Re: Battery of the Future?

James Beck wrote:
In article <2264c3lkppe08lve5674rplvlst7g9a9ri@xxxxxxx>, rhaddad@xxxxxxxxxxxxxxx says...
On Tue, 14 Aug 2007 11:11:48 -0400, I said, "Pick a card, any card"
and James Beck <jim@xxxxxxxxxxxxxxxxxxxxxxx> instead replied:

In article <ftl1c3tiol815ndn5kbn6utohv21ce0d4g@xxxxxxx>, rhaddad@xxxxxxxxxxxxxxx says...
It's incredible sometimes to see what today's young people are
capable of doing.

Imagine a self charging solar battery that is also the covering of
your plane. Shouldn't be long now.

http://www.breitbart.com/article.php?id=D8R0CGT00&show_article=1

Even if you get get 100% efficiency (and you can't) the MAXIMUM power you can get from 1 square meter of sunlight is ~100 watts. That's a lot of covering to get that kind of power. Take into account real world efficiencies and so on and you are looking at a pretty crappy power system for a sport RC plane, even if just to charge a flight pack. The real grand idea is to cover as many surfaces as possible with this stuff and add all of that power together to make a dent in the amount of fossil/imported energy we use. Flexible, cuttable, now make it efficient and cheap to manufacture..........
You didn't miss the word 'future' in my subject line?
I understood that you meant future.
I was just throwing in a little reality check on just how much power you can expect to get period.
You aren't going to harvest more power than the sun is providing. When you take the total area of the earth it is an ENORMOUS amount of energy, but the amount that actually falls on the covering of a plane is quite modest and most hobbists are not going to go out for some super light weight exotic plane just to say it is solor powered.
You're correct on all points. However, the technology is very young.
Remember when the only storage for electricity was a Leyden jar?
Before our time, certainly, but look at the leaps in battery
technology over the past 100 years. Just the past 10 years of
advances have been phenomenal.

You are still bound by physics.
Average solar power is ~146 watts/square meter.
Peak solar power is `600 watts/square meter.
That's the best you can do unless you turn up the sun ;)

Well you could have a 747 equipped with mirrors flying above it to deflect extra sunlight on it.

I reckon that with a perfectly efficient power train, you can *just* stay aloft at 3W/lb. Realistically you need about 12W/lb to do it with normal props/motors etc.

At 150W/sq meter, you can just about crawl a 10lb model off the ground with a square meter of wing.

The wing loading would be ~14 oz per sq foot. So its not totally pie in the sky. You could probably get the weight well below 10lb on a square meter of wing too. If you could get cheap >30% efficient lightweight photocells its probably a goer.

Not a hugely interesting model to fly..wouldn't knife edge a damn :-) but it would probably fly..




Jim
.

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