The EmDrive

[vbloke]

this sounds a bit dubious to me, although I don't have the physics knowledge to figure it out. Plus, they're being a bit sketchy on the details.
Any thoughts?
The EM Drive (http://www.emdrive.com/)

[Ducky]

Originally posted by vbloke
this sounds a bit dubious to me, although I don't have the physics knowledge to figure it out. Plus, they're being a bit sketchy on the details.
Any thoughts?
The EM Drive (http://www.emdrive.com/)


I have heard of people talk about "solar Sails" though I don't know if it was purely fiction or not.

This quote seems dubious to me.

Thrust is produced by the amplification of the radiation pressure of an electromagnetic wave propagated through a resonant waveguide assembly.

So you're using an amplifier? How? What is the emitting apparatus? EM speakers? Or is this some sort of EM fanjet?

Seems a bit dubious without any explanation.

[kmortis]

On the site he mentions that a paper describing the theory and expirmental evidence is available, if you give him your name and affiliation.

I figure that I'm and EMI engineer, working in aerospace...why not?

[kmortis]

Originally posted by fowlsound
I have heard of people talk about "solar Sails" though I don't know if it was purely fiction or not.

This quote seems dubious to me.



So you're using an amplifier? How? What is the emitting apparatus? EM speakers? Or is this some sort of EM fanjet?

Seems a bit dubious without any explanation.

Actually, the thing that's sticking in my craw the most is that this high-tech company is using an AOL email account......

[Ducky]

Originally posted by kmortis
On the site he mentions that a paper describing the theory and expirmental evidence is available, if you give him your name and affiliation.

I figure that I'm and EMI engineer, working in aerospace...why not?


I'd like to read that if you get it. Possible to email it to me?

[Ducky]

Originally posted by kmortis
Actually, the thing that's sticking in my craw the most is that this high-tech company is using an AOL email account......


Just noticed that. Heh.

Also, given the previous reply the homeopaths come to mind. "Prove to me you can understand and I'll explain it. What are your credentials?" How many times have I heard that from Mas?

[kmortis]

a Freeper has a better write-up on it. Of course, most of the text comes from the Eureka article that the site links to, but Freep at least has a "picture".
http://www.freerepublic.com/focus/f-news/1455622/posts

[John Jackson]

From companies house (UK):

SPR Ltd.

Status: Liquidation

Nature of Business (SIC(03)):
7011 - Development & sell real estate

Next Accounts Due: 31/01/1995 OVERDUE

[kmortis]

Originally posted by fowlsound
I'd like to read that if you get it. Possible to email it to me?

Sure.

John,
Does that "Liquidation" status mean that the co.'s in liquidation (ie no longer in existance) or what?

[John Jackson]

Yes, in liquidation means that the company's assets are to be sold to cover its debts. It's gone broke in other words.

I notice that the company hasn't submitted accounts for 10 years!

I was just wondering if, like those with free-energy machines, he's looking for private investors...

[Ducky]

Originally posted by John Jackson
Yes, in liquidation means that the company's assets are to be sold to cover its debts. It's gone broke in other words.

I notice that the company hasn't submitted accounts for 10 years!

I was just wondering if, like those with free-energy machines, he's looking for private investors...


A bankrupt company making wild claims that would redefine physics.

Hey nothing strange there. sign me up!

[kevin]

Originally posted by vbloke
this sounds a bit dubious to me, although I don't have the physics knowledge to figure it out. Plus, they're being a bit sketchy on the details.
Any thoughts?
The EM Drive (http://www.emdrive.com/)

Without even really reading the site the following jumps out at me:

Advertising on business site. Not professional.
AOL e-mail address. Not professional (at least use a domain e-mail forwarder)

Closer examination reveals:
The performance of the EmDrive is such that the launch mass of a satellite would be halved

Huh? How do they manage to halve the mass of something? Maybe it's just marketing speak.

