A kerosene-fueled X-33 as a single stage to orbit vehicle.

On Jul 18, 9:25*am, Jeff Findley wrote:
In article ,
says...



In sci.space.history Jeff Findley wrote:

Stage separation is an existing technology that's been in place on
the very first orbital launch vehicle. *It's at least a fairly well
known quantity, especially if you do your stage separation above the
bulk of the atmosphere.

I'll simply toss some shells from the peanut gallery not meant to
suggest favoring one side of the other... And yet even in 2010 (or was
it 2009) SpaceX still had their stages bump

Yes they did, but the problems they had were early on in the development
program and were fixed. *

Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011

Jesus, Jeff has a ob with SpaceX - haha - I think I will sell my
shares! lol.

Here's the deal;

The weight of wings in an aircraft system is around 8% to 10% of the
total weight

http://adg.stanford.edu/aa241/struct...tatements.html

When re-entering the Earth's atmosphere, a low density air frame slows
to subsonic speed without the use of rockets. (1,000 km/hr - 280 m/
sec) To reduce this speed to zero requires;

Ve u Isp

3.8 0.0710 388 sec
4.0 0.0676 408 sec
4.2 0.0645 428 sec
4.4 0.0617 449 sec
4.6 0.0591 469 sec

Which are ALL less than 8% the total weight!

On Jul 18, 10:29*am, Fred J. McCall wrote:
wrote:
On Jul 18, 9:25*am, Jeff Findley wrote:
In article ,
says...

In sci.space.history Jeff Findley wrote:

Stage separation is an existing technology that's been in place on
the very first orbital launch vehicle. *It's at least a fairly well
known quantity, especially if you do your stage separation above the
bulk of the atmosphere.

I'll simply toss some shells from the peanut gallery not meant to
suggest favoring one side of the other... And yet even in 2010 (or was
it 2009) SpaceX still had their stages bump

Yes they did, but the problems they had were early on in the development
program and were fixed. *

Jesus, Jeff has a ob with SpaceX - haha - I think I will sell my
shares! lol.

Jesus, Mookie thinks he owns shares - haha - I think it's just one
more delusion! lol.

--
"Ordinarily he is insane. But he has lucid moments when he is
*only stupid."
* * * * * * * * * * * * * * -- Heinrich Heine

YOU ARE MAKING **** UP AND PRESENTING IT LIKE ITS THE GOSPEL TRUTH -
YOU LYING SACK OF ****! lol.

Pat Flannery writes:

It's going to be more than a "bit bigger" to get this to work; and if
the second stage has to provide the vast majority of horizontal
acceleration to orbital speed it's going to need a very good mass
fraction and really high isp engines just to allow it to get into orbit
at all, payload or not, because what you then have is something like a
ET grafted into the Shuttle orbiter.

Where's the problem here? The Shuttle ET goes very much nearly into
orbit anyway and with an internal tank instead of an external one you
get a craft with a much lower specific weight (it will be mostly empty
tanks on reentry) and this it quite a bit easier for the TPS. You might
even get away with active film cooling with residual H2 then.

Forgetting the TPS on the exterior of the thing, if you could somehow
attach the wings, engines, cockpit, and tail of a orbiter to a super
lightweight ET you would have used up all of your payload capacity, as
empty it weighs 58,500 pounds.

No. The ET goes into orbit anyway. Well, not really, but very nearly.
The engines are in the Shuttle and the Shuttle has no fuel. It's the
puny OMS engines and fuel that make the sole difference between the
Shuttle going into orbit and the ET not. Keeping the ET attached and
taking it into orbit would cost maybe a few hundred pounds of payload.

The disturbing thing about the Shuttle is that if someone told you
today to build something with a cargo bay that big and payload that
heavy, and do it at minimal cost, you would end up with almost the
same system with only some detail changes, like possibly liquid fueled
boosters and hopefully a more robust TPS. Space technology really
hasn't had any major breakthroughs since the Shuttle was built

Shuttle 2.0 should have been something like a Shuttle with an internal
tank and still two SRBs. Or like Venture Star with SRBs as a parallel
first stage. SSTO is hard, but booster-assisted SSTO should be totally
doable now.

And there has been quite a bit of progress in the last 40 years,
really. The Shuttle uses almost no composites and no lightweight
aluminum/lithium alloys.


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery

In article
tatelephone,
says...

On 7/18/2011 5:37 AM, Jeff Findley wrote:
The goal for a sane reusable TSTO would be to minimize both
development
and operational costs. If a bit of "performance" has to be traded to
reduce the complexity of the vehicle (e.g. simpler TPS), I'd make that
trade every time. Why? Because costs scale with complexity much more
strongly than they scale with size.

