Oct 312014
The effectiveness of current laser-propulsion techniques is limited by the instability of supersonic gas flow, caused by shock waves that “choke” the inlet of the nozzle, reducing thrust. Those effects can be reduced with the help of laser ablation, redirecting the plasma plume so that it flows close to the interior walls of a supersonic nozzle and significantly improving the overall thrust. Credit: Y.Rezunkov/IOIE

The effectiveness of current laser-propulsion techniques is limited by the instability of supersonic gas flow, caused by shock waves that “choke” the inlet of the nozzle, reducing thrust. Those effects can be reduced with the help of laser ablation, redirecting the plasma plume so that it flows close to the interior walls of a supersonic nozzle and significantly improving the overall thrust.
Credit: Y.Rezunkov/IOIE

New hybrid approach may help power rockets, launch satellites, enable future aircraft to exceed Mach 10

Scientists and science fiction writers alike have dreamt of aircrafts that are propelled by beams of light rather than conventional fuels. Now, a new method for improving the thrust generated by such laser-propulsion systems may bring them one step closer to practical use.

The method, developed by physicists Yuri Rezunkov of the Institute of Optoelectronic Instrument Engineering, Russia and Alexander Schmidt of the Ioffe Physical Technical Institute in Saint Petersburg, Russia is described today in The Optical Society’s (OSA) journal Applied Optics.

Currently, the maximum speed of a spacecraft is limited by the amount of solid or liquid fuel that it can carry. Achieving higher speeds means that more fuel must be burned—fuel that, inconveniently, has to be carried by the craft and hefted into space. These burdensome loads can be reduced, however, if a laser—one located at a remote location, and not actually on the spacecraft—were used to provide additional propulsive force.

A number of systems have been proposed that can produce such laser propulsion. One of the most promising involves a process called laser ablation, in which a pulsed laser beam strikes a surface, heats it up, and burns off material to create what is known as a plasma plume—a column of charged particles that flow off the surface. The outflowing of that plasma plume—essentially, exhaust—generates additional thrust to propel the craft.

In their Applied Optics paper, Rezunkov and Schmidt describe a new system that integrates a laser-ablation propulsion system with the gas blasting nozzles of a spacecraft. Combining the two systems, the researchers found, can increase the speed of the gas flow out of the system to supersonic speeds while reducing the amount of burned fuel.

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Nov 172013


Based on a penguin’s shoulder-and-wing system

Back in 1991, Nature published a picture from the IMAX movie Antarctica, along with the caption: “Emperor penguins may be waddling jokes on land, but underwater they can turn into regular rockets…accelerating from 0 to 7 m/s in less than a second.”

That’s all it took to inspire Flavio Noca, who at the time was a graduate student in Caltech‘s Aeronautics Department, and now teaches aerodynamics at the Univ. of Applied Sciences Western Switzerland (hepia) and the Swiss Federal Institute of Technology (EPFL), to explore leveraging penguins’ “rocket” properties to create new propulsion technologies with high maneuverability and improved hydrodynamic efficiency.

At the American Physical Society’s (APS) Division of Fluid Dynamics meeting, Nov. 24 – 26, in Pittsburgh, Pa, Noca will present a penguin-inspired propulsion system that uses a novel spherical joint mechanism developed and manufactured by Bassem Sudki, a research assistant within Noca’s aerodynamics group, under the supervision of Professor Michel Lauria who leads hepia’s Robotics Laboratory.

Based on a penguin’s shoulder-and-wing system, the mechanism features a spherical joint that enables three degrees of freedom and a fixed center of rotation. “Unlike an animal shoulder joint, however, this spherical joint enables unlimited rotational range about the main shaft axis like a propeller,” Noca said.

To achieve this they needed to overcome the technical challenges of spherical joints, such as the lack of rigidity and the inability to generate high torques. To understand the challenge involved, just try lifting a 10-pound weight on your hand with your arm extended.

The researchers maneuvered around these challenges by choosing a parallel robotic architecture for this type of mechanism, because it enables rigidity as well as high actuation frequencies and amplitudes.

