Author Topic: Propellantless Field Propulsion and application  (Read 663919 times)

Offline kurt9

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Re: Propellantless Field Propulsion and application
« Reply #1640 on: 03/29/2012 02:44 PM »
And we're to have a definitive answer to both concepts by the end of this summer. Is this correct?

Offline Star-Drive

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Re: Propellantless Field Propulsion and application
« Reply #1641 on: 03/30/2012 04:37 AM »
And we're to have a definitive answer to both concepts by the end of this summer. Is this correct?

Dr. White and I hope to have at least two Q-Thruster test articles run through their paces by the end of September.  We also hope to have started the warp-field interferometer work as well, but Sonny keeps getting dragged off to work on other more pressing NASA projects at the moment, so we will see how far that Eagleworks project gets when Sept shows up. 

As far as the M-E work is concerned, you'll have to ask Dr. Woodward what his M-E test schedule is going to be for the rest of this year, but at least he has already demontrated a 10uN thruster back in January that could be the M-E in action or it could be something else equally interesting, but he won't be able to tell IMO until he can figure out the frequency scaling of the thrust effect he is measuring with his current shuttler test article.  Whether Dr. Woodward will be able to accomplish that feat this year is TBD.

Best,
« Last Edit: 03/30/2012 04:38 AM by Star-Drive »
Star-Drive

Offline tdperk

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Re: Propellantless Field Propulsion and application
« Reply #1642 on: 03/31/2012 12:26 PM »
"Let's hope that at least one of them is near the mark..."

And clearly enough so it is easily accepted.

Ignaz Semmelweiss.

Offline MP99

Re: Propellantless Field Propulsion and application
« Reply #1643 on: 04/01/2012 03:01 PM »
Harry White's and Paul March's PDF at NETS2012 about "Advanced Propulsion Physics: Harnessing the Quantum Vacuum"

http://www.lpi.usra.edu/meetings/nets2012/pdf/3082.pdf

Quote
Historical test results
have yielded thrust levels of between 1000-4000 micro-
Newtons, specific force performance of 0.1N/kW,
and an equivalent specific impulse of ~1x1012 seconds.

Where does that Isp come from?

cheers, Martin

See attached slide.

Thanks, but I'm not seeing that derivation unless your power source is pure matter/anti-matter with 100% conversion efficiency to usable power. ISTR you mentioning a spacecraft a while ago powered by an H2/O2 power-cell. By retaining the reactants, only the mass of the power output (by E=MC2) goes overboard.

If I've remembered that correctly, that seems to be completely the wrong way to analyse the situation. Instead, you are producing power by reacting H2 & O2. To calculate Isp correctly, the reaction product (water) should be sent overboard, and the thrust equated to the rate of consumption / disposal of hydrolox.

cheers, Martin

Martin:

   Try to remember that we are NOT talking about rockets in this example, which you are trying to do, though I tried to use a standard rocket parameter to bridge the gap between the two propulsion concepts and to demonstrate the performance enhancements that such a field propulsion device could bring to bear on the tyranny of the rocket equation.   Instead we are talking about gravity/inertial (G/I) field propulsion systems that use the ambient G/I field to generate the Mach-Effect (M-E) momentum transfers from the vehicle to the field and thus to the rest of the universe that created this field in the first place.  So the G/I field propulsion process does not require the expulsion of mass or E&M radiation away from the vehicle to generate the noted reactive forces, for it directly reacts with the G/I field instead just like a ship uses its propeller to interact with the ocean's water to generate thrust.

Paul,

completely clear on the "propellantless" element of the topic title, but you're really missing the point here.

Isp relates the consumption of consumables against the amount of impulse generated. If you are producing electricity via H2/O2 in a fuel cell, a kilogram of consumables will be converted to a certain amount of impulse through the thruster. That is clearly the basis on which Isp is calculated, and works irrespective of whether you throw the reactants overboard.



Again, I ask the simple question - given "specific force performance of 0.1N/kW", how much impulse could you generate from consuming 1kg of H2/O2?

I presume you'd need to start from the energy density of H2/O2, apply efficiency of the fuel cell and note losses in your electrical sub-system to calculate net energy at the thruster from 1kg of fuel. If you multiply this by "specific force performance of 0.1N/kW" shouldn't it give Isp in m/s? (Or divide by g to give it in seconds.)

