RLV physicaly impossible ?

Virtually all managers and most all engineers that have grown up in the
current space hardware design bureaus have been steeped in the "rockets
as artillery" school. Design constraints are fire the engine once for
testing, put it on the stand for its first flight, then through it away
after four or five minutes operation. Any effort or materials to give
it a longer life are considered a waste. This does not mean that large
rocket engines can't be built for longer service, only that the
engineers don't need it for "artillery" use. A good example of a flight
weight engine with long life is the RL-10. This engine used on several
upper stages was used (in the short bell version) for the DC-X, and has
had dozens of starts and hours of total time.
Another area that is not considered by most engineers developing RLVs is
that propellents used by most designs are about three orders of
magnitude lower in cost than flight hardware, and that adding propellent
to reduce the quantity of flight hardware will eliminate any failure
modes that were possible in the eliminated hardware. An example would
be if the Shuttle had no wings there would have been no wing leading
edge failure.
RLVs require companies and engineers willing to try new paradigm, not
just incremental improvements. The Space Shuttle was a try, however
many of its design requirements were made for political reasons not
economic or technical.

Mike

In article ,
(Henry Spencer) wrote:

In article ,
Paul Spielmann wrote:
that i have asked peoeple that i think are credible people that work
in the field of physics (not space engineering though) and accoarding
to what they have said: the energy and heat stress of going to orbit
and back are much more higher than for example what a car experience
and therefore it cuts back what is possible to do with space crafts.

...I still wonder though how long
life spans sub/orbital rlv vehicles will have though..

(Henry Spencer) wrote in message ...
In article ,
Paul Spielmann wrote:

The extent of these problems is much exaggerated, especially by people who
don't have direct knowledge of space engineering.

I tend to belive this is true. I get the feeling they know more about
mathematical forumlas than what they are really talking about.

In some cases, there are real problems but they are artifacts of current
design practices, which can and should be changed. For example, rocket
engines often experience a great deal of thermal stress during startup,
due to very rapid temperature rises. But there is no fundamental reason
why their startup sequences need to be so fast. Limiting warmup to rates
normally found in jet engines is not a big problem, once designers start
caring about reliability and long life rather than absolute maximum
performance.

I belive that this is the solution. Alot of small changes in our way
of thinking that could make rlvs possible. There should be a website
out there that count up all these small things thats could make rlvs
possible. I think its sad that there are people out there that knows
approaches on how to make rlvs but there really is no good information
source for it??? Where is the websites? Where is the books? I read
armadillo aerospace website witch i think is good, but is there more?

Paul.

(Henry Spencer) wrote in message ...
In article ,
Paul Spielmann wrote:

The extent of these problems is much exaggerated, especially by people who
don't have direct knowledge of space engineering.

I tend to belive this is true. I get the feeling they know more about
mathematical forumlas than what they are really talking about.

In some cases, there are real problems but they are artifacts of current
design practices, which can and should be changed. For example, rocket
engines often experience a great deal of thermal stress during startup,
due to very rapid temperature rises. But there is no fundamental reason
why their startup sequences need to be so fast. Limiting warmup to rates
normally found in jet engines is not a big problem, once designers start
caring about reliability and long life rather than absolute maximum
performance.

I belive that this is the solution. Alot of small changes in our way
of thinking that could make rlvs possible. There should be a website
out there that count up all these small things thats could make rlvs
possible. I think its sad that there are people out there that knows
approaches on how to make rlvs but there really is no good information
source for it??? Where is the websites? Where is the books? I read
armadillo aerospace website witch i think is good, but is there more?

Paul.

Mike Swift wrote in message ...

Another area that is not considered by most engineers developing RLVs
is
that propellents used by most designs are about three orders of
magnitude lower in cost than flight hardware, and that adding
propellent
to reduce the quantity of flight hardware will eliminate any failure
modes that were possible in the eliminated hardware. An example would
be if the Shuttle had no wings there would have been no wing leading
edge failure.

I suppose you mean an approach that is simple is prefered, to make
rlvs possible ? anyway i tend to like "simple" and "clean"
approaches... like thouse of scaled composites and armadillo
earospace. It seems the space shuttle as you meantioned is really
"complex"

Mike Swift wrote in message ...

Another area that is not considered by most engineers developing RLVs
is
that propellents used by most designs are about three orders of
magnitude lower in cost than flight hardware, and that adding
propellent
to reduce the quantity of flight hardware will eliminate any failure
modes that were possible in the eliminated hardware. An example would
be if the Shuttle had no wings there would have been no wing leading
edge failure.

I suppose you mean an approach that is simple is prefered, to make
rlvs possible ? anyway i tend to like "simple" and "clean"
approaches... like thouse of scaled composites and armadillo
earospace. It seems the space shuttle as you meantioned is really
"complex"

In article ,
Paul Spielmann wrote:
...I think its sad that there are people out there that knows
approaches on how to make rlvs but there really is no good information
source for it??? Where is the websites? Where is the books? I read
armadillo aerospace website witch i think is good, but is there more?

There is, but it's thinly spread and not easy to find. Much of it is not
on the Internet at all, in fact.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

In article ,
Paul Spielmann wrote:
...I think its sad that there are people out there that knows
approaches on how to make rlvs but there really is no good information
source for it??? Where is the websites? Where is the books? I read
armadillo aerospace website witch i think is good, but is there more?

