Low Cost Shuttle Competition

[robert arndt]

http://www.nytimes.com/2003/07/01/science/space/01ORBI.html?ex=1057636800&en=e08df88fc4310282&ei=5 062&partner=GOOGLE

Rob

[Emilio]

Study was done in the past concerning space flight cost. The conclusion was
that space flight cost will never come down close to jet flight cost.
Typical airliner flight consists of flying to point A to B, refuel, pilot
gets out and kick the tire, and fly back to point A. Typical space flight
is totally different. Space craft leave for orbit, come back, technicians
must go over and certify all systems for flight worthiness before the next
flight. That includes checking every inch of external surface. The space
system consequently has terrible turnover, not to mention capacity of
delivery is a fraction of system weight.

Emilio.

"robert arndt" > wrote in message
om...
>
http://www.nytimes.com/2003/07/01/science/space/01ORBI.html?ex=1057636800&am
p;en=e08df88fc4310282&ei=5062&partner=GOOGLE
>
> Rob

[Keith Willshaw]

"Emilio" > wrote in message
...
> Study was done in the past concerning space flight cost. The conclusion
was
> that space flight cost will never come down close to jet flight cost.
> Typical airliner flight consists of flying to point A to B, refuel, pilot
> gets out and kick the tire, and fly back to point A. Typical space flight
> is totally different. Space craft leave for orbit, come back, technicians
> must go over and certify all systems for flight worthiness before the next
> flight. That includes checking every inch of external surface. The space
> system consequently has terrible turnover, not to mention capacity of
> delivery is a fraction of system weight.
>
> Emilio.
>

The problem is much more fundamental IMHO

1) Putting an object into orbit requires a considerable
expenditure in energy since you have to accelerate it
to around 18,000 mph

2) You have to dissipate that energy to come home,
currently that means using atmospheric friction with its
resultant high temperatures.

Given that we havent been able to manufacture
aircraft that could operate economically at mach 2
expecting that a space vehicle could match the costs
of subsonic airliners is unrealistic.

Keith

[David Pugh]

"Emilio" > wrote in message
...
> Study was done in the past concerning space flight cost. The conclusion
was
> that space flight cost will never come down close to jet flight cost.
> Typical airliner flight consists of flying to point A to B, refuel, pilot
> gets out and kick the tire, and fly back to point A. Typical space flight
> is totally different. Space craft leave for orbit, come back, technicians
> must go over and certify all systems for flight worthiness before the next
> flight. That includes checking every inch of external surface. The space
> system consequently has terrible turnover, not to mention capacity of
> delivery is a fraction of system weight.

Only if it is something designed by NASA. It is possible to build craft that
opperate in very demanding environments that don't require a standing army.
The SR-71 and DC-X are the classic examples.

You'll never make something that is as cheap to operate as a 737 but there
is a three orders of magnitude difference between the cost of a flight and
the cost of a launch. There should be some room for improvement.

[W. D. Allen Sr.]

One more Shuttle disaster and Congress will put us out of
the manned space flight business permanently. But NASA will
never give up the Shuttle cash cow it has been riding for
almost half a century for a safer, better industry designed
system.

WDA

end

"David Pugh" -cay> wrote in message
...
> "Emilio" > wrote in message
> ...
> > Study was done in the past concerning space flight cost.
The conclusion
> was
> > that space flight cost will never come down close to jet
flight cost.
> > Typical airliner flight consists of flying to point A to
B, refuel, pilot
> > gets out and kick the tire, and fly back to point A.
Typical space flight
> > is totally different. Space craft leave for orbit, come
back, technicians
> > must go over and certify all systems for flight
worthiness before the next
> > flight. That includes checking every inch of external
surface. The space
> > system consequently has terrible turnover, not to
mention capacity of
> > delivery is a fraction of system weight.
>
> Only if it is something designed by NASA. It is possible
to build craft that
> opperate in very demanding environments that don't require
a standing army.
> The SR-71 and DC-X are the classic examples.
>
> You'll never make something that is as cheap to operate as
a 737 but there
> is a three orders of magnitude difference between the cost
of a flight and
> the cost of a launch. There should be some room for
improvement.
>
>

[Tarver Engineering]

"W. D. Allen Sr." > wrote in message
t...
> One more Shuttle disaster and Congress will put us out of
> the manned space flight business permanently. But NASA will
> never give up the Shuttle cash cow it has been riding for
> almost half a century for a safer, better industry designed
> system.

