Unlimited Power?

[Spacetraindriver]

I was just wondering... What if someone were to take a solar panel, hook it up to a light, then aim that light at the solar panel? Would that work? IDK. 

[Gaarst]

No, for a bunch of thermodynamic reasons.

Basically, unless every single photon is absorbed and converted with electric power with absolutely no loss, this won't work, and even then you won't produce any "free" energy. And that is impossible.

[cubinator]

Some of the energy is lost to heat instead of being converted to electricity. You can't get rid of this amount, but you can make it smaller, raising efficiency.

[NSEP]

Its a simple but ridicilous thought, everyone could have thought of it, but geuss what, it is not a real thing because it does not work.

[Slam_Jones]

From what I've read, one would be very hard-pressed to even achieve a 50% efficiency with solar panels.  So even in the best of cases with current tech, half of the energy is lost constantly.

As stated by Gaarst, even if you achieved 100% efficiency, you would never gain additional energy... you would just be constantly recycling the energy you put in.  And 100% efficiency, as far as I've read, is impossible with our current tech at least.

I think I tried to come up with a similar idea many years ago.  And then I tried to come up with a perpetual motion machine using magnets... and learned about thermodynamics and magnetism, and realized all I did was make a very inefficient electric generator.   :\

Edited February 4, 2017 by Slam_Jones

[StrandedonEarth]

Or, you could wire a generator to an electric motor, and drive the generator with said motor. That was my brilliant idea when I was ten...

Unfortunately for both of our ideas, there's this thing called "The Law of Conservation of Energy" which says that energy cannot be created or destroyed, only converted from one form to another. Of course, there are usually losses associated with that conversion, unless you're converting to heat, which is where losses generally ultimately end up. E=mc² allows energy to be converted to and from mass, but a tiny amount of mass contains a stupendous amount of energy, which is what makes nuclear power and bombs so powerful.

In other words, you cannot get out more energy than you put in. Losses due to friction and/or electrical resistance mean such attempts at perpetual motion will slow and eventually stop, warming up in the process.

Edited February 5, 2017 by StrandedonEarth

[StupidAndy]

its kind of like powering a wind turbine with house fans, it wont give you as much electricity

[Dman979]

Of course there is a relevant XKCD for this.

 

[kerbiloid]

8 hours ago, Spacetraindriver said:

What if someone were to take a solar panel, hook it up to a light, then aim that light at the solar panel? Would that work?

Of course, it works. Just don't hide it from sun.

[WinkAllKerb'']

5 minutes ago, Dman979 said:

Of course there is a relevant XKCD for this.

 

^^ kinda for sure ^^

[kerbiloid]

2 hours ago, StupidAndy said:

ts kind of like powering a wind turbine with house fans, it wont give you as much electricity

This also works, just the fans would be neighbour's.

P.S.
Btw, a brain candy: a sail-propelled zeppelin, would it fly?

Edited February 5, 2017 by kerbiloid

[StupidAndy]

50 minutes ago, kerbiloid said:

This also works, just the fans would be neighbour's.

Somewhere there's a Simpsons for this...

[Camacha]

This is very much like the traditional hooking up of an electric motor to a dynamo. It will slow down slower than usual, but it will slow down nonetheless. If you could have ideal parts, you might stand a chance. Unfortunately, pesky real world condition ruin everything.

[p1t1o]

On 2/5/2017 at 5:41 AM, kerbiloid said:

Btw, a brain candy: a sail-propelled zeppelin, would it fly?

Being lighter-than-air, they're never technically "flying"

                       - Capt. Pedantic

[kerbiloid]

11 minutes ago, p1t1o said:

Being lighter-than-air, they're never technically "flying"

Ok, can a blimp be propelled by sails rather than engine?

(For non-magic fantasy with no appropriate engines for this.)

Edited February 6, 2017 by kerbiloid

[p1t1o]

17 minutes ago, kerbiloid said:

Ok, can a blimp be propelled by sails rather than engine?

(For non-magic fantasy with no appropriate engines for this.)

Don't see why not, though you'd have less control than with a ship, because they lack a keel (and a medium to stick it in).

In a ship: wind pushes sail which pushes ship, which pushes against the keel which pushes against the water, which is how a ship can travel in a direction different to that in which the wind is blowing.

[kerbiloid]

5 minutes ago, p1t1o said:

wind pushes sail which pushes ship, which

moves slower than the wind.

So, wind is always faster than a sail-propelled ship due to the water drag.

A blimp floats inside the wind. Once its velocity is near the wind speed, its sails would only tremble due to turbulences.
So, sails can be used only as launch boosters for initial acceleration.
(Then you can decouple them if you want a multistage blimp).

Edited February 6, 2017 by kerbiloid

[p1t1o]

4 minutes ago, kerbiloid said:

moves slower than the wind.

So, wind is always faster than a sail-propelled ship due to the water drag.

A blimp floats inside the wind. Once its velocity is near the wind speed, its sails would only tremble due to turbulences.
So, sails can be used only as launch boosters for initial acceleration.
(Then you can decouple them if you want a multistage blimp).

Yes, a degree of "sailsmanship" would be required, once you are in equilibrium with the wind, you would lose all control.

I'd imagine that, just like on a real sailing ship, it would take continuous adjustment of the rigging to make the wind work for you. You would have to avoid ending up in a situation where you were just floating along on the wind (unless that happened to be the direction you wanted to go in), but by putting out and taking in sail at opportune times, and use of control surfaces, and the body-drag of your craft, one might be able to build up a technique of "sailing" a dirigible in some manner.

When the wind is blowing in a certain direction, there are only certain ways in which a sailing ship can travel, I imagine there would be a similar-but-different set of conditions for sailing a dirigible.

