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'[EE]: Reactionless Drive'
2006\09\19@120445 by Russell McMahon

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New Scientist Tech website is offering free access for 1 week from 18
September.
You MAY have to be on their email mailing list already, maybe not.
Joining is free.

The article on the "emdrive" - microwave powered reactionless drive
with no moving parts or external exhaust etc is available for reading
at

       http://www.newscientisttech.com/article/mg19125681.400.html?DCMP=ILC-OpenHouse&nsref=mg19125681.400INT

Please advise if you can't access this.

As already noted on ARocket - it "*can't* work - but wouldn't it be
nice if he was right, even though he's not :-(.

For those who haven't met the emdrive before - it's not your usual
snake oil and mirrors type device - the inventor is highly capable and
has convinced a number of substantial organisations, including the US
Air Force, British Govt research granters and NASA to be cautiously
interested. All of which just means that it's not yet obvious to all
where the hole in his theory is.



       Russell



2006\09\19@122242 by David VanHorn

picon face
At millinewtons per kilowatt, it's not all that spectacular, but it is
interesting.

And imagine the efficiencies when you load the hovering train track with
chickens ready to be cooked!

2006\09\19@161153 by gacrowell

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You know, this device sounds a lot like the one in the amusing short SF
novel "Star Driver" by G. Harry Stine (Lee Correy).

Gary

> {Original Message removed}

2006\09\19@162202 by Sergey Dryga

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Russell McMahon <apptech <at> paradise.net.nz> writes:

<SNIP>
> The article on the "emdrive" - microwave powered reactionless drive
> with no moving parts or external exhaust etc is available for reading
> at

This is actually a reaction drive because it is based on reaction (reactive)
force, unless I missed something in the description.  In the regular "jet"
engine the reactive force is provided by expulsion of matter, in this case by
expulsion of wave, somewhat similar to photonic drive (a-la startrek etc.).  
What they mean is the drive has no momentum because it has no moving parts.

I wonder what the force an engine consisting of high-power laser will provide.  
Also, they have a picture of an aircraft using this type of engine to provide
hoover capability.  I bet amount of microwave radiation it will produce will
wreak havoc on electronic equipment below the craft.

Sergey Dryga
http://beaglerobotics.com



2006\09\19@170215 by David VanHorn

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On 9/19/06, spam_OUTgacrowellTakeThisOuTspammicron.com <.....gacrowellKILLspamspam@spam@micron.com> wrote:
>
> You know, this device sounds a lot like the one in the amusing short SF
> novel "Star Driver" by G. Harry Stine (Lee Correy).



That was a favorite of mine. I liked how they did the testing :)

2006\09\19@175717 by gacrowell

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Stine wrote what he knew, at the time, he owned the same type of plane
as was in the novel (a Beech IIRC), and I think he used his own tail
numbers.

Gary

> {Original Message removed}

2006\09\20@094358 by Mike Hord

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> This is actually a reaction drive because it is based on reaction (reactive)
> force, unless I missed something in the description.  In the regular "jet"
> engine the reactive force is provided by expulsion of matter, in this case by
> expulsion of wave, somewhat similar to photonic drive (a-la startrek etc.).
> What they mean is the drive has no momentum because it has no moving parts.

Or, better, reaction MASS-less drive.  It uses no reaction mass to provide
thrust.  Which is EXCELLENT, because most forms of propulsion these days
(rocket, jet, etc.) require quite a bit of reaction mass.

> Also, they have a picture of an aircraft using this type of engine to provide
> hoover capability.  I bet amount of microwave radiation it will produce will
> wreak havoc on electronic equipment below the craft.

The end goal is to have nearly none of that microwave radiation leaking out of
the chamber.  The energy poured into the chamber would go into lift, with
very little (remember the goal of a Q in the billions) leaking out.

If my physics logic is right, once a craft reached altitude, the
amount of energy
required to keep it there would be minimal.  After all, energy is
force integrated
over distance.  If the distance being travelled is zero (no net motion up or
down in the gravitational field), the only energy that would have to be placed
into the "bottle" would be to replace leakage, and with a Q of several billion,
that's not much.

I don't see this making flying cars a reality, but imagine the applications in
trade.  A ship is loaded with trinkets in Hong Kong, a generator on shore is
used to provide the initial umph to lever it up out of the water, onboard
generation good enough to KEEP it up takes over, then it zips across the
ocean to California or where ever.  Or to science:  a satellite using this
could maintain a geosynchronous "orbit" at any altitude!  Power generation:
those LEO geosync satellites could beam down the excess energy they
capture to local power stations.

