Using atmosphere as propellant

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

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MSimon
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Postby MSimon » Wed Jul 07, 2010 3:03 pm

The entire scheme sounds like some of the perpetual motion machines the US patent office gets plans for 10 times a day.

Actually the physics is rather solid and comes out of both Maxwell and quantum mechanics. What is lacking is SOLID experimental proof.
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GIThruster
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Postby GIThruster » Wed Jul 07, 2010 3:22 pm

Colonel_Korg wrote:
GIThruster wrote:And I will also beg to differ that we don't know how to make a reactionless drive. We do.


I followed NASA's Breakthrough Propulsion Labs work and I didn't see where the work on the Mach Effect thruster had been peer reviewed and that it would actually work. The entire scheme sounds like some of the perpetual motion machines the US patent office gets plans for 10 times a day. Does a charged capacitor have more mass than an uncharged one?

That's what the M-E thruster comes down to. If it really works and we have power available then we have our "inertia less" drive that the sci-fi writers have dreamed about for generations.

Experiments

In 2004, John G. Cramer, Curran W. Fey, and Damon V. Cassisi of the University of Washington reported that they had conducted tests of Woodward's hypothesis, but that results were inconclusive.

On January 20, 2006 Paul March and Andrew Palfreyman reported experimental results at an American Institute of Physics conference. Test results exceeded Woodward's predictions by one to two orders of magnitude.

In 2006, researchers at the Austrian Research Centers reported results of a study of the effect using a very sensitive thrust balance. Results did not seem to be in full agreement with the findings claimed by Woodward and collaborators. However, given the importance of the subject the researchers recommended further tests


So far, only Paul March has seen positive results. I would really want the M-E Trusters to work and produce large amounts of thrust so we can get out of this gravity well. But until we see the conclusive results from multiple reliable sources, then the M-E is still in the realm of sci-fi.


This is all only partially correct--no fault there, we're almost playing the telephone game here. . .

The work at Marshall by Tony Robertson had nothing to do with BPP and was several years after BPP closed shop. Tony didn't get to run the experiments he'd planned and nothing was ever written or reviewed. That's not because Tony wasn't focused but rather because he was reassigned as result of the decision for NASA to end all research into advanced propulsion, as result of defunding to pay for VSE.

Most of the work done in M-E research has been done by Dr. Woodward himself. He's the only person who has been working on this anything approaching full-time. All of his experiments have had success though some have been disappointing. The work by March has the largest claims, but that work did not provide adequate scientific controls (such as vacuum) to make hard claims. The claim concerning that thrust in excess of what Woodward's theory predicts was observed is inaccurate. Andrew Palfreyman extrapolated Woodward's theory into a predictive model and the thrusts observed by March were in excess of that prediction. However, Woodward has been very plain that his theory cannot be used to make predictions in Wormhole territory, and so the "prediction"is not Woodward's, it was March and Palfreyman's. Since that time, March has identified reasons that the predictive model was in error, so even that prediction is useless and the claim is out of place. Thrust was noted, but there is no correlation as to it's value as compared to prediction because a predictive model for this does not yet exist.

Most importantly above is your assertion that this has not been peer reviewed. This is correct. The experiments have not been peer reviewed except in forums like STAIF and SPESIF which are not what you'd call "peer review" forums. The early theoretical work has all been peer reviewed in places like Foundations of Physics and has emerged unscathed, but certainly there needs to be more stringent peer review of experiment, as well as replication of tests, just as soon as experiment produces results inspiring enough for this. So far, the test results of the MLT, the Rotator and the UFG have all been impressive that they show thrust (or in the case of the rotator--simple M-E) in vacuum under very controlled conditions. What we need to see is lots more thrust, and perhaps some scaling with things like voltage and frequency, and I'm sure people with purses will step forward and fund replications. Rarely does anyone do these things for free, at least not with the controls we need to see, like vacuum.

Colonel_Korg wrote:The entire scheme sounds like some of the perpetual motion machines the US patent office gets plans for 10 times a day. Does a charged capacitor have more mass than an uncharged one?


There's much more involved than charging and discharging the caps. Each time the cap is simultaneously charged then discharged, while accelerated, it generates an M-E or Mach Effect whereby the rest mass fluctuates both positively and negatively around the unfluctuated mass, at the second harmonic. So for example, if you have 2 grams of active mass, and generate an M-E of 50% fluctuation at say 50 Khz, then the mass will go to 3 grams, then down to 1 gram and back to 2 grams, at 100Khz. To produce thrust rather than just M-E, you need to rectify this fluctuation by pushing the active mass when it's heavy, and pulling it in the opposite direction when it's light--so the whole endeavor is more complex than you'd guess.

