Southampton engineers fly the world's first 'printed' aircraft

Southampton engineers fly the world's first 'printed' aircraft

  10:10:00 AM    Science Lover

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Engineers at the University of Southampton have designed and flown the world's first 'printed' aircraft, which could revolutionise the economics of aircraft design.

SULSA is the world's first "printed" aircraft.
Credit: University of Southampton

The SULSA (Southampton University Laser Sintered Aircraft) plane is an unmanned air vehicle (UAV) whose entire structure has been printed, including wings, integral control surfaces and access hatches. It was printed on an EOS EOSINT P730 nylon laser sintering machine, which fabricates plastic or metal objects, building up the item layer by layer.

No fasteners were used and all equipment was attached using 'snap fit' techniques so that the entire aircraft can be put together without tools in minutes.

The electric-powered aircraft, with a 2-metres wingspan, has a top speed of nearly 100 miles per hour, but when in cruise mode is almost silent. The aircraft is also equipped with a miniature autopilot developed by Dr Matt Bennett, one of the members of the team.

Laser sintering allows the designer to create shapes and structures that would normally involve costly traditional manufacturing techniques. This technology allows a highly-tailored aircraft to be developed from concept to first flight in days. Using conventional materials and manufacturing techniques, such as composites, this would normally take months. Furthermore, because no tooling is required for manufacture, radical changes to the shape and scale of the aircraft can be made with no extra cost.

This project has been led by Professors Andy Keane and Jim Scanlan from the University's Computational Engineering and Design Research group.

Professor Scanlon says: "The flexibility of the laser sintering process allows the design team to re-visit historical techniques and ideas that would have been prohibitively expensive using conventional manufacturing. One of these ideas involves the use of a Geodetic structure. This type of structure was initially developed by Barnes Wallis and famously used on the Vickers Wellington bomber which first flew in 1936. This form of structure is very stiff and lightweight, but very complex. If it was manufactured conventionally it would require a large number of individually tailored parts that would have to be bonded or fastened at great expense."



Professor Keane adds: "Another design benefit that laser sintering provides is the use of an elliptical wing planform. Aerodynamicists have, for decades, known that elliptical wings offer drag benefits. The Spitfire wing was recognised as an extremely efficient design but it was notoriously difficult and expensive to manufacture. Again laser sintering removes the manufacturing constraint associated with shape complexity and in the SULSA aircraft there is no cost penalty in using an elliptical shape."

SULSA is part of the EPSRC-funded DECODE project, which is employing the use of leading edge manufacturing techniques, such as laser sintering, to demonstrate their use in the design of UAVs.

The University of Southampton has been at the forefront of UAV development since the early 1990s, when work began on the Autosub programme at its waterfront campus at the National Oceanography Centre, Southampton. A battery powered submarine travelled under sea ice in more than 300 voyages to map the North Sea, and assess herring stocks.

Now, the University is launching a groundbreaking course which enables students to take a Master's Degree in unmanned autonomous vehicle (UAV) design.

Provided by University of Southampton

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The Pentagon Approves a Flying Car! The Pentagon wants a flying car, and one seriously out-there military concept has been given the go-ahead. Here is a look at the Pentagon's next armored, armed, airborne Humvee.

The Pentagon Approves a Flying Car! The Pentagon wants a flying car, and one seriously out-there military concept has been given the go-ahead. Here is a look at the Pentagon's next armored, armed, airborne Humvee.

  9:27:00 AM    Science Lover

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The race to build the world's first flying military jeep just moved a step closer to the finish line. The Pentagon's Defense Advanced Research Projects Agency (DARPA) has selected two companies to proceed with the next stage of its Transformer, known as TX—a fully automated four-person vehicle that can drive like a car and then take off and fly like an aircraft to avoid roadside bombs. Lockheed Martin and AAI Corp., a unit of Textron Systems, are currently in negotiations with DARPA for the first stage of the Transformer project, several industry sources told Popular Mechanics at a robotics conference here in Denver. DARPA has not announced the official winners yet.

It's unclear how many companies competed for the DARPA project, but the competition brought together an unusual mix of large defense companies with smaller aviation firms vying to build the vertical takeoff and landing craft. Perhaps most surprising—and for some competitors galling— is that DARPA selected a rotor-based aircraft for one of the two winning submissions. At an industry day held earlier this year, DARPA officials had initially said they weren't interested in a traditional rotary-wing aircraft, though they might consider a vehicle if the rotor was shrouded.

AAI's winning concept does not have a shrouded rotor, but it is also far from being a traditional helicopter. The company, which produces the Shadow unmanned aerial vehicle, is basing its proposal in part on the slowed-rotor/compound concept, a technology that uses rotor blades heavily weighted in the tips, or high inertia. The rotor provides lift on takeoff, and then as it gains speed, the rotor slows down and the wings provide lift.

Lockheed Martin has declined to detail any aspect of its submission, but those familiar with the Phantom Works project speculated that it might combine aspects of the company's Joint Tactical Light Vehicle, a follow-on to the Humvee, with a ducted fan propulsion system that it would use to fly.