Click the link for the Eureka article and they are claiming they've created a reactionless drive using a "bottle of microwave energy":
Hence, it is possible to have a bottle full of electromagnetic waves exerting more force on one end than the other, whereas this is not possible for anything else that an engineer would normally be expected to encounter. In the case of the prototype unit, the closed resonating cavity is wider at one end than the other. Mathematical analysis shows that group velocity is higher at the wide end than the narrow end and, as a consequence, there is a net force exerted on the wider end. Furthermore, the net force exerted is proportional to Q (Q being the effectiveness that the cavity shows as a resonator). Most academics have blanched at the very idea of getting involved in such a controversial idea. One, however, Dr Richard Paris, a reader in mathematics at the University of Abertay in Dundee, has endorsed the calculations.

A) they need a editor to clean up their article. that's tough reading.
B) I don't think this is possible. I thought solar sails worked because they used photons from the sun. I didn't think you could mount the photon source on the device to be moved by the sails. Not that I'm an expert in solar sails.

[kmortis]

Originally posted by kevin

A) they need a editor to clean up their article. that's tough reading.
B) I don't think this is possible. I thought solar sails worked because they used photons from the sun. I didn't think you could mount the photon source on the device to be moved by the sails. Not that I'm an expert in solar sails.

Yeah, I thought some of the site's language was a bit hokey. In the Eureka piece, the start talking about how a uwave transmitter emits photons at uwave frequencies.....no it doesn't. It emits electrons at uwave frequencies.

I was hoping that the "technical" papers would clarify some of the press's garblings?

And, from what I understand, yes, solar sails do use photons in a similar manner as a regular sail uses wind. So, a flashlight mounted on the ship wouldn't activate it (leaving out the lack of volume issue for a minute).

Well, if this guy ever gets back to me, we can disect the theory together, eh?

[Ducky]

Originally posted by kmortis
Yeah, I thought some of the site's language was a bit hokey. In the Eureka piece, the start talking about how a uwave transmitter emits photons at uwave frequencies.....no it doesn't. It emits electrons at uwave frequencies.

I was hoping that the "technical" papers would clarify some of the press's garblings?

And, from what I understand, yes, solar sails do use photons in a similar manner as a regular sail uses wind. So, a flashlight mounted on the ship wouldn't activate it (leaving out the lack of volume issue for a minute).

Well, if this guy ever gets back to me, we can disect the theory together, eh?


I would love to. Send me a copy when you get a chance.

The ideas he has about the wave phasing and wave mass is complete wack. I'm confirming this as best I can with some friends I have.

[luchog]

Originally posted by kmortis
And, from what I understand, yes, solar sails do use photons in a similar manner as a regular sail uses wind. So, a flashlight mounted on the ship wouldn't activate it (leaving out the lack of volume issue for a minute).

From what I can understand in the article; it's more a case of mounting the EM equivalent of a large fan, like on a swamprunner. Instead of catching existing photon winds (and yes, microwaves are photons, just like light, simply on a wavelength longer than visible light) in a sail, it creates its own.

Theoretically, I don't see a problem with it. It doesn't violate any of the known tenets of physics. Small variations of the effect are fairly well-known. In application, however, actually creating enough energy to achieve a usable thrust is probably not practically feasible. It would probably require a thruster in the megawatt range, and would still probably not be enough to overcome the mass of the drive itself, let alone any sort of sattelite or exploratory craft. Like using a battery-powered hair-dryer to power an inflatable raft.

[kmortis]

i've received the EM Drive Theory paper. He's copywriten it, so I don't think I can legally post it here in it's entirity.

[Hellbound]

Originally posted by kevin
Huh? How do they manage to halve the mass of something? Maybe it's just marketing speak.

Actually, this is probably accurate if the device works as advertised (big if, but bear with me).

About 90% (rough estimate from memory, but correct +9%/-20%, I'd say) of the mass in a launch of any object into orbit is contained in fuel, reaction mass, and engines. A more efficent launch system could cause a huge reduction in launch mass, because you need less fuel and less reaction mass. This is one of the proposed advantages in theoretical anti-matter drives. Using hydrogen as a reaction mass, and anti-matter as a fuel, you can use the same ship to go into orbit or to go to Jupiter. For short trips, use less antimatter witht the same amount of hydrogen...slower exhaust for shorter trips. For longer trips, you increase the anti-matter/hydrogen ratio...so you use the same 800 tons (or whatever) of hydrogen, but the additional anti-matter makes a higher velocity exhaust, allowing for longer trips witht he same reaction mass.

IIRC, Ion drives offer the same type of benefits (reduced reaction mass), but I might be mis-remembering that.

[John Jackson]

This company is not SPR limited, it's:

SATELLITE PROPULSION RESEARCH LIMITED

Nature of Business (SIC(03)):
7310 - R & D on nat sciences & engineering

The company is solvent and currently active.

Having posted this correction, I should point out that Roger Shawyer should not be calling his company SPR Ltd (which is what he's doing). You cannot legally use another company's name.

[kmortis]

Seeing as the report that I recieved from Roger is...um...vague in parts, I've emailed him back for clarification on certain parts. Like the engine description.

If anyone wants the report, PM me and I'll get it to you.

[oglommi]

Originally posted by vbloke
this sounds a bit dubious to me, although I don't have the physics knowledge to figure it out. Plus, they're being a bit sketchy on the details.
Any thoughts?
The EM Drive (http://www.emdrive.com/)

The resonant waveguide thingy is just to focus the microwave beam, nothing woo hoo about that. Microwaves are just radiowaves or light at a different frequency and Lasers can push stuf when focused so I guess it is theoreticly possible to push things but inefficient compared to rocket engines..... Yet

[kmortis]

To the inefficency point: I totally agree. He mentions that the engine is 15.5 kg (~150 N at rest) and that it produced 16 mN. Now, it's unclear if that's a total thrust or just what it produces over and above the weight of the engine.

It looks like it's a total number as it seems that he's got the engine attached to a counter-balance.

If it is the total thrust, then it doesn't even produce enough to overcome it's own weight, let alone the rest of the ship and cargo.

[L7Cz]

Wouldn't it be just as (indeed, more so) efficient and effective pointed backwards and pushing a non-sail-equipped craft, thereby saving the weight of the sail and support structure?

[kmortis]

Originally posted by L7Cz
Wouldn't it be just as (indeed, more so) efficient and effective pointed backwards and pushing a non-sail-equipped craft, thereby saving the weight of the sail and support structure?

It SEEMS like that's what he's got in mind. The tech paper doesn't mention a possible ship configuration, just the test config.

[oglommi]

Originally posted by L7Cz
Wouldn't it be just as (indeed, more so) efficient and effective pointed backwards and pushing a non-sail-equipped craft, thereby saving the weight of the sail and support structure?


In space weigth or mass is not much of an issue except when the spacecraft is changing course and more mass means more sentrifuagl force and more energy is needed to change the course of the spacecraft.

[Hellbound]

Originally posted by oglommi
In space weigth or mass is not much of an issue except when the spacecraft is changing course and more mass means more sentrifuagl force and more energy is needed to change the course of the spacecraft.

Mass is an issue anytime you change velocity, whether it is directional (as you indicate) or acceleration/deceleration. It takes more energy to speed up or slow down a larger mass, which is a primary concern with spacecraft. This is a major issue for chemical rockets, because to get fast enough you add more reaction mass, which slows your rate of acceleration, which means you need more reaction mass, which means a slower rate of acceleration, etc, etc, etc. That's why the majority of weight in a spacecraft ends up in engines, fuel, and reaction mass.

It's also a reason why alternative methods of getting craft into orbit (such as space elevators or rail launch systems) that us ground-based power are so attractive...you could cut the launch mass of a spacecraft by a signifigant percentage.

[oglommi]

Excellent point. Didn't think of that.

[Ducky]

Couple of things. I'm a sound engineer, so if I am inaccurate, please correct me. I think this paper makes jumps in logic it cannot support.