The possibilities are endless:  what this represents is nothing less than the
means to build a structure at any height from the surface of the Earth,
without the need for physical contact with the Earth.  HUGE.

That's if it works.  Something about it seems not quite right to me.  ;-)

Mike H.

2006\09\20@160356 by Sergey Dryga

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Mike Hord <mike.hord <at> gmail.com> writes:

>
> > This is actually a reaction drive because it is based on reaction (reactive)
> > force, unless I missed something in the description.  In the regular "jet"
> > engine the reactive force is provided by expulsion of matter, in this case
by
> > expulsion of wave, somewhat similar to photonic drive (a-la startrek etc.).
> > What they mean is the drive has no momentum because it has no moving parts.
>
> Or, better, reaction MASS-less drive.  It uses no reaction mass to provide
> thrust.  Which is EXCELLENT, because most forms of propulsion these days
> (rocket, jet, etc.) require quite a bit of reaction mass.
>
> > Also, they have a picture of an aircraft using this type of engine to
provide
{Quote hidden}

billion,
> that's not much.

Something not right here, I just cannot put a handle to it.  You still have to
counter the force of gravity (I assume all this happens around earth).  Let's
make an imaginary experiment: I pick a stone from ground and lift it up to the
height of 1m.  The stone is stationary, so there is no need to spend energy to
maintain it at that height, right?  But practical experience tells me that the
stone will fall down.  

I also think that the engine will have to radiate  alot of energy, unless, of
course the 3rd Newton's law is not working anymore.  

I have to go and re-read Feinman's lectures now.

Sergey Dryga



2006\09\21@010737 by Gerhard Fiedler

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Sergey Dryga wrote:

>> If my physics logic is right, once a craft reached altitude, the amount
>> of energy required to keep it there would be minimal.  After all,
>> energy is force integrated over distance.  If the distance being
>> travelled is zero (no net motion up or down in the gravitational
>> field), the only energy that would have to be placed into the "bottle"
>> would be to replace leakage, and with a Q of several billion, that's
>> not much.
>
> Something not right here, I just cannot put a handle to it.  You still have to
> counter the force of gravity (I assume all this happens around earth).  

Resulting force determines resulting acceleration. If you want 0
acceleration (to not travel any distance), you need to achieve a sum of 0
of the forces -- so you need to counter the gravitation force to get to a 0
traveled distance :)

Now if you can generate a force without moving anything, you might be able
to not need any energy for that. But this might prove to be difficult.

Gerhard

2006\09\21@060356 by Michael Rigby-Jones

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>-----Original Message-----
>From: piclist-bouncesspamKILLspammit.edu [.....piclist-bouncesKILLspamspam.....mit.edu]
>Sent: 20 September 2006 21:03
>To: EraseMEpiclistspam_OUTspamTakeThisOuTmit.edu
>Subject: Re: [EE]: Reactionless Drive
>
>
>Something not right here, I just cannot put a handle to it.  
>You still have to
>counter the force of gravity (I assume all this happens around
>earth).  Let's
>make an imaginary experiment: I pick a stone from ground and
>lift it up to the
>height of 1m.  The stone is stationary, so there is no need to
>spend energy to
>maintain it at that height, right?  But practical experience
>tells me that the
>stone will fall down.

Only if you let go the stone, whereupon it's potential energy is converted into kinetic energy.  If you put the stone on a shelf it would stay there, and you don't have to provide power to a shelf do you?

 
>
>I also think that the engine will have to radiate  alot of
>energy, unless, of
>course the 3rd Newton's law is not working anymore.  

The whole point of this drive is that as little energy as possible is lost from the cavity.  The energy which is lost as radiation does not contribute to the thrust produced.

I really hope this is real, but it just seems to be too good to be true.

Regards

Mike


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2006\09\21@081918 by Gerhard Fiedler

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Michael Rigby-Jones wrote:

> Only if you let go the stone, whereupon it's potential energy is
> converted into kinetic energy.  If you put the stone on a shelf it would
> stay there, and you don't have to provide power to a shelf do you?

But you have to provide force. Movement is not only about energy, it is
primarily about (resulting) force.

> The whole point of this drive is that as little energy as possible is
> lost from the cavity.  The energy which is lost as radiation does not
> contribute to the thrust produced.

I have a problem with the explanation of how the thrust is generated. As
with any propulsion mechanism, this is not primarily a question of energy,
it is a question of force.

