Em drives

[jroly]

I am going to call BS on this. The Website looks very amature, definitively not professional.

18.
Q. How can the EmDrive produce enough thrust for terrestrial applications?
A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.

So the power of one regular microwave oven is enough to make large cars fly????

A comprehensive design study has shown that an early Demonstrator Vehicle could be flying within 3 years of the start of a 2nd generation EmDrive development programme.

Their demonstrator vehicle looks a lot like the Orbiter Shuttle-A :hmm:

Sorry to sound negative but it looks suspect.

 

[kamaz]

I am going to call BS on this. The Website looks very amature, definitively not professional.

So, you're saying that if something has a professional website then it is not a scam?

NB check out http://www.berkshirehathaway.com/

 

[jroly]

Ok your point noted on that kamaz, but that is not the only thing.

The guy is saying things like $224 per kg to orbit and flying cars etc. Hardly anyone is aware of this, or were aware of it, only one independent party has tested the emdrive and said the results were interesting.

Any serious scientist at this early stage would not be making presentations about flying cars and comparing payload to orbit etc.

 

[Urwumpe]

So, you're saying that if something has a professional website then it is not a scam?

NB check out http://www.berkshirehathaway.com/

That page looks very professional to me. Not a single bit wasted. :tiphat:

But really: The scam factor is not the lack of a professional website, but the lack of a professional attitude.

 

[jroly]

He says in the presentation the reason emdrive is able to deliver 4 times more mass to GSO than LEO is because of the lower orbital velocity in GSO :shrug:

 

[Andy44]

He says in the presentation the reason emdrive is able to deliver 4 times more mass to GSO than LEO is because of the lower orbital velocity in GSO :shrug:

That sounds like the kind of "logic" moon hoaxers use to explain why a Saturn V cannot possibly transport people to the moon.

 

[boogabooga]

Regarding the Cannae drive website, I want to point something out.

They claim to have numerical results that support their position.

Well, computer simulations are only coded using known physical laws. If they get a result that shows the existence of an unbalanced force in the simulation, it is because the simulation was coded to allow such a result.

It is an inherent contradiction to claim a new and previously unknown phenomenon of physics AND claim that numerical analysis (simulation) supports its existence.

 

[Quick_Nick]

Regarding the Cannae drive website, I want to point something out.

They claim to have numerical results that support their position.

Well, computer simulations are only coded using known physical laws. If they get a result that shows the existence of an unbalanced force in the simulation, it is because the simulation was coded to allow such a result.

It is an inherent contradiction to claim a new and previously unknown phenomenon of physics AND claim that numerical analysis (simulation) supports its existence.

If you can find and watch the video about their numerical results, he reiterates over and over that they only account for conventional physics and that his unbalanced forces theory is the 'only claim' that isn't conventional physics. I could be misunderstanding but that seemed the case to me. I'll try to embed the video here later.

 

[Urwumpe]

Numerical simulation proves little actually... you use numerical simulation for predicting experimental results or verifying that the results of an experiment are caused by the effects of a hypothesis.

Claiming that a numerical simulation proves that a technology works is wrong - what counts is the reality. Even if the simulation is conform to the experiment, this must not mean, that the theory behind the simulation is correct - especially in theoretical physics, you have many theories, which have similar current experimental results, but currently unmeasurable effects, which could prove them wrong.

 

[boogabooga]

If you can find and watch the video about their numerical results, he reiterates over and over that they only account for conventional physics and that his unbalanced forces theory is the 'only claim' that isn't conventional physics. I could be misunderstanding but that seemed the case to me. I'll try to embed the video here later.

That's my point. The simulation will only include "conventional" physics. If "unconventional" physics appear in the simulation, it's because the simulation was already programmed to include it.

You can't use a simulation of conventional physics as a validation of unconventional physics.

 

[kamaz]

Actual papers from AIAA/ASME/SAE/ASEE Joint Propulsion Conference (2014) .

Also in this reddit thread someone says what was actually shown at the conference:

I was actually at these presentations. There are two competing theories as to how it works. Fetta believes that it works based on asymetry in the design, while White believes it works on pushing against the quantum vacuum. They did 3 cases. An asymetric, a symetric, and a null test. The Asymetric produced thrust at the same rate in all tests, the symmetric produced varying levels of thrust depending on its orientation, and the null test produced no net thrust above background levels.

They actually used a few shapes. The asymmetric test was a very flat cyllindrical chamber, about 10 cm high by maybe 30 cm in diameter. One face had short slots (about 4 x 1 cm) carved into it. The symmetric test article was the same as the first, except without the slots. The null case was just a circuit to dissipate the current induced by the rf waves. They also did a test on a generally bell shaped container. I didn't get to see that one in person but based on the pictures I would say its diameter at the top was around 10 cm and at the bottom was around 30 cm. It also produced net thrust but with lower efficiency than the regular cyllinder. Dr. White said that the bell shaped device incorporated findings from the chinese test, so I assume that one had a similar shape.

I'm using the term null test differently than the paper. When I say null test, I mean the RF load that was supposed to not do anything to prove that the testing apparatus was not the cause of the anomalous readings.