There is, but it's thinly spread and not easy to find. Much of it is not
on the Internet at all, in fact.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

(Paul Spielmann) wrote in message . com...

I suppose you mean an approach that is simple is prefered, to make
rlvs possible ? anyway i tend to like "simple" and "clean"
approaches... like thouse of scaled composites and armadillo
earospace. It seems the space shuttle as you meantioned is really
"complex"

The shuttle also had to do a lot of things that the Scaled Composites
and Armadillo Aerospace X-Prize vehicles did not.

For example, the shuttle had to reach orbital velocities and return
from them. No X-Prize vehicle that I know of is approaching 1/4 of
orbital velocity (17500mph); I think the Scaled Composites vehicle is
topping out at ~2500mph.

The shuttle had to meet a lot of military needs, like a 1500-mile
cross-range so it could land at its launch site after a single polar
orbit. Before the USAF joined the shuttle project, some shuttle
designs featured small, stub wings optimized for low-speed
performance. On designs like Faget's "stub wing orbiter," the shuttle
would aerobrake with its belly (~60-degree angle of attack) with
leading edges...well, they weren't really leading edges. But Faget was
designing for a civilian vehicle that could accept 200-300 miles of
cross-range and wait in orbit until it was again lined up with its
landing site. Metallic heat shields were also considered before the
USAF jumped/was shoved aboard. After the USAF signed up, only ceramic
heat shields would get the job done.

A lot was asked of the shuttle, more than most current RLV designs are
expected to do.

Mike Miller, Materials Engineer

(Paul Spielmann) wrote in message . com...

I suppose you mean an approach that is simple is prefered, to make
rlvs possible ? anyway i tend to like "simple" and "clean"
approaches... like thouse of scaled composites and armadillo
earospace. It seems the space shuttle as you meantioned is really
"complex"

The shuttle also had to do a lot of things that the Scaled Composites
and Armadillo Aerospace X-Prize vehicles did not.

For example, the shuttle had to reach orbital velocities and return
from them. No X-Prize vehicle that I know of is approaching 1/4 of
orbital velocity (17500mph); I think the Scaled Composites vehicle is
topping out at ~2500mph.

The shuttle had to meet a lot of military needs, like a 1500-mile
cross-range so it could land at its launch site after a single polar
orbit. Before the USAF joined the shuttle project, some shuttle
designs featured small, stub wings optimized for low-speed
performance. On designs like Faget's "stub wing orbiter," the shuttle
would aerobrake with its belly (~60-degree angle of attack) with
leading edges...well, they weren't really leading edges. But Faget was
designing for a civilian vehicle that could accept 200-300 miles of
cross-range and wait in orbit until it was again lined up with its
landing site. Metallic heat shields were also considered before the
USAF jumped/was shoved aboard. After the USAF signed up, only ceramic
heat shields would get the job done.

A lot was asked of the shuttle, more than most current RLV designs are
expected to do.

Mike Miller, Materials Engineer

(Mike Miller) wrote in message . com...
(Paul Spielmann) wrote in message . com...

I suppose you mean an approach that is simple is prefered, to make
rlvs possible ? anyway i tend to like "simple" and "clean"
approaches... like thouse of scaled composites and armadillo
earospace. It seems the space shuttle as you meantioned is really
"complex"

The shuttle also had to do a lot of things that the Scaled Composites
and Armadillo Aerospace X-Prize vehicles did not.

Well ofcourse thats why burt rutan and amradillo are doing suborbital
vehecles. But one still have to wonder "if it is so damn easy to make
suborbital rlvs" then why havent NASA allready made one of them? well
ofcourse they made x15 but what good is that vehicle to me ?

For example, the shuttle had to reach orbital velocities and return
from them. No X-Prize vehicle that I know of is approaching 1/4 of
orbital velocity (17500mph); I think the Scaled Composites vehicle is
topping out at ~2500mph.

Let me correct you, non of the xprize teams have made a suborbital
trip yet, Burt Rutan has been at altitudeds of 50000 feet but i have
not herd about him fireing off the hybrit rocket yet. So i wont give
xprize teams any credit until the prove me wrong. However it is only a
matter of time til some of thouse teams do.


The shuttle had to meet a lot of military needs, like a 1500-mile
cross-range so it could land at its launch site after a single polar
orbit. Before the USAF joined the shuttle project, some shuttle
designs featured small, stub wings optimized for low-speed
performance. On designs like Faget's "stub wing orbiter," the shuttle
would aerobrake with its belly (~60-degree angle of attack) with
leading edges...well, they weren't really leading edges. But Faget was
designing for a civilian vehicle that could accept 200-300 miles of
cross-range and wait in orbit until it was again lined up with its
landing site. Metallic heat shields were also considered before the
USAF jumped/was shoved aboard. After the USAF signed up, only ceramic
heat shields would get the job done.

A lot was asked of the shuttle, more than most current RLV designs are
expected to do.

I dont blame NASA for anything, im not from America so i dont pay my
taxes there. But if i would pay my taxes there i would not think the
shuttle project was worth anything of it. I am not to happy with the
thought that people can build stuff in their garage and NASA needs a
army to do things, even though they make slightly diffrent things.
Anyway i think you catch my drift.

Paul.