Worse still, access to space is controlled by physicists that low balled
engineering slots years ago. As they say in LA, "you can't get there from
here".


>
> WDA
>
> end
>
> "David Pugh" -cay> wrote in message
> ...
> > "Emilio" > wrote in message
> > ...
> > > Study was done in the past concerning space flight cost.
> The conclusion
> > was
> > > that space flight cost will never come down close to jet
> flight cost.
> > > Typical airliner flight consists of flying to point A to
> B, refuel, pilot
> > > gets out and kick the tire, and fly back to point A.
> Typical space flight
> > > is totally different. Space craft leave for orbit, come
> back, technicians
> > > must go over and certify all systems for flight
> worthiness before the next
> > > flight. That includes checking every inch of external
> surface. The space
> > > system consequently has terrible turnover, not to
> mention capacity of
> > > delivery is a fraction of system weight.
> >
> > Only if it is something designed by NASA. It is possible
> to build craft that
> > opperate in very demanding environments that don't require
> a standing army.
> > The SR-71 and DC-X are the classic examples.
> >
> > You'll never make something that is as cheap to operate as
> a 737 but there
> > is a three orders of magnitude difference between the cost
> of a flight and
> > the cost of a launch. There should be some room for
> improvement.
> >
> >
>
>

[Tarver Engineering]

"Keith Willshaw" > wrote in message
...
>
> "W. D. Allen Sr." > wrote in message
> t...
> > One more Shuttle disaster and Congress will put us out of
> > the manned space flight business permanently. But NASA will
> > never give up the Shuttle cash cow it has been riding for
> > almost half a century for a safer, better industry designed
> > system.
> >
> > WDA
> >
> > end
>
> The shuttle was designed by the aerospace industry, North American
Rockwell
> was the prime contractor.
>
> Rockwell Rocketdyne Division designed and developed the main engines.
>
> Rockwell Space Transportation Systems selected to designed and developed
> the orbiter.
>
> Martin Marietta got the external tank contract and Morton Thiikol got
> the contract for solid rocket boosters.

Jesus, I sometimes wonder how Willshaw remembers to breath.

[Bradford Liedel]

I find this stuff very interesting. I'm curious to see if (within the
next 30 years) space travel actually becomes a consumer industry
rather than a government only industry. With backstreet boys being
launched into space, towers into the atmosphere, corporations
competing on new shuttle designs, etc...who knows what this will all
bring.

On 2 Jul 2003 03:59:44 -0700, (robert arndt) wrote:

>http://www.nytimes.com/2003/07/01/science/space/01ORBI.html?ex=1057636800&en=e08df88fc4310282&ei=5 062&partner=GOOGLE
>
>Rob

[Keith Willshaw]

"Bradford Liedel" > wrote in message
...
>
> I find this stuff very interesting. I'm curious to see if (within the
> next 30 years) space travel actually becomes a consumer industry
> rather than a government only industry. With backstreet boys being
> launched into space, towers into the atmosphere, corporations
> competing on new shuttle designs, etc...who knows what this will all
> bring.
>
>

The nearest thing to an initiative for this is the X-prize competiton

http://www.xprize.org/

One of the teams involved, the UK based starchaser group
claims to be building a reusable space vessel for suborbital launch
next year

http://www.starchaser.co.uk/

Another is using an aircraft based approach

http://www.bristolspaceplanes.com/

Keith

[W. D. Allen Sr.]

Right! And my fellow Rockwell employees did a great job for
their time - remember slide rules and T squares?

But why continue with a forty year old vehicles that are now
falling out of the sky and killing people, especially with
NASA insisting on flying with ice cycles hanging off the
shuttle, leaking booster gas seals, and fuel tanks shedding
insulation?

We could certainly do it much cheaper, safer, and better
today, right?

WDA

end

"Keith Willshaw" > wrote
in message ...
>
> "W. D. Allen Sr." > wrote in message
> t...
> > One more Shuttle disaster and Congress will put us out
of
> > the manned space flight business permanently. But NASA
will
> > never give up the Shuttle cash cow it has been riding
for
> > almost half a century for a safer, better industry
designed
> > system.
> >
> > WDA
> >
> > end
>
> The shuttle was designed by the aerospace industry, North
American Rockwell
> was the prime contractor.
>
> Rockwell Rocketdyne Division designed and developed the
main engines.
>
> Rockwell Space Transportation Systems selected to designed
and developed
> the orbiter.
>
> Martin Marietta got the external tank contract and Morton
Thiikol got
> the contract for solid rocket boosters.
>
> Keith
>
>
>

[Keith Willshaw]

"W. D. Allen Sr." > wrote in message
t...
> Right! And my fellow Rockwell employees did a great job for
> their time - remember slide rules and T squares?
>

Sure I worked on designs for Petrochem cracker plants
using them.

> But why continue with a forty year old vehicles that are now
> falling out of the sky and killing people, especially with
> NASA insisting on flying with ice cycles hanging off the
> shuttle, leaking booster gas seals, and fuel tanks shedding
> insulation?
>

Because nobody will pony up the money for a replacement.
I imagine NASA would be overjoyed if Congress said
'Go procure a new shuttle - here's $20 billion


> We could certainly do it much cheaper, safer, and better
> today, right?
>

Probably but the political will seems to be lacking

NASA's budget for the Shuttle last year was $3.3 billion
enough to buy 2 B-2 bombers, that seems unlikely to be adequate
to fund a replacement

Keith

[Walt BJ]

The real seemingly inescapable problem (I haven't seen an answer in
some fifty years) is that all the real sharp 'Skunkworks' types retire
or get elbowed aside by career bureaucrats whose main thrust in life
is never having to make a single-handed decision, because it might be
wrong and oops there goes the career. Better to place the action in
the hands of a committee (share the blame), wait for someone else to
stick their neck out, or temporize (wait) and hope the problem goes
away or is overtaken by events. In the meantime relie on dubious
statistics to show the problem really isn't that serious in the first
place. Both Shuttle losses can be attributed to this kind of thinking.
- "It's only a few degrees colder . . ."
- "We haven't had any problems with pieces of foam so far . . .
A personnel staffing problem that needs fixing - the question remains
- how? Mybe private industry could do it, but the bean-counters and
short-term bottom-line thinking from the Harvard Business School
eventually killed the Skunkworks . . .
Walt BJ

[Emilio]

Remember VenurStar? http://www.fas.org/spp/guide/usa/launch/x-33.htm It
was built by Skunkworks in the late 1990s. The project was canceled after
the propulsion tank failed the test. The tank had to have very complex
shape because it had to fit with in the airframe that resemble flattened
cone. To cut weight, they had to used Graphite composite. The Graphite
composite simply didn't work too well at the liquid Hydrogen temperature.
I mean they had to push the envelop of technology in every area to achieve
single stage to orbit. To date we don't have the material to build such
space ship.

The most efficient single stage vehicle ever built was in 1960s. It was
Atlas. It had 1% throw weight and the tank was made out of .030 inch
stainless steel. Unless the tank was filled with fuel or pressurized the
whole thing would crumple down to scrap metal!

Emilio

"Walt BJ" > wrote in message
om...
> The real seemingly inescapable problem (I haven't seen an answer in
> some fifty years) is that all the real sharp 'Skunkworks' types retire
> or get elbowed aside by career bureaucrats whose main thrust in life
> is never having to make a single-handed decision, because it might be
> wrong and oops there goes the career. Better to place the action in
> the hands of a committee (share the blame), wait for someone else to
> stick their neck out, or temporize (wait) and hope the problem goes
> away or is overtaken by events. In the meantime relie on dubious
> statistics to show the problem really isn't that serious in the first
> place. Both Shuttle losses can be attributed to this kind of thinking.
> - "It's only a few degrees colder . . ."
> - "We haven't had any problems with pieces of foam so far . . .
> A personnel staffing problem that needs fixing - the question remains
> - how? Mybe private industry could do it, but the bean-counters and
> short-term bottom-line thinking from the Harvard Business School
> eventually killed the Skunkworks . . .
> Walt BJ

[Keith Willshaw]

