This is my own

Nov 25, 2010

Submarines fly

Posted by Fakhriyah on 6:10 PM

GUILLEMOTS and gannets do it. Cormorants and kingfishers do it. Even the tiny insect-eating dipper does it. And if a plan by the Pentagon's Defense Advanced Research Projects Agency (DARPA) succeeds, a remarkable airplane may one day do it too: plunge beneath the waves to stalk its prey, before re-emerging to fly home.The DARPA plan, announced in October 2008, calls for a stealthy aircraft that can fly low over the sea until it nears its target, which could be an enemy ship, or a coastal site such as a port. It will then alight on the water and transform itself into a submarine that will cruise under water to within striking distance, all without...

First piloted solar

Posted by Fakhriyah on 5:42 PM

Submarines fly

The DARPA plan, announced in October 2008, calls for a stealthy aircraft that can fly low over the sea until it nears its target, which could be an enemy ship, or a coastal site such as a port. It will then alight on the water and transform itself into a submarine that will cruise under water to within striking distance, all without alerting defences.

DARPA, which has a $3 billion annual budget, has begun to study proposed designs. In the next year or so it could begin allocating funding to developers. Though the agency itself is unwilling to comment, Hawkes and others working on rival designs have revealed to New Scientist how they would solve the key problems involved in building a plane that can travel under water - or, to put it another way, a flying submarine.

The challenges are huge, not least because planes and submarines are normally poles apart. Aircraft must be as light as possible to minimise the engine power they need to get airborne. Submarines are heavyweights with massive hulls strong enough to resist crushing forces from the surrounding water. Aircraft use lift from their wings to stay aloft, while submarines operate like underwater balloons, adjusting their buoyancy to sink or rise. So how can engineers balance the conflicting demands? Could a craft be designed to dive into the sea like a gannet? And how will it be propelled - is a jet engine the best solution, both above and below the waves?

That may have been because the navy had already commissioned another aircraft manufacturer, Convair, to build what became known as the "subplane". It dispensed with heavy floats, relying instead on its streamlined fuselage, like the hull of a flying boat, to land on the water. In a paper in the September 1964 issue of Naval Institute Proceedings (p 144), hydrodynamics engineer Eugene Handler at the US Bureau of Naval Weapons claimed this flying sub would be ideal for attacking Soviet shipping in the Baltic, Black and Caspian seas. Convair drew up detailed designs and even built scale models which were tested in water tanks. Though the results looked promising, the project never made it any further; it was cancelled by Congress in 1966.

So is DARPA's new project destined for a similar fate? "What the Americans want sounds incredibly ambitious," says UK Royal Navy commander Jonty Powis, head of NATO's submarine rescue service. "If they achieve half of what they want from this machine they will be doing well." Others are more optimistic, especially in the light of advances in engineering and materials science since the last attempt - notably in lightweight carbon fibre composites and energy-dense batteries. "There's probably no reason why it can't be done," says Hawkes.

Hawkes admits that an awful lot of power will be needed to get the Super Falcon airborne, and only jet engines have enough oomph to do the job. Polmar agrees, and points out that the piston engines used in conventional light planes are ruled out for other reasons: they would fail if any water leaked into the cylinders. "You cannot immerse a reciprocating engine and expect it to work," he says. But protect a jet engine against saltwater corrosion and position it high on the craft so the spray doesn't enter the intake during take-off and landing, and it will work fine. Russian aircraft maker Beriev has proved this with its Be-200 amphibious plane.Others are already thinking along these lines. Last year, aircraft manufacturer Airbus patented a hybrid electric jet engine for airliners which can be powered by both conventional kerosene and electricity. Most jet engines have an electric starter motor, and this motor could spin the turbine's shaft under water, Hawkes suggests. The blades would rotate more slowly than normal, he says, and the engine won't be particularly efficient. "But I believe this could work perfectly well."

First piloted solar

A solar powered aircraft masterminded by a Swiss adventurer has made history as the first manned plane to fly around the clock on the sun's energy, bringing a step closer the dream of perpetual flight.

The aircraft, built by Swiss company Solar Impulse, also broke the records for highest altitude and longest duration for a piloted solar flight.
The craft took off at 6:51 local time yesterday morning from the Payerne airbase in Switzerland.
Its power was collected by 12,000 solar panels built into its 63-metre wingspan. During the hours of bright sun, batteries siphoned off some energy to power the plane through the night.
The craft climbed to a height of 8564 metres, which it reached about ten hours into the flight. When the sun began to fade around 7:30 in the evening, the plane began a slow descent to around 1500 metres, where it stayed from 11 pm until sunrise.
After 26 hours in the plane, Borschberg landed it at 9:00 this morning.
This is the last milestone for Solar Impulse's prototype aircraft. Its first was the "flea hop" of last December: a short flight around one metre from the ground.
The company's dreams for the next plane are bigger. To be constructed in 2011, its objectives are to cross the Atlantic, and then to circumnavigate the globe on solar power alone, by 2013. For such missions, let's hope they consider a more adventurous name for the plane than its current moniker: HB-SIB.
"The flight was really zen. It's very peaceful, during this time you have the time to think and to concentrate," he explained.
Piccard revealed that Solar Impulse had emerged from darkness with three hours of energy left in its batteries, a far bigger margin than expected.
The first prototype, shaped like a giant dragonfly, is clad with solar panels across a wingspan of 63 metres, the size of an Airbus A340 airliner.
The solar cells and nearly half a tonne of batteries provide energy for four small electric motors and propellers - the "power of a scooter", as the crew put it - and weigh little more than a saloon car.
The team is driven by a desire to demonstrate that clean energy is technically feasible and should be developed and used more widely for transport, in the household and at work.

This is my own

Nov 25, 2010

Submarines fly

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First piloted solar

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