For instance, if H2 has an energy density of 123 MJ/kg, then H2/O2 at stochiometric ratio has energy density of 13.66 MJ/kg.

Assuming 33% combined efficiency in fuel cell output and conditioning power for the MLT (a WAG!), the thruster will see 4.55 MJ/kg of fuel consumed.

4550 KJ/kg * 0.1 N/(kJ/s) = 455 N.s/kg (by mass) = 455 m/s. Divide by g to get a specific impulse of 46.5s (by weight), about 1/10th that of an RL-10.

Obviously, if you have better figures for H2 energy density (apologies for using Wiki figures), or efficiency of the fuel cell and electrical sub-system that would affect the final result.



Of course, you're not limited by chemical energy densities - power it from a solar cell and you can keep going for ever. However, with SEP having such high Isp it will compete quite well for Dawn-like solar powered missions.

cheers, Martin

Offline QuantumG

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Re: Propellantless Field Propulsion and application
« Reply #1644 on: 04/16/2012 07:25 AM »
"Alternative derivation of the Feigel effect and call for its experimental verification" - O. A. Croze

http://arxiv.org/abs/1008.3656

Maybe sometime in the next decade someone will test it :)

Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline aceshigh

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Re: Propellantless Field Propulsion and application
« Reply #1645 on: 07/05/2012 12:18 PM »
funny that this thread has died here, since there were plenty of news posted at Talk Polywell forum and NextBigFuture blog.

Offline Sith

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Re: Propellantless Field Propulsion and application
« Reply #1646 on: 08/10/2012 02:20 PM »
Any recent news?

Offline aceshigh

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Re: Propellantless Field Propulsion and application
« Reply #1647 on: 08/10/2012 02:34 PM »
there are several recent news and discussions at Talk Polywell...

Offline Sith

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Re: Propellantless Field Propulsion and application
« Reply #1648 on: 08/10/2012 05:30 PM »
there are several recent news and discussions at Talk Polywell...
I haven't been here since several months and I lost the records. Can you update me pls.

Offline sanman

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Re: Propellantless Field Propulsion and application
« Reply #1649 on: 08/17/2012 09:52 PM »

completely clear on the "propellantless" element of the topic title, but you're really missing the point here.

Isp relates the consumption of consumables against the amount of impulse generated. If you are producing electricity via H2/O2 in a fuel cell, a kilogram of consumables will be converted to a certain amount of impulse through the thruster. That is clearly the basis on which Isp is calculated, and works irrespective of whether you throw the reactants overboard.

But dude, as the ESA's SMART-1 probe to the Moon showed, you don't even need all your consumables to even be onboard in the first place. Well, sure the propellant for that mission was onboard the spacecraft, but the energy used to accelerate and eject it wasn't - it was coming from the Sun.
So you don't necessarily need your energy to come from an onboard fuel cell, because it could come from solar power even.

Your argument seems to be that action-reaction by propellant expulsion is always going to be more efficient than action-reaction by other means such as Mach-Woodward (ie. so why bother with Mach-Woodward at all?)

Well, you may not always be able to gather propellant mass along the journey if you run out, but you'll probably still be able to gather light energy.

« Last Edit: 08/17/2012 09:58 PM by sanman »

Offline 93143

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Re: Propellantless Field Propulsion and application
« Reply #1650 on: 08/17/2012 10:29 PM »
Your argument seems to be that action-reaction by propellant expulsion is always going to be more efficient than action-reaction by other means such as Mach-Woodward (ie. so why bother with Mach-Woodward at all?)

Well, you may not always be able to gather propellant mass along the journey if you run out, but you'll probably still be able to gather light energy.

Don't worry about it; it's not true.  At least theoretically.  His conclusion is only valid for the low-performance thrusters demonstrated to date.

WarpStar 1, IIRC, was designed assuming 1 N/W thrusters were available.  Last I heard, there was no theoretical reason why this would not be possible, though the new force prediction derivation may have something to say on the feasibility front...  anyway, let's assume that number for now.

1 N/W, in the context of a conventional rocket, means that mdot*v_exh = 0.5*mdot*v_exh^2 (assuming 100% efficiency).  In other words, v_exh = 2 m/s, for a specific impulse of 0.204 seconds.