Perhaps, if you are looking for ideas, advantage could be taken of different air currents at different altitudes, by either handing some rope-borne rigging downwards or by floating an auxilliary, sail-carrying ballooon upwards. If you are high enough, maybe even simply hanging a long cable downwards might provide enough effect to be useful as a makeshift "keel".

 

[kerbiloid]

Just remembered Poul Anderson's "The Sky People".
Have read it long ago and then had been thinking aboit its sail blimps possibility.

[TopHeavy11]

Now that's just Troll Science right there.

[kerbiloid]

27 minutes ago, TopHeavy11 said:

Now that's just Troll Science right there.

This is Incredible Machine game series too. At its later descendants.

[Randox]

On 04/02/2017 at 9:20 PM, StrandedonEarth said:

... Of course, there are usually losses associated with that conversion, unless you're converting to heat, which is where losses generally ultimately end up. E=mc² allows energy to be converted to and from mass, but a tiny amount of mass contains a stupendous amount of energy, which is what makes nuclear power and bombs so powerful...

E=mc² is indeed powerful. Since I find it interesting, I will point out for anyone who doesn't know that the mass being converted is merely that of the potential chemical energy stored in an atomic nucleus, which forms the mass defect (an atomic nuclear has more mass than the constituent protons and neutrons, since the potential energy stored in that system itself has mass, as all energy does).

[Gargamel]

On 2/6/2017 at 6:20 AM, kerbiloid said:

moves slower than the wind.

So, wind is always faster than a sail-propelled ship due to the water drag.

A blimp floats inside the wind. Once its velocity is near the wind speed, its sails would only tremble due to turbulences.
So, sails can be used only as launch boosters for initial acceleration.
(Then you can decouple them if you want a multistage blimp).

There is a land yacht, or sail car, that has achieved faster than wind speeds using only a wing sail.  The same is possible with sail boats, using the latest advances in foil and wing sail tech.  Doable?  maybe, it'll take some pretty perfect conditions for it to work.   EDIT:  I'm correcting my self here, they already do this.  The latest America's Cup racers were doing 30-45 knots in 20-25 knot winds.  That's 45 knots, on a 72 foot long catamaran, with a wingsail the size of a 737 wing, supported only by a hydrofoil the size of surfboard.   Check out the youtube's, they are amazing. 

But what land yachts and sailboats have that a blimp doesn't, is a medium to translate lateral force to forward momentum.  As mentioned, on a boat, there is the keel, on a sail car, there are wheels.  These take the sideways heeling motion of the sails and convert it into forward motion. 

Sails, and wing sails, aren't always "pushed" by the wind, they create an airfoil and create lift which pulls the boat along.  Yes, running downwind, sails are pushed, but there are sometimes more efficient ways to sail towards a mark.  Sometimes sailing at an angle to where you want to go will increase your speed such that you are actually arriving sooner than if you had sailed straight downwind, thus increasing your velocity made good (VMG).   With a wing sail, you correct it's angle of attack relative to the apparent wind direction, not the true wind direction, thus increasing the lifting force by the wing. 

So, with a properly aligned array of wingsails on a blimp, you could have some angled to create a forward force, and some angled to counter the 'heeling' force of the winds.  There would definitely be directions this vessel could not travel, but I think with careful tacking, it should be able to arrive at any destination it chooses.    But, the amount of wingsails required to move such a vessel may be impractical to lift with the size of the blimp provided. 

 

FWIW I race and design sailboats. 

[kerbiloid]

So, an external reaction force is required for the faster-than-wind motion, to convert it into an additional "pushing" force. (And/or inertia, like for the "bij de wind" motion, with a series of sideways maneuvers, but this also requires an external reaction). Yachts have it, blimps not.

[p1t1o]

10 hours ago, gargamel said:

There is a land yacht, or sail car, that has achieved faster than wind speeds using only a wing sail.  The same is possible with sail boats, using the latest advances in foil and wing sail tech.  Doable?  maybe, it'll take some pretty perfect conditions for it to work.   EDIT:  I'm correcting my self here, they already do this.  The latest America's Cup racers were doing 30-45 knots in 20-25 knot winds.  That's 45 knots, on a 72 foot long catamaran, with a wingsail the size of a 737 wing, supported only by a hydrofoil the size of surfboard.   Check out the youtube's, they are amazing. 

But what land yachts and sailboats have that a blimp doesn't, is a medium to translate lateral force to forward momentum.  As mentioned, on a boat, there is the keel, on a sail car, there are wheels.  These take the sideways heeling motion of the sails and convert it into forward motion. 

Sails, and wing sails, aren't always "pushed" by the wind, they create an airfoil and create lift which pulls the boat along.  Yes, running downwind, sails are pushed, but there are sometimes more efficient ways to sail towards a mark.  Sometimes sailing at an angle to where you want to go will increase your speed such that you are actually arriving sooner than if you had sailed straight downwind, thus increasing your velocity made good (VMG).   With a wing sail, you correct it's angle of attack relative to the apparent wind direction, not the true wind direction, thus increasing the lifting force by the wing. 

So, with a properly aligned array of wingsails on a blimp, you could have some angled to create a forward force, and some angled to counter the 'heeling' force of the winds.  There would definitely be directions this vessel could not travel, but I think with careful tacking, it should be able to arrive at any destination it chooses.    But, the amount of wingsails required to move such a vessel may be impractical to lift with the size of the blimp provided. 

 

FWIW I race and design sailboats. 

At this point though, you are approaching the point where you would be much better off ditching the envelope and using a bit of aerodynamic lift instead (noone is going to be dragging a blimp enevelope through the air at 45kts), drag would drop waaay down and now you have a conventional glider, and we know those can be made to work very well, and can travel much faster than the wind and in fact would be tied to it [the wind] far less than a dirigible.