Author Topic: Propellantless Field Propulsion and application  (Read 666574 times)

Offline Nathan

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Re: Propellantless Field Propulsion and application
« Reply #20 on: 05/18/2008 01:32 AM »
Quote
hop - 18/5/2008  10:12 AM

Quote
Nathan - 17/5/2008  4:03 PM
EM-Drive is not fake science. They have a WORKING prototype and are moving towards a flight test in 2009. www.emdrive.com. This uses actual physics and obeys all the convervation laws.
He claims to have a working prototype. He claims it doesn't violate conservation of momentum, but many experts disagree.

See http://www.newscientist.com/blog/fromthepublisher/2006/10/emdrive-on-trial.html for various objections.

His main challange is to prove that it is actually an open system and not a closed one - which he obviously hasn't done to anyone's satisfaction. I'm convinced by the video of the device actually moving. If it is a closed system then the particles are simply going to bounce around on the walls of the device. If it is truly an open system then he is on to something.

On the general thrust of this thread - NASA cannot throw money into wormhole research etc because the phycisists haven't figured out how to do that and no amount of money can make a difference. One the ideas are on a firm footing then they should be funded. Sails are a good option.
The EM-drive probably shouldn't be funded until there is a peer reviewed proof that it is an open system and can do what it says it does. That said, given that it has government funding and has produced what looks like a working prototype - it certainly cannot be dismissed quite so easily.
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline tnphysics

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Re: Propellantless Field Propulsion and application
« Reply #21 on: 05/18/2008 02:24 AM »
It is possible to perform propulsion with light as reaction mass.

But this requires a large energy input and the light is ejected.

Offline gospacex

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Re: Propellantless Field Propulsion and application
« Reply #22 on: 05/18/2008 07:36 PM »
Quote
tnphysics - 17/5/2008  9:24 PM
It is possible to perform propulsion with light as reaction mass.
But this requires a large energy input and the light is ejected.

And also it requires 99.99999999% efficient energy-to-light conversion, if you don't want your ship to instantly vaporize.

Offline publiusr

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Re: Propellantless Field Propulsion and application
« Reply #23 on: 06/26/2008 06:02 PM »
Thus the anti-matter photon drive--meant for starships of the far, far future.

Online hop

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Re: Propellantless Field Propulsion and application
« Reply #24 on: 06/30/2008 07:47 AM »
If you think this is all science fiction that's your privilege, but the peer reviewed experimental data showing that this is all possible with enough development effort put into it over the next 25-to-50 years is readily aviable on the web and elsewhere, like the American Institute of Physics (AIP) if you care to look for it. 
Uh-huh. If you are so confident about this, how about providing and actual link or citation ?

Offline khallow

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Re: Propellantless Field Propulsion and application
« Reply #25 on: 06/30/2008 12:40 PM »
The only true way to make a starship is to be able to create a spacedrive that can modifiy gravity and/or inertia.  Everthing else talked about here except perhaps the EM drive is just for use on solar system scale missions.

I don't know what you mean by a "starship". but if you're willing to settle for slower travel times between stars (on the order of thousands or tens of thousands of years), then chemical engines and gravity assists will do. You need the really advanced propulsion technologies, if you're attempting high travel speeds (significant fraction of the speed of light), then you'll need something special. My point here is that if you are willing to spend a lot of time, then current propulsion technologies are sufficient for traveling between the stars. It all depends on the profile of the trip.
Karl Hallowell

Offline marsavian

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Re: Propellantless Field Propulsion and application
« Reply #26 on: 06/30/2008 02:04 PM »
The only true way to make a starship is to be able to create a spacedrive that can modifiy gravity and/or inertia.  Everthing else talked about here except perhaps the EM drive is just for use on solar system scale missions. 

