Recommended TSTO technical papers?

What are the best technical papers to read that deal with TSTO launch
vehicle studies? I'd like to survey the best thinking that's been put
into the topic.

I'm also curious about simple hydrocarbon fuels like propane/methane and
their relative merits. For one thing: does propane soot if used in a
fuel-rich preburner? I've heard methane works fine in FRSC.

Last I heard, there were people like Henry Spencer advocating LOX/Propane,
for SSTO if I remember. Would LOX/Propane still be the way to go for
TSTO, or would another propellant choice be better?

Do the ground infrastructure issues outweigh the advantages of using two
fuels for a TSTO, i.e. propane/hydrogen rather than propane/propane.

WvB wrote:
What are the best technical papers to read that deal with TSTO launch
vehicle studies? I'd like to survey the best thinking that's been put
into the topic.

I'm also curious about simple hydrocarbon fuels like propane/methane and
their relative merits. For one thing: does propane soot if used in a
fuel-rich preburner? I've heard methane works fine in FRSC.

Last I heard, there were people like Henry Spencer advocating LOX/Propane,
for SSTO if I remember. Would LOX/Propane still be the way to go for
TSTO, or would another propellant choice be better?

For TSTO, it's a bit easier than SSTO.
The second stage can live with less dense fuels, as it has no need to fly
through significant atmosphere, and overall strucutral fraction can be a tad
higher.

All the same arguments apply for fuels as do to SSTO, but less so, though there
is the added issue of if you want to use common fuels or not.
TSTO is just plain easier, and will probably work whether you chose all
LOX/LH2, or go for something like H2O2/kerosene for stage 1 and LH2/LOX for
stage 2.

You may well end up looking at a very stubby stage 2, of similar diameter
as stage 1, so there is almost no drag penalty, which is a significant
driver for going to LOX/propane, or other 'dense' fuels for the bottom
stage.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
Among a mans many good possessions, A good command of speech has no equal.

Ian Stirling wrote

TSTO is just plain easier, and will probably work whether you chose all
LOX/LH2, or go for something like H2O2/kerosene for stage 1 and LH2/LOX for
stage 2.

Kerosene is safer and easier to use than propane, but you'd get a slightly
better isp with propane or even ethane, methane or lng. I don't know if
that's enough to make them better overall than kerosene though.

Where ground support is available and there are no special storage
requirements, lox is probably the only sensible choice of oxidiser,
especially if you are doing lots of launches. It's by far the cheapest, it
gives good isp, it's non-toxic, and it's reasonably safe as long as you keep
things clean.


It's only disadvantage is that you are at the edge of the possible,
especially for reusable engines. It's pretty harsh as far as long engine
life and switch-on-and-off-ability goes. For reuseability, you might want to
look at something slightly gentler.

H2O2 is a no-no for reuseables. Forms unstable explosive peroxides which
accumulate in nasty places. There isn't a real aircraft or spacecraft
anywhere that doesn't have minor leaks.

N2O4 is also a no-no, for environmental and cost reasons. IRFNA is similar,
and IWFNA is still pretty bad. N2O is a bad greenhouse gas and gives lower
isp.

Me? I'd stick to lox, and work on the engineering.

You may well end up looking at a very stubby stage 2, of similar diameter
as stage 1, so there is almost no drag penalty, which is a significant
driver for going to LOX/propane, or other 'dense' fuels for the bottom
stage.

The Skylab 1 Saturn V 2 was stubby like that. It used two stages,
lox/kerosene and lox/LH2. It put 75 tons into LEO for a launch weight of
around 2,500 tons - 5% payload, not bad for the '70s, and considering it
wasn't designed for that.

I really liked the Saturn V, "the rocket that never failed".


--
Peter Fairbrother

Peter Fairbrother wrote:

Kerosene is safer and easier to use than propane,

Propane has the substantial advantage of being easier to purge
from the system. This is important since a little bit of hydrocarbon
left in the LOX plumbing can be catastrophic.

Paul

Peter Fairbrother wrote in message ...

H2O2 is a no-no for reuseables. Forms unstable explosive peroxides which
accumulate in nasty places. There isn't a real aircraft or spacecraft
anywhere that doesn't have minor leaks.


What do you base this on? Peroxide has more extensive use in reusable
engines than any other rocket propellant. All the rocket belts,
rocket dragsters, rocket helicopters, as well as a commercial reusable
RATO in England all were long service life peroxide engines. True,
they were all monoprop, but that does exonerate the oxidizer.

Leaked high concentration peroxide doesn't hang around very long.
Practically anything it leaks onto will cause it to start decomposing,
not forming explosive peroxides. Only if you made the incredibly bad
system design choice to use high concentration peroxide and alcohol in
a biprop system would this be a credible danger -- simultanious leaks
from both tanks could indeed combine to form a detonable mixture.
With kerosene and most other hydrocarbons, they aren't miscable. Lox
can also form explosive mixtures with quite a few fuels, like propane.
Peroxide leaks onto random surfaces may well be a fire hazard, but
the same can be said for any oxidizer (except nitrous oxide).

Higher cost and somewhat lower performance are valid reasons not to
use peroxide, but "Forms unstable explosive peroxides" really isn't.

Lots of people have negative things to say about peroxide that are
mostly extrapolations from historic folklore, but most of these people
(assuming they aren't strictly armchair engineers) have had much more
direct experience with, say, frozen lox valves...

John Carmack
www.armadilloaerospace.com

Peter Fairbrother wrote in message ...

I really liked the Saturn V, "the rocket that never failed".


Except that it did fail once. SA-502 failed to perform its
assigned mission when its S-IVB J-2 engine failed to restart,
leaving the rocket's Apollo 6 payload far short of its intended
orbit (360 km apogee vs. planned 528,024 km apogee, or a
velocity shortfall of nearly 26% (about 2,728 meters per
second). Today's media would howl "failure" after such a
performance.

- Ed Kyle

Ian Stirling wrote:
And the minor (?) advantage of possibly being able to share a common bulkhead
with LOX, without lots of insulation.

Whether you'd actually want to do this is another question. What happens
if during chill-down you get a crack through the bulkhead?

AIAA 86-1413, "Two-Stage Earth-to-Orbit Vehicles with Series and
Parallel Burn", Martin, James A., 22nd AIAA/SAE/ASME/ASEE Joint
Propulsion Conference, Huntsville, AL, June 16-18, 1986.

Jim Davis

There were a few more at the last JPC in July... I'll dig up the paper
numbers when I get home.

John Carmack wrote

Peter Fairbrother wrote in message
...

H2O2 is a no-no for reuseables. Forms unstable explosive peroxides which
accumulate in nasty places. There isn't a real aircraft or spacecraft
anywhere that doesn't have minor leaks.


What do you base this on?

Science, accident reports and experience.

A bit of chemistry (I'm still an amateur, but not armchair, rocket-ist but I
was a professional chemist before I became a mathematian/cryptographer).

Caveat: this is not professional opinion, it should be considered as just
general chatter. Peroxides are not my speciality. Don't rely on it for
safety.

1) Inorganic peroxides. I'm sure you use high purity aluminium for your
peroxide tanks, but Al/Mg alloys are better from a weight point of view for
the rest of the structure, and Al/Mg will form both straight magnesium
peroxides and mixed magnesium/aluminium peroxides.

I've even heard of Al peroxides. I theorise that the oxide layer on the Al
is what protects it, and it will form a peroxide under some circumstances,
like perhaps leaks.

Cu, Zn, Ni, brass and bronze will all form peroxides, and there are many
other mixed inorganic peroxides, including some Fe ones. Yes those metals
decompose the H2O2, but they _also_ form peroxides. These can be highly
reactive or explosive by themselves, and likely will be explosive if they
come into contact with organic materials.



2) Many salts will form addition compounds with H2O2, a bit like the
hydrates. I don't know offhand which ones do, but it's probably broadly
similar to the hydrates. Washing soda is an example, off the top of my head.
They can decompose violently, perhaps explosively, just by themselves, and
are likely to react explosively if in contact with organics.


3) Organic peroxides. It is well known that ethers, acetals and alcohols
will form organic peroxides with hydrogen peroxide, but so will almost any
organic with an oxygen atom in it, and even aliphatic hydrocarbons will do
so eventually in leak conditions with air and metals present to act as
catalysts. Many organic peroxides are sensitive explosives.



BTW, alcohol is pretty bad here. It can oxidise in air (or slowly with H2O2)
to acetaldehyde or acetic acid, when it will form really nasty peroxides
with H2O2. Are you the guy who uses 50% aqueous H2O2 with small amounts of
added alcohol? Beware. That's a bad combination to leave around.


Nobody knows that much about any of these, they tend to be too dangerous to
experiment on. There are probably unknown dangers involving mixed peroxides
too. Chemists don't like working with them.


There are many reports of not-quite-fully-explained accidents and explosions
relating to the previous storage and use of H2O2. Things like shelves
exploding when disassembled. Even a water-filled drainage pond (!).

Peroxide has more extensive use in reusable
engines than any other rocket propellant. All the rocket belts,
rocket dragsters, rocket helicopters, as well as a commercial reusable
RATO in England all were long service life peroxide engines. True,
they were all monoprop, but that does exonerate the oxidizer.

"Were" is probably the operative word here. The Royal Navy won't use it in
it's torpedoes. The US navy has stopped using it. Even the Russians have
withdrawn their peroxide torpedoes after the Kursk explosion.

Whether that's because of peroxides building up from leaks or the "normal"
dnagers of H2O2 I don't know. But I'd have to have a powerful reason, and do
lots of research, before I used it in a reuseable (torpedoes are frequently
test fired and reused).

Leaked high concentration peroxide doesn't hang around very long.
Practically anything it leaks onto will cause it to start decomposing,
not forming explosive peroxides.

There may well be peroxides forming while it's decomposing. Slow leaks are
bad for that. The peroxides build up until..


--
Peter Fairbrother

Ian Woollard wrote:
Ian Stirling wrote:
And the minor (?) advantage of possibly being able to share a common bulkhead
with LOX, without lots of insulation.

Whether you'd actually want to do this is another question. What happens
if during chill-down you get a crack through the bulkhead?

IIRC, you can't actually mix propane and LOX, and get a explosive mix.
Still a very bad thing to happen.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
"Give a man a fire, and he's warm for a day. Set him on fire, and he's warm
for the rest of his life" -- Terry Pratchett-Jingo