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Solar-Powered Plane to Fly Around the World
securitas writes "The BBC's Carolyn Fry reports on the Solar Impulse project, a plan to circumnavigate the globe in a solar-powered airplane. Adventurers Brian Jones and Dr. Bertrand Piccard, who were the first people to circumnavigate the globe in a balloon in 1999, are behind the Solar Impulse project. The project is proceeding to the design stage after a feasability study determined that the solar-powered airplane concept is a viable idea. While other solar-powered planes like the Helios prototype have relied on a secondary power source (fuel cells), this project will be powered by solar energy alone. Batteries will store energy received in daylight hours to fly all night. The first prototype is scheduled for launch in 2006."
Where is this a quote from? The article and site show an aircraft with traditional propellers on its tail.
What ESA is claiming is new about this mission
European Space Agency? Where were they mentioned?
is that they'll be combining ion propulsion with gravity assist maneuvers
Aircraft, as a rule, do not perform gravity assist maneuvers. It's a horrible faux paus.
The parent was likely cut-n-pasted from somewhere else. Moderate appropriately.
Back for a return engagement..
Around the World in a Solar Plane
The Piccards are well known for scientific exploration and adventure. Bertrand went around the world in the a balloon. The Piccard family is known as the inventor of the modern hot air balloon. Here is info on Don Piccard, one of his relatives. The bathyscaphe used to explore deep ocean areas was developed by Auguste Piccard. I've had the pleasure of speaking with Don Piccard before. Great family all around.
In one sense they are in that hydrogen is usually seen as an energy storage mechanism rather than a source (i.e. there aren't many natural sources of pure hydrogen). However, the relevance to this article is that the hydrogen fuel cells on helios were filled with hydrogen on the ground before takeoff, not filled with hydrogen during flight (presumably from electrolyzed water vapour, the electricity being provided by the solar cells). These batteries will be charged by the solar cells during flight.
No reason why it wouldn't be manned.
They state a 60 meter wingspan. That would like be about 6 meters wide, if they keep a 10-1 ratio. The ground and sea also reflect a certain percentage of solar energy. Overall, it looks to me that the would have about 360m^2 of direct sunlight potential and about the same amount of reflected sunlight.
The solar power is about 1.3kw/m^2. That is 460KW of direct energy. If they get a 30% reflection on the underside, that is another 140KW of potential energy. About 600KW total. Figure about 15% efficiency and you get about 90KW of power. That is about 120 HP, which is the same power as the rear engine of used on Voyager on it's round the world flight. Electric engines have an advantage here in that they don't lose power with altitude, so their effective engine power at altitude would be higher than that used on Voyager.
Voyager only required two engines for take-off and to provide a secondary engine in case of problems with the first. The weight here will be constant throughout, so they will not need a second engine for take-off. (Voyager was basically a flying fuel tank on take-off and needed 300HP to take-off on it's runway. Once airborne, it only needed 110HP. Without all the fuel on board, 110HP was enough for take-off).
Also, solar panel efficiency improves with a slight reduction in temperature, so they might manage better solar efficiency.
Hmm. There is a dodge I wonder if they have considered. One of the problems with that they are doing is the weight. They have a background in ballooning. I wonder if they have considered incorporating sealed helium bladders in the wings and other areas that are not going to be occupied by people. If they can lower the effective density of the aircraft, then they will effectively lower it's weight. Not sure if it is worth the effort though. The other would be use open those sections to the air, then allow the heat from the solar panels heat the inner wings also effectively lowering the density of the aircraft, but this would not be as effective.
No reason why it wouldn't be manned.
:)
Especially given that the pictures show what look like cockpit windows
They state a 60 meter wingspan. That would like be about 6 meters wide, if they keep a 10-1 ratio. The ground and sea also reflect a certain percentage of solar energy. Overall, it looks to me that the would have about 360m^2 of direct sunlight potential and about the same amount of reflected sunlight.
There is also the fuselage and the horizontal stabaliser.
Voyager only required two engines for take-off and to provide a secondary engine in case of problems with the first. The weight here will be constant throughout, so they will not need a second engine for take-off. (Voyager was basically a flying fuel tank on take-off and needed 300HP to take-off on it's runway.
Constant weight throughout the flight means also that the trim does not need altering to compensate for burning fuel.