I wonderwhat a Musk built shuttle version 2 would cost to build and operate?

In article id,
lid says...

In sci.space.shuttle message -
september.org, Wed, 30 May 2012 08:46:47, Jeff Findley
posted:

LOX is one
of the cheapest fluids on the planet because you can make it from air in
industrial quantities in factories on the ground.

Exactly. LOX is one of the cheapest fluids ON the planet (though air is
a fluid, and free) - for delivery by road, rail, or sea.

I see no reason to
abandon that extremely cheap source of oxidizer and replace it with an
extremely complex, expensive, air breathing engine which only gets you
part of the way to orbit.

But LOX is not cheap if you are at high speed and umpty thousand metres
up; but, for a considerable range of umpty, air is still free up there.

There are two ways to get O2 at that altitude:

1. You carry it along in the form of (relatively dense) LOX which
requires extra tank space.
2. You can gather it from the atmosphere along the way. A side effect
of this is that you get a bunch of N2 "along for the ride" since the
atmosphere is mostly N2, not O2. And note you still have to carry O2
with you for the phase of flight which is out of the atmosphere.

It's not at all clear to me that there will ever be a net win for an air
breathing SSTO when compared to a rocket powered SSTO. The goal is to
get out of the atmosphere as quickly as possible (to minimize drag and
gravity losses) and get up to orbital speed as quickly as possible (to
minimize gravity losses).

Sure the air breather may look good on paper, but we don't *know* if it
can ever be made to work. Air breathing engines tend to be far bigger
(intake), heavier (turbines, casings, etc), and more complex than liquid
fueled rocket engines. On top of that a "sane" air breather either
needs to be winged or a lifting body, further adding size, weight, and
complexity. It's not clear that trading extra O2 tankage for complex
engines, wings, horizontal landing gear, and etc. is going to win over a
rocket powered, VTVL, SSTO.

Since cost scales closely with complexity and weakly with size, it just
seems daft to make an air breather for this mission. As SpaceX has
shown, two stage LOX/kerosene rocket powered launch vehicles can be made
much more cheaply than the traditional players ever thought. It's just
not clear that an air breathing SSTO will ever be practical or
economically viable, especially as companies like SpaceX continue to
innovate and fly hardware as Sabre spends billions of research dollars
in labs on the ground.

The bottom line is that there just isn't anything obvious about taking
off and landing on a runway that will make spaceflight cheaper in the
next couple of decades. The devil is in the details, and those details
have yet to make themselves clear.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

On Fri, 1 Jun 2012 08:23:06 -0400, Jeff Findley
wrote:

There are two ways to get O2 at that altitude:

1. You carry it along in the form of (relatively dense) LOX which
requires extra tank space.
2. You can gather it from the atmosphere along the way. A side effect
of this is that you get a bunch of N2 "along for the ride" since the
atmosphere is mostly N2, not O2. And note you still have to carry O2
with you for the phase of flight which is out of the atmosphere.

And you have to lug along hardware to convert gaseous oxygen into the
liquid oxygen the engine can use.

It's not at all clear to me that there will ever be a net win for an air
breathing SSTO when compared to a rocket powered SSTO. The goal is to
get out of the atmosphere as quickly as possible (to minimize drag and
gravity losses) and get up to orbital speed as quickly as possible (to
minimize gravity losses).

Sure the air breather may look good on paper,

I'm not even sure I agree with that. Skylon/Sabre looks like
engineering welfare, not the road to a practical vehicle.

but we don't *know* if it
can ever be made to work. Air breathing engines tend to be far bigger
(intake), heavier (turbines, casings, etc), and more complex than liquid
fueled rocket engines.

And produce much less thrust per pound. The most powerful jet engine
is the GE90 family for the Boeing 777, which produces 115,000 lbs.
thrust while weighing 18,000 lbs. The Space Shuttle Main Engine
produced 460,000 lbs. thrust while weighing 7,700 lbs. You can buy a
lot of tankage and carry a lot of LOX with that extra horsepower!

Brian

In sci.space.shuttle message -
september.org, Fri, 1 Jun 2012 08:23:06, Jeff Findley
posted:
In article id,
says...

But LOX is not cheap if you are at high speed and umpty thousand metres
up; but, for a considerable range of umpty, air is still free up there.

It's not at all clear to me

I don't think that's likely to be considered important.


It's just
not clear that an air breathing SSTO will ever be practical or
economically viable, especially as companies like SpaceX continue to
innovate and fly hardware as Sabre spends billions of research dollars
in labs on the ground.

In principle, I don't think they spend many dollars at all - perhaps you
have forgotten something.

But their chief risks do appear to be firstly competition from Falcon 9
as is etc., and secondly competition from reusable Falcon 9. That must
frighten their cost estimators.

--
(c) John Stockton, nr London, UK. Turnpike v6.05.
Website http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms
PAS EXE etc. : http://www.merlyn.demon.co.uk/programs/ - see in 00index.htm
Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.

On May 29, 10:20*am, Jeff Findley wrote:
In article 05c79af9-794e-4d6a-b87e-37bee5fdc0a8
@c19g2000yqk.googlegroups.com, says...



With the 40 years of what was good about the shuttle what wasnt...

It would be interesting to at least here their ideas. Perhaps using
the same basics for a extreme heavy lifter?

Why in the world would someone who wants to copy the shuttle? *That's
just a dumb idea, IMHO.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
* up anymore... and when they can, it doesn't stay up long. "
* *- tinker

the shuttle had unique abilities, like servicing hubble that will be
hard to replace.

unless some sort of service vehicle / tug is built. it would need
refuleable engines, living area, work platforms, at least one arm, and
lots of replaceable consumables. getting it from one orbit to another
might be tough to impossible, plus large downmass capacity.....

it may be a long time before these abilities are replicated at least
by nasa.

a super heavy lifter with shuttle option would be interesting

In article m,
says...

air breather.

Could they not push air into the rocket engine instead of LOX ?
Obviously, have to change the mixture so that there is the right amount
of H2 and O2 in the mix.

Once above a certain altitude, then you gradually increase flow of LOX
(adjusting the pump flows accordingly).

The big question: how much LOX weight could be saved this way ? Since
most of the fuel is burned at lower altitude when the ship is heaviest,
being able to carry less LOX because you can use air during that first
phase would possible save a lot of weight, wouldn't it ?

The other problem is that once you get high enough, you have to stop
breathing air and use LOX you carried along. Once you make that
transition, you have to haul all of the extra mass for your air
breathing engines all the way to LEO. And as Brian Thorn pointed out, a
typical air breathing engine has a much worse thrust to mass ratio than
a rocket engine. Air breathers are great for long range cruise, but not
so good for rapid acceleration.

So, you're trading carrying extra LOX and tankage during the early part
of the flight for carrying the dead mass of an air breathing engine, and
likely wings as well, during the later part of the flight to LEO.

Also, if you've ever played around with a launch vehicle simulator,
you'll know that you want the early part of the flight to have high
thrust (which can come at the expense of some ISP and some thrust to
weight ratio) and the latter part of the flight to have high efficiency
(high ISP and high thrust to weight ratio). The specs for the shuttle
SRB's and SSME's are a shining example of this.

An engine like Sabre will have lower thrust early in the flight
(compared to a rocket engine) and have poor thrust to weight ratio,
especially when its air breathing mode has ended. From a performance
point of view, this makes it a poor choice for a launch vehicle engine.

Sabre's only redeeming quality is that it doesn't need as much LOX at
launch compared to a rocket engine. I'm just not convinced that this
one redeeming quality makes up for its many negatives.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

In article 23e2329b-fcc1-4b88-99a5-34b5533024f2
@p16g2000yqc.googlegroups.com, says...

On May 29, 10:20*am, Jeff Findley wrote:
In article 05c79af9-794e-4d6a-b87e-37bee5fdc0a8
@c19g2000yqk.googlegroups.com, says...



With the 40 years of what was good about the shuttle what wasnt...

It would be interesting to at least here their ideas. Perhaps using
the same basics for a extreme heavy lifter?

Why in the world would someone who wants to copy the shuttle? *That's
just a dumb idea, IMHO.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
* up anymore... and when they can, it doesn't stay up long. "
* *- tinker

the shuttle had unique abilities, like servicing hubble that will be
hard to replace.

