Simple large solid.

Would it be possible to build one enormous single stage solid launcher and
offset the cost of the quantities involved by the saving on the
technological costs of multi-stage elements in a conventional launcher?

What I mean is, an oversized "Minuteman" type with a guidance (payload)head
using transverse thrusters to control it's attitude?


I'm looking at the low cost of propellant materials in enormous quantity.
There would be a payoff in reliability due to the simplicity of the system.

TIA

Would it be possible to build one enormous single stage solid launcher
BRBR

There's a limit to how large you can pour a solid-fuel stage. Make it too
large, and the grain will crack from internal stresses as the rubbery material
cools and settles. I forget the size of the largest one ground-tested, but
it's hard to believe you could make one bid enough for SSTO with significant
payload.


Matt Bille
)
OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR

MattWriter wrote:

Would it be possible to build one enormous single stage solid launcher
BRBR

There's a limit to how large you can pour a solid-fuel stage. Make it too
large, and the grain will crack from internal stresses as the rubbery material
cools and settles. I forget the size of the largest one ground-tested...


260-inch diameter. Aerojet.

--
Scott Lowther, Engineer
Remove the obvious (capitalized) anti-spam
gibberish from the reply-to e-mail address

(MattWriter) wrote in message ...
Would it be possible to build one enormous single stage solid launcher
BRBR

There's a limit to how large you can pour a solid-fuel stage. Make it too
large, and the grain will crack from internal stresses as the rubbery material
cools and settles. I forget the size of the largest one ground-tested, but
it's hard to believe you could make one bid enough for SSTO with significant
payload.

So instead of making a single-pouring stage that is hollow and burns
from the inside out, pour a number of solid columns that burn from the
outside in and are bundled in one large casing.

"Horatio." wrote in message ...
Would it be possible to build one enormous single stage solid launcher and
offset the cost of the quantities involved by the saving on the
technological costs of multi-stage elements in a conventional launcher?

The two problems you run into with *solid* single-stage-to-orbit
(SSTO) launchers a

1) Fuel efficiency. Solids have low fuel efficiencies for the thrust
they provide, and rockets demonstrate a nasty exponential weight
increase with decreasing fuel efficiency.

For example, a good, single-staged liquid fueled rocket might put 1
kilogram (cargo and spaceship both) into orbit for every 10 kilograms
of launch mass; in other words, 9kg of fuel are needed for every
kilogram of spaceship. On the other hand, a decent solid fueled rocket
will put 1kg into orbit for every ~30kg of launch mass. In other
words, the solid fueled rocket needs 29kg of fuel per kilogram of
spaceship and cargo.

But then there's the next problem, which makes it unlikely solids will
manage that 29:1 ratio.

2) Dry mass. Solid fueled rockets are thick-skinned, heavy critters
because the entire body of the rocket is the combustion chamber. The
walls of the shuttles' SRBs are 1-2cm stainless steel, IIRC. Their
empty, unfueled, cargo-free mass is about 15% of their fully loaded
mass; the shuttles' SRBs are ~580 tons, of which ~500 tons is fuel.
500:80 (6.25:1) far short of 29:1. Even the best liquid fueled rockets
cannot get to orbit with a single stage and 6.25:1 fuel:dry mass
ratio.

On the other hand, liquid fueled rockets can have very thin-skinned
fuel tanks and can approach or exceed 10:1 mass ratios. Barely. It's
easier to use a second stage and more generous mass ratios.

So my answer to your question is "probably not."

You'd have a better chance with big, single stage liquid fueled
vehicles.

I'm looking at the low cost of propellant materials in enormous quantity.

Then you'll want to consider liquid fuels.

*Liquid oxygen is much cheaper than soda, bottled water, or gasoline.
I think LOX goes for about $0.08 per liter (~$0.30 per gallon) when
purchased in bulk. Individual steel plants with 1 megaton of annual
steel production use around 500 tons of LOX per day; the demands of
rocket launches (600 tons of LOX per shuttle launch) are a drop in the
bucket of annual LOX production.

*Kerosene can be had (in bulk) at about $0.60 to $0.80 per gallon, I
think. If I did the conversions right, US airlines were using
something like 200000 tons of kerosene (jet fuel) per day in 2000AD.
It would take a lot of rocket launches to match airlines' usage.