"Emilio" > wrote in message
...
> Remember VenurStar? http://www.fas.org/spp/guide/usa/launch/x-33.htm It
> was built by Skunkworks in the late 1990s. The project was canceled after
> the propulsion tank failed the test. The tank had to have very complex
> shape because it had to fit with in the airframe that resemble flattened
> cone. To cut weight, they had to used Graphite composite. The Graphite
> composite simply didn't work too well at the liquid Hydrogen temperature.
> I mean they had to push the envelop of technology in every area to achieve
> single stage to orbit. To date we don't have the material to build such
> space ship.
>
> The most efficient single stage vehicle ever built was in 1960s. It was
> Atlas. It had 1% throw weight and the tank was made out of .030 inch
> stainless steel. Unless the tank was filled with fuel or pressurized the
> whole thing would crumple down to scrap metal!
>
> Emilio

The Atlas remains in production to this day in the form of the II,III
and V but the design has been continually updated since the
60's and the Atlas now has the highly efficient Russian designed
RD-180 engine.

The RD-180 is a closed cycle engine meaning that the expanding
O2 used to power the fuel pumps is used in the combustion chamber
rather than dumped outboard as is the practise in American engines.

This makes the engine much more efficient. The engine is also
much more powerful than the US engines it replaces and its
throttlable and cheaper. Indeed the RD-180 is likley to power
the new Expendable Launch Vehicles for the USAF

Keith

[John Halliwell]

In article >, Keith Willshaw <keithNoSpa
> writes
>The RD-180 is a closed cycle engine meaning that the expanding
>O2 used to power the fuel pumps is used in the combustion chamber
>rather than dumped outboard as is the practise in American engines.

Is that the one that was subject to a BBC Horizon (or similar) where
some US rocket engineers were shown a warehouse full of engines they
themselves had considered impossible having failed to get them to work?

--
John

[Mike Zaharis]

>Keith Willshaw wrote:
>
> The Atlas remains in production to this day in the form of the II,III
> and V but the design has been continually updated since the
> 60's and the Atlas now has the highly efficient Russian designed
> RD-180 engine.

The Atlas V is not a pressure-supported structure - it has an isogrid
tank structure that does not require pressure to support itself. The
II and III essentially use the same pressure-supported tankage as
before, lengthened and adapted as necessary.

[NoHoverStop]

"John Halliwell" > wrote in message
...
> In article >, Keith Willshaw <keithNoSpa
> > writes
> >The RD-180 is a closed cycle engine meaning that the expanding
> >O2 used to power the fuel pumps is used in the combustion chamber
> >rather than dumped outboard as is the practise in American engines.
>
> Is that the one that was subject to a BBC Horizon (or similar) where
> some US rocket engineers were shown a warehouse full of engines they
> themselves had considered impossible having failed to get them to work?
>
> --
> John

Sadly "Horizon" has been noticeably "dumbed-down" of late, preferring
hyperbole to subtlety, relishing in constantly trotting out the same
"established scientists said it couldn't work/happen/exist, but these
renegades/upstarts/FSU-engineers have proven them wrong" line whether the
programme is about dinousaurs, rockets, asteroids or aircraft. Rockets are
not my field, but I am given to understand that the SSME (noticeably
American when I last checked) is a closed-cycle design.

[Keith Willshaw]

"John Halliwell" > wrote in message
...
> In article >, Keith Willshaw <keithNoSpa
> > writes
> >The RD-180 is a closed cycle engine meaning that the expanding
> >O2 used to power the fuel pumps is used in the combustion chamber
> >rather than dumped outboard as is the practise in American engines.
>
> Is that the one that was subject to a BBC Horizon (or similar) where
> some US rocket engineers were shown a warehouse full of engines they
> themselves had considered impossible having failed to get them to work?
>

Yep

Keith

[Keith Willshaw]

"NoHoverStop" > wrote in message
...
> "John Halliwell" > wrote in message

>
> Sadly "Horizon" has been noticeably "dumbed-down" of late, preferring
> hyperbole to subtlety, relishing in constantly trotting out the same
> "established scientists said it couldn't work/happen/exist, but these
> renegades/upstarts/FSU-engineers have proven them wrong" line whether the
> programme is about dinousaurs, rockets, asteroids or aircraft. Rockets are
> not my field, but I am given to understand that the SSME (noticeably
> American when I last checked) is a closed-cycle design.
>
>

The statement about the US having abandoned close cycle engines was
made by one of the US engineers who was involved with licensing
the rocket motor design from Energomash and in this instance I
dont recall any rubbishing of US efforts by the program maker.

The Channel 4 web site carries the same story by the way stating

http://www.channel4.com/science/microsites/C/cosmo/timeline.html

<Quote>

US rocket scientists are taken to see stored NK33s.

