Solar Plane Completes 24-Hour Flight 88
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.
Re:bah (Score:2, Informative)
Re:Hybrid Planes (Score:3, Informative)
You are above the clouds so you have a steady supply of power, but I dont know anything about the amount of energy a jet plane needs.
Going off some numbers for a (relatively old and inefficient) 747, you burn through ~5gal of kerosene per mile, at 550mph. That's about 6lbs of fuel per second, or around 120MW of thermal output. Using average efficiency available for commercial solar panels, you're looking at a half square kilometer array to power a single aircraft at cruise conditions. If you were to replace the turbine powered ducted fan engines for electric powered ones, you would cut that power consumption in about half.
Re:vanes (Score:3, Informative)
im kinda suprised they didnt make the wings longer from back to front, for more solar panel area.
Larger chord length would result in lower aspect ratio, higher induced drag, and lower efficiency. They could put propellers out on the wingtip to counter induced drag...
Re:How much juice was left? (Score:3, Informative)
Check out http://www.solarimpulse.com/nightFlights/charts.php [solarimpulse.com]. Notice that it took 6.5 hours to go from 46% charge to 100%charge. By extrapolation it should take about 12 hours to get a full charge though that may not be true as the solar cell efficiency seems to decrease as the cells cool below 0 degrees. Here are a few other interesting points from the graph.
1. They need a more accurate speed and altitude sensor. There are quite a few spikes in the charts. Some of them have "disappeared". They were probably fixed in the data by averaging.
2. They started with the battery 69% charged.
3. The low point in battery level was 46%
4. It took 7.5 hours to get to full charge.
5. When air temp decreased below 0 the efficiency of the solar cells also decreased dramatically.
6. For a 2.5 hour period when the engine power was at 4% with 0% solar charging the battery charge did not decrease; strange.
7. When the battery was used, it drained at about 10% per hour.
8. The airspeed was about 23kmph most of the time. That is probably the minimum sink speed for the aircraft.