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an idea for your ridicule



 
 
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  #1  
Old February 5th 04, 08:49 PM
aSkeptic
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Hi sci.space.tech

It seems that nuclear power is useless for booster applications and it
has forever been religated to upperstages. Propellant temperature is
constrained to what a solid core reactor can tolerate and this
temperature is certainly not breakthrough. I can see how a material
that could withstand temperatures above 5500 k would revolutionize
rocket propulsion systems practically overnight..

Not going to happen, anytime soon, if ever.

NTR is only interesting when using pure H2 as a propellant. H2 or
better yet, just H, has the smallest molecular weight of all
propellants. Power is ironically (to me) a reason why an NTR is
impractical as a booster. Although it has better gas milage than a
chemical rocket, it doesn't have the power push it's own gas. In other
words, power to weight ratio is a big issue. Hows a few extra
gigawatts sound? Sounds like a really heavy reactor!

Chemical rocket efficency has theoretically peaked with the SSME.

My question now boiled down is:

Would preheating the H2, to break it down to H, before it enters the
combustion chamber improve a chemical rocket's "gas milage"/exhast
velocity?
  #2  
Old February 6th 04, 07:17 PM
Henry Spencer
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In article ,
aSkeptic wrote:
Would preheating the H2, to break it down to H, before it enters the
combustion chamber improve a chemical rocket's "gas milage"/exhast
velocity?


If you could do that... yes, very considerably. You could forget the
oxidizer, and just let the H recombine to H2 -- an *IMMENSELY* energetic
reaction, which would not only make most other chemical rockets obsolete,
but would eliminate all interest in solid-core nuclear-thermal rockets.
Nothing short of gas-core nuclear could compete.

Trouble is, all that energy has to *come* from somewhere. As you might
guess from the above, you need extremely high temperatures to break down
H2 to H. This isn't some little add-on to the propulsion system; it
*becomes* the propulsion system.

Practical interest in such approaches centers on finding a way to
stabilize H, so you can invest all that energy on the ground, and release
it in flight without having to carry the powerplant along. Unfortunately,
nobody has yet found any workable stabilizing technique.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |
  #3  
Old February 7th 04, 02:55 AM
BllFs6
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Default an idea for your ridicule

ractical interest in such approaches centers on finding a way to
stabilize H, so you can invest all that energy on the ground, and release
it in flight without having to carry the powerplant along. Unfortunately,
nobody has yet found any workable stabilizing technique.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |



could you trap a solitary H atom inside something like a buckyball?

take care

Blll
  #4  
Old February 7th 04, 02:16 PM
Paul F. Dietz
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BllFs6 wrote:

could you trap a solitary H atom inside something like a buckyball?


You might be able to, but...

(1) the energy/mass now sucks, and
(2) the buckyball+H is a molecular radical, and they will react with
each other.

Paul
  #5  
Old February 7th 04, 04:42 PM
Gordon D. Pusch
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(BllFs6) writes:

[P]ractical interest in such approaches centers on finding a way to
stabilize H, so you can invest all that energy on the ground, and release
it in flight without having to carry the powerplant along. Unfortunately,
nobody has yet found any workable stabilizing technique.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |


could you trap a solitary H atom inside something like a buckyball?


Not if you want it to stay "solitary." Or "inside."

Setting aside for the moment the fact that a single hydrogen atom is so small
that it can slip out through the holes in a buckyball with impunity, you need
to realize that monatomic hydrogen is what chemists call a "free radical."
Free radicals have one or more "dangling bonds" that are just _ITCHING_
to react with something. Get a monotomic hydrogen atom close to anything
with a higher electronegativity, and it will say "take my electron ---
PLEASE !!!" While carbon is not _that_ much more electronegative than
hydrogen, its coordination number in a buckyball is only three, and since
carbon "wants" to be fourfold coordinated, each of those carbons technically
has a "dangling bond" that it has attempted to amortize by "hybridizing" it
between its three neighbors. Stick in a monatomic hydrogen atom making its
tempting offers of an electron donation into that strained arrangement,
and one of those carbons is going to JUMP at the opportunity to take it ---
which is going to make the potential dangling fourth bond of all the other
carbons that much "stickier" by breaking the buckyball's nice neat symmetry.
And since hydrogen is small enough to slip in and out of a buckyball with
impunity, pretty soon what you are going to have is just a few fat and
satisfied fully saturated C60H60's mixed in with bunch of envious C60's...