Gene Rodenberry pretty much nailed it when he created the Starship Enterprise that was equipped with inertia modification "impulse-drive" system for solar system based travels and a wormhole based "warp-drive" for interstellar jumps measured in days to weeks and not tens to hundreds of years for both the ship crew and the folks back home.  If any of you are curious how this might be done, we have to look at the confulence of General Relativity and Quntum Mechancis to first find the means to transiently modify the inertial properties of mass by manipulating its stored energy and bulk acceleration of that mass relative to the distant stars.  That Mach/Lorentz technology will provide us the Startrek like "impluse drive" we need to start down this path.  We then use this same "gravinertial" technology to create traversalble wormholes shortcuts through spacetime that our starships can use to star hop.   

If you think this is all science fiction that's your privilege, but the peer reviewed experimental data showing that this is all possible with enough development effort put into it over the next 25-to-50 years is readily aviable on the web and elsewhere, like the American Institute of Physics (AIP) if you care to look for it. 

Hmmm, so that's how the UFOs do it ! ;) Seriously though why are we bothering with Ares V if it's only 25 years away ? What's the catch ?

Offline sandrot

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Re: Propellantless Field Propulsion and application
« Reply #27 on: 06/30/2008 02:48 PM »
Last time I checked to establish a traversable wormhole you needed large amounts of negative mass, that unfortunately cannot be provided by antimatter. But maybe there have been recent breakthroughs.
"Paper planes do fly much better than paper spacecrafts."

Offline khallow

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Re: Propellantless Field Propulsion and application
« Reply #28 on: 06/30/2008 10:47 PM »
sandrot, you need negative curvature in a wormhole "handle" (maybe you can get by with a positive cosmological constant and a smaller nonnegative curvature) somewhere in your wormhole (it's a result out of topology). Negative mass-energy is a known way to do that. I don't know if it's required though. And who knows? We might be able to create wormholes, but not naked negative energy.
Karl Hallowell

Offline sandrot

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Re: Propellantless Field Propulsion and application
« Reply #29 on: 07/01/2008 04:28 AM »
HOP:

Sure, try this one: http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=APCPCS000813000001001321000001&idtype=cvips&gifs=yes
And if you want any more citations, let me know...

[...]


The part I like, is:

Quote from: March&Palfreyman

When Woodward's (2004a, 2004b, 2005) and our test results were compared with the model's predictions, the test results exceeded predictions by one to two orders of magnitude. Efforts are underway to understand the discrepancies and update the model.


Are March and Palfreyman going to be the Pons and Fleischmann of the 21st Century?
« Last Edit: 07/01/2008 04:40 AM by sandrot »
"Paper planes do fly much better than paper spacecrafts."

Offline sandrot

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Re: Propellantless Field Propulsion and application
« Reply #30 on: 07/01/2008 04:31 AM »
[...] See Dr. Harold White's following paper on Space-time metric engineering at the following link for details:

http://www.springerlink.com/content/t52g457576w8m2x2/ 


The fact that something can be theorized doesn't mean it exists nor that it can be observed. There are tons of publications on string theory, for instance.

I wouldn't go around screaming that men in black are hiding the truth.
"Paper planes do fly much better than paper spacecrafts."

Offline sandrot

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Re: Propellantless Field Propulsion and application
« Reply #31 on: 07/01/2008 04:58 AM »
The money will go where there's money to be made. That's the way it works. This might not lead to the Star Trek world we all dream of.
"Paper planes do fly much better than paper spacecrafts."

Offline Lampyridae

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Re: Propellantless Field Propulsion and application
« Reply #32 on: 07/01/2008 05:07 AM »
Agreed, sandrot.

The negative energy densities involved in opening a wormhole throat open are frightening. With current physics, you're talking about the equivalent negative mass / energy of something like a terrestrial planet. It ain't happening soon.

The Standard Model of physics doesn't explain everything, and it is probably not correct and will in time be superceded, just as Newtonian was superceded by Einsteinian physics. But at the moment, the discrepancies are tiny and whether or not it will enable FTL / reactionless drives / unicorns is unknown and unknowable. What is known is that all propellantless propulsion solutions are either pseduoscience or generate laughably miniscule amounts of thrust. That's why they are not throwing $$$$$$ at it. Ares I and V are engineering longshots as it is, and they are based on technology that is essentially "off the shelf."
SKYLON... The League of Extraordinary Gentlemen's preferred surface-to-orbit conveyance.