"Wormhole territory" occurs when the fluctuation is more than 100% because then you are temporarily generating exotic matter, that has negative mass and its negative inertia. So a 200% fluctuation of 2 grams would be positive fluctuation to 6 grams, and negative to -2 grams. It's precisely because we don't have experience handling exotic matter that Dr. Woodward refuses to extrapolate his theory as to what we ought to see when handling it, but his model DOES make predictions of what we ought to see outside wormhole territory or with fluctuations of less than 100%--which is where he does his experimentation and why he has smaller thrust figures than Paul March, who has worked in wormhole territory.
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DeltaV
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Postby DeltaV » Wed Jul 07, 2010 6:25 pm

More power to Plan A (pun intended). Back to Plan B in the interim:

KitemanSA wrote:SSTO, not hypersonic aircraft. But even so, if you have SSTO capability, tooling around in the atmosphere is still dumb. Sub-orbital skipping will get you there faster and you still won't have the atmospheric dwell. Dwelling in the atmosphere only makes sense if you DON'T have man rated vacuum capability.
...
SSTO, single stage TO ORBIT. Why would I NOT go to orbit if I want to go TO ORBIT? Makes no sense to me. If you want to talk about SSNTO (single stage not to orbit) fine, but please don't use it to attempt to denegrate my statements wrt a SSTO vehicle.

You are missing the point. Would you rather launch an SSTO to orbit from sea level, or from a 100K ft high plateau? . It's NOT a rocket OR a hypersonic vehicle before then. Polywell raises the "surface" you are "launching" from. And you reach that 100K ft plateau without needing to burn thousands and thousands of gallons of fuel or fuel/oxidizer. That's an advantage whether your "launch" speed is 3000 ft/s, 1500 ft/s, or 0 ft/s. I'm not talking about going hypersonic BEFORE the QED-ARC REB is switched on. The hypersonic heating, and the transition from all-air to all-onboard-propellant, occur AFTER the REB is switched on. Before REB-on it's a mid-supersonic airplane consuming only small amounts of H and B11. Yeah, the airframe design is not optimal for that flight regime. It doesn't have to be. You can fuse all day, and have power to spare prior to REB-on. WHY NOT employ that capability to use the air-space ports of your choice and the orbits of your choice. About suborbital skipping -- If that doesn't eat too far into the propellant mass needed to reach orbit, fine. Add that as an optional mode. BUT, if you want to operate to/from your choice of air-space ports, instead of just Edwards AFB or Cape Canaveral, you're going to have to enter the civilian traffic control system. When you do this, you'll want to be an airplane, not a fuel-hungry rocket or a fuel-depleted hypersonic glider. Stop thinking like NASA.

Colonel_Korg wrote:Lets assume that we do the same with our electric fan jet. So maybe the fanjet regime will be comparable to Blackswift's flight envelope of 0-3, (electric-turbofan) then 3-6 (ram-arc-jet?) Still leaves Mach 6-25 to get to orbit.

QED-ARC is not limited to M6. M2.5 to orbit. The reaction mass used transitions smoothly from all-air to all-onboard-propellant as the atmosphere thins out.

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Postby KitemanSA » Wed Jul 07, 2010 6:34 pm

DeltaV wrote:
KitemanSA wrote:SSTO, not hypersonic aircraft. But even so, if you have SSTO capability, tooling around in the atmosphere is still dumb. Sub-orbital skipping will get you there faster and you still won't have the atmospheric dwell. Dwelling in the atmosphere only makes sense if you DON'T have man rated vacuum capability.
...
SSTO, single stage TO ORBIT. Why would I NOT go to orbit if I want to go TO ORBIT? Makes no sense to me. If you want to talk about SSNTO (single stage not to orbit) fine, but please don't use it to attempt to denegrate my statements wrt a SSTO vehicle.
You are missing the point. Would you rather launch an SSTO to orbit from sea level, or from a 100K ft high plateau? . It's NOT a rocket OR a hypersonic vehicle before then. ...I'm not talking about going hypersonic BEFORE the QED-ARC REB is switched on.
Well ya see, we were discussing different things. My first foray into this topic was in response to a "keeping the skin cool" statement wrt the SR71. That implies very high speed thru the atmosphere for long periods. My point, with SSTO, need not be an issue. K?

