RLV physicaly impossible ?

(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.

(Paul Spielmann) :

(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?

First, you say that you read armadillo aerospace website. Notice that he has
already restarted, and even flew his rocket designs more than once. That
automaticly tells you that rockets can be fired more than once.

Second, most RLV designers are only looking for 10-100 flights before
scrapping a craft. Logical if the the total cost of maintenance and the cost
of the craft total is less then the cost of the same number of flights of
one-shot craft then you are saving money.

Notice you car does not last forever either, but imagine what it would cost
to drive your car if after every trip you needed to buy a new one?

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

(Paul Spielmann) :

(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?

First, you say that you read armadillo aerospace website. Notice that he has
already restarted, and even flew his rocket designs more than once. That
automaticly tells you that rockets can be fired more than once.

Second, most RLV designers are only looking for 10-100 flights before
scrapping a craft. Logical if the the total cost of maintenance and the cost
of the craft total is less then the cost of the same number of flights of
one-shot craft then you are saving money.

Notice you car does not last forever either, but imagine what it would cost
to drive your car if after every trip you needed to buy a new one?

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp