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Solar motorized paraglider

solar panels sewn onto parasail, run motor directly or via capacitors
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Solar panels, will be sewn or pasted onto the para-sail.

There will be a need for a Solaredge type device that allows for maximizing output although non equal sunlight on all cells.

If ultracapacitors work as said, and are lightweight enough, use them for intermediate storage so we get a constant current to the motor, or use a small battery if necessary.

See video of solar powered glider, by my friend the late Hanan Einav-Levi, who passed away at young age this year.

pashute, Jun 21 2013

solar powered glider http://www.youtube....watch?v=sXC5tBVC0wE
[pashute, Jun 21 2013]

Solar powered plane http://www.youtube....watch?v=H6chzgkA3xM
[pashute, Jun 21 2013]

Current situation http://www.mothswor...wered-paramotor.asp
[pashute, Jun 21 2013]

[link]






       The beauty of the paraglider is that the inflatable wing is lightweight, robust and can be packed into a rig. These advantages offset the fairly draggy nature of a flexible ram-air canopy.   

       If you start attaching solar panels, you will surely lose many of those advantages, no?
MaxwellBuchanan, Jun 21 2013
  

       Are these things flown at night or in cloudy weather? Solar will be weak or none at those times.
popbottle, Jun 22 2013
  

       No. Each solar cell attached in a way that keeps the wing quite flexible. Were talking about a motorized paraglider.   

       And of course this is good for nice weather and daytime only. I wasn't aware of people flying paragliders of any kind at night or in fogs. I don't think its much fun.
pashute, Jun 24 2013
  

       A typical paraglider engine is 20-30HP, which is 15- 20kW. Given an insolation of 1kW/m^2, and an efficiency of 15%, you're going to need something like 100 square metres of solar cell, whereas a typical paraglider has a wing area of about 30 square metres.   

       It's a nice idea (and people have, as you know, made solar-assisted sailplanes), but solar cells would have to have a much higher efficiency than they currently have.
MaxwellBuchanan, Jun 24 2013
  

       Drat. I didn't check that.
pashute, Jun 26 2013
  

       Based on the third link, it looks like this isn't your idea. It's just the dream of the person who wrote that web page. (or is that you?) But yeah, I'd like to see this become a reality as well.   

       I'll trust [Max]'s calculations to the first order, though he didn't include the affect of the weight of the solar panels, but besides making solar cells more efficient, the other possiblities are making the paraglider more efficient and/or larger to have more surface area for solar cells. How much will the weight of the solar cells affect the power requirments?   

       Increasing solar cell efficieny to be above 45% is not something I expect to happen. I'm not saying there can't be a major breakthrough but my money is on incremental improvments that won't get to that level in my lifetime.
scad mientist, Jun 28 2013
  

       //I'll trust [Max]'s calculations to the first order//   

       MaxCo. cannot be held responsible for any damages, loss or injury however amusing resulting from decisions, actions or pharmaceuticals taken on the basis of its calculations. All numbers are for illustrative purposes only; actual digits may vary. Orders of magnitude are shown larger than actual size.
MaxwellBuchanan, Jun 28 2013
  

       Actually, I have a not unrelated question for anyone who knows aerodynamics. What is the minimum thrust-to-weight ratio necessary for level flight in still air? Is this ratio the same as the lift-to-drag ratio?
MaxwellBuchanan, Jun 28 2013
  

       //Is this ratio the same as the lift-to-drag ratio?// Yes, because, by definition, for steady level flight lift = weight, and thrust = drag (ignoring the signs).   

       [edit] That's non necessarily all that useful, though, because powering an aircraft is likely to alter its lift and drag. So the best achievable power to weight ratio may be (slightly) different from the best achievable lift to drag ratio (the glide ratio) of an un-powered glider.
spidermother, Jun 30 2013
  

       That makes sense. And for an unpowered glider, lift- to-drag is the same as the glide slope?   

       In which case, if an aircraft has a glide slope of 1 in 30, then a thrust equal to 1/30th of its weight should (ideally) be sufficient to maintain level flight?
MaxwellBuchanan, Jun 30 2013
  

       To a close approximation, yes (^^ see edit).
spidermother, Jun 30 2013
  

       Thanks. Yes, point taken about the effect of thrust on velocity and hence drag.   

       I was trying to work out if "lifter" technology (basically in-air ion thrusters, which entrain air in a stream of ions between two fixed electrodes) could feasibly power an untethered aircraft.   

       Thrusts (measured as ability to lift dead weight, including itself) of 100 grams have been generated in air from 17W of power, and with a relatively non-draggy electrode array. So I'm guessing that a glider-style model with a decent (15:1) glide ratio ought be able to have about 1.5kg of total mass. The question then is whether sufficient solar cellage (or battery) to furnish 17W, plus the necessary hardware to step the voltage up to several kV, can be built within that weight.
MaxwellBuchanan, Jun 30 2013
  

       How do spiders lift themselves to the stratosphere? or is that an urban legend?   

       This weekend the Motzash newspaper dealt with four urban legends by Israeli youth, and found THREE of FOUR to be surprisingly true and even the fourth has a lot to it! a. Girl had skirt ripped off by car door when getting out of ride she decided not to take. b. Girl brought to summer camp by rich parents with helicopter. c. Kids ritually married as joke with a pretzel as ring, received formal status of divorcees. d. Some real weird names were actually given to kids by their parents, but "Disappointment" and "Held an Almond Tree Branch" never existed. "Like" in fact does.
pashute, Jun 30 2013
  

       They spin fine threads which have sufficient drag to be carried by air currents.
MaxwellBuchanan, Jun 30 2013
  

       [max] Actually I was just thinking that if you are right, it should be a phenomenon found in nature. When observing the clouds it seems that air currents from earth do not rise to such heights.   

       [scad] no, its mot ne. But my idea was to use the current PV cells, rather than pasting them on rigid panels, pasting them on the wings, which would leave them flexible (to a point).   

       But it seems the amount of current produced is powerfully the factoring limit.
pashute, Jun 30 2013
  

       // When observing the clouds it seems that air currents from earth do not rise to such heights.//   

       Cumulonimbus (storm) clouds reach up into the lower part of the stratosphere; and of course air currents need not be associated with visible clouds. There are also all kinds of things like mountain waves (ie, air rising up to pass over mountains).   

       Quick Google says that the world altitude record for a glider is about 59,000ft, reached using the lee waves off a mountain.
MaxwellBuchanan, Jul 01 2013
  
      
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