Scientists from the US company Aerojet are amazed to find a store of over 60
pristine engines, of a compact design that they had never seen before. What
surprised them most was that the engines used the closed-cycle technology
that had been rejected by American rocket scientists as being too risky.

</Quote>

As does wired.com

http://www.wired.com/wired/archive/9.12/rd-180.html

It agrees that the SSME has a closed cycle engine but states that its
the exception and of course the SSME is quite unusual in being
a restartable engine. Most rocket engines are one shot devices.

Keith

[Peter Stickney]

In article >,
"Keith Willshaw" > writes:
>
> "NoHoverStop" > wrote in message
> ...
>> "John Halliwell" > wrote in message
>
>>
>> Sadly "Horizon" has been noticeably "dumbed-down" of late, preferring
>> hyperbole to subtlety, relishing in constantly trotting out the same
>> "established scientists said it couldn't work/happen/exist, but these
>> renegades/upstarts/FSU-engineers have proven them wrong" line whether the
>> programme is about dinousaurs, rockets, asteroids or aircraft. Rockets are
>> not my field, but I am given to understand that the SSME (noticeably
>> American when I last checked) is a closed-cycle design.
>>
>>
>
> The statement about the US having abandoned close cycle engines was
> made by one of the US engineers who was involved with licensing
> the rocket motor design from Energomash and in this instance I
> dont recall any rubbishing of US efforts by the program maker.
>
> The Channel 4 web site carries the same story by the way stating
>
> http://www.channel4.com/science/microsites/C/cosmo/timeline.html
>
> <Quote>
>
> US rocket scientists are taken to see stored NK33s.
>
> Scientists from the US company Aerojet are amazed to find a store of over 60
> pristine engines, of a compact design that they had never seen before. What
> surprised them most was that the engines used the closed-cycle technology
> that had been rejected by American rocket scientists as being too risky.
>
> </Quote>
>
> As does wired.com
>
> http://www.wired.com/wired/archive/9.12/rd-180.html
>
> It agrees that the SSME has a closed cycle engine but states that its
> the exception and of course the SSME is quite unusual in being
> a restartable engine. Most rocket engines are one shot devices.

That's not quite true, Keith. Thus far, all U.S. liquid rockets for
space boosters, anyway, have been reusable to some extent. They're
all proff-fired before use. Some, such as the RL-10 have demonstrated
(in ground testing) the ability to be restarted over 30 times.
We just haven't been using them that way.
Most booster engines, with the exception of upper stages for systems
that will need to change orbit, like, say, an Apollo leaving parking
orbit to go to the Moon, or a Mars Probe, or such, aren't restartable
in flight. Once they are lit, you can turn 'em off, but there's not
way to get them lit again.

I think there may be a bit of overstating the case here, too. It's
not so much that a closed-cycle engine is _that_ much more difficult,
but it does reflect a different design philosophy than most
U.S. rocket manufacturers have used. The again, nearly all
U.S. liquid fuelled rocket motor are either late 1950s designs, or
derivitives of designs from the late 1950s and the 1960s. There've
been plenty of incremental improvements, but not a lot of new
development.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

[Emilio]

>Thus far, all U.S. liquid rockets for space boosters, anyway, have been
reusable to some extent.

True. I met an engineer who worked on one of the one-shot booster engine.
After assembly, since thrust output various with each engine, they test fire
it at given condition to get the thrust measurement. According to
measurement, tweak the fuel flow system to meet the engine thrust
specification. Fire it for the second time to verify the thrust. So all
engine gets fired at least three times counting real flight. The duty
cycle of the engine is far grater than its flight duration.

Emilio.