Microwave energy is fed from a magnetron, via a tuned feed to a closed, tapered waveguide, whose overall electrical length gives resonance at the operating frequency of the magnetron.

So you're reinventing a summing amplifier? How does this increase pressure at the working end of the engine? If we were to transpose this theory down to audible frequencies, it would take one hell of a subwoofer to push a go-cart down the street.

We note that if the forces had been the mechanical result of a working fluid within the closed waveguide assembly, then the resultant force would merely introduce a mechanical strain in the waveguide walls. This would be the result of a closed system of waveguide and working fluid. In the present system the working fluid is replaced by an electromagnetic wave propagating close to the speed of light and Newtonian mechanics must be replaced with the special theory of relativity.

well, yes, but only for the wave particles themselves, not the engine. Also if there was thrust of any kind, there would still be strain on the waveguide walls.

We now suppose that the beam enters a vacuum-filled waveguide. The waveguide tapers from free-space propagation, with wavelength �0, to dimensions that give a waveguide wavelength of �g and propagation velocity vg .

well yes, you are in space. But how are we tapering the wavelength? are you changing frequency? How does this propell anything?



That's my 2 cents for the 5 minutes I've looked it over. I'll read more into it tonight.

[kmortis]

Originally posted by fowlsound

well yes, you are in space. But how are we tapering the wavelength? are you changing frequency? How does this propell anything?

Fowlsound,
It's the waveguide that is tapered (thereby increasing the waveguide-beyond-cutoff, thereby "tapering" the wave length).

In other news, the response I got from Roger when I requested more info was

A full technical report was prepared, reviewed and is now government property! The magnetrons were low cost oven spec devices with no isolator and were therefore susceptable to arc damage due to reflected power. We have moved a long way since then.

Regards

Roger Shawyer
SPR Ltd


I'm half temped to ask if that means that it's totally unavailable for review. If so, this goes one more notch up the "Crank" scale, IMO.

-ken

[Ducky]

Originally posted by kmortis
Fowlsound,
It's the waveguide that is tapered (thereby increasing the waveguide-beyond-cutoff, thereby "tapering" the wave length).

In other news, the response I got from Roger when I requested more info was



I'm half temped to ask if that means that it's totally unavailable for review. If so, this goes one more notch up the "Crank" scale, IMO.

-ken



Yeah I just noticed that. Ha! Well it's my mistake. nothing changes the fact this looks bunk though.

[Ducky]

From what I can make of this the author seems to either think that by "funnelling" microwaves he can produce thrust enough to move something, or he's reinventing a microwave oven to cook his burrito.


Is there anything to this? I don't think so.


If someone with a better physics background could dissect this I'd like to know if I'm off.

[jmercer]

Well... I don't think microwaves can be used as a basis for thrust the way they describe it - although microwaves could possibly be used to fire up a plasma drive.

The solar sail concept should work with microwaves as well, since both have photons. (http://physicsweb.org/articles/news/6/6/1) So it might be possible to create a "microwave sail" that could make use of the pressure from a spaced-based microwave "beam" generator to provide thrust. But to generate enough thrust on-board the ship by expelling microwaves... nah. I suspect the mass required for such a power source would make the inefficiencies of it untenable.

The solar sail concept only works because we've got the Sun as the generator, with it's tremendous output - and the mass of that generator stays "at home". Even so, you need a sail of enormous size and very light weight to make this work. But technically speaking, there's really no reason to think that a sufficiently strong space-based microwave generator couldn't also provide thrust. Damfino how you could build a spaced-based power generator big enough to make this worthwhile, though. :)

[Hellbound]

jmercer:

Solar panel the moon, use it to power a microwave beam, aim at a$$ of ship, off you go!

Getting back could be an issue...