The two companies are still a ways away from building flying Humvees; the first stage of the DARPA project is merely working on conceptual designs. The total funding available for Transformer is about $40 million.

Officials from both companies declined to comment on the record about the negotiations, and DARPA did not respond to request to comment.

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A Plane That Lands Like a Bird

A Plane That Lands Like a Bird

  6:22:00 AM    Science Lover

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Everyone knows what it's like for an airplane to land: the slow maneuvering into an approach pattern, the long descent, and the brakes slamming on as soon as the plane touches down, which seems to just barely bring it to a rest a mile later. Birds, however, can switch from barreling forward at full speed to lightly touching down on a target as narrow as a telephone wire. Why can't an airplane be more like a bird?

A smoke visualization still of the actual vortex wake behind our glider during a free-flight high angle of attack landing. (Credit: Jason Dorfman/CSAIL)

MIT researchers have demonstrated a new control system that allows a foam glider with only a single motor on its tail to land on a perch, just like a pet parakeet. The work could have important implications for the design of robotic planes, greatly improving their maneuverability and potentially allowing them to recharge their batteries simply by alighting on power lines.

Birds can land so precisely because they take advantage of a complicated physical phenomenon called "stall." Even when a commercial airplane is changing altitude or banking, its wings are never more than a few degrees away from level. Within that narrow range of angles, the airflow over the plane's wings is smooth and regular, like the flow of water around a small, smooth stone in a creek bed.

A bird approaching its perch, however, will tilt its wings back at a much sharper angle. The airflow over the wings becomes turbulent, and large vortices -- whirlwinds -- form behind the wings. The effects of the vortices are hard to predict: If a plane tilts its wings back too far, it can fall out of the sky. Hence the name "stall."

The smooth airflow over the wings of a normally operating plane is well-understood mathematically; as a consequence, engineers are highly confident that a commercial airliner will respond to the pilot's commands as intended. But stall is a much more complicated phenomenon: Even the best descriptions of it are time-consuming to compute.

Reap the whirlwind

To design their control system, MIT Associate Professor Russ Tedrake, a member of the Computer Science and Artificial Intelligence Laboratory, and Rick Cory, a PhD student in Tedrake's lab who defended his dissertation this spring, first developed their own mathematical model of a glider in stall. For a range of launch conditions, they used the model to calculate sequences of instructions intended to guide the glider to its perch. "It gets this nominal trajectory," Cory explains. "It says, 'If this is a perfect model, this is how it should fly.'" But, he adds, "because the model is not perfect, if you play out that same solution, it completely misses."

So Cory and Tedrake also developed a set of error-correction controls that could nudge the glider back onto its trajectory when location sensors determined that it had deviated from it. By using innovative techniques developed at MIT's Laboratory for Information and Decision Systems, they were able to precisely calculate the degree of deviation that the controls could compensate for. The addition of the error-correction controls makes a trajectory look like a tube snaking through space: The center of the tube is the trajectory calculated using Cory and Tedrake's model; the radius of the tube describes the tolerance of the error-correction controls.

The control system ends up being, effectively, a bunch of tubes pressed together like a fistful of straws. If the glider goes so far off course that it leaves one tube, it will still find itself in another. Once the glider is launched, it just keeps checking its position and executing the command that corresponds to the tube in which it finds itself. The design of the system earned Cory Boeing's 2010 Engineering Student of the Year Award.

The measure of air resistance against a body in flight is known as the "drag coefficient." A cruising plane tries to minimize its drag coefficient, but when it's trying to slow down, it tilts its wings back in order to increase drag. Ordinarily, it can't tilt back too far, for fear of stall. But because Cory and Tedrake's control system takes advantage of stall, the glider, when it's landing, has a drag coefficient that's four to five times that of other aerial vehicles.

From spy planes to fairies

For some time, the U.S. Air Force has been interested in the possibility of unmanned aerial vehicles that could land in confined spaces and has been funding and monitoring research in the area. "What Russ and Rick and their team is doing is unique," says Gregory Reich of the Air Force Research Laboratory. "I don't think anyone else is addressing the flight control problem in nearly as much detail." Reich points out, however, that in their experiments, Cory and Tedrake used data from wall-mounted cameras to gauge the glider's position, and the control algorithms ran on a computer on the ground, which transmitted instructions to the glider. "The computational power that you may have on board a vehicle of this size is really, really limited," Reich says. Even though the MIT researchers' course correction algorithms are simple, they may not be simple enough.

Tedrake believes, however, that computer processors powerful enough to handle his and Cory's control algorithms are only a few years off. In the meantime, his lab has already begun to address the problem of moving the glider's location sensors onboard, and although Cory will be moving to California to take a job researching advanced robotics techniques for Disney, he hopes to continue collaborating with Tedrake. "I visited the air force, and I visited Disney, and they actually have a lot in common," Cory says. "The air force wants an airplane that can land on a power line, and Disney wants a flying Tinker Bell that can land on a lantern. But the technology's similar."

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