Perpetual Motion or free energy devices 1

[jmw]

OK, I was browsing you tube and came across the Gravity plane.
It uses Helium for lift and compressed air for weight.
So, we start with the thing on the ground and then it expels compressed air which reduces weight and allows helium bags to expand and becomes lighter than air.
It climbs.
Then it uses compressed air to compress more air which collapses the helium bags and makes it heavier than air again.
As it dives the air flow drives turbine air compressors to recharge the compressed air banks.
When it gets too low it discharges compressed air to allow the helium bags to reflate, climbs and repeats.

It is, wait for it, environmentally friendly and uses no fuel.
OK, I'm sold, where do i get one?

http://uk.youtube.com/watch?v=0QZ1KzveIic

JMW

http://www.ViscoAnalyser.com

 

[jmw]

Some confusion between Hunt websites:

http://www.fuellessflight.com/

where it seems to use a "special liquid" and solar power and the other website where it uses helium and compressed air and where there is a link to a sled towed in the sea which harnesses kinetic energy from the sea through a turbine to do something else that's clever....

http://www.fuellessflight.com/techno/tech.htm

and the sea glider is at:

http://www.fuellessflight.com/SEA GLIDER.htm

Gee, I guess you can patent pretty well anything in the USA, set up a company and find investors.



JMW

http://www.ViscoAnalyser.com

 

[MikeHalloran]

A different Seaglider, no overunity claims made, has been produced in modest quantities:

http://www.apl.washington.edu/projects/seaglider/summary.html

Mike Halloran
Pembroke Pines, FL, USA

 

[Comcokid]

There was a perpetual motion machine on the local TV news here a few days ago. You run an electric motor from a battery that drives a generator - Humm fine - but this one drives two generators that recharge the battery providing additional energy! The inventor pointed out that the battery lasted longer than when just driving the motor by itself.

They also interviewed a local small liberal-arts college science professor who congratulated the inventor on his experiments, but the prof didn't point out that it was a pointless perpetual motion machine - I couldn't figure out if the prof was just being polite - or not?.

 

[csd72]

Maybe he did but they just edited it out. Experiments with promise may have been deemed more newsworthy than pointless ones.

 

[GregLocock]

A couple of real life proposals.

Self rectifying water turbine, always turns the same way even if the water flow reverses

http://www.cetusenergy.com.au/action.php

The linear motion experiment was funny, he put a rectifing turbine under a float, and the wave action drove the thing along at about 1 knot, it didn't matter which way the waves were going.

and if you really want big engineering

http://www.biopowersystems.com/biostream.php

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[HamishMcTavish]

jmw, if it uses no fuel how does it compress the air? Your original post states it "uses compressed air to compress more air which collapses the helium bags and makes it heavier than air again"...

something is inconsistent!

No more things should be presumed to exist than are absolutely necessary - William of Occam

 

[SomptingGuy]

I watched the film until the continual repetition of "using compressed air to compress air to create thrust that turns turbines to compress air that's used to compress more air that's...." started to make my head spin.

I guess there's no violation of the 1st law of thermodynamics in moving a mass from one place to another, but the second law will prevent it being done by moving energy back and forth between different storage methods/media.

- Steve

 

[jmw]

Hamish,
The proposition is that, on the ground and tethered, the wind will spin the turbines which will compress air and charge batteries (for instrumentation etc.)

Once there is enough of it you can take off.

But, assuming there is no compressed air to begin with then the helium bags are fully expanded and the thing is going to be free floating somewhere or floating on the mooring lines.

My immediate concerns are about the air compression.
Compressed air has to do three things:
[il][li]compress the helium to take away lift[/li]
[li] provide ballast[/li]
[li]provide propulsion aids (its not all gravity gliding)[/li][/ul]
These are going to have to be pretty efficient turbines.

This won't work, we are told, with to small a vehicle because of the weight of the structure. To create something that will not only support its own weight, and carry a significant cargo it has to be very large to contain enough helium.
That requires a correspondingly large volume of air and it needs compressing.

But, how much compression to deflate the helium, how much to run propulsors (and while the turbines flap OK in a wind, how efficient will they be using stored compressed air?)

In a gravity glide, how fast do you need to go to and how long a glide is necessary to develop any realistic air compression? and, how fast can you go in a giant +/-neutral buoyancy vehicle?


It'll probably end up that this would work fine on a low G low density planet with a deep atmosphere but will it work on earth?

I would hope this guy Hunt has done his sums time and again and had them checked by a sceptic.

There would appear to be a hell of a lot of things that have to add up for it all to have the faintest chance. The higher the compressed air storage pressure, the stronger the tanks and the more weight. But if you compress more, you need less volume and that means less weight...

But, if we assume that the turbines/compressors work well in any reasonable air flow then yes, they can harvest wind energy even when sitting idle on the ground and that is what starts to make some sense, this isn't a closed system.
Any airflow that will turn the turbines will generate electricity for instruments and thence for controls which means compressing air between the shell and the helium bags.

