Solar Glider Goal

Design and build a glider/airplane that can remain aloft for days at a time using a solar powered electric engine.

Solar Glider Requirements

• Carrying capacity: Minimum: 1 person. Maximum: 2 people plus cargo
• Enough comfort for long duration flights
• Very good glide characteristics
• Electric engine capable of extending flight times and prefereably taking off
• Lightweight solar panels on (or integral with) the upper surface of the wings and possibly fuselage
• As much electricity storage as weight will allow

I've heard of a 'glider' that has a small engine. The blades retract into a cowl when not in use. I can't remember if the engine was powerful enough for takeoff, or was just used to extend flight times. I need to find references for it. That would be the Stemme S10.

Another motor-glider is the KK36 Diamon Katana Extremee (see http://philip.greenspun.com/flying/soaring), however it doesn't seem to have anywhere near the gliding characteristics of the Stemme S10.

More motor gliders. The Apis/Bee, for example, has a glide ratio of 39. Or the Taurus (which now comes in an electric version!) with a max glide ratio of 41. They both have fully retractable engines. Thanks to B.J. for the pointer to these.

Here are some weight values that might be useful:

• From Deep Space 1: 45 watts of power for each kilogram of the [solar] array's weight
• Electric Fuel's Unmanned Aerial Vehicles (UAV) batteries: 400 Wh/kg.
• Best lithium batteries: 150-200 Wh/kg (from an eWorld story)
• Micro batteries: "will be roughly 360 kiloamperes per cubic meter"
• From: monkeytroop'motor-glider'. The Grob 103A has a glide ratio of up to 37-1 and minimum sink rate of less than 150 feet per minute. If towed to an altitude of 5,000 feet above the ground, even in still air it could stay up for half an hour and travel 30 miles.
• The Europa Motor Glider has a glide ration of 27:1 at 50 knots (with feathering propeller)
• The Stemme S-10VT motorglider developed Rainer Stemme seems like the best motor-glider I've read about, so far.
• 'But right now, "there's no solar-powered plane out there that can store enough energy to get it through the night," said John Del Frate, a NASA solar aircraft project manager.' From NY Times article.
• Looks like Bertrand Piccard may try it, see here and here.
• A battery powered airplane.

Comments are welcome.