Science and Exploration

[Corkey]

I'm thinking of the return energy from the props, put a generator on the spin and add it back to the batteries...yes? Solar and kinetic. Where's AJ when I need her?

[dreadgeek]

Originally Posted by Corkey

I'm thinking of the return energy from the props, put a generator on the spin and add it back to the batteries...yes? Solar and kinetic. Where's AJ when I need her?

The idea of a solar airplane is really beautiful! I'll have to watch the show. As far as your idea, unfortunately, it's a perpetual motion machine. Because there's friction, you will *always* lose some amount of energy whenever you do work--as it is defined in physics. For our purposes here, work means "keeping an airplane flying". No matter how efficient we make the propellers or how efficient we make the solar panels, the First and Second Laws of Thermodynamics absolutely prevent the kind of thing you're describing.

I had to think about it for a while and toss the idea around with my wife but here's why it won't work.

Let's say it takes 50 units of energy to move a plane with enough forward motion to stay flying and the solar panels generate 100 units of energy. The excess can go into the batteries. If I understand what you're describing, all 100 units from the solar panels go to the propellers but the motion of the propellers generates energy. That would mean that you would get more energy out of a system than you put in. The problem is friction.

Even if we had *perfect* solar cells that got 100% efficiency out of solar capture and could build the propeller mechanism in such a manner that it was and efficient as is possible, there would still be friction of the propellers hitting the air. That means that it takes a small bit of energy to overcome that friction. That energy is lost.

Your idea is beautiful and elegant but the universe simply doesn't allow it.

Cheers
Aj

[Corkey]

Originally Posted by dreadgeek

The idea of a solar airplane is really beautiful! I'll have to watch the show. As far as your idea, unfortunately, it's a perpetual motion machine. Because there's friction, you will *always* lose some amount of energy whenever you do work--as it is defined in physics. For our purposes here, work means "keeping an airplane flying". No matter how efficient we make the propellers or how efficient we make the solar panels, the First and Second Laws of Thermodynamics absolutely prevent the kind of thing you're describing.

I had to think about it for a while and toss the idea around with my wife but here's why it won't work.

Let's say it takes 50 units of energy to move a plane with enough forward motion to stay flying and the solar panels generate 100 units of energy. The excess can go into the batteries. If I understand what you're describing, all 100 units from the solar panels go to the propellers but the motion of the propellers generates energy. That would mean that you would get more energy out of a system than you put in. The problem is friction.

Even if we had *perfect* solar cells that got 100% efficiency out of solar capture and could build the propeller mechanism in such a manner that it was and efficient as is possible, there would still be friction of the propellers hitting the air. That means that it takes a small bit of energy to overcome that friction. That energy is lost.

Your idea is beautiful and elegant but the universe simply doesn't allow it.

Cheers
Aj

Thanks AJ, I was also thinking that the kinetic energy only had to last until the solar cells could re power the batteries, so even if say 5% kinetic energy were lost to friction, 95% of the energy would still remain to energize the batteries/hour of darkness. Now I'm not math minded, but it seems that 5% x 9 or 10/hours of darkness would still mean that there would be at least enough left to power the batteries, and then if solar and kinetic were used in unison, would not the loss of friction be less and therefore power more of the batteries than solar alone? Sorry to be a pest but I'm so removed from physics by age it's a bit daunting.

[dreadgeek]

Originally Posted by Corkey

Thanks AJ, I was also thinking that the kinetic energy only had to last until the solar cells could re power the batteries, so even if say 5% kinetic energy were lost to friction, 95% of the energy would still remain to energize the batteries/hour of darkness. Now I'm not math minded, but it seems that 5% x 9 or 10/hours of darkness would still mean that there would be at least enough left to power the batteries, and then if solar and kinetic were used in unison, would not the loss of friction be less and therefore power more of the batteries than solar alone? Sorry to be a pest but I'm so removed from physics by age it's a bit daunting.