Offline khallow

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Re: Propellantless Field Propulsion and application
« Reply #33 on: 07/01/2008 11:55 AM »
Khallow:

IMO multiple generation starships are out of the running since they would only be attempted by our current world governments out of a desparate need to survive as a race.  It's much better to think a bit more creatively and out of the current power and propulsion (P&P) box, and then put some development R&D resources into it to see what really can be done in this advnaced P&P venue.

Who said multigenerational? Extreme longevity (here, living long enough that the same crew can be used for the entire tens of thousands of years trip) is probably more feasible than some of the other ideas bounced around here.
Karl Hallowell

Offline sandrot

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Re: Propellantless Field Propulsion and application
« Reply #34 on: 07/01/2008 01:04 PM »
Sandrot:

[...] And when that happens, we will have signed our death warrants in the long term for when the next killer asteroid comes along, we still won't have enough of our civilization off this rock to survive. [...]

I am a little fed-up with catastrophism. Yes, I am a human-induced-global-warming skeptic.

Even if another Chicxulub event should happen tomorrow (figuratively speaking) I am not concerned for the future of humankind. As much as I like spaceflight I believe that we would not try to place survivors on the Moon or on Mars (maybe around the Earth?), but that we would invest our resources in building shelters.

It's more likely you'll see P&P advances when they can be applied to weapons.

Last time I checked it was the DoD that was interested in space based solar power.
"Paper planes do fly much better than paper spacecrafts."

Offline sandrot

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Re: Propellantless Field Propulsion and application
« Reply #35 on: 07/01/2008 06:06 PM »
Sandrot & Crew:

Ok, let's not be dramatic [...]


Good idea. I dropped participating to discussions over Direct because they're usually too emotional.

As Lampyridae points out, money will go where big thrust can be demonstrated. The next thing in line (i.e. where some money is being put) is VASIMR.

About other more exotic phenomena, there's not yet enough "critical mass" to get the things going. Experience from the past has shown that extraordinary claims were not followed by extraordinary evidence.
"Paper planes do fly much better than paper spacecrafts."

Offline sandrot

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Re: Propellantless Field Propulsion and application
« Reply #36 on: 07/01/2008 07:30 PM »
[...] As to what is unambiguous for most folks seem to fall around 1.0 Newton (101.971 gram-force) of force output at a minimum with preference being given to being able to levitate the test article into the conference hall.    

Not quite there. We didn't go to the Moon with those guys levitating coffee tables in the late 1800.

If you have the tastebuds for this kind of stuff, search through the countless patents awarded for antigravity generators. I wonder why my car isn't flying yet.

:)
« Last Edit: 07/01/2008 07:30 PM by sandrot »
"Paper planes do fly much better than paper spacecrafts."

Offline scienceguy

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Re: Propellantless Field Propulsion and application
« Reply #37 on: 07/01/2008 08:57 PM »
Is sunlight strong enough out at Mars to power a VASIMR roundtrip?
e^(pi)i = -1

Offline khallow

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Re: Propellantless Field Propulsion and application
« Reply #38 on: 07/01/2008 09:19 PM »
Yes, sunlight is half the intensity at Earth. It does mean that you do have half the thrust that you would at Earth. But I don't believe this is a significant problem. The main effect is to enlarge somewhat the configuration space for which fission power is superior to solar power.
Karl Hallowell

Offline A_M_Swallow

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Re: Propellantless Field Propulsion and application
« Reply #39 on: 07/02/2008 03:31 AM »
Is sunlight strong enough out at Mars to power a VASIMR roundtrip?

A VASIMR spacecraft for Mars could have approximately twice the area of solar cells that a Moon spacecraft has.  Alternatively the route could be planned so that the spacecraft spends about twice as much time near Mars than Earth or a mixture of both.

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