:D

Even better, solar panel the moon, use the power to run particle accelerators optomized to produce anti-matter, use anti-matter for thrust (and to intimidate the nations of Earth into funding your plot for world domination by building hordes of anti-matter powered, self-replicating killer robots under MY COMMAND, AND NO ONE ELSES!!! BOW, BOW TO ME, PUNY LEADERS OF EARTH!!! BWAHAHAHAHAHAH!!!!)


*ahem*

Need to refill my prescription.

[jmercer]

Originally posted by Huntsman
jmercer:

Solar panel the moon, use it to power a microwave beam, aim at a$$ of ship, off you go!


OMG, that's almost as scary as the Orion concept... atom bombs going off under my ass while a pusher-plate absorbs the shock waves. :D

Originally posted by Huntsman

Getting back could be an issue...


Nah. Who the hell would want to come back here, anyway? ;)

Originally posted by Huntsman

Even better, solar panel the moon, use the power to run particle accelerators optomized to produce anti-matter, use anti-matter for thrust (and to intimidate the nations of Earth into funding your plot for world domination by building hordes of anti-matter powered, self-replicating killer robots under MY COMMAND, AND NO ONE ELSES!!! BOW, BOW TO ME, PUNY LEADERS OF EARTH!!! BWAHAHAHAHAHAH!!!!)


*ahem*

Need to refill my prescription.

How... HOW DID YOU GET MY SECRET PLANS? Now, Huntsman, I must do ... something ... about you... you know too much.... MUAHAHAHAHAHAHAAHA! I shall send my super-secret assassin, Rebecca, to seduce you and then remove your brain at the earliest possible moment! YES! THE WORLD WILL BE MINE, MINE, MINE!!!!

*cough*

What the hell is IN those drugs, anyway?

[Ducky]

Ok I sent a copy of this to a friend of mine, who is a physicist.

We'll see what he has to say about it.






Edited for idiotry.

[Lucky]

Perhaps a bit hyper-sceptical to label the thing as ‘woo’? Even if you have no physics background I should think a quick glance at the Eureka article would make it clear that the idea is based on respectable science (though the science-journalist author is plainly not a physicist, makes some important blunders, and doesn’t give an adequate explanation of the supposed principle). There are no claims of free energy, novel radiation or particles unknown to science etc. It is no scam either: the ‘company’ is not touting for sales or private backers.

Having said that, the EmDrive theory could well turn out to be completely wrong in all respects, and my best guess is that it will. Here’s the meat of the claim:it is possible to have a bottle full of electromagnetic waves exerting more force on one end than the other ….. the closed resonating cavity is wider at one end than the other. Mathematical analysis shows that group velocity is higher at the wide end than the narrow end and, as a consequence, there is a net force exerted on the wider end.I can’t tell from that summary whether it’s prima facie bunk, something I don’t fully understand the maths of, or something that can’t be judged without a lot more information. (Don’t know if ‘group velocity is higher at the wide end than the narrow end’, and, even so, if there is necessarily ‘a net force exerted on the wider end’.) Even if this should prove to be mathematically plausible, the additional theory that could generate usable energy from the effect may be wrong.

Some other possibilities: It’s a brilliant idea and will be developed to immense profit, but not in the UK.
The prototype device actually works, but for some completely different reason.
The theory is OK, but no practical application will ever be found because of technological difficulties.
It will work, but not for the huge amounts of energy required in space technology. Totally different applications will be found.If I were the UK government I would certainly think it worth investing a small amount for preliminary research. (Fund a few mathematicians to investigate the theory and develop some simulations?) In fact, it seems that an initial feasibility study has been carried out. Perhaps the maths was found to be wrong (wouldn’t surprise me). The fact that the thing appears to have attracted no further funding since 2002 is certainly suggestive, but by no means conclusive. Generally, in the UK, science and technology are expected to compete in the world by unaided market forces.

I think some people here don’t understand the difference between ‘woo’ (magic) and respectable scientific/technological ideas that turn out to be wrong (almost all of them). Although there is no logical dividing line, in practice the difference is usually quite large.