“Because the motors are fixed, inertial forces are lower than for a serial robotic mechanism, such as a multi-joint arm,” explains Noca. “The resulting spherical parallel mechanism with coaxial shafts was designed and manufactured with these specifications: a fixed center of rotation (spherical joint), a working frequency of ~2.5 Hz under charge, an unlimited rotation about the main axis, and an arbitrary motion within a cone of +/- 60°.”

The manner in which penguins swim is still poorly understood, aside from the technological perspective, according to Noca. “By accurately reproducing an actual penguin wing movement, we hope to shed light on the swimming mysteries of these underwater rockets,” he said.

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via R&D Magazine


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Mar 302012
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By combining an ancient concept with modern scientific breakthroughs, the global think tank, Syndicate8, has developed a zero-emission propulsion system for recreational boats, and the technology could eventually be utilized by commercial shippers.

Boaters and the environment are about to profit in a major way thanks to a breakthrough technology: electricity generated by saltwater! By combining an ancient concept with modern scientific breakthroughs, the global think tank, Syndicate8, has developed a zero-emission propulsion system for recreational ocean boats. By retrofitting portions of the exposed hull with a proprietary blend of metal electrodes, the boat, as it sits in the ocean, uses the ocean (e.g., saltwater) as a chemical compound to generate a renewable, storable form of electricity. Although the experiments have only been conducted on a small scale, the group is now in the process of raising funds to create a larger scale model.

“This has been a very exciting process for us. While the rest of the world focuses on making cars burn cleaner, we thought it would be a great idea to focus on the over 14 million registered boats in the United States,” Anthony Silva, the project leader, commented. “This breakthrough could remove millions of gallons of gasoline and diesel from the waterways, ultimately preserving our oceanic ecosystem. We foresee the commercialization of this technology in the very near future.”

Wanting to take the concept to the masses, rather than corporate venture capitalists, the team has decided to use IndieGoGo as its crowdfunding source. If you would like to read more about the project, you can visit the project website on IndieGoGo at http://igg.me/p/85085?a=487738.

via PR Web

Bookmark this page for “throwable robots” and check back regularly as these articles update on a very frequent basis. The view is set to “news”. Try clicking on “video” and “2” for more articles.

May 032011

Image by faunzy via Flickr

An electric propulsion technology for miniature satellites aims to give them more mobility — and may eventually allow them to take on deep-space missions.

Right now, 10 to 15 Rubik’s Cube-sized satellites are orbiting high above Earth. Known as cube satellites, or “CubeSats,” the devices help researchers conduct simple space observations and measure characteristics of Earth’s atmosphere. One advantage is that they are relatively cheap to deploy: While launching a rocket may cost between $50 million and $300 million, a CubeSat can “piggyback” onto a large rocket platform at an additional cost of as little as $40,000. But their small size also means they lack on-board propulsion systems, which is why they generally remain locked to a particular orbit.

That could soon change, however. Paulo Lozano, the H.N. Slater Assistant Professor of Aeronautics and Astronautics at MIT, is designing a tiny propulsion system that could allow the satellites, which weigh about a kilogram and are used for tasks that don’t require precise orbit control, to travel great distances and perform more serious tasks, such as searching for planets outside our solar system. The technology, which is based on the process of extracting and accelerating charged ions, or atoms that have gained or lost an electron, could make CubeSats much more useful for organizations or countries that until now have had limited access to space.

For decades, the only way to get objects into space from Earth — and then propel them through space — was to use chemical propulsion systems. But the systems require a lot of propellant, or fuel, and haven’t been miniaturized to the scale appropriate for a CubeSat. By changing the design from chemical to electric, and to one that relies on a simple power supply, Lozano has created a system that produces more efficient thrust — the force created when mass is accelerated in a certain direction — than that produced by a chemical-based system, which produces a low thrust per gram of propellant. About the size of a computer chip, the mini-thruster design also overcomes the size constraints of chemical propulsion and other forms of electric propulsion because it does not require a bulky chamber to burn (chemical) or extract ions from (electric) the propellant. Although other electric propulsion systems have been developed, Lozano’s is considered superior because it uses only one power supply.