>From the article:

"Shawyer calculates the microwaves striking the end wall at the narrow end
of his cavity will transfer less momentum to the cavity than those striking
the wider end (see Diagram). The result is a net force that pushes the
cavity in one direction. And that's it, Shawyer says."

See also section 2.4 in
http://www.newscientist.com/data/images/ns/av/shawyertheory.pdf.

He is only considering the forces generated by the reflections on the end
pieces. That's fine as long as the waveguides are cylindrical, because then
the forces generated by the reflections on the sides cancel themselves out.
But with a cone-shaped waveguide, the reflections on the side walls have a
resulting force towards the smaller end, which possibly cancels out the
difference between the forces generated by the reflections at the end
pieces.

I haven't made the calculations to show how much force this reflection on
the cone shaped side walls generates and whether it matches the difference
in force generated at the end pieces, but neither has he in his paper.
Which seems strange. To me, it may be that there is a net difference, but
it at least would have to be considered -- and in any case it would reduce
the effect.

Gerhard

2006\09\21@085555 by Michael Rigby-Jones

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>-----Original Message-----
>From: piclist-bouncesspamspam_OUTmit.edu [@spam@piclist-bouncesKILLspamspammit.edu]
>Sent: 21 September 2006 13:18
>To: KILLspampiclistKILLspamspammit.edu
>Subject: Re: [EE]: Reactionless Drive
>
>
>Michael Rigby-Jones wrote:
>
>> Only if you let go the stone, whereupon it's potential energy is
>> converted into kinetic energy.  If you put the stone on a shelf it
>> would stay there, and you don't have to provide power to a shelf do
>> you?
>
>But you have to provide force. Movement is not only about
>energy, it is primarily about (resulting) force.

Work = Force x Distance

Remove either force or distance and work = 0.  There is no primary dependance on either force or motion.



{Quote hidden}

I agree that this is a possible explanation.  The first thing I thought was if the net thrust is produced by the difference in area between the ends of the conical cylinder, then why not reduce the shape to a pure cone?  Perhaps this would not produce a resonant cavity with high enough Q?

Regards

Mike

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2006\09\21@140757 by Gerhard Fiedler

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Michael Rigby-Jones wrote:

>>> Only if you let go the stone, whereupon it's potential energy is
>>> converted into kinetic energy.  If you put the stone on a shelf it
>>> would stay there, and you don't have to provide power to a shelf do
>>> you?
>>
>> But you have to provide force. Movement is not only about energy, it is
>> primarily about (resulting) force.
>
> Work = Force x Distance
>
> Remove either force or distance and work = 0.  There is no primary
> dependance on either force or motion.

???

Distance is a consequence of motion. Motion (or its absence) is what
creates (or not) the distance. So if you are saying that distance = 0, you
assume that there is no movement. And that there is no resulting force.

Energy changes are a consequence of movement, not a cause. It's the force
that causes the movement.

Gerhard

2006\09\21@141452 by Michael Rigby-Jones

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{Quote hidden}

What I am saying is that if distance=0 then force could be infinite, but no work is needed.  i.e., given a strong enough support, you can hold up any amount of mass without performing any work.

Regards

Mike

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2006\09\21@144726 by Mike Hord

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> I really hope this is real, but it just seems to be too good to be true.

As do I, but the whole thing kind of smacks of a cartoon character
sitting in a sailboat with an electric fan pointed at the sail.

The question of forces on the sloped edges of the conical chamber
is a good one, but that may only be valid from a Newtonian physics
standpoint.  As far as Newtonian physics is concerned, this whole
idea is bunk.  Einstein may have something more to say about the
subject, however.

Mike H.

2006\09\21@200507 by Mike Hord

picon face
> What I am saying is that if distance=0 then force could
> be infinite, but no work is needed.  i.e., given a strong
> enough support, you can hold up any amount of mass
> without performing any work.

And without consuming any energy.

Or, to put it another way, when was the last time the
batteries ran out on your chair and it collapsed under you?

When I was younger, I used to think floating cities (i.e.,
Cloud City in "The Empire Strikes Back") were an
impossibility because of the massive amount of energy
needed to hold them up.  Then one day I realized that if
the losses in the system were small enough (high Q),
you could run the thing for decades on a watch battery,
as long as you don't plan on raising or lowering it.

Because mechanical energy is force integrated over
distance, if one or the other of those components is
zero, the net energy change is zero, too.

Mike H.