Group and phase velocity, waveguides, continuous-wave lasers (http://www.rp-photonics.com/encyclopedia.html) ..... an area where it’s very easy to have superficially plausible ideas that are proven theoretically wrong on further investigation. That is respectable, legitimate science/technology (so long as you don’t become enamoured of your idea to the point that you will accept no disproof). By definition, ‘woo’ is not superficially plausible to knowledgeable people in the field.

If this one had been developed by academics, no matter how renegade, I would say it is a bit reminiscent of cold fusion, or perhaps semiconductors (travelling holes, anyone?). Probably wrong, but …..

Without a doubt, Satellite Propulsion Research Ltd is not a real business, but no reason either to think it’s a fraud. The bogus-seeming company with reputable links doesn’t seem at all suspicious in itself to any British academic involved in research and development ‘spin-out’ (as I am). (However, one possible danger signal: Who is Roger Shawyer?)

In very important ways the engineering mind advances the frontiers of science ….. the invention of apparatus to test ideas generates further ideas ….. many fairly simple ideas could be (and have been) discovered by engineers ….. (still thinking about this, may have more to say).

Some more ‘woo’ for you (http://physicsweb.org/articles/news/4/7/8/1) …..or is it? (ignore horrible ‘explanation’ of group velocity vs phase velocity).

[Ducky]

Originally posted by Lucky
Perhaps a bit hyper-sceptical to label the thing as ‘woo’? Even if you have no physics background I should think a quick glance at the Eureka article would make it clear that the idea is based on respectable science (though the science-journalist author is plainly not a physicist, makes some important blunders, and doesn’t give an adequate explanation of the supposed principle). There are no claims of free energy, novel radiation or particles unknown to science etc. It is no scam either: the ‘company’ is not touting for sales or private backers.

Having said that, the EmDrive theory could well turn out to be completely wrong in all respects, and my best guess is that it will. Here’s the meat of the claim:I can’t tell from that summary whether it’s prima facie bunk, something I don’t fully understand the maths of, or something that can’t be judged without a lot more information. (Don’t know if ‘group velocity is higher at the wide end than the narrow end’, and, even so, if there is necessarily ‘a net force exerted on the wider end’.) Even if this should prove to be mathematically plausible, the additional theory that could generate usable energy from the effect may be wrong.

Some other possibilities: It’s a brilliant idea and will be developed to immense profit, but not in the UK.
The prototype device actually works, but for some completely different reason.
The theory is OK, but no practical application will ever be found because of technological difficulties.
It will work, but not for the huge amounts of energy required in space technology. Totally different applications will be found.If I were the UK government I would certainly think it worth investing a small amount for preliminary research. (Fund a few mathematicians to investigate the theory and develop some simulations?) In fact, it seems that an initial feasibility study has been carried out. Perhaps the maths was found to be wrong (wouldn’t surprise me). The fact that the thing appears to have attracted no further funding since 2002 is certainly suggestive, but by no means conclusive. Generally, in the UK, science and technology are expected to compete in the world by unaided market forces.

I think some people here don’t understand the difference between ‘woo’ (magic) and respectable scientific/technological ideas that turn out to be wrong (almost all of them). Although there is no logical dividing line, in practice the difference is usually quite large.

Group and phase velocity, waveguides, continuous-wave lasers (http://www.rp-photonics.com/encyclopedia.html) ..... an area where it’s very easy to have superficially plausible ideas that are proven theoretically wrong on further investigation. That is respectable, legitimate science/technology (so long as you don’t become enamoured of your idea to the point that you will accept no disproof). By definition, ‘woo’ is not superficially plausible to knowledgeable people in the field.

If this one had been developed by academics, no matter how renegade, I would say it is a bit reminiscent of cold fusion, or perhaps semiconductors (travelling holes, anyone?). Probably wrong, but …..

Without a doubt, Satellite Propulsion Research Ltd is not a real business, but no reason either to think it’s a fraud. The bogus-seeming company with reputable links doesn’t seem at all suspicious in itself to any British academic involved in research and development ‘spin-out’ (as I am). (However, one possible danger signal: Who is Roger Shawyer?)