With funding from the Air Force Office of Scientific Research, Lozano has been developing the technology to make the mini-thruster. The Air Force and other government agencies are interested in using CubeSats that can move between different orbits in space, and more specifically, that have the propulsion required to reenter Earth’s atmosphere and destroy themselves at the end of their mission (thereby keeping them from becoming “space junk”). The thruster design requires that the total volume of the propulsion system be less than 10 percent of the CubeSat.

“The goal is to have a space engine that leaves plenty of room for the payload, or cargo, of the CubeSat,” Lozano said. Certain missions require chemical propulsion, such as a trip to the moon, because in order to land on the moon’s surface, the amount of force from the engine must be at least equal to the weight of the lander, a value that Lozano said is generally “way too high” for electric propulsion engines. But chemical-based systems are severely limited by the fact that the vehicle mass must be made mostly of propellant, which leaves little room for the payload. Quite often the propellant must also be stored in a pressurized container with thick walls and pipes, further limiting the payload size. Although other electric propulsion systems exist, they require a pressurized container to store the propellant.

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Dec 242010

BAE is developing a parallel version of its HybriDrive system for medium and heavy-duty trucks

The HybriDrive series propulsion system developed by BAE Systems is currently enhancing the fuel efficiency and cutting emissions on more than 3,000 transit buses in cities around the world, including New York and London.

The system is specifically suited to the driving patterns of urban transport, which involve low average speeds and frequent stopping and starting. To meet the needs of applications that have higher operating speeds and less frequent stops, BAE is developing a new parallel hybrid propulsion system to bring the fuel-saving benefits of its technology to medium and heavy-duty trucks.

HybriDrive series propulsion is a diesel-electric system that consists of a generator, an electric motor, and a lithium-ion battery energy storage system that is managed by computerized controls. The diesel engine that turns the generator operates independently of the electric motor, which allows it to run at a nearly constant speed for optimum efficiency. Since the electric motor is what makes the wheels turn, the vehicle also accelerates smoothly with no sudden jerks. Additionally, during braking the electric motor acts as a generator to recapture energy that is stored in the batteries.

While the series propulsion system doesn’t use a transmission – cutting down on maintenance costs – the HybriDrive parallel system integrates a single electric machine between the engine and the transmission. BAE says the system is easy to install and enhances propulsion and lowers fuel consumption and emissions by optimizing the blending of the internal combustion engine power and electric power.

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Dec 212010
SHENZHEN, CHINA - OCTOBER 14:  The Household C...
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An advancement in hybrid electric vehicle technology is providing powerful benefits beyond transportation.

Researchers at the Department of Energy’s Oak Ridge National Laboratory have designed, fabricated and demonstrated a PHEV traction drive power electronics system that provides significant mobile power generation and vehicle-to-grid support capabilities.

“The new technology eliminates the separate charging mechanism typically used in PHEVs, reducing both cost and volume under the hood,” said Gui-Jia Su of ORNL’s Power Electronics and Electric Machinery Research Center. “The PHEV’s traction drive system is used to charge the battery, power the vehicle and enable its mobile energy source capabilities.”

Providing more power than typical freestanding portable generators, the PHEV can be used in emergency situations such as power outages and roadside breakdowns or leisure occasions such as camping. Day-to-day, the PHEV can be used to power homes or businesses or supply power to the grid when power load is high, according to Su.

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Aug 032010

Boeing Sugar Volt

Although the theme of AirVenture 2010 was “Salute to Veterans,” the future of air travel was also brought to the fore – and that means electric airplanes.

The focus on e-aviation culminated in the World Symposium of Electric Aircraft last Friday and among the many interesting designs discussed was Boeing’s Subsonic Ultra Green Aircraft Research (SUGAR) Volt concept. Borne out of the same NASA research program that gave birth to MIT’s D “double bubble” concept, the SUGAR Volt is a twin-engine aircraft design notable for its trussed, elongated wings and electric battery gas turbine hybrid propulsion system – a system designed to reduce fuel burn by more than 70 percent and total energy use by 55 percent. Could this be the future shape of commercial air transportation?

The SUGAR Volt (a choice of name that Chevrolet might have something to say about) is envisioned as running on either fuel or electricity and could include hinges in the wing design so that they could be folded when on the ground. It is designed to fly at Mach 0.79, carry 154 passengers over a range of 3,500 nautical miles and achieve shorter takeoff distance.

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