With a Mach-effect thruster capable of 1 N/W, hydrogen/oxygen consumption to produce one newton of thrust with fuel cells at 60% efficiency relative to the HHV would be ~1e-7 kg/s, leading to an effective v_exh based on thrust/mass flow of ~9.5 million m/s, or a specific impulse of about 970,000 seconds.  Even using MP99's much more pessimistic power system assumptions, you're still looking at about 464,000 seconds.  Assuming you dump the resulting water overboard, which I would not necessarily recommend...

In other words, the operating principle of a Mach-effect thruster decouples the specific impulse from the thrust-to-power ratio.
« Last Edit: 08/17/2012 10:54 PM by 93143 »

Offline sanman

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Re: Propellantless Field Propulsion and application
« Reply #1651 on: 08/18/2012 12:27 AM »
I don't even know what this grandly named WarpStar1 is, so I guess I'll have to look it up in the pantheon of mythological superships.

But electric charge is only one example of increased energy density. In principle, you could claim the same Mach-Woodward effect by high-cyclical manipulation of magnetic spin, strong force, etc.

What would it take to utilize these other forces for Mach-Woodward experiments?

Offline MP99

Re: Propellantless Field Propulsion and application
« Reply #1652 on: 08/18/2012 10:06 AM »

completely clear on the "propellantless" element of the topic title, but you're really missing the point here.

Isp relates the consumption of consumables against the amount of impulse generated. If you are producing electricity via H2/O2 in a fuel cell, a kilogram of consumables will be converted to a certain amount of impulse through the thruster. That is clearly the basis on which Isp is calculated, and works irrespective of whether you throw the reactants overboard.

But dude, as the ESA's SMART-1 probe to the Moon showed, you don't even need all your consumables to even be onboard in the first place. Well, sure the propellant for that mission was onboard the spacecraft, but the energy used to accelerate and eject it wasn't - it was coming from the Sun.
So you don't necessarily need your energy to come from an onboard fuel cell, because it could come from solar power even.

Your argument seems to be that action-reaction by propellant expulsion is always going to be more efficient than action-reaction by other means such as Mach-Woodward (ie. so why bother with Mach-Woodward at all?)

Well, you may not always be able to gather propellant mass along the journey if you run out, but you'll probably still be able to gather light energy.

You do seem to have missed the final paragraph of that post:-

Of course, you're not limited by chemical energy densities - power it from a solar cell and you can keep going for ever. However, with SEP having such high Isp it will compete quite well for Dawn-like solar powered missions.

cheers, Martin

Offline MP99

Re: Propellantless Field Propulsion and application
« Reply #1653 on: 08/18/2012 02:53 PM »
Your argument seems to be that action-reaction by propellant expulsion is always going to be more efficient than action-reaction by other means such as Mach-Woodward (ie. so why bother with Mach-Woodward at all?)

Well, you may not always be able to gather propellant mass along the journey if you run out, but you'll probably still be able to gather light energy.

Don't worry about it; it's not true.  At least theoretically.  His conclusion is only valid for the low-performance thrusters demonstrated to date.

WarpStar 1, IIRC, was designed assuming 1 N/W thrusters were available.  Last I heard, there was no theoretical reason why this would not be possible, though the new force prediction derivation may have something to say on the feasibility front...  anyway, let's assume that number for now.

1 N/W, in the context of a conventional rocket, means that mdot*v_exh = 0.5*mdot*v_exh^2 (assuming 100% efficiency).  In other words, v_exh = 2 m/s, for a specific impulse of 0.204 seconds.

With a Mach-effect thruster capable of 1 N/W, hydrogen/oxygen consumption to produce one newton of thrust with fuel cells at 60% efficiency relative to the HHV would be ~1e-7 kg/s, leading to an effective v_exh based on thrust/mass flow of ~9.5 million m/s, or a specific impulse of about 970,000 seconds.  Even using MP99's much more pessimistic power system assumptions, you're still looking at about 464,000 seconds.  Assuming you dump the resulting water overboard, which I would not necessarily recommend...

In other words, the operating principle of a Mach-effect thruster decouples the specific impulse from the thrust-to-power ratio.

Agree that if you can improve the efficiency of conversion of power to thrust by a factor of 10,000, then the Isp will also improve by the same factor. The reference given was for 0.0001 W/N.

Quite frankly, the difference between 33% & 60% conversion of chemical energy to MHz or GHz driving current for the MLT (fuel cell efficiency, DC-to-AC conversion, presumed cooling for the power electronics and thrusters, etc, etc) is just lost in the noise - only increases Isp to 84.5s with a 0.0001 N/W thruster - still gives ballpark-a-million-seconds with 1 N/W.