In very important ways the engineering mind advances the frontiers of science ….. the invention of apparatus to test ideas generates further ideas ….. many fairly simple ideas could be (and have been) discovered by engineers ….. (still thinking about this, may have more to say).

Some more ‘woo’ for you (http://physicsweb.org/articles/news/4/7/8/1) …..or is it? (ignore horrible ‘explanation’ of group velocity vs phase velocity).


Excellent post. I agree, and remove my original woo statement. I will however be skeptical that it works until I hear back from my physicist freind. Since he's the one with the expertise in this area, I'll defer to his analysis.

[Lucky]

fowlsound: What I am trying to say is that this is not a case of random scientific-sounding phrases cobbled together in order to sell a ‘woo’ product.

This is genuine fringe science! (and therefore very likely completely wrong :().

[Ducky]

Originally posted by Lucky
fowlsound: What I am trying to say is that this is not a case of random scientific-sounding phrases cobbled together in order to sell a ‘woo’ product.

This is genuine fringe science! (and therefore very likely completely wrong :().


Yeah that nuance I missed ;)

I apologise for obtuse behavior.

Still, interesting to see what Harvey thinks of it.

[YouBelieveWHAT?]

Hi Fowlsound,

You have a physicist friend called Harvey?

IIRC Harvey's a big Rabbit (James Stewart film?).

So you're going to believe what a big Rabbit tells you - maybe you also need to check your medication, :D

Ok - Only joking - Ah, you realised that anyway.m :)

YBW

[Ducky]

Originally posted by YouBelieveWHAT?
Hi Fowlsound,

You have a physicist friend called Harvey?

IIRC Harvey's a big Rabbit (James Stewart film?).

So you're going to believe what a big Rabbit tells you - maybe you also need to check your medication, :D

Ok - Only joking - Ah, you realised that anyway.m :)

YBW

I did get a good laugh about that.

Actually, his name is Harvey Slatin, and he's a very tenacious 90 year old physicist that not only worked on the bomb under oppenheimer, but hits shamelessly on every woman in the room. Gotta love him.

[YouBelieveWHAT?]

I think I have a new hero to worship!

YBW

[jmercer]

Move over - so do I! :D

[Ducky]

Here's Harvey's reply, reprinted with permission:

...have read the article and have sent away for his theory and data supporting his theory. There are many questions to be anwered, namely, the photograph shows the space vehicle in lift off. No amount of electromagnetic energy can be generated to effect a lift off. Once in space even the smallest amount of energy can propel a space vehicle. We considered using nuclear enerrgy to propel an airplane, but that project failed because of shielding. However with unmanned vehicles, who cares. He claims to convert solar rays to electromagnetic energy. What happens when you are far from the sun and the amount of rays you can collect have been diminished by the remoteness? Our rockets in space tend to need very little expenditure of energy for propolsion. Finally the wave guides had better be darn good and the frequency low enough not to be a hazard to humans.
We had a theoretical project to collect solar emissions that miss the earth by could be collected on the moon. This would then be beamed back to earth by microwaves. Any additional energy beamed back to earth would raise the heat content of the earth and global warming could really take off.
I'll keep you posted.
Love Harvey


So possibly some valid points, but he's going to look into it deeper.

[jmercer]

Thanks, FS. I'll keep watching for an update. You're fortunate to know Harvey. :)

[Ducky]

Originally posted by jmercer
Thanks, FS. I'll keep watching for an update. You're fortunate to know Harvey. :)

I count that as a blessing every day :)

He's awesome.

[YouBelieveWHAT?]

If it wasn't for timezones I'd have beaten jmercer, so for now I'll just agree with him. :)

I have a holiday next week, so will be interested to see what's happened when I get back!


YBW

[kmortis]

John Jackson,
What exactly is the DTI SMART programme? He mentions that he was given a grant from the DTI (Dept of Trade and Industry) under the SMART programme. Since I'm an ignorant Yank, I have no idea what that is. A cursory Google produced links to other companies who have won it as an R&D effort of HM Gvmnt.