Furthermore, launch costs today are so much higher than fuel/oxidizer
costs that making the vehicle a bit bigger for a given payload isn't
going to impact launch costs by much.

It's going to be more than a "bit bigger" to get this to work; and if
the second stage has to provide the vast majority of horizontal
acceleration to orbital speed it's going to need a very good mass
fraction and really high isp engines just to allow it to get into orbit
at all, payload or not,


True that the second stage is a "near SSTO" with this approach. Still,
it's still less challenging to build to the required mass fraction than
an SSTO.

This sort of architecture appeals to me because it gives you much more
"wiggle room" than SSTO.

because what you then have is something like a
ET grafted into the Shuttle orbiter. Forgetting the TPS on the exterior
of the thing, if you could somehow attach the wings, engines, cockpit,
and tail of a orbiter to a super lightweight ET you would have used up
all of your payload capacity, as empty it weighs 58,500 pounds.

If you're comparing apples to apples, the ET actually goes most of the
way to orbit. It would only be "dead mass" if you kept it attached
through the OMS burn(S). Remember all those proposals to use ET's in
space?

At any rate, TPS would be easier, because such a vehicle would be mostly
empty tankage (i.e. "fluffy"). The fluffier a reentry vehicle is, the
easier it is on the TPS. The shuttle is *not* "fluffy" since it keeps a
lot of heavy bits (like the SSME's) while ditching the "fluffy" bit (the
empty ET).

The disturbing thing about the Shuttle is that if someone told you
today
to build something with a cargo bay that big and payload that heavy, and
do it at minimal cost, you would end up with almost the same system with
only some detail changes, like possibly liquid fueled boosters and
hopefully a more robust TPS. Space technology really hasn't had any
major breakthroughs since the Shuttle was built

Depends who you'd ask. If you as an ex-shuttle engineer, I'm sure
that's the design you'd get. The shuttle design is by no means optimal.
Asking a non-shuttle aerospace engineer would likely yield a very
different answer.

After all, the non-shuttle aerospace engineer has had about four decades
to reconsider the (clearly economically failed) shuttle design. ;-)

Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011

In article , says...

Shuttle 2.0 should have been something like a Shuttle with an internal
tank and still two SRBs. Or like Venture Star with SRBs as a parallel
first stage. SSTO is hard, but booster-assisted SSTO should be totally
doable now.

And there has been quite a bit of progress in the last 40 years,
really. The Shuttle uses almost no composites and no lightweight
aluminum/lithium alloys.

Agreed. The only thing I'd really like to change for a Shuttle 2.0
would be to drop the SRB's and replace them with an all liquid fueled
first stage. Despite the near perfect record for the shuttle SRB's, I
really don't like the failure modes of large segmented solids.

If we drop the Shuttle name, I'd also drop the horizontal landing
requirement. Sure astronauts piloting a gigantic glider in for a
landing is a spectacular sight to see, but beyond that, I see nothing
about horizontal landing that appeals to me.

Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011

On 7/18/2011 5:37 AM, Jeff Findley wrote:
In article
tatelephone,
says...

On 7/15/2011 9:07 AM, Rick Jones wrote:
In sci.space.history Jeff wrote:

Stage separation is an existing technology that's been in place on
the very first orbital launch vehicle. It's at least a fairly well
known quantity, especially if you do your stage separation above the
bulk of the atmosphere.

I'll simply toss some shells from the peanut gallery not meant to
suggest favoring one side of the other... And yet even in 2010 (or was
it 2009) SpaceX still had their stages bump

If you have the reusable first stage replace a booster first stage and
separate in the upper atmosphere at around Mach 3-6, you run into that
trouble Lockheed had with their D-21 drones coming off of the back of
the M-2i carrier aircraft (it cut it in half on one flight) due to
shockwave interference between the two components
Have it separate outside the atmosphere at Mach 12-17 like a booster
second stage (That was how the Faget intended the flyback booster on his
shuttle concept to work) and now it needs a pretty involved TPS and
strong airframe structure in its own right, as it's going to get pretty
severe heating and g loads because of its steep descent trajectory
during reentry. You also run into the problem that it will be going at
such a high velocity away from the launch site at separation that it's
going be hard to get it to return to there, so you may have to transport
it back from its landing site via air or sea. The Faget concept would
have worked better if launched from the west, not east, coast. At least
then you could have the flyback booster come down as well as lift off in
the continental US.
Almost forgotten now are the post X-33 studies NASA had various
aerospace firms do under the Space Launch Initiative regarding fully
reusable launch systems using two or three components, and just how
small the payload looked in comparison to the thing that was going to
launch it:
http://forum.nasaspaceflight.com/index.php?topic=6504.0
That program came and went so fast that if you blinked you would have
missed it.

