Re: Metastable metallic hydrogen propulsion

[spudboy100 via Everything List]

Hmm Professor, I am thinking metallic h2 as a primo fusion fuel. Forget 
magnetic fusion, use inertial confinement fusion against metallic targets. 
Having said this, it's probably an energy sink, with the immense pressures 
needed to form metallic hydrogen. 



-Original Message-
From: Hans Moravec 
To: 'Chris de Morsella' via Everything List 
Sent: Thu, Jan 26, 2017 7:23 pm
Subject: Metastable metallic hydrogen propulsion

Something like antimatter propulsion, but much easier?

Metallic hydrogen: The most powerful rocket fuel
http://iopscience.iop.org/article/10.1088/1742-6596/215/1/012194/meta

Hydrogen Squeezed Into a Metal, Possibly Solid, Harvard Physicists Say
https://www.nytimes.com/2017/01/26/science/solid-metallic-hydrogen-harvard-physicists.html


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Re: Metastable metallic hydrogen propulsion

[Hans Moravec]

That's pretty consistent with the first paper, which only claimed a
rocket chamber temperature of ~6,000K for pure metallic hydrogen.
Diluting it with LH2 or water was just an idea to reduce the temperature
to something more manageable, at the cost of specific impulse.

Can't do the calculations myself, but it would surprise me to find
that STP chemical bond calculations still apply at 5 million
atmospheres, with electrons squeezed out from between the
hydrogen nuclei and freely roaming metal.
(The metastability must be some kind of collective interaction,
like the high temperature superconductivity metallic hydrogen
is also often predicted to possess)

Another amateur take on it: all that squeezing must put quite a
bit of energy into the hydrogen, that wasn't there at the start.



> On Jan 27, 2017, at 00:01 , Brent Meeker  wrote:
> 
> First, the H atoms in metallic hydrogen are already bound to other H atoms, 
> so you don't get that H+H=H2+436kJ/mol.  Second, H2+O=H2O+517kJ/mol.  Since a 
> mol of water is 9 times as heavy as a mol of H2 it's sonic velocity is 3 
> times lower.  So even if you could take advantage of the H+H reaction the Isp 
> would only be 3 times as high.  Still far lower than nuclear rocket and 52e3K.
> 
> Brent
> 
> On 1/26/2017 8:05 PM, Hans Moravec wrote:
>> I think the intent is that metallic hydrogen alone is the fuel,
>> as a metastable way of storing some fraction of atomic
>> hydrogen recombination energy.  H + H -> H2 at 52,000K
>> 
>>> On Jan 26, 2017, at 20:51 , Brent Meeker  wrote:
>>> 
>>> Makes no sense.  Isp it just exhaust velocity which depends on the energy 
>>> release per molecule of the combustion products.  The energy per H2O 
>>> molecule isn't going to be any different when the H came from metallic 
>>> instead of liquid hydrogen.  Having metallic hydrogen might make the rocket 
>>> structurally more compact and lighter, but don't see how it can raise the 
>>> combustion temperature of the Isp.
>>> 
>>> Brent
>>> 
>>> On 1/26/2017 4:24 PM, Hans Moravec wrote:
 Something like antimatter propulsion, but much easier?
 
 Metallic hydrogen: The most powerful rocket fuel
 http://iopscience.iop.org/article/10.1088/1742-6596/215/1/012194/meta
 
 Hydrogen Squeezed Into a Metal, Possibly Solid, Harvard Physicists Say
 https://www.nytimes.com/2017/01/26/science/solid-metallic-hydrogen-harvard-physicists.html
 
 
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Re: Metastable metallic hydrogen propulsion

[Brent Meeker]

First, the H atoms in metallic hydrogen are already bound to other H 
atoms, so you don't get that H+H=H2+436kJ/mol.  Second, 
H2+O=H2O+517kJ/mol.  Since a mol of water is 9 times as heavy as a mol 
of H2 it's sonic velocity is 3 times lower.  So even if you could take 
advantage of the H+H reaction the Isp would only be 3 times as high.  
Still far lower than nuclear rocket and 52e3K.


Brent

On 1/26/2017 8:05 PM, Hans Moravec wrote:

I think the intent is that metallic hydrogen alone is the fuel,
as a metastable way of storing some fraction of atomic
hydrogen recombination energy.  H + H -> H2 at 52,000K


On Jan 26, 2017, at 20:51 , Brent Meeker  wrote:

Makes no sense.  Isp it just exhaust velocity which depends on the energy 
release per molecule of the combustion products.  The energy per H2O molecule 
isn't going to be any different when the H came from metallic instead of liquid 
hydrogen.  Having metallic hydrogen might make the rocket structurally more 
compact and lighter, but don't see how it can raise the combustion temperature 
of the Isp.

Brent

On 1/26/2017 4:24 PM, Hans Moravec wrote:

Something like antimatter propulsion, but much easier?

Metallic hydrogen: The most powerful rocket fuel
http://iopscience.iop.org/article/10.1088/1742-6596/215/1/012194/meta

Hydrogen Squeezed Into a Metal, Possibly Solid, Harvard Physicists Say
https://www.nytimes.com/2017/01/26/science/solid-metallic-hydrogen-harvard-physicists.html



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Re: Metastable metallic hydrogen propulsion

[Hans Moravec]

I think the intent is that metallic hydrogen alone is the fuel,
as a metastable way of storing some fraction of atomic
hydrogen recombination energy.  H + H -> H2 at 52,000K

> On Jan 26, 2017, at 20:51 , Brent Meeker  wrote:
> 
> Makes no sense.  Isp it just exhaust velocity which depends on the energy 
> release per molecule of the combustion products.  The energy per H2O molecule 
> isn't going to be any different when the H came from metallic instead of 
> liquid hydrogen.  Having metallic hydrogen might make the rocket structurally 
> more compact and lighter, but don't see how it can raise the combustion 
> temperature of the Isp.
> 
> Brent
> 
> On 1/26/2017 4:24 PM, Hans Moravec wrote:
>> Something like antimatter propulsion, but much easier?
>> 
>> Metallic hydrogen: The most powerful rocket fuel
>> http://iopscience.iop.org/article/10.1088/1742-6596/215/1/012194/meta
>> 
>> Hydrogen Squeezed Into a Metal, Possibly Solid, Harvard Physicists Say
>> https://www.nytimes.com/2017/01/26/science/solid-metallic-hydrogen-harvard-physicists.html
>> 
>> 
> 
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Re: Metastable metallic hydrogen propulsion

[Brent Meeker]

Makes no sense.  Isp it just exhaust velocity which depends on the 
energy release per molecule of the combustion products.  The energy per 
H2O molecule isn't going to be any different when the H came from 
metallic instead of liquid hydrogen.  Having metallic hydrogen might 
make the rocket structurally more compact and lighter, but don't see how 
it can raise the combustion temperature of the Isp.


Brent

On 1/26/2017 4:24 PM, Hans Moravec wrote:

Something like antimatter propulsion, but much easier?

Metallic hydrogen: The most powerful rocket fuel
http://iopscience.iop.org/article/10.1088/1742-6596/215/1/012194/meta

Hydrogen Squeezed Into a Metal, Possibly Solid, Harvard Physicists Say
https://www.nytimes.com/2017/01/26/science/solid-metallic-hydrogen-harvard-physicists.html




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