I assume that there are guidelines to this grant. Can we find out what level of proof is needed to be granted it? Also, is it a matter of public record? Can it be researched to see if he's giving us the straight poop?

[Ducky]

Harvey has informed me he has recieved further data, and is asking further questions.

More soon.

[jmercer]

BUMP, with hopes of eventual resolution. :)

[kmortis]

Originally posted by fowlsound
Harvey has informed me he has recieved further data, and is asking further questions.

More soon.

After thinking about this for the last couple of days, I think what we'll find is that the technology is possible (to create thrust with EMag, that is); but the system that this gentleman has proposed doesn't seem to be all that efficent and therefore not practical for lifting off the earth.

Or. he's a crank. Take yer pick. ;P

[TjW]

While I have no idea as to whether or not the technology could work, I think a great number of posters have missed the application that it is intended for.
It is not, so far as I can see, intended to be used for launch, but for "station keeping".
The Earth is not the idealized sphere of uniform mass so beloved of physics classes. It's got lumps and bumps and heavy spots and lighter spots. There's also the solar wind to consider. The long term effects are that satellite orbits don't stay in one place. They drift around.
Most satellites that need to be in a particular place at a particular time are launched with a maneuvering system. Now, gyros can change the satellite's attitude, but it requires reaction mass to change the satellite's orbit.
For some satellites, once that reaction mass is gone, it's effectively useless, so it's launched with a fair chunk of reaction mass.
With a reactionless thruster (should one exist), you wouldn't have to carry that mass to orbit, so either the satellite can be bigger or the booster can be smaller, or there can be multiple payloads.
The energy to change orbits can be gathered on-site by solar panels.
In that application, two grams of thrust might be enough. If enough energy is available, it can be applied all the time, to get the same effect as a shorter, higher power burn of a reaction control system.
So even a small thrust that did not require reaction mass could be enormously useful.

[kmortis]

Originally posted by TjW
While I have no idea as to whether or not the technology could work, I think a great number of posters have missed the application that it is intended for.
It is not, so far as I can see, intended to be used for launch, but for "station keeping".
The Earth is not the idealized sphere of uniform mass so beloved of physics classes. It's got lumps and bumps and heavy spots and lighter spots. There's also the solar wind to consider. The long term effects are that satellite orbits don't stay in one place. They drift around.
Most satellites that need to be in a particular place at a particular time are launched with a maneuvering system. Now, gyros can change the satellite's attitude, but it requires reaction mass to change the satellite's orbit.
For some satellites, once that reaction mass is gone, it's effectively useless, so it's launched with a fair chunk of reaction mass.
With a reactionless thruster (should one exist), you wouldn't have to carry that mass to orbit, so either the satellite can be bigger or the booster can be smaller, or there can be multiple payloads.
The energy to change orbits can be gathered on-site by solar panels.
In that application, two grams of thrust might be enough. If enough energy is available, it can be applied all the time, to get the same effect as a shorter, higher power burn of a reaction control system.
So even a small thrust that did not require reaction mass could be enormously useful.

Hrm...hadn't thought of that. It would be very well suited for that application. Although, it would be nice to see something like this for an actual launch vehicle.

[pmurray]

Hmm.

Well, amplification of an EM wave happens all the time - lasers, masers and so on. Cool.

These devices have to be pumped with energy - electrical or optical. These guys claim they are doing it directly with sunlight. Sounds unlikely. Sunlight is a real mix of frequencies. While the science might possibly be vaguely plausible, it's unlikely that these guys have done anything like it.

They claim that they can propel a spaceship with it. Woah! Conservation of momentum! Yes, it's possible to absorb one photon at high frequency and emit several at a lower frequency, but the momentum is the same because for photons, momentum is directly related to energy. So even if you could get 100% efficiency, you could do no better than a solar sail doing this. You could not, for instance, sail against the sun.