Solar powered plane



Solar Impulse is not comparable to planes like Lindbergh's Spirit of St Louis because Solar Impulse is using very sharply limited source of power. Not energy, but power. You can't make practical solar plane no matter how much solar panels improve because solar power is limited and you can't go over 100% efficiency in converting that to mechanic energy.

Maybe you could do a practical blimp that uses solar powering the motors instead. I for one would not care if the trip takes a bit longer if it would resemble more a luxury cruiser than cramped airplane.

Make sure to never book a red eye flight.

@Timo, who knows? Maybe somebody will come up with a technology that is capable of accumulating sun power like a magnifying glass focues light...

(Sorry, not very good at technical jargon)


(and not very good at spell checking)

We know that max power from the Sun radiation at ground level is about one kilowatt per square meter in near optimal conditions. That's just physical fact.

Efficiency of the Solar Impulse solar panels is a bit over 22% so you can only get about four times better than it even with imaginary near-perfect cells. That's the limit. You can't go over that no matter what.

With that little power available you cannot make practical plane other than some sort of power-assisted glider, like what that Solar Impulse practically is.

But if you fly overhead with a magnifying giant diffraction grating you get more power!


Merely bank them towards the sun to maximize the collection.

Keep them below supersonic to save on power.

Link dozens of these aircraft together with cables to multiply the collector area and the number of motors.

Use tanker re-chargers that would lower a cable instead of a refueling boom.

A mounted windmill would generate power (I know that was already discussed for cars here).

Tether the planes to the ground and use winches to pull them around, sort of like an aerial Hyperloop.

Go to high altitudes, then dive straight down so that the propellers spin up the motors and regenerate the batteries. If you pull up in time, you could travel forever.

A magnet in the nose would attract it north or south, thus helping on half the flight at least.

Sails would catch the jet streams, and they are evidently quite fast.

Or simply don't fight it, just drift and accept that you will land where you land, go with the flow, have an adventure wherever (possibly ruling out maybe N.Korea, etc).


I wonder when first serious comment for that comes for battery-powered airplanes....

Actually, we already have solar powered planes.

They're called gliders.

There must be a way to attract a large amount of sun energy into a small place while the plane is flying. We just don't know how yet.

"Everything that can be Invented has been Invented"

Charles H. Duell, Commissioner of US patent office in 1899.

Sure there is, just put a huge mirror in the orbit. Not very practical though, people below would be rather annoyed.

You can't increase area without increasing area. Neither you can do anything to Sun itself. Impossible is impossible, accept it and move along.

There is one practical way though: batteries (and other energy storage systems). Use Solar to charge those while plane is at the ground. Some less practical systems would be lasers or similar shooting at the plane when it is flying, but couple of hundred kW laser pointed at you wouldn't be very...comfortable.

Sun as a power source is weak.

I am a layperson, but I know that they found a way to increase the surface of the antennae, and they even squeezed it into a much smaller place at the same time....

Who says they can't do the same with sun rays?

They can. You use lenses, or as Timo already pointed out, mirrors.
Not at all practical.

The problem is that there is only so much solar energy per square foot and even if a solar panel was a magnifying glass that would create a hot spot of concentrated energy, there would be no more energy available in that hot spot than what hit the panel in the first place.

Energy cannot be multiplied.

Physics-wise, it takes a certain amount of energy to move and accelerate masses and there is only so much solar energy available per square foot and you can't get around that.

However, technology promises to improve on collecting what is there, how it is stored, how it is transmitted and the motors and other devices that use energy. Along with conserving it of course.

In time you won't even care about magnifying solar energy because it will not matter.

I understand that solar energy is constant, but if we could figure out a way to store it very fast, it would replenish as fast as we can store it. Just because we have stored it, it won't stop coming. It comes as fast as it is being stored.

Not sure if this makes sense, and not sure if this is right, just throwing it for consideration.

Another thing is that we can't possibly know everything how sun rays work. It is possible that they are not quite straight, we could discover a way to bend them (without mirrors) and if we find a way to do that to a great extent, we could gather 1000x the energy we can at present.

Again, just playing with ideas.

Another way would be to intercept them by using some other rays, diagonally, or at a certain degree, that might (just might) break them (change frequency, whatever) make them much stronger.....

The imaginable possibilities are endless. All we have to admit is that we can't possibly know everything.

You're just storing as much as you can of what you get. Same-old same-old.

Any interceptor/magnifier casts a shadow.

OK, how about combining it with something else?