*Liquid hydrogen is about $4 per kilogram, but a kilogram of liquid
hydrogen is close to 4 gallons.

*I'm not sure of the pricing of solid fuels, but the ability to
quickly order millions of gallons of inexpensive liquid oxygen,
kerosene, and/or hydrogen from commercial vendors is attractive. Solid
fuels are not so easily shipped and pumped into the rocket.

Mike Miller, Materials Engineer

In article ,
(MattWriter) wrote:

Would it be possible to build one enormous single stage solid launcher
BRBR

There's a limit to how large you can pour a solid-fuel stage. Make it too
large, and the grain will crack from internal stresses as the rubbery material
cools and settles. I forget the size of the largest one ground-tested, but
it's hard to believe you could make one bid enough for SSTO with significant
payload.


Matt Bille
)
OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR

What experiments have been done to examine incorporating some sort of
fiber reinforcement into the grain to prevent cracking? How about the
obvious: carbon fiber?

(MattWriter) wrote in message ...
Would it be possible to build one enormous single stage solid launcher
BRBR

There's a limit to how large you can pour a solid-fuel stage. Make it too
large, and the grain will crack from internal stresses as the rubbery material
cools and settles. I forget the size of the largest one ground-tested, but
it's hard to believe you could make one bid enough for SSTO with significant
payload.


Matt Bille
)
OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR

Back in the Sixties before the Saturn was chosen for Apollo, Aerojet proposed
a gigantic first stage for the Nova that was simply a big solid fuel booster.
Instead of pouring the fuel like they do for Shuttle, a bunch of guys would
swarm into the thing and lay solid fuel blocks inside it with an adhesive like
construction workers laying cinder block for a house foundation. I have no
idea what the concept was called or any technical references. It seems to
me there was something about it in the main American Rocket Society public
-ation about 1959 (before it became the AIAA). The thing was as big as Sea
Dragon and it may have been one of Bob Truax's ideas. Sorry that's all I
remember.

"MattWriter" wrote in message
...
Would it be possible to build one enormous single stage solid launcher
BRBR

There's a limit to how large you can pour a solid-fuel stage. Make it too
large, and the grain will crack from internal stresses as the rubbery
material
cools and settles. I forget the size of the largest one ground-tested,
but
it's hard to believe you could make one bid enough for SSTO with
significant
payload.


The largest ever tested was the Aerojet monolithic 260-inch-diameter solid.
These were about twice the diameter and mass of the shuttle's solids.

The problem is that SSTO requires really high Isp combined with very high
mass fractions. Solid motors can achieve neither.

For instance, the full-length 260-inch Aerojet solid motor (never built)
would have been a long way from SSTO even with no payload at all - with no
second stage, delta-vee would be around 5.5 km/s, not much more than half of
orbital speed. Gee loading would be substantial, at 23!

Regards,
Jonathan Wilson

In article ,
Wallace Berry wrote:
There's a limit to how large you can pour a solid-fuel stage. Make it too
large, and the grain will crack from internal stresses...

What experiments have been done to examine incorporating some sort of
fiber reinforcement into the grain to prevent cracking? How about the
obvious: carbon fiber?

Carbon fiber in particular is probably a bad choice, because it's quite a
good thermal conductor, and solid fuels want low thermal conductivity
(partly to insulate the outer case, partly to concentrate combustion heat
near the inner fuel surface to encourage the surface to boil off).

I think fiber reinforcement of solid fuels has been done, but the mass
penalty is substantial if you want good reinforcement.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

"Horatio." wrote in message ...

There would be a payoff in reliability due to the simplicity of the
system.

I've never considered solids that simple. Sure thay look simple, but
try making one, then try making a big one.

To first order approximation a solid is a pressure feed liquid with a
oversized combustion chamber(and all that it implies) and under
performing fuel combinations. And i left out the part were its kinda a
big stick of dynamite. Hybrids are better, but SSTO will be a liquid
fueled rocket.

Solids are best left for the military applications thay were orginaly
devloped for.

IMHO of course.

Greg