For the cost of those servicing missions, we could have launched several
brand new Hubble copies with the proper fixes (like a primary mirror
that had the right shape). It's not at all clear that the shuttle's
"unique capabilities" were ever worth their extremely high costs.

unless some sort of service vehicle / tug is built. it would need
refuleable engines, living area, work platforms, at least one arm, and
lots of replaceable consumables. getting it from one orbit to another
might be tough to impossible, plus large downmass capacity.....

You're talking about capabilities found on a space station (or mobile
servicing tug). It would be far cheaper to build and fly a space
station (or tug) on Falcon Heavy than it would be to replicate those
capabilities on a reusable vehicle. Plus it would be better to keep it
in orbit and refuel it as needed rather than bringing it all the way
back down earth's gravity well after every mission.

Also, note that ISS is getting along just fine since it replaces many of
those "unique capabilities" by keeping the hardware associated with
their functions attaches to ISS rather than bringing it up and down on
every flight like the shuttle.

it may be a long time before these abilities are replicated at least
by nasa.

It's abilities aren't needed in a vehicle which goes up and down with a
mission duration best measured in days. Better to keep those
capabilities in orbit so they are available at all times.

a super heavy lifter with shuttle option would be interesting

Yawn.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

it may be a long time before these abilities are replicated at least
by nasa.

It's abilities aren't needed in a vehicle which goes up and down with a
mission duration best measured in days. *Better to keep those
capabilities in orbit so they are available at all times.

a super heavy lifter with shuttle option would be interesting

Yawn.

Jeff

the trouble with a service tug is moving it from one orbit to
another......

In article f30d1822-eac9-4c63-bbc9-9be22748b976
@x39g2000yqx.googlegroups.com, says...

it may be a long time before these abilities are replicated at least
by nasa.

It's abilities aren't needed in a vehicle which goes up and down with a
mission duration best measured in days. *Better to keep those
capabilities in orbit so they are available at all times.

a super heavy lifter with shuttle option would be interesting

Yawn.

Jeff

the trouble with a service tug is moving it from one orbit to
another......

Depends. Shuttle costs were on the order of $1 billion per flight. At
today's commercial launch costs, that would launch *a lot* of fuel for a
space based reusable tug. Repeating the mistakes of the past isn't the
way forward.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker

"Jeff Findley" wrote in message
...

In article f30d1822-eac9-4c63-bbc9-9be22748b976
, says...

it may be a long time before these abilities are replicated at least
by nasa.

It's abilities aren't needed in a vehicle which goes up and down with a
mission duration best measured in days. Better to keep those
capabilities in orbit so they are available at all times.

a super heavy lifter with shuttle option would be interesting

Yawn.

Jeff

the trouble with a service tug is moving it from one orbit to
another......

Depends. Shuttle costs were on the order of $1 billion per flight. At
today's commercial launch costs, that would launch *a lot* of fuel for a
space based reusable tug. Repeating the mistakes of the past isn't the
way forward.

Heck, forget a tug. Just launch everything you need from the ground each
time. Still cheaper than the shuttle.



Jeff

--
Greg D. Moore http://greenmountainsoftware.wordpress.com/
CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

On Jun 10, 9:19*pm, JF Mezei wrote:
Jeff Findley wrote:
The other problem is that once you get high enough, you have to stop
breathing air and use LOX you carried along. *Once you make that
transition, you have to haul all of the extra mass for your air
breathing engines all the way to LEO.

But couldn't you combine airbreathing with a rocket engine ? *Instead of
carrying a jet engine and a rocket engine, just modify the rocket engine
to be able to either feed LOX or air to the combustion chamber (or a
mixture of both at mid altitudes).

If the weight of the extra air pump is less than the weight of LOX you
save by pumping air instead of LOX at lower altitudes, then it would be
a net win.

Or you could attach 4 GE90 engines that give about 400,000lbs of thrust
and then separate the engines once the rocket has reached above 40k feet
and recuperate them. *This would only work if the weight of LOX saved is
greater than the weight of those 4 engines. For that one, I suspect the
equation does not favour the jet engines.

or you do the obvious........

build the largest airliner ever built.5 times the size of that russia
biggest plane

use regular airline technology to get it to 40K feet or there abouts.
refuel as you get to release altitude

detach the rocket plane parts that use liquid oxygen hydrogen etc.

the airline part returns to base to fly again withot the rigors of
space.

the space plane lands on a runway and is reused