You're not being a pest at all, brother. Here's the thing (I'm going to try to spare you as much math as I can here) if the solar cells are used to power the propellers and then anything *not* used for that purpose is stored in the batteries that's perfectly legal according to the laws of thermodynamics. If, on the other hand, all of the energy from the solar cells goes to the props and then the turning of the propeller generates its own energy, you're actually getting more energy in. Remember that thrust is work and in *any* system, no matter how efficient you can imagine it being, where work is done some energy is lost.

However, your idea gave me a brainstorm. Imagine a zeppelin where the upper two-thirds was covered in solar panels. Since a lighter than air gas would provide lift, the electric engines would only be needed to provide thrust and internal power. You *still* couldn't get more energy out than you put in, but you would have a relatively cheap means of air travel. It would be slower than jets but I kind of like that idea, actually.

Cheers
Aj

[Corkey]

Originally Posted by dreadgeek

You're not being a pest at all, brother. Here's the thing (I'm going to try to spare you as much math as I can here) if the solar cells are used to power the propellers and then anything *not* used for that purpose is stored in the batteries that's perfectly legal according to the laws of thermodynamics. If, on the other hand, all of the energy from the solar cells goes to the props and then the turning of the propeller generates its own energy, you're actually getting more energy in. Remember that thrust is work and in *any* system, no matter how efficient you can imagine it being, where work is done some energy is lost.

However, your idea gave me a brainstorm. Imagine a zeppelin where the upper two-thirds was covered in solar panels. Since a lighter than air gas would provide lift, the electric engines would only be needed to provide thrust and internal power. You *still* couldn't get more energy out than you put in, but you would have a relatively cheap means of air travel. It would be slower than jets but I kind of like that idea, actually.

Cheers
Aj

My brain was on overdrive last night thinking about this. If kinetic energy was used to power all of the in flight systems and a small heating system, then it may solve some of the problems. The pilot had to endure night temps of 14*F, what if some of the kinetic energy were to power a small fan heating system? The vents could be open spaces in the wings that permit a flow of air to the pilot, warmed by the power of the spin of the props. It could work to cool the pilot as well by using the ambient air outside as well. And since high altitudes are relatively easier to fly through it wouldn't put too much of a strain on the flight systems, ???

[dark_crystal]

ooooh i been wantin to talk to some geeks about this:

The Coming Technological Singularity: How to Survive in the Post-Human Era

(guy spoke at ALA Midwinter so he's on the librarian hive-mind right now)

I argue in this paper that we are on the edge
of change comparable to the rise of human life on Earth. The precise
cause of this change is the imminent creation by technology of
entities with greater than human intelligence. There are several means
by which science may achieve this breakthrough (and this is another
reason for having confidence that the event will occur):

• The development of computers that are "awake" and superhumanly intelligent. (To date, most controversy in thearea of AI relates to whether we can create human equivalence in a machine. But if the answer is "yes, we can", then there is little doubt that beings more intelligent can be constructed thereafter.
• Large computer networks (and their associated users) may "wake up" as a superhumanly intelligent entity.
• Computer/human interfaces may become so intimate that users may reasonably be considered superhumanly intelligent.
• Biological science may find ways to improve upon the naturalhuman intellect.

if it's "Computer/human interfaces become so intimate that users may reasonably be considered superhumanly intelligent" then i am SO DOWN WITH POST-HUMANISM

i have wanted to become a cyborg for years

[Corkey]

I'm not sure I'd want to survive in a post-human world, and technically isn't that an oxymoron?

I think computers will eventually replace the labor industry and then humans will have to find something other than war to occupy themselves. While it may be helpful to have a smart house for example, I like doing certain chores myself, not all 'cause I'm differently abled, but having a computer do most of the things I enjoy takes the fun outta life. But hey I won't make it 30 more years, and I'm fine with that.

[dreadgeek]

Originally Posted by Corkey

I'm thinking of the return energy from the props, put a generator on the spin and add it back to the batteries...yes? Solar and kinetic. Where's AJ when I need her?

By the way thank you for asking me to come to this thread.

Cheers
Aj