The human or animal body is basically a hydraulic system powered by (very little) electricity.

A bird can fly regardless of its size, as long as it has the right proportions and aerodynamics. Basically, if a bird the size of an airplane existed, it could fly, right? Not too fast, but some birds reach a speed of 60mph.

If we could make a plane based on relatively little electricity, combined with hydraulics with the right shape, it could fly on electricity alone.... And would not use too much of it.

I know this sounds crazy, but everything we have invented so far, has being used by nature, much more efficiently than any of our inventions. If we look at what nature is capable of doing, we can do things we would never have imagined.

Sure it could be done. Look up Gossamer Albatross.
Human powered flight. If you make the wing area large enough with light enough materials and thin-film photovoltaics, you could have solar powered flight. But, how slowly do you want to fly?


False. Birds have maximum weight limit where it becomes impossible for them to sustain powered flight. Muscles have limits. All largest flying animals have been basically gliders. (Largest is quite large though: Quetzalcoatlus. Google it).

Maybe "electric assisted flying bicycle" could be made though. Human propelled aircraft is a lot smaller than Solar Impulse.

All of this is of course besides the point. You can make "solar powered aircraft" just use batteries, and store that solar to them at the ground. Don't put those solar panels at the plane itself.

Some have analysed those flyers and conclude the atmosphere was thicker when they flew. Makes takeoffs and feeding/hunting maneuvers possible, which are very difficult or even improbable in the current atmosphere. (Pressure helps with oxygen transport, too.)

I think gravity was less, thus allowing for everything to be huge. If we cloned a dinosaur he wouldn't live long, crushed my modern gravity. It also explains why I can no longer dunk a basketball. Gravity has gotten a lot stronger lately.

I looked at the article and imained I was the pilot. I would request that the battery be charged before I took off. the battery would then be capable of poweing the plane for 16 of the 24 hour flight. I would call this a solar assisted battery powered plane

Thanks Timo. There goes my theory. *kidding*.

As I said I am into sci-fi. Not the kind with wormholes, but I am interested in what the future will look like.

I have googled Quetzalcoatlus. Actually, nobody saw them flying, gliding or even walking. We are just theorizing about what animals might have done millions of years ago. I am much more practical than that. I do have my own theory on dinosaurs, but that would be much more outlandish and I am not into shocking people :)

What I was trying to say was that the body shows that it is possible to do a lot with very little electricity, so the possibility is there to build something that needs less electricity than the sun rays can generate.

I am afraid we won't be that advanced in my lifetime. Not even in ten lifetimes. But it is interesting to see that everything we have discovered so far, has already existed in nature. Just a food for thought.

My point was that there is no such thing as impossible as we have by far not have exhausted all the possibilities.

Oh, and one more thing. According to scientists, the bumble bee should not be able to fly. LOL. So, we really-really don't know everything.

That last point is old urban legend. Bumblebees cause strong updraft above it by pressing wings together and then flapping them down causing a low pressure area.

Sun is lost cause, but there are a lot of things that can happen which are close enough that we can see them in our lifetime. And if immortality gets invented a lot more (not a joke, if scientist advance stem cell research good enough and cybernetic implants develop as fast as they do now there is not really any limit how long you can live just few decades from now)

Quetzalcoatlus flew. Why else if would had those wings? Saying that it needed thicker atmosphere is claiming that modern gliders can't fly. While it was large it was also very slender reptile, only about 200kg at max, probably less.

(BTW, Quetzalcoatlus was not dinosaur, birds OTOH are dinosaurs)

Wait for room temperature superconductors, practical fusion, industry-scale graphene production and you will see things that are beyond anything we have now.

@Brian, are you serious what that link? That's a joke at best. I hope that was meant to be a joke.

"Quetzalcoatlus flew. Why else if would had those wings?"

For the same reason why ostriches have theirs?

As far as these ancient creatures are concerned, all we know is that we have found some huge bones we had no explanation for, tried to imagine what the animals might have look like, made up stories about how they might have lived and gave them names.

This is what happened. Every story on what they did and why and when they lived and why they got extinct is guessing. Educated guessing, but guessing. We can't use these guesses as facts in arguments.

By your argument if you find human skeleton it is guesswork what the human looks like. Bones tell a lot. Not all but a lot nevertheless.

Wikipedia had one reference link hat you might find interesting:

Wings of planes and birds etc. are (necessarily) optimized for air density. Pteranodons etc. fall on the curve at the 3+ bar point.

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