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'
  #6  
Old February 7th 04, 05:43 PM
Henry Spencer
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Default an idea for your ridicule

In article ,
BllFs6 wrote:
...centers on finding a way to
stabilize H, so you can invest all that energy on the ground, and release
it in flight without having to carry the powerplant along. Unfortunately,
nobody has yet found any workable stabilizing technique.


could you trap a solitary H atom inside something like a buckyball?


Such approaches have been suggested -- although I'm not sure it was recent
enough for buckyballs in particular to be mentioned -- but they wouldn't
make very good rocket fuels, alas. The whole point of H is the enormous
energy *per unit mass*; if it takes a buckyball (mass = 720) to contain
each H (mass = 1), that just doesn't work out very well.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |
  #7  
Old February 7th 04, 06:34 PM
aSkeptic
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Default an idea for your ridicule

Thanks for your insight, Henry.

I think what I proposed is way too severe. Making H2 into H H is
impractical and fantastic.

The silly idea I have is using something like NERVA to preheat one or
both components of a chemical bipropellant. Dissociation would be
interesting, but what I'm getting at is.. uh..

Ok heres annother wild example. Yes this is probably one of the
dumbest/impractical ideas you'll find here.. The combustion
temperature of the SSME is around 4000 K (if memory serves). Could a
greater combustion temperature be achieved by heating both components
(O2/H2) to say 2000 K before they are burned? Or would the burn still
be close to 4000 K as they are now?

(Henry Spencer) wrote in message ...
In article ,
aSkeptic wrote:
Would preheating the H2, to break it down to H, before it enters the
combustion chamber improve a chemical rocket's "gas milage"/exhast
velocity?


If you could do that... yes, very considerably. You could forget the
oxidizer, and just let the H recombine to H2 -- an *IMMENSELY* energetic
reaction, which would not only make most other chemical rockets obsolete,
but would eliminate all interest in solid-core nuclear-thermal rockets.
Nothing short of gas-core nuclear could compete.

Trouble is, all that energy has to *come* from somewhere. As you might
guess from the above, you need extremely high temperatures to break down
H2 to H. This isn't some little add-on to the propulsion system; it
*becomes* the propulsion system.

Practical interest in such approaches centers on finding a way to
stabilize H, so you can invest all that energy on the ground, and release
it in flight without having to carry the powerplant along. Unfortunately,
nobody has yet found any workable stabilizing technique.

  #8  
Old February 8th 04, 09:28 AM
Mike Swift
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Default an idea for your ridicule

Lets see now, carbon has an atomic weight of 12. We have 60 of them in a
buckyball, and it will be storing 1 hydrogen atom. That may work as far
as stabilizing the H but Im not to sure it would be of any help in a
propulsion system for use in space : ).

Mike

In article ,
(BllFs6) wrote:

ractical interest in such approaches centers on finding a way to
stabilize H, so you can invest all that energy on the ground, and release
it in flight without having to carry the powerplant along. Unfortunately,
nobody has yet found any workable stabilizing technique.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |




could you trap a solitary H atom inside something like a buckyball?

take care

Blll

  #10  
Old February 9th 04, 03:57 AM
Chung Leong
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Default an idea for your ridicule

Magnetic confinment? Then again, the energy density of a plasma is probably
pretty low.

Uzytkownik "Henry Spencer" napisal w wiadomosci
...
In article ,
aSkeptic wrote:
Would preheating the H2, to break it down to H, before it enters the
combustion chamber improve a chemical rocket's "gas milage"/exhast
velocity?


If you could do that... yes, very considerably. You could forget the
oxidizer, and just let the H recombine to H2 -- an *IMMENSELY* energetic
reaction, which would not only make most other chemical rockets obsolete,
but would eliminate all interest in solid-core nuclear-thermal rockets.
Nothing short of gas-core nuclear could compete.

Trouble is, all that energy has to *come* from somewhere. As you might
guess from the above, you need extremely high temperatures to break down
H2 to H. This isn't some little add-on to the propulsion system; it
*becomes* the propulsion system.

Practical interest in such approaches centers on finding a way to
stabilize H, so you can invest all that energy on the ground, and release
it in flight without having to carry the powerplant along. Unfortunately,
nobody has yet found any workable stabilizing technique.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |




 




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