July 2009 Archives

US research engineers at Princeton plan to study how fuel additives made of tiny particles

of graphene can help supersonic jets fly faster and make diesel engines cleaner and more

efficient.  

Physorg.com reports that to create the graphene particles, researchers will remove carbon dioxide molecules from graphite oxide which leaves a irregular bond pattern that creates a buckle in the otherwise flat graphene molecule. This ridge prevents the graphene molecule from folding into ball.

The interdisciplinary team of scientists led by Princeton engineers has been awarded a $3 million grant to study such fuel additives made of tiny particles known as nanocatalysts made up of snippets of molecular sheets carbon only a few Angstroms thick.

These particles have been shown to help fuels ignite and burn faster, a quality that could lead to the next generation of combustion engines.

For supersonc aircraft to travel even faster, engines must operate at faster speeds and fuel must move through them more rapidly, but the ignition time and burn rate of current jet fuels limits the speed of the engines.

"Right now we don't know what actual reactions enhance the combustion rates when the particles are added to fuels," said Ilhan Aksay, a professor of chemical engineering at Princeton and the lead investigator on the project. "If we understand it further, we can make it more effective."

The funding, which comes from the Air Force as part of the 2009 American Recovery and Reinvestment Act Research Program, will be used to tackle a fundamental barrier to designing faster supersonic aircraft.

The world's first piloted aircraft capable of taking to the air using only power from fuel

cells has flown, producing zero carbon dioxide emissions during the landmark mission.

Click here to watch the video. 

The Antares DLR-H2 - developed by the German Aerospace Centre DLR together with Lange

Aviation, BASF Fuel Cells and Denmark's Serenergy - has a range of 750 kilometres (465

miles) and can fly for five hours at maximum flying speeds of approximately 170 kilometres per hour.

DLR says it has improved fuel cell performance capabilities and efficiency to such an

extent that the motor glider can take off using fuel cell power alone.

"This enables us to demonstrate the true potential of this technology," said DLR's Johann-Dietrich Wörner who concedes however that fuel cell use constitutes a more likely alternative to existing onboard energy systems than main propulsion alternatives.

The system uses hydrogen as its fuel which is converted into electrical energy in a direct, electrochemical reaction with oxygen in the ambient air, without any combustion occurring and producing only water.

To accommodate the fuel cell and the hydrogen supply, two additional external load carriers weighing 100 kgs were slung under the specially reinforced wings whose aeroelastic properties had to be reconfigured to safeguard flight stability.

The fuel cell system used to power the Antares delivers up to 25 kilowatts of electrical power although operates at an efficiency level of approximately 52 percent when the aircraft is flying in a straight line, which requires around ten kilowatts of power.

The total efficiency of the drive system from tank to powertrain, including the propeller, is around  44 percent, making it about twice as efficient as conventional propulsion technologies based on combustion processes.

Another innovation is the way its fuel cell is connected to the main electric motor that powers the aircraft. Developed jointly with Lange Aviation and the College of Advanced Technology in Berne/Biel, it is capable of taking in and controlling voltages from 188 to 400 V increasing efficiency, cost and, reliability.

The Antares DLR-H2 will be based at Lufthansa Technik in Hamburg where, over the next `three years, it will be acting as a flying test platform for the fuel cell test activities of DLR as part of its Fuel Cell Labs project.

Proving that defence kit boffins are really just big schoolboys at heart, FutureProof gets wind 

of the Pentagon awarding half a billion dollars to develop a radical new electromagnetic

catapult, intended to toss navy jets off future aircraft carriers.

The Electro Magnetic Aircraft Launch System (EMALS) could replace Cold War-era steam

catapults after it was announced that General Atomics has won $573 million ceiling-priced

contract to build one for the next planned US fleet carrier, CVN 78 or USS Gerald R Ford.

Here's the low-down: "General Atomics, San Diego, Calif., is being awarded a $573,000,000

ceiling priced, undefinitized contract action for the production of the Electromagnetic Aircraft

Launch System (EMALS) CVN 78 Shipset.  EMALS is the catapult launch system on CVN-

78 class aircraft carriers, replacing the steam catapults used on prior generations of aircraft

carriers.  Work will be performed in San Diego, Calif., (49 percent); Tupelo, Miss., (19

percent); Mankato, Minn., (12 percent); Waltham, Mass., (4 percent); and various locations

across the United States (16 percent), and work is expected to be completed in September

2015. Contract funds will not expire at the end of the current fiscal year."

As for its application in civil air transport, airfield power devices assist take-off and landing 

allowing aircraft to use less installed

power and less energy is nothing

new.

One idea from the Out of the Box

European think tank whose Gallery of

image ideas can be found here 

would be to use a maglev propulsive

rail to allow the aircraft to take-off from

virtually a flat surface.

A floating airport at sea could also be

considered with international super-

hub airports located in international

seas.

Being floating structures these could

be turned into the wind to maximize

capacity.

And as for landing the aircraft, what

about water-borne landings or

parafoil-assisted descents?

Aeropak, the latest in fuel cell power systems, could increase the flight endurance of

small and stealthy electric unmanned aerial systems (UAS) by as much as 300 per cent,

making them more effective in persistent intelligence, surveillance and reconnaissance

missions.

The new fuel cell system, developed by Horizon Fuel Cell Technologies, is also designed for

high-impact and able to operate at up to 22,000 feet (6,500m).

Weighing in at just 4.4 lbs (2kg), it integrates fuel cell technology with new refillable dry-fuel

cartridges, storing 900Wh of usable electrical energy, thus providing up to four times the

endurance capability of advanced lithium batteries currently in use.

Horizon says the miniaturized power system also makes it very easy to use as drop-in

replacement for battery packs currently in service, eliminating costly airframe modifications.

In addition to increasing flight endurance, the new fuel cell system also makes it possible

for small tactical UAS to integrate more power-hungry electronic devices such as

electro-optical sensors, infrared cameras and laser designators.

The new fuel cell systems can also be used to power remote ground systems and recharging

stations, or even serve as an auxiliary electric power supply for larger systems.