But while it doesn't present as a true perpetual motion machine, what worries is that it is a great balancing act of various factors and it all depends on being able to compress enough air into a small enough volume and at a high enough pressure, fast enough to do any good.

So we have to start either up in the air or on the ground. If on the ground and tethered, then the turbines will run in the wind. Of course, up in the air held aloft by helium buoyancy and with no compressed air, its only source of energy is air flow through the turbines and if this is a free floating object the vehicle will tend to go with the wind so the available differential could be quite low. To have any hope of compressing enough air to provide propulsion, to wing the wings, and compress the helium bags, it is going to have collect and compress air pretty quick before someone shoots it down as a hazard.

I'd guess free floating with no compressed air reserve would be a pretty tough situation.



JMW

http://www.ViscoAnalyser.com

 

[KENAT]

I looked at this a while back. It strikes me as a bit hokey but then started to draw me in.

As I recall when I looked at it it doesn't claim over unity, but it does claim extreme efficiency. The sea glider is based on how they think Whales swim so far with so little apparant energy or something like that.

I say lets build a big one, put it down as an economic stimulus package for Engineers & Dreamers.

KENAT,

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[rb1957]

"This won't work" enough said, leave it there ...

why have "swing wings" ? how fast is this supposed to go ? M1+ ?? ... good grief

 

[monkeydog]

Swing wings are cool.

 

[JStephen]

Total hooey.

The fundamental principle, though never stated, is that you're going to harvest way more energy while descending than what you need to re-ascend.

Why don't we just build our trucks on eccentric wheels, and they'll accelerate more on the downward stroke than they decelerate on the rebound? The difference here is that with all the talk of helium and buoyancy and compressed air compressing other air, it confuses the issues enough that the underlying silliness is not readily apparent.

Consider this simpler proposal: We put a flywheel in a helicopter. We start the flywheel spinning at high speed on the ground with some outside source. Then use that power to fly up to altitude. Then when power runs out, we use the rotor as a wind generator during the plummet phase to bring the flywheel back up to speed. Then up we go again.

Some additional considerations:
-There's no reason to have a double fuselage other than cosmetics. Nor is there any reason to have folding wings.
-Storing large amounts of compressed air leads to very heavy construction.
-Filling a commercial jet fuselage with helium wouldn't begin to lift it off the ground- it takes something much lighter built to be buoyant. Take a look at the old dirigibles, and compare the cabin to the gas-containment area.

 

[KENAT]

Why have compressed air at all?

Just have your helium buoyancy 'bags', and some compressed helium storage with a pump in-between. Allow the buoyancy bags to ‘deflate’ by pumping air backing into the storage cylinders when you need to drop, & vice versa (you may not need the pumps this direction is pressure in storage is high enough. Or you could go real retro and try just heating cooling the helium.

Using turbines to ‘catch’ more energy as you rise/drop than is used to displace the air/helium is I think the part that I think is problematic wrt thermodynamic laws.

Their write up appears to have changed now from when I came across it before though, that or my memory’s shot.

Do they really mean swing wings or that they change the angle of incidence?


KENAT,

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[rb1957]

"Filling a commercial jet fuselage with helium ..." ... good idea, for making the pax talk like donald duck for a couple of minutes (before they expire from lack of O2).

in any case, why helium, why not a vaccuum ?

but, in any case, "Total hooey" ... a case of BS baffling ignorance.

 

[handleman]

in any case, why helium, why not a vaccuum

Because tension is much easier to withstand in light objects. Have you ever seen anything, ever, float up into the air due to internal vacuum?

-handleman, CSWP (The new, easy test)

 

[btrueblood]

A coupla blondes come to mind...

 

[GregLocock]

So, what size of evacuated Titanium alloy hollow sphere would float in the atmosphere? density=4700 kg m-3, yield stress=1500 MPa, E=140 GPa (guessing that elastic buckling might be an issue)?

airdensity=1.22 kg m-3, airpressure=101325 Pa

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[KENAT]

Well if we're gonna go for it, can't we reinforce it with carbon nanotubes?

KENAT,

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[jmw]

According to them:

Start by using advanced new strong, lightweight materials that are now available, such as carbon fiber or Kevlar bonded with epoxy resin to construct a rigid frame and outer skin. Additionally, lightweight non-porous Mylar will be used to form the balloon type gas-bags to hold the helium gases, which can escape more porous materials.

But that doesn't sound like they have made a decision which means they haven't got the answers yet, or at least, answers they like.

See also the Hunt Power Cycle which uses heat energy at low altitudes to vaporise a special liquid, the vapours drive a turbine, and at altitude, where the temperature is lower, the gas is condensed..... i.e. using external heat energy... but is there enough of it?

So, this puts me in mind of that nodding bird that is forever sipping water from a glass tumbler....

Of course, it is easy to take the mickey (especially after some of the proposals we have seen) but somewhere in here might lie an opportunity, provided it doesn't rely on some as yet undiscovered miracle lightweight material so all the sums will work out.


JMW

http://www.ViscoAnalyser.com