how to build a solar plane

[pockarn]

hello everyone. as for my school project, my teacher gave me an individual project to actually build a plane and use solar energy for power it up. I've none experience of doing an airplane but after doing some research, i'm planning to build a sailplane then attached the solar on its wing. but have anyone know where to get the plan for any sailplane with a wingspan less than 3m. and where to get the solar, how to install it, the requirement and everything i need to know. thanks

[Aten W Arthog]

You must be rich!

To get a solar plane to fly at all "well", requires high efficiency thin-film cells that can be curved to fit the airfoil. Depending on if you have any kind of battery between the cells and the motor, you are looking at a significant number of cells to get enough juice out for directly driving the motor. Fewer cells reduce weight, but require super efficiency, we're talking satellite grade cells there, very expensive. Cheaper cells will require more of them in total. Now with more solar cells you have more weight, so your wing loading goes up and your flying speed has to be higher, or you make the wings longer, to get a better glide and lower wing loading, if you can get to around 12 oz/ square inch or less you have good chances of extending flight by thermalling. Everything in solar aircraft design is a delicate balance.

What many developers do is build an electric glider that counts on thermalling for most of the flight, putting no load on the motor and re-charging cells in flight. What they are doing is reading the rules like a lawyer and looking for loopholes. For example, if I read your exact words in your post like a lawyer (or someone looking for a loophole), I'd notice it didn't specify the plane needed to have solar cells *on it*. Nor did it even specify it had to be *electric*. It just said "use solar energy for powering it up".

What does that have to do with anything?

Well, going strictly by the rules and the loopholes, and that sentence, you could build a standard electric RC plane of most any type, and just use a ground-based solar panel to charge the plane's regular battery. Leaving the heavy cells behind on the ground! technically, that's within the rules implied by the sentence!

Since the rules didn't specify electric only, you could also go another way, and use solar heat from a concentrating lens and/or mirror to heat up a steam engine or even just a hot water-powered rocket. You wouldn't get a LONG flight, but you'd be within the letter of the rules.

If you wanted to get REALLY pedantic about this, technically, a standard sailplane is already 'solar-powered', in the sense that the thermals and slope winds it uses to gain altitude are generated by solar heating of the earth's surface.

This is why in engineering competitions, great care is taken to specify ALL the possible rules and situations. If they didn't apply such care, someone would usually find a loophole to "cheat". (Cheat is a too-strong word here for what in this case is really "applied creativity")

You could also do something like make a helium blimp and hang a solar cell, motor, and prop from it, with a very low-geared motor, and have a solar-powered free flight. Use a hand-held spotlight aimed at the cell to power it in an indoor area.

The rules are everything. They define the problem and limit the solutions.

[fhhuber506771]

Or... you can just use solar power to charge batteries on the ground, then fly leaving the heavy solar panels on the ground.

The thin film panels needed to directly power the plane would be more expensive than using a solar panel to charge some batteries.

As for the aircraft design... you could pick just about any kit you want that meets the limitations of the rules...

[Rufcut]

I found a web site that might interest you.http://www.powerfilmsolar.com/

[fhhuber506771]

I found a web site that might interest you.
http://www.powerfilmsolar.com/

^^^^^^

Appx 9 watts per lb...

Not what I would call a good power:weight for flight.