Oh, and by the way, with a an air-breathing Polywell, I don't think I'd care much cuz I'd be able to get to 100k' very quickly, with little fuel use, and without TOO great a thermal load. IMHO.

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Postby DeltaV » Wed Jul 07, 2010 6:35 pm

Colonel_Korg wrote:Can we somehow use that voltage+current in an air breathing arc jet?

That was touched on here:
http://www.talk-polywell.org/bb/viewtopic.php?t=2287

The arc heaters used in hypersonic test tunnels can produce about half the chamber pressure of an SSME. Probably not enough flow rate for propulsion though. They also use much lower voltage than Polywell would output.

GIThruster
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Postby GIThruster » Wed Jul 07, 2010 7:26 pm

If you don't have the flow rate, perhaps a pulse detonation version? That's even closer to a lighting strike. . .
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Aero
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Postby Aero » Thu Jul 08, 2010 1:16 am

Hmm - wikipedia gives quite different stats by half.
http://en.wikipedia.org/wiki/Space_Shuttle_main_engine
Aero

DeltaV
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Postby DeltaV » Thu Jul 08, 2010 3:09 am

I based my earlier chamber pressure statement on the Wikipedia SSME value of 204 bars and arc heater info at the AEDC website.

GI, that's an interesting idea. Chemical PDEs are limited to around M5 or 6 I think, but maybe that limit wouldn't apply to an "arc pulse engine" (APE) since chemicals are not the driver.

I still think REB would be more effective.
Last edited by DeltaV on Thu Jul 08, 2010 4:02 am, edited 1 time in total.

GIThruster
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Postby GIThruster » Thu Jul 08, 2010 3:57 am

I'm pretty sure you'd still have an upper limit but it would be much higher than with chemical since you don't need to mix combustibles, just hit whatever you have with your alpha stream. A PDE would be easier with a DPF since it's not intended to operate in stasis. With a Poly, you have to switch off the stream without interrupting the reactor, so best is probably to route the HV to another task. If you try to store it in caps, you have the same HV handling mass issue you're trying to avoid.

One solution might be to reroute the power intermittently to the skin of the craft to build a plasma envelope. IIRC, Boeing or LockMart is looking at this to mitigate shock waves for flying supersonic over land. Could be you can remove some of the TPS needs by building such an envelope.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

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Postby WizWom » Fri Jul 09, 2010 1:43 am

GIThruster wrote:just hit whatever you have with your alpha stream.

If the waste product alphas recirculate, there is no "Alpha stream" as such.
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MSimon
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Postby MSimon » Fri Jul 09, 2010 4:09 am

WizWom wrote:
GIThruster wrote:just hit whatever you have with your alpha stream.

If the waste product alphas recirculate, there is no "Alpha stream" as such.


Actually there is. The magnetic fields focus the alphas into beams. Obviously the focus is not optimized. No doubt a deeper took into beams will be taken once net power is in sight.

It is a relatively unimportant question until the engineering of direct conversion becomes important. We are probably a ways from that.
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GIThruster
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Postby GIThruster » Fri Jul 09, 2010 4:27 am

Yes well, the best study I've seen of this portion of the issue was a study done at AFRL on fusion drives. IIRC, what they were proposing was a trimodal operation where one uses the alphas in all three modes. In the launch mode you have an airbreather (which will tear up normal runways at launch, BTW), in high altitude you have much less thrust but higher Isp as you dump stored propellant into the alpha and in space you have just the alpha stream which provides very little thrust but constant acceleration. I think the study was run by Frank Meade and I'm sure I posted it over at NSF but blamed if I can find it. Was a whole computer ago and I lost a lot of stuff during my first and only crash.

IIRC, they were looking at DPF and recommending storing N2 for propellant since it's not so corrosive at high temp and pressure. Certainly if you had a poly that can run on air, you've got to be tempted to build an ACES and fly a ship just to harvest N2 and put it in orbit.

The study was for a HTHL SSTO craft like Bussard's but as I recall they did a lot more calcs of how much to "dilute the alpha stream" and showed the comparisons of various dilutions. The more you dilute, the more thrust you get, but the more propellant you burn. They didn't raise the question raised by DeltaV whether you could get enough air for a breather, and that's a valid concern, IMHO. Was just maybe 15 page study.
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