TPS on the first stage isn't *that* bad if you launch it virtually
straight up to get the second stage out of the atmosphere. Such a
trajectory would be more like Spaceship One's, rather than a more
"optimized" trajectory like the one you're describing.

As long as stage two can then get going 18,000 mph sideways all on its
own, that would work.
As to what sort of deceleration g forces stage one takes as it falls
straight back down into the atmosphere would be interesting to figure
out; It could feather like Spaceship One/Two does I suppose.
To give some idea just how challenging to get into orbit is if it has to
be done mainly by the upper stage for horizontal velocity, look at the
Soviet Spiral/50-50 space fighter design:
http://www.buran.ru/htm/str126.htm
In that case the flyback booster was supposed to get the whole works up
to Mach 6, and it still needed a big expendable second stage (burning
fluorine/LH2, no less) to put the spaceplane into orbit.
That's what was showing up in those totally reusable Space Launch
Initiative designs...you had this huge composite vehicle sticking this
dinky little payload into orbit. Whatever economic gains you made by
having full reusability rather than semi-reuasbility like in the Shuttle
were getting offset by the huge payload reduction per mission, meaning a
very limited max payload capacity and more missions needing to be flown
to get the same weight of payload into LEO.
And no matter what anyone says, both of the components are going to get
a pretty good going over between flights,particularly the upper one that
has to do a reentry from orbit on each flight.

Yes you take a payload hit by launching the first stage "straight up",
but this approach not only makes the TPS easier, but it also makes
recovery of the first stage easier because it could conceivably land
either at the launch site, or very close to it. This would be a very
desirable feature for the first stage of a reusable TSTO.

Yes, that would be a lot better than having it come down thousands of
miles away and having to get it back to the launch site again via air or
sea transport. It cost a lot just to bring the Shuttle orbiter back to
the Cape whenever it had to land at Edwards (the drag of it atop the 747
turned the aircraft into a real fuel hog), which is why NASA was so keen
to get the Cape's runway up to speed and add the braking chute to the
orbiters ASAP.

The goal for a sane reusable TSTO would be to minimize both development
and operational costs. If a bit of "performance" has to be traded to
reduce the complexity of the vehicle (e.g. simpler TPS), I'd make that
trade every time. Why? Because costs scale with complexity much more
strongly than they scale with size.

Furthermore, launch costs today are so much higher than fuel/oxidizer
costs that making the vehicle a bit bigger for a given payload isn't
going to impact launch costs by much.

It's going to be more than a "bit bigger" to get this to work; and if
the second stage has to provide the vast majority of horizontal
acceleration to orbital speed it's going to need a very good mass
fraction and really high isp engines just to allow it to get into orbit
at all, payload or not, because what you then have is something like a
ET grafted into the Shuttle orbiter. Forgetting the TPS on the exterior
of the thing, if you could somehow attach the wings, engines, cockpit,
and tail of a orbiter to a super lightweight ET you would have used up
all of your payload capacity, as empty it weighs 58,500 pounds.
The disturbing thing about the Shuttle is that if someone told you today
to build something with a cargo bay that big and payload that heavy, and
do it at minimal cost, you would end up with almost the same system with
only some detail changes, like possibly liquid fueled boosters and
hopefully a more robust TPS. Space technology really hasn't had any
major breakthroughs since the Shuttle was built

Pat

Pat Flannery writes:

Lockheed tried the concept of a flying propellant tank shuttle with
their Venturestar design...no luck on SSTO.
I don't know, if you stuck some SRBs on a VentureStar it might be
workable, but I've never seen anything like that designed.
There was Lockheed's i968 Star Clipper which looked a lot like
VentureStar with a wrap-around drop tank though:
http://www.pmview.com/spaceodysseytw...lvs/sld019.htm
That was the program that had a linear plug nozzle engine as a
classified alternative form of rocket propulsion on it that Lockheed
used as leverage to get the X-33 chosen.

Well, any sane approach with a good chance to end up on budget must
raise red flags there...

And there has been quite a bit of progress in the last 40 years,
really. The Shuttle uses almost no composites and no lightweight
aluminum/lithium alloys.

Well, maybe you could do it, but NASA (read Goldin) got really hung up
on the SSTO concept, which is a very tough nut to crack with any payload
at all aboard.

