Reasonable Space Vehicle

I've thought about what a reasonable, achievable, less expensive
earth-to-orbit launch vehicle would look like.

I keep coming back to a two-stage-to-orbit vehicle that reuses both
stages. The first stage is a LOX/RP1 powered 'big cheap booster' -
not necessarily pressure fed - that flies straight up, releases the
second stage, and flies straight down to land at the launch site. The
second stage is a LOX/LH2 powered near-SSTO, shaped like an elongated
Soyuz reentry capsule, with a conventional heatshield on the bottom
and a expendable payload fairing on top. After deploying the payload,
the second stage also reenters and lands vertically at the launch
site.

For simplicity, both stages are VTVL. The only thing close to new
engineering is jettisoning or retracting the second stage exhaust
bells and closing the holes in the heatshield for reentry, then
opening the holes for the engines to fire through on landing.

The DC-X, Armadillo Aerospace, and the Japanese RVT vehicle have
demonstrated VTVL. The Shuttle has holes in it's heatshield that it
closes and opens (landing gear). Apollo had heatshields. Soyuz does
a good job on reentry. There are lots of engines available. If the
stages were only built for 10-20 reuses, we could keep fielding
improved versions, learning about SSTO and BDB in the process. It
would likely help the US launch industry regain market share. Many
rocket scientists have proposed some or all of this before.

So why is there no interest? Is the concept goofed up in some
non-obvious way? Am I missing something?

Tom

he first stage is a LOX/RP1 powered 'big cheap booster' -
not necessarily pressure fed - that flies straight up, releases the
second stage, and flies straight down to land at the launch site. The
second stage is a LOX/LH2 powered near-SSTO, s BRBR


Sounds a lot like the Kistler K-1 design. With Kistler, though, the first
stage just falls ballistically, recovered by parachutes and airbags - making it
fly to the launch site would, it seems to me, add considerable complexity.

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

"Tom Kalvelage" wrote in message
om...
For simplicity, both stages are VTVL. The only thing close to new
engineering is jettisoning or retracting the second stage exhaust
bells and closing the holes in the heatshield for reentry, then
opening the holes for the engines to fire through on landing.

It's been suggested that instead of doing anything fancy like that, you
could just run some LH2 through the engines during re-entry, or even run the
engines at "idle" during re-entry. Either of these would greatly reduce the
heat load on the engines.

The DC-X, Armadillo Aerospace, and the Japanese RVT vehicle have
demonstrated VTVL. The Shuttle has holes in it's heatshield that it
closes and opens (landing gear).

True, but you've got to be very careful about this. Failure of any of the
doors to close would result in loss of vehicle if re-entry is attempted.
Furthermore, failure of the doors to open (on landing gear and/or braking
rockets) would also result in a crash upon landing.

Apollo had heatshields. Soyuz does
a good job on reentry. There are lots of engines available. If the
stages were only built for 10-20 reuses, we could keep fielding
improved versions, learning about SSTO and BDB in the process. It
would likely help the US launch industry regain market share. Many
rocket scientists have proposed some or all of this before.

So why is there no interest? Is the concept goofed up in some
non-obvious way? Am I missing something?

There certainly is interest (as evidenced by start-ups which are pursuing
similar designs), but NASA is another story. If they go ahead with plans to
return to the moon, that leaves little money to develop new launch vehicles
like you're talking about. They'll be spending the money on the CEV and on
the missions this modular spacecraft flies.

Jeff
--
Remove icky phrase from email address to get a valid address.

"Tom Kalvelage" wrote in message
om...
I've thought about what a reasonable, achievable, less expensive
earth-to-orbit launch vehicle would look like.

I keep coming back to a two-stage-to-orbit vehicle that reuses both
stages. The first stage is a LOX/RP1 powered 'big cheap booster' -
not necessarily pressure fed - that flies straight up, releases the
second stage, and flies straight down to land at the launch site. The
second stage is a LOX/LH2 powered near-SSTO, shaped like an elongated
Soyuz reentry capsule, with a conventional heatshield on the bottom
and a expendable payload fairing on top. After deploying the payload,
the second stage also reenters and lands vertically at the launch
site.

First of all ... a big reuseable booster, typically does not mean cheap
though if it can fly enough flights and each individual flight does not
cost too much it can be economical.

Secondly, you should go to http://www.kistleraerospace.com/ where you will
find something remarkably similar to your proposal with some differences.

The first stage is a LOX/RP1 powered 'big cheap booster' -
not necessarily pressure fed - that flies straight up, releases the
second stage, and flies straight down to land at the launch site.
Something like 80% of the system's total fuel is spent to obtain the
horizontal component of orbital flight.
Thus, the booster would get a few hundred miles down-range and would need
wings to get back and that's what's called a flyback booster, something
everybody knows will be required for CATS but designing it needlessly
intimidates everyone at the same time.
^
//^\\
~~~ near space elevator ~~~~
~~~members.aol.com/beanstalkr/~~~

Allen Meece wrote:
The first stage is a LOX/RP1 powered 'big cheap booster' -
not necessarily pressure fed - that flies straight up, releases the
second stage, and flies straight down to land at the launch site.
Something like 80% of the system's total fuel is spent to obtain the
horizontal component of orbital flight.
Thus, the booster would get a few hundred miles down-range and would need
wings to get back and that's what's called a flyback booster, something
everybody knows will be required for CATS but designing it needlessly
intimidates everyone at the same time.

Not me. As soon as I make my third billion... :_

It probably improves system reliability (and thus reduce overall cost)
to use parallel staging. You don't launch until you see all engines on
both stages running. It also provides a survivable abort for the
orbiter in many (not all) cases of something awful happening to the
booster. Of course the beauty of true complete reusability is that it
allows you to wring all of the errors both out of the design of the
vehicles and of their manufacturing processes, and so the probablities
of "something awful" happening go way down.

Allen Meece included:

The first stage is a LOX/RP1 powered 'big cheap booster' -
not necessarily pressure fed - that flies straight up, releases the
second stage, and flies straight down to land at the launch site.
Something like 80% of the system's total fuel is spent to obtain the
horizontal component of orbital flight.
Thus, the booster would get a few hundred miles down-range ...

In other words, the OP did not understand his question.

I also think straight up and straight down,
for a first stage with a throttleable motor,
are interesting. That is to say,
the booster is controlled to stay at or very near *zero*
miles downrange throughout its flight.

All it does is put the upper stages up where the air is,
in expansion-nozzle terms, close enough to gone.
They do all the horizontal component.


--- Graham Cowan
http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.doc --
"Boron: A Better Energy Carrier than Hydrogen?"

Thanks, everybody! I don't think I'm getting all the posts (I
certainly can't see my original post), but here's my thoughts on those
who I did see.

On previous implementations of the reusable TSTO idea:
The nearest almost-flight example is SpaceX's Falcon, I think,
although it only reuses the first stage and that by parachute. Bob
Truax's various two stage boosters are the earliest design example I
can think of. There is a web-only fiction story (The Rocket Company
by Patrick J. G. Stiennon & David M. Hoerr) that is very similar.

On Kistler Aerospace:
It's not obvious that their first stage will land on land, or anywhere
near the launch site, based on their site. They do show a picture of
the second stage on land. They also use parachutes and airbags, not
propulsion, to land. It is close, thanks for the tip.

On idling the engines during reentry:
I've heard of this idea, too. I picked hatches because they are known
technology, and we have already bought into the risks (if the Shuttle
landing gear doors don't open, it's a problem). If the US had a
program to try out near-term reentry technology or operations this
engine-idle technique would be high on the list. A small TSTO like
the one I mentioned, with a very small payload, could be used for this
sort of technology exploration, and only risk the second stage.

On NASA doing the Moon, but not this TSTO idea.
I agree that NASA won't do this, but I don't think it has anything to
do with the Moon and CEV. NASA had Congressional consensus and over
$4B to do launch technology (SLI), and didn't do a launch program like
‘my' idea, the DC-X, or even Saturn-I (the X-37 looked at on-orbit ops
and reentry, not launch). So they don't appear to be looking at
launch testbeds, even in the best of situations.

On 20% of fuel spent on horizontal velocity:
That something like 20% of the energy goes into the horizontal
component of velocity is a good point. My spreadsheet model showed
the first stage provided something like 22% of the delta V, if I redo
it to about 15%, the first stage is a smaller fraction of the vehicle
(down from 72% to 55% of total mass), and results in a 10% smaller
payload. Just for grins, my model assumes the BDB first stage is 26%
structure and the SSTO second is 12% (not counting payload), which
should be beatable in the real world. This was worth my post by
itself. Thanks!

On the flyback booster:
By doing land propulsive VTVL I was hoping to keep the number of types
of staff that have to be paid to a minimum, and total costs down. The
vehicle takes off from land using rocket engines; since you need those
folks for take off, you might as well use them for landing. If you
add parachutes and put it into the water, you need those types of
people and engineering. If you use wings, you have to bring in
aeronautical engineers and technicians for the wings, aerodynamics,
landing gear, engines, APUs, and so on, and that's expensive (not that
it shouldn't be looked at, too). Truax addressed this by both taking
off and landing in the water.

Thanks again!

On 20% of fuel spent on horizontal velocity: That something like 20% of the
energy goes into the horizontal
component of velocity is a good point.

Correction: I very roughly guessed that 20% of the energy is used for the
*vertical* altitude component of the orbital flight.
Accelerating horizontally to 18000 mph is what takes perhaps 80% of the
fuel.
^
//^\\
~~~ near space elevator ~~~~
~~~members.aol.com/beanstalkr/~~~

"The Rocket Company" By Stiennon & Hoerr has been published by the AIAA
and is avalable from: AIAA, Barnes and Noble, or Amazon