"Peter Stickney" > wrote in message
...
> In article >,
> "Keith Willshaw" > writes:
> >
> > "NoHoverStop" > wrote in message
> > ...
> >> "John Halliwell" > wrote in message
> >
> >>
> >> Sadly "Horizon" has been noticeably "dumbed-down" of late, preferring
> >> hyperbole to subtlety, relishing in constantly trotting out the same
> >> "established scientists said it couldn't work/happen/exist, but these
> >> renegades/upstarts/FSU-engineers have proven them wrong" line whether
the
> >> programme is about dinousaurs, rockets, asteroids or aircraft. Rockets
are
> >> not my field, but I am given to understand that the SSME (noticeably
> >> American when I last checked) is a closed-cycle design.
> >>
> >>
> >
> > The statement about the US having abandoned close cycle engines was
> > made by one of the US engineers who was involved with licensing
> > the rocket motor design from Energomash and in this instance I
> > dont recall any rubbishing of US efforts by the program maker.
> >
> > The Channel 4 web site carries the same story by the way stating
> >
> > http://www.channel4.com/science/microsites/C/cosmo/timeline.html
> >
> > <Quote>
> >
> > US rocket scientists are taken to see stored NK33s.
> >
> > Scientists from the US company Aerojet are amazed to find a store of
over 60
> > pristine engines, of a compact design that they had never seen before.
What
> > surprised them most was that the engines used the closed-cycle
technology
> > that had been rejected by American rocket scientists as being too risky.
> >
> > </Quote>
> >
> > As does wired.com
> >
> > http://www.wired.com/wired/archive/9.12/rd-180.html
> >
> > It agrees that the SSME has a closed cycle engine but states that its
> > the exception and of course the SSME is quite unusual in being
> > a restartable engine. Most rocket engines are one shot devices.
>
> That's not quite true, Keith. Thus far, all U.S. liquid rockets for
> space boosters, anyway, have been reusable to some extent. They're
> all proff-fired before use. Some, such as the RL-10 have demonstrated
> (in ground testing) the ability to be restarted over 30 times.
> We just haven't been using them that way.
> Most booster engines, with the exception of upper stages for systems
> that will need to change orbit, like, say, an Apollo leaving parking
> orbit to go to the Moon, or a Mars Probe, or such, aren't restartable
> in flight. Once they are lit, you can turn 'em off, but there's not
> way to get them lit again.
>
> I think there may be a bit of overstating the case here, too. It's
> not so much that a closed-cycle engine is _that_ much more difficult,
> but it does reflect a different design philosophy than most
> U.S. rocket manufacturers have used. The again, nearly all
> U.S. liquid fuelled rocket motor are either late 1950s designs, or
> derivitives of designs from the late 1950s and the 1960s. There've
> been plenty of incremental improvements, but not a lot of new
> development.
>
> --
> Pete Stickney
> A strong conviction that something must be done is the parent of many
> bad measures. -- Daniel Webster

[Keith Willshaw]

"Peter Stickney" > wrote in message
...
> In article >,
> "Keith Willshaw" > writes:
> >
> > "NoHoverStop" > wrote in message
> > ...
> >> "John Halliwell" > wrote in message
> >
> >>
> >> Sadly "Horizon" has been noticeably "dumbed-down" of late, preferring
> >> hyperbole to subtlety, relishing in constantly trotting out the same
> >> "established scientists said it couldn't work/happen/exist, but these
> >> renegades/upstarts/FSU-engineers have proven them wrong" line whether
the
> >> programme is about dinousaurs, rockets, asteroids or aircraft. Rockets
are
> >> not my field, but I am given to understand that the SSME (noticeably
> >> American when I last checked) is a closed-cycle design.
> >>
> >>
> >
> > The statement about the US having abandoned close cycle engines was
> > made by one of the US engineers who was involved with licensing
> > the rocket motor design from Energomash and in this instance I
> > dont recall any rubbishing of US efforts by the program maker.
> >
> > The Channel 4 web site carries the same story by the way stating
> >
> > http://www.channel4.com/science/microsites/C/cosmo/timeline.html
> >
> > <Quote>
> >
> > US rocket scientists are taken to see stored NK33s.
> >
> > Scientists from the US company Aerojet are amazed to find a store of
over 60
> > pristine engines, of a compact design that they had never seen before.
What
> > surprised them most was that the engines used the closed-cycle
technology
> > that had been rejected by American rocket scientists as being too risky.
> >
> > </Quote>
> >
> > As does wired.com
> >
> > http://www.wired.com/wired/archive/9.12/rd-180.html
> >
> > It agrees that the SSME has a closed cycle engine but states that its
> > the exception and of course the SSME is quite unusual in being
> > a restartable engine. Most rocket engines are one shot devices.
>
> That's not quite true, Keith. Thus far, all U.S. liquid rockets for
> space boosters, anyway, have been reusable to some extent. They're
> all proff-fired before use. Some, such as the RL-10 have demonstrated
> (