Full SSTO, yes. In the long run it's the only way to really have routine
and cheap spaceflight, since throwing away and/or recovering/returning a
first stage or boosters *is* expensive, but it's hard even if you try to
get it done. And if you just try to milk the budget... never.

But it's all moot anyway. Investing in a reusable SSTO craft makes sense
only with high launch frequencies and there are just no customers and
payloads for that. You'd need to outright create a market (for space
tourism, SPS or whatever) and to do this you'd need to drive down the
costs per flight massively and this would require lots of money to
invest first with a very high risk to burn it.


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery

On 7/18/2011 5:58 AM, Jeff Findley wrote:


Carrying wheels to orbit and back is more expensive than bolting them on
once the vehicle reaches the ground.

Better have a prepared landing pad then if you don't a repeat of the
DC-X burning up its rear end.
"Why did you want it to land vertically on unprepared ground, Jerry
Pournelle?"
"Heinlein said it would work! Heinlein said it would work!"
"Maybe on the Moon, Jerry...maybe on the Moon..."



VTVL can land on virtually unprepared relatively flat surfaces. HTHL
needs a runway, typically such vehicles would need a particularly long
runway. Furthermore, ditching a VTVL vehicle in water is going to be
far easier and safer than ditching a HTHL vehicle.

VTVL wins big on abort scenarios.

Point to remember: five, not four, landing gear, in case one doesn't
extend right...three is right out. ;-)


Irrelevant. Shuttle changed to a partially reusable design the moment
the final design was picked. Large SRB's and a drop tank aren't
reusable in my book. This design choice made many things harder for the
orbiter (including TPS).

They did reuse the SRB segments though, although by the time they had
finished inspecting them and refurbishing them it was almost as cheap to
just build new ones, as they were the most low-tech thing on the whole
Shuttle. They also were inherently tough because of their thick-walled
steel construction, so could take the fairly rough ocean landing.
The Soviets were going to have the four liquid fueled Energia boosters
come down on land, and to get their landing to be soft enough not to
damage them was a real mess - involving parachutes, landing rockets, and
retractable landing gear: http://www.buran.ru/htm/09-3.htm
They never did try it out on either of the two Energia flights, and the
weight of the booster recovery systems was so high that it pretty much
took away the Buran shuttle's ability to carry any cargo at all.

The design deliberately does NOT integrate the engines with the
airframe, because that hugely simplifies development.


Given my aerospace engineering background, I'm skeptical of this, to say
the least.

I think they got the layout from the Blue Steel Mk.2 ramjet-powered
cruise missile project.
It also had a streamlined body, nose canards, and wingtip mounted engines.
Another inspiration may have been the Avro 730 bomber project:
http://prototypes.free.fr/tsr2/imagewof/avro730_05.jpg


Pat

On 7/18/2011 10:48 AM, Jochem Huhmann wrote:

No. The ET goes into orbit anyway. Well, not really, but very nearly.
The engines are in the Shuttle and the Shuttle has no fuel. It's the
puny OMS engines and fuel that make the sole difference between the
Shuttle going into orbit and the ET not. Keeping the ET attached and
taking it into orbit would cost maybe a few hundred pounds of payload.

Lockheed tried the concept of a flying propellant tank shuttle with
their Venturestar design...no luck on SSTO.
I don't know, if you stuck some SRBs on a VentureStar it might be
workable, but I've never seen anything like that designed.
There was Lockheed's i968 Star Clipper which looked a lot like
VentureStar with a wrap-around drop tank though:
http://www.pmview.com/spaceodysseytw...lvs/sld019.htm
That was the program that had a linear plug nozzle engine as a
classified alternative form of rocket propulsion on it that Lockheed
used as leverage to get the X-33 chosen.


The disturbing thing about the Shuttle is that if someone told you
today to build something with a cargo bay that big and payload that
heavy, and do it at minimal cost, you would end up with almost the
same system with only some detail changes, like possibly liquid fueled
boosters and hopefully a more robust TPS. Space technology really
hasn't had any major breakthroughs since the Shuttle was built

Shuttle 2.0 should have been something like a Shuttle with an internal
tank and still two SRBs. Or like Venture Star with SRBs as a parallel
first stage. SSTO is hard, but booster-assisted SSTO should be totally
doable now.

And there has been quite a bit of progress in the last 40 years,
really. The Shuttle uses almost no composites and no lightweight
aluminum/lithium alloys.

Well, maybe you could do it, but NASA (read Goldin) got really hung up
on the SSTO concept, which is a very tough nut to crack with any payload
at all aboard.

Pat