical links work better. For systems that use microwaves and millimeter waves, the transmitters typically employ solid-state electronic amplifiers and phased-array, parabolic, or metamaterial antennas. The receiver for microwaves or millimeter waves uses an array of elements called rectennas. This word, a portmanteau of rectifier and antenna, reflects how each element converts the electromagnetic waves into direct-current electricity. Any system designed for optical power transmission would likely use a laser--one with a tightly confined beam, such as a fiber laser. The receivers for optical power transmission are specialized photovoltaic cells designed to convert a single wavelength of light into electric power with very high efficiency. Indeed, efficiencies can exceed 70 percent, more than double that of a typical solar cell. At the U.S. Naval Research Laboratory, we have spent the better part of the past 15 years looking into different options for power beaming and investigating potential applications. These include extending the flight times and payload capacities of drones, powering satellites in orbit when they are in darkness, powering rovers operating in permanently shadowed regions of the moon, sending energy to Earth's surface from space, and distributing energy to troops on the battlefield. You might think that a device for sending large amounts of energy through the air in a narrow beam sounds like a death ray. This gets to the heart of a critical consideration: power density. Different power densities are technically possible, ranging from too low to be useful to high enough to be dangerous. But it's also possible to find a happy medium between these two extremes. And there are also clever ways to permit beams with high power densities to be used safely. That's exactly what a team I was part of did in 2019, and we've successfully extended this work since then. One of our industry partners, PowerLight Technologies, formerly known as LaserMotive, has been developing laser-based power-beaming systems for more than a decade. Renowned for winning the NASA Power Beaming Challenge in 2009, this company has not only achieved success in powering robotic tether climbers, quadcopters, and fixed-wing drones, but it has also delved deeply into the challenges of safely beaming power with lasers. That's key, because many research groups have demonstrated laser power beaming over the years--including teams at the Naval Research Laboratory, Kindai University, the Beijing Institute of Technology, the University of Colorado Boulder, JAXA, Airbus, and others--but only a few have accomplished it in a fashion that is truly safe under every plausible circumstance. This diagram shows the peak power levels and distance achieved in 11 power-beaming demonstrations carried out between 1975 and 2021 There have been many demonstrations of power beaming over the years, using either microwaves [blue] or lasers [red], with the peak-power record having been set in 1975 [top]. In 2021, the author and his colleagues took second and third place for the peak-power level achieved in such experiments, having beamed more than a kilowatt over distances that exceeded a kilometer, using much smaller antennas. David Schneider Perhaps the most dramatic demonstration of safe laser power beaming prior to our team's effort was by the company Lighthouse Dev in 2012. To underscore how safe the system was, the host of the BBC science program "Bang Goes the Theory" stuck his face fully into a power beam sent between buildings at the University of Maryland. This particular demonstration took advantage of the fact that some infrared wavelengths are an order of magnitude safer for your eyes than other parts of the infrared spectrum. That strategy works for relatively low-power systems. But as you push the level higher, you soon get to power densities that raise safety concerns regardless of the wavelength used. What then? Here's where the system we've demonstrated sets itself apart. While sending more than 400 watts over a distance that exceeded 300 meters, the beam was contained within a virtual enclosure, one that could sense an object impinging on it and trigger the equipment to cut power to the main beam before any damage was done. Other testing has shown how transmission distances can exceed a kilometer. Careful testing (for which no BBC science-program hosts were used) verified to our satisfaction the functionality of this feature, which also passed muster with the Navy's Laser Safety Review Board. During the course of our demonstration, the system further proved itself when, on several occasions, birds flew toward the beam, shutting it off--but only momentarily. You see, the system monitors the volume the beam occupies, along with its immediate surroundings, allowing the power link to automatically reestablish itself when the path is once again clear. Think of it as a more sophisticated version of a garage-door safety sensor, where the interruption of a guard beam triggers the motor driving the door to shut off. The 400 watts we were able to transmit was, admittedly, not a huge amount, but it was sufficient to brew us some coffee. For our demonstrations, observers in attendance were able to walk around between the transmitter and receiver without needing to wear laser-safety eyewear or take any other precautions. That's because, in addition to designing the system so that it can shut itself down automatically, we took care to consider the possible effects of reflections from the receiver or the scattering of light from particles suspended in the air along the path of the beam. [svg] [svg] This set of three images shows a large white parabolic dish at the top, a gold-colored square in the middle, and a tall metal tower at the bottom. Last year, the author and his colleagues carried out a demonstration at the U.S. Army's Blossom Point test facility south of Washington, D.C. They used 9.7-gigahertz microwaves to send 1,649 watts (peak power) from a transmitter outfitted with a 5.4-meter diameter parabolic dish [top] over a distance of 1,046 meters to a 2-by-2-meter "rectenna" [middle] mounted on a tower [bottom], which transformed the beam into usable electric power.U.S. Naval Research Laboratory The 400 watts we were able to transmit was, admittedly, not a huge amount, but it was sufficient to brew us some coffee, continuing what's become de rigueur in this line of experimentation: making a hot beverage. (The Japanese researchers who started this tradition in 2015 prepared themselves some tea.) Our next goal is to apply power beaming, with fully integrated safety measures, to mobile platforms. For that, we expect to increase the distance covered and the amount of power delivered. But we're not alone: Other governments, established companies, and startups around the world are working to develop their own power-beaming systems. Japan has long been a leader in microwave and laser power beaming, and China has closed the gap if not pulled ahead, as has South Korea. At the consumer-electronics level, there are many players: Powercast, Ossia, Energous, GuRu, and Wi-Charge among them. And the multinational technology giant Huawei expects power beaming for smartphone charging within "two or three [phone] generations." For industrial applications, companies like Reach Labs, TransferFi, MH GoPower, and MetaPower are making headway in employing power beaming to solve the thorny problem of keeping batteries for robots and sensors, in warehouses and elsewhere, topped off and ready to go. At the grid level, Emrod and others are attempting to scale power beaming to new heights. On the R&D front, our team demonstrated within the past year safe microwave wireless power transmission of 1.6 kilowatts over a distance of a kilometer. Companies like II-VI Aerospace & Defense, Peraton Labs, Lighthouse Dev, and others have also recently made impressive strides. Today, ambitious startups like Solar Space Technologies, Solaren, Virtus Solis, and others operating in stealth mode are working hard to be the first to achieve practical power beaming from space to Earth. As such companies establish proven track records for safety and make compelling arguments for the utility of their systems, we are likely to see whole new architectures emerge for sending power from place to place. Imagine drones that can fly for indefinite periods and electrical devices that never need to be plugged in--ever--and being able to provide people anywhere in the world with energy when hurricanes or other natural disasters ravage the local power grid. Reducing the need to transport fuel, batteries, or other forms of stored energy will have far-reaching consequences. It's not the only option when you can't string wires, but my colleagues and I expect, within the set of possible technologies for providing electricity to far-flung spots, that power beaming will, quite literally, shine. This article appears in the June 2022 print issue as "Spooky Power at a Distance." From Your Site Articles * Emrod Chases The Dream Of Utility-Scale Wireless Power ... > * A Critical Look at Wireless Power - IEEE Spectrum > * Solar Power from Space? Caltech's $100 Million Gambit - IEEE ... > Related Articles Around the Web * Wireless power transfer - Wikipedia > * Wireless Power - When Will All These Cables Disappear? > * Wireless Power Transfer - an overview | ScienceDirect Topics > Keep Reading | Show less