2006\09\21@221225 by Gerhard Fiedler

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Mike Hord wrote:

> When I was younger, I used to think floating cities (i.e., Cloud City in
> "The Empire Strikes Back") were an impossibility because of the massive
> amount of energy needed to hold them up.  Then one day I realized that
> if the losses in the system were small enough (high Q), you could run
> the thing for decades on a watch battery, as long as you don't plan on
> raising or lowering it.
>
> Because mechanical energy is force integrated over distance, if one or
> the other of those components is zero, the net energy change is zero,
> too.

The only thing missing here is a concept how to create the necessary force
without a structure and without using the energy from the watch battery...
:)

So far, all known (to me, at least) methods to create force without using
structural means require movement. And therefore energy.

Gerhard

2006\09\21@221855 by Jinx
face picon face
> So far, all known (to me, at least) methods to create
> force without using structural means require movement.
> And therefore energy

Apart from magnetism. Which is a powerful and useful
force, if you can harness and direct it

2006\09\21@225538 by peter green

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> -----Original Message-----
> From: RemoveMEpiclist-bouncesspamTakeThisOuTmit.edu [piclist-bouncesEraseMEspam.....mit.edu]On Behalf
> Of Jinx
> Sent: 22 September 2006 03:19
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE]: Reactionless Drive
>
>
> > So far, all known (to me, at least) methods to create
> > force without using structural means require movement.
> > And therefore energy
>
> Apart from magnetism. Which is a powerful and useful
> force, if you can harness and direct it
and electric charge interation for that matter.

trouble is neither electrostatics or magnetics can provide stable levitation
from a static field. In both cases there will be an equipotential (surface
that the levitated device can move in without doing work against the field)
and since this equiptotential will surround the base station it will be
possible to fall down it.

so you need to dynamically adjust the field to correct for errors in the
objects position and try and keep the object sitting on top of the field.
This will take energy and the ammount will increase significantly if the
load contains any movement.

2006\09\22@040331 by Michael Rigby-Jones

picon face


{Quote hidden}

The point is that the device we are talking about claims to do this.  Although it does consume some energy, this is purely down to losses in the system (i.e. Q < infinity), not because the device is performing work to hold a mass in a fixed position.  However, IF the device works, then the energy consumption may be very  acceptable for many applications.

BTW, both magnetic and electrostatic devices can create a static force without using energy (or doing any useful work).

Regards

Mike

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2006\09\22@070952 by Tony Smith

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> > So far, all known (to me, at least) methods to create force without
> > using structural means require movement.
> > And therefore energy
>
> Apart from magnetism. Which is a powerful and useful force,
> if you can harness and direct it


Reminds me of the bloke a few weeks who made a floating bed, suspended by
magnets.  Not a 'real' floater as he used some cables to stop it getting
away.  Bah humbug.  Looked neat.

Shouldn't be too hard to make a real one.  Permanent magnets to provide most
of the force, and electromagnets to even things out.  Bonus points for
adding a vibrating mode.  Downside is providing a clear gap under the bed.
The 'easy' levitation methods don't give you that.  Makes sideways movement
control a bit difficult.

Given the chemist down the road had both 'magnetic therapy' stuff and a
petition to ban transmission towers, I wonder it it would cure or cause
cancer.

And since my last bed effort was chaining some telegraph posts together
(4-poster loft bed), I don't think I'll be allowed to make one.

Tony

2006\09\22@072549 by olin piclist

face picon face
Gerhard Fiedler wrote:
> The only thing missing here is a concept how to create the necessary
> force without a structure and without using the energy from the watch
> battery... :)

But such a mechanism would not violate the laws of physics as we currently
understand them.  Since it's not theoretically impossible, it probably is
possible, just that we haven't learned enough how to do it, at least at a
practical level.

> So far, all known (to me, at least) methods to create force without
> using structural means require movement. And therefore energy.

Both electrostatic and magnetic forces can be maintained with no or little
energy consumption today.

Bouyancy such as blimps use is another example.  Although mechanical it is
not structural.

A theoretical example is using light pressure from a beam constantly
bouncing between the ground and the levitating object.  Today we don't know
how to make the reflectors efficient enough to not require constant
replenishment of the light beam energy, but there is no theoretical
limitation on "perfect" or at least highly efficienct reflectors.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\09\22@074607 by Gerhard Fiedler

picon face
Michael Rigby-Jones wrote:

>>So far, all known (to me, at least) methods to create force
>>without using structural means require movement. And therefore energy.
>
> The point is that the device we are talking about claims to do this.

I know, but I also mentioned that I have my doubts about the calculations.
If reflection causes a force on a reflecting surface -- well, then
reflection does cause a force on the reflecting surfaces, including the
side walls. And tilting the walls changes the direction of the force. Which
is not considered in the calculations. I'm not saying there can't be a
remaining net effect, but leaving out such an obvious contribution speaks
strongly about the depth of the whole thing.

