SSTO to LEO, 80,000 pound payload or Bust. [was Bigelow launch vehicle mistake]

On 11 Mar 2006 21:26:50 -0800, "H2-PV NOW" wrote:

That is 6 times the WEIGHT of Oxygen to 1 part Hydrogen WEIGHT.
The burned Hydrogen-Oxygen ratios (H2O) are 2 parts H weight to 16
parts O weight. In short, the LOX is not available to burn 6 oxygen
atoms per one hydrogen atom as stated by the parent poster.

Funny - I didn't see that post. Can you possibly find it and
re-qoute it for me...?

Anybody careless about knowledge of weights does not step foot on
spaceplanes. Period. Ever.
No. It's one hydrogen to six oxygen.
And when burned makes HO6????
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Then why did you post this - unless you yourself are careless about
knowledge of chemistry? ;-)

I think it is fairly obvious, given all other things that a
stoiciometric mixture (in vacuo of course) gives the maximum energy. An
S mixture of H2/O2 will expand outwrds at a little over 4.5km/s. If you
put in an excess of hydogen it has the effect of giving a cooler flame
with relatively little penalty. Remember that specific heat is
proportional to moles not mass.

4 parts O to 1 H by weight is stoiciometric. This we shall say gives an
energy of X and has a weight of 5

The Shuttle is 3 parts O to 1H. This means that 4 units of O have 1.33
units of H associated so we have an energy of X with a weight of 5.33.
Not that great a penalty considering that the specific heat is
increased by a factor of 25% or so. Also LH cools the combusion chamber.

In article om,
wrote:
I think it is fairly obvious, given all other things that a
stoiciometric mixture (in vacuo of course) gives the maximum energy.

A stoichiometric mixture does indeed give maximum energy release, assuming
that the flame isn't hot enough to cause dissociation of the reaction
products (not a safe assumption for rocket engines, by the way).

But that's thermal energy. Converting thermal energy to kinetic energy is
a different story, especially in very rapid expansion. Some exhaust gases
are good at that, and others aren't; notably, H2 is considerably better
than H2O. Which is why most rocket systems yield best performance running
fuel-rich, and LOX/LH2 in particular gives best results running *very*
fuel-rich -- the penalty in energy release per kilogram is more than paid
back by more efficient energy conversion in the nozzle.

The stoichiometric ratio for LOX/LH2 is 8:1, but maximum exhaust velocity
typically requires running about 4:1 -- with only about half the LH2
actually burning. Real rockets actually tend to run around 6:1, because
LH2 is so ridiculously bulky that if you go still richer, you lose more in
extra tank mass than you gain in improved exhaust velocity.

4 parts O to 1 H by weight is stoiciometric.

Uh, no. Atomic weight of O is 16, atomic weight of H is 1, and you need
two Hs per O. So stoichiometric is 8:1.

The Shuttle is 3 parts O to 1H.

Uh, no. 616_t of LOX, 103_t of LH2, essentially exactly 6:1.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

wrote:
I think it is fairly obvious, given all other things that a
stoiciometric mixture (in vacuo of course) gives the maximum energy. An
S mixture of H2/O2 will expand outwrds at a little over 4.5km/s. If you
put in an excess of hydogen it has the effect of giving a cooler flame
with relatively little penalty. Remember that specific heat is
proportional to moles not mass.

4 parts O to 1 H by weight is stoiciometric. This we shall say gives an
energy of X and has a weight of 5

Oxygen has atomic weight of 16. Hydrogen has atomic weight of 1. H2+O
burned stoichiometrically without waste is 16:2, or simplifed to 8:1.
It is not 4:1

H2O has atomic weight of 18, not 5.


The Shuttle is 3 parts O to 1H. This means that 4 units of O have 1.33 ...

"Parts" as in atoms? or "parts" as in weight?

Exactly, according to published data, (which camefrom NASA originally)
http://en.wikipedia.org/wiki/Image:S...ternaltank.jpg
the ET is filled with 1,361,936 pounds of LOX, and 227,641 pounds of
LH2.

1361936 / 227641 = 5.98 / 1

Round that off at 6. There are 6:1 units of weight of LOX:LH2

The hydrogen fraction, by weight, is greater than it can find oxygen
partners to bond with. There are NOT six oxygen atoms to every hydrogen
atom; there are six units of atomic weight of Oxygen for every unit of
atomic weight of Hydrogen, which is a vast difference.


... units of H associated so we have an energy of X with a weight of 5.33.
Not that great a penalty considering that the specific heat is
increased by a factor of 25% or so. Also LH cools the combusion chamber.

You know, kids, this is a perfect example of why we tell you to only
make models using airplane glue in WELL VENTILATED AREAS. The senseless
blathering you see displayed by Parker can happen to you if you too
don't take this warning seriously.