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Solar Plane Completes 24-Hour Flight
asukasoryu writes "An experimental solar-powered plane landed safely Thursday after completing its first 24-hour test flight, proving that the aircraft can collect enough energy from the sun during the day to stay aloft all night. The record feat completes seven years of planning and brings the Swiss-led project one step closer to its goal of circling the globe using only energy from the sun. The team will now set its sights on an Atlantic crossing, before attempting a round-the-world flight in 2013." We ran a story about the flight's departure yesterday.
I'm not sure how you would get solar to work with a jet engine unless you switched over to a ducted fan type setup. A jet engine requires combustion. You would need two completely different propulsion systems on board the aircraft...and that adds weight. With the additional weight, power needs will increase, lift generation will need to increase and your stall speed increases.
Solar wouldn't even come close to offsetting jet fuel. A commercial airliner requires HUGE amounts of energy to fly that much weight at speeds around 500mph.
It could be used to provide electrical power to an airplane but the savings would be minimal.
Another question is: if they were 100% efficient, would they offset the cost of jet fuel?
Hardly the same thing, in my opinion. We know the power densities required to move cargo and people through the air at acceptable speeds and solar just cannot realistically supply it. This thing has the wing span of a 777 and the carrying capacity of an ultralight. Even assuming that you can increase the efficiency of the solar cells by five times you're still not talking anything remotely practical for commercial use.
Don't get me wrong, it's some very impressive technology. An unmanned variant might someday even has some military and civilian uses but it's never going to replace our chemically powered, high speed transportation aircraft.
We know the power densities required to move cargo and people through the air at acceptable speeds and solar just cannot realistically supply it.
However, as supplies of really dense energy start to become lower, some folks are looking ahead at a future that may just have a different definition of what is "acceptable". There may come a day where the only place we will still see chemically powered aircraft is in a museum.
People replying to my sig annoy me. That's why I change it all the time.
Semi-related to this (the power density bit). There was a design for small arms ammunition in the '90s that used an electrical heating element. The propellant was water flashed into superheated steam. I don't know what the momentum impulse energy would be for superheated steam, but the escaping vapor would at least be supersonic, making it an interesting idea for a renewable propellant.
Just find a source for more water (clouds) than you are using and you could stay up indefinitely. Heh, an "atmospheric bussard ramjet". OK probably not.
BTW, the ammo melted and expended its aluminum heating element to get the effect. So you'd need something that heated up to those temperatures without expending itself per pulse,like a ceramic casing around a molten core. I guess.
PS a quick search revealed the inventor to be Rusi Taleyarkhan (of Bubblegate infamy). Lol
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