The paper refers to the symmetric test aparatus as the null test, because it was meant to test a prediction of Fetta's theory on how the device produces thrust (that the force is produced by an imbalance of the lorentz force caused by the asymmetric chamber). This test seems to indicate that Fetta's theory is incorrect (or at the very least innacurate). Dr. White's theory on how thrust is produced however predicted that both test articles should produce thrust, which they did.

I'm not saying that the abstract is wrong, I'm saying it is incomplete and that quote, taken out of context, implies the opposite of what actually happened.

Now the debate on this subject is not over. Fetta sticks to his theory, and is planning on publishing a paper in the next few months (probably around october) on the subject. I do not speak to the validity of either side's claim, I'm merely stating that the issue is different from the one /u/IsTom thinks it is.

Note: Fetta is the guy behind Cannae LLC. White is NASA JSC employee.

Also from the same thread, by someone else:

The drive NASA tested was not the same one that the Chinese tested. NASA tested Guido Fetta's "Cannae Drive", while the Chinese tested Roger Shawyer's "EmDrive."

At the end of the article, Shawyer is quoted as saying that he believes Fetta's drive works by the same mechanism as his own, but is weaker because [reasons not very clearly explained because Wired article.]

 

[Quick_Nick]

Okay. That helps clear up a lot. (Namely the null confusion)
It seems to me that Fetta is very likely wrong. His theory is so simple that it should be obvious whether or not it would work. And this introduction of White explains why Fetta makes no mention of quantum vacuum. (although it's called Q-Drive!!) And we see why NASA thinks this could be a quantum effect even without requiring them to subscribe to Fetta's physics.

 

[boogabooga]

Actual papers from AIAA/ASME/SAE/ASEE Joint Propulsion Conference (2014) .

I enjoy how Fetta calls it "Novel" and the NASA team calls it "Anomalous"

 

[Quick_Nick]

I enjoy how Fetta calls it "Novel" and the NASA team calls it "Anomalous"

One runs a business and the others run scientific tests.

 

[kamaz]

He says in the presentation the reason emdrive is able to deliver 4 times more mass to GSO than LEO is because of the lower orbital velocity in GSO :shrug:

In Orbiter terms, he wants to use e-m drive as hover thruster and chemical engine as main thruster. The vehicle uses hover (e-m) thruster to lift itself to orbital altitude and then fires main thruster to accelerate horizontally to stay in orbit. As higher orbits have lower velocity, higher orbit will use less fuel for the main engine. Hover fuel (i.e. energy) is assumed to be infinite (solar cells, nuclear source, etc.).

What he doesn't realize is that if he has an e-m thruster capable of producing 1g acceleration (which is a requirement for hovering), then just put two of these on the vehicle, your net acceleration is now +1g up, and you can launch upwards and then pitch over exactly the same way a rocket does...

---------- Post added at 10:21 PM ---------- Previous post was at 10:14 PM ----------

(Note that the video is from 2007)

 

[jedidia]

A. The second generation engines will be capable of producing a specific thrust of 30kN/kW. Thus for 1 kilowatt (typical of the power in a microwave oven) a static thrust of 3 tonnes can be obtained, which is enough to support a large car. This is clearly adequate for terrestrial transport applications.

Now give me a break here, there's only two possible ways I can deal with that statement.
a) I'm understanding something completely wrong in the quote or my physics are very rusty, or
b) someone is talking quite ridiculously out of his ass.

As far as I can tell, when lifting a tonne (of whatever) for one second with a force of 30 kN, against the earths gravitational field, results in an acceleration of 20.19 m/s^2 (30 m/s^2 total acceleration, minus 1 G). In other words, you can get it to 20.19m "altitude" in one second.

Now the problem I see with that is that lifting 1000 kg (9806.65 N) for 20.19 m represents a workload of a whopping 198 kJ (slightly rounded).

The engine was consuming 1 kW for 1 second... in other words, the actual work invested is a lousy 1000 Joules.

Even if the thing produces thrust in some weird way, I'd say it's a pretty save bet that it doesn't release (orders of magnitude) more energy than it uses to do so. :facepalm:

 

[kamaz]

Earth's gravity exerts pull of 10N/kg. Hovering (a.k.a. anti-gravity) requires you to exert 10N/kg in the opposite direction.

10N/kg * 3'000kg = 30000N = 30kN.

 

[Face]

Even if the thing produces thrust in some weird way, I'd say it's a pretty save bet that it doesn't release (orders of magnitude) more energy than it uses to do so. :facepalm:

Oh come on! The perpetuum-mobile builders already gathered and prepared the party. :rofl:

Seriously, though, I'll really believe it if it flies. The last hick-up lasted some weeks, then it was silent for a year. So let's wait and see.

 

[Urwumpe]

Earth's gravity exerts pull of 10N/kg. Hovering (a.k.a. anti-gravity) requires you to exert 10N/kg in the opposite direction.

10N/kg * 3'000kg = 30000N = 30kN.

Yes, and just countering gravity still consumes energy.

 

[kamaz]

British patent office has a good rule: perpetual motion machines can be patented if you can deliver a working prototype.

---------- Post added at 11:23 PM ---------- Previous post was at 11:17 PM ----------

Yes, and just countering gravity still consumes energy.

Indeed. What is actually dubious in this argument is the 30kN/kW figure.