> BTW, both magnetic and electrostatic devices can create a static force
> without using energy (or doing any useful work).

Duh... of course :)  

But so far, eg. the electromagnetic railway systems haven't been able to
really compete.

Gerhard

2006\09\22@150552 by Howard Winter

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picon face
Peter,

On Fri, 22 Sep 2006 03:55:26 +0100, peter green wrote:

{Quote hidden}

It can be done, by "shaping" the field so that it produces stability, but it has to be at close quarters.  MagLev trains do it.

Cheers,


Howard Winter
St.Albans, England


2006\09\22@182646 by Jinx

face picon face
> It can be done, by "shaping" the field so that it produces
> stability, but it has to be at close quarters.  MagLev trains
> do it.

Howard, odd that I haven't heard of MagLev trains for
ages, until you mentioned them, then this happens

http://news.bbc.co.uk/1/hi/world/europe/5370564.stm

2006\09\22@200239 by Howard Winter

face
flavicon
picon face
Jinx,

On Sat, 23 Sep 2006 10:25:59 +1200, Jinx wrote:

> Howard, odd that I haven't heard of MagLev trains for
> ages, until you mentioned them, then this happens
>
> http://news.bbc.co.uk/1/hi/world/europe/5370564.stm

Wow, yes indeed - and it's only just happened, too.

There used to be a MagLev train at Birmingham International, taking people between the railway station and the airport.  I went on it many years
ago, but I understand it was taken out of service due to being too expensive to maintain.  I thought low maintenance was one of the reasons for it -
no wear and tear on the tracks!

Cheers,


Howard Winter
St.Albans, England


2006\09\22@202412 by peter green

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face

> There used to be a MagLev train at Birmingham International,
> taking people between the railway station and the airport.  I
> went on it many years
> ago, but I understand it was taken out of service due to being
> too expensive to maintain.  I thought low maintenance was one of
> the reasons for it -
> no wear and tear on the tracks!
compared to high speed rail certainly (the ammount of maintinace the tracks
need for the bullet train is insane)

but i strongly suspect that maglev has a lot of maintinace costs that are
more or less fixed per year its kept in operaion (e.g. weather damage) and
that for a short distance shuttle it is a lot more expensive to maintain
than a crude narrow gauge rail line (or even a crude standard gauge line)
and over those distances speed isn't a major issue.

2006\09\22@203010 by Jinx

face picon face

> There used to be a MagLev train at Birmingham International

A little bit of its history

http://www.bhx.co.uk/page.aspx?type=T0NaZj9WNoU=&id=5sqdhXe0N48=

Have to Copy/Paste

(how do you post a link like that without dropping the "=" ?)

And according to

http://en.wikipedia.org/wiki/Maglev_train

"It was in operation for nearly eleven years, but obsolescence
problems with the electronic systems made it unreliable in its
later years"

"Alleged theft of maglev technology"

"In a serious incident in December 2004, Chinese engineers
entered into the Transrapid maintenance room in the middle
of the night in Shanghai, took measurements of the train, and
even filmed the whole incident, according to the German
Economic Weekly, Wirtschaftswoche. Wirtschaftswoche
further speculated that it was a case of Transrapid technology
theft"

2006\09\22@215057 by Jinx

face picon face

> > news.bbc.co.uk/1/hi/world/europe/5370564.stm
>
> Wow, yes indeed - and it's only just happened, too.

And wikipedia already includes it (injury stats are different
but that will settle down)

A very good example for a discussion I'm having on another
group about books vs web

2006\09\25@000625 by Russell McMahon

face
flavicon
face
{Quote hidden}

"Magnetic levitation" does this right now. Static ML is not stable
with positively paramagnetic materials but a little trickery allows
one to utilise some negative paramagnetic materials in the mix to do
this wholly stably. Also a little mechanical input.

A tall tower serves the same role - and, as it achieves this feat
using the known nuclear forces, what is being proposed here should not
be disbelieved solely on the basis that it "feels wrong". There are,
alas, enough other complaints about the claim that it seems doomed to
be disproven.

I'm still waiting for the flying cars.

I used to tell people that, sadly, Dick Tracy style communicators were
impossible due to practical limitations of radio communications. I'd
not allowed for cell sites or LEO satellite constellations. Being sure
to qualify the conditions under which something is seen to be
impossible is usually wise :-)



       Russell



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