I don't think a Dawn-type mission would gain any value from retaining the reactants after they've produced power, but agree that you'd probably retain it in a vessel carrying Humans or a robotic vessel where water is one of the delivered cargos.

BTW, I also mis-spoke when I said that the resulting water needed to be dumped overboard to calculate Isp (though it is if you want to apply the rocket equation). Was trying to say (very poorly) that the mass that has to be counted is the rate at which propellant or reactants is consumed, not the E=mc2 equivalent mass of just the energy released.

cheers, Martin

Offline 93143

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Re: Propellantless Field Propulsion and application
« Reply #1654 on: 08/18/2012 08:42 PM »
Technically, if you retain the reaction products you can still use the rocket equation - your Isp becomes the number Star-Drive uses.  And your mass ratio becomes ~1...

Offline mboeller

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Re: Propellantless Field Propulsion and application
« Reply #1655 on: 09/02/2012 11:53 AM »
GeeGee just posted on talk-polywell.org that Prof. Woodward book "Making Starships and Stargates: The Science of Interstellar Transport and Absurdly Benign Wormholes" can now be preordered at amazon:

http://www.amazon.com/Making-Starships-Stargates-Interstellar-Exploration/dp/1461456223/ref=pd_rhf_gw_p_t_1

I have already preordered the book :)

Offline Star-Drive

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Re: Propellantless Field Propulsion and application
« Reply #1656 on: 09/15/2012 11:45 PM »
GeeGee just posted on talk-polywell.org that Prof. Woodward book "Making Starships and Stargates: The Science of Interstellar Transport and Absurdly Benign Wormholes" can now be preordered at amazon:

http://www.amazon.com/Making-Starships-Stargates-Interstellar-Exploration/dp/1461456223/ref=pd_rhf_gw_p_t_1

I have already preordered the book :)

Folks:

I haven't posted over here at NSF lately becuase there wasn't much to report on, but I think you might find the attached slides from Jim Woodward's latest PZT stack experiments of interest.  Dr. Woodward is now actually getting some respectable thrust levels that are now over 30 dB (~130 uN) above the ~0.1 micro-Newton (uN) noise floor of his ARC-Lite torque pendulum located at his CSUF laboratory.  A few slides reflecting the N5 Test article and thrust traces are attached.  The next things to do is to make this just-so cycle-15 data run example the norm instead of the exception.  That will happen when Woodward's team can find one or more ways to phase and frequency lock his N5 PZT-Stack's mechancial and electrical resonant frequencies.

Best,
« Last Edit: 09/16/2012 02:17 PM by Star-Drive »
Star-Drive

Offline sanman

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Re: Propellantless Field Propulsion and application
« Reply #1657 on: 09/16/2012 11:07 PM »
So with 130 uN of thrust, how long would it take to get a small nanosat or cubesat to the Moon from LEO?

Offline simonbp

Re: Propellantless Field Propulsion and application
« Reply #1658 on: 09/17/2012 06:22 AM »
Well, a cubesat has a max mass of 1.3 kg, and so the acceleration (assuming all the Q thrust bits fit in the 1.3 kg) would be 0.1 mm/s2 or 0.00864 km/s per day. Accounting for gravity and drag losses and etc, it's about 4 km/s to get to the Moon on a low-thrust trajectory, which means roughly 1.25 years. Enough for a powerful demonstration, but not immediately practical.

And, that's assuming you can cram enough solar cells in the cubesat package.

Offline A_M_Swallow

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Re: Propellantless Field Propulsion and application
« Reply #1659 on: 09/17/2012 05:51 PM »
Well, a cubesat has a max mass of 1.3 kg, and so the acceleration (assuming all the Q thrust bits fit in the 1.3 kg) would be 0.1 mm/s2 or 0.00864 km/s per day. Accounting for gravity and drag losses and etc, it's about 4 km/s to get to the Moon on a low-thrust trajectory, which means roughly 1.25 years. Enough for a powerful demonstration, but not immediately practical.

And, that's assuming you can cram enough solar cells in the cubesat package.

Which implies that if the thrust can be doubled the trip will take about 8 months.  A bit long for a masters degree but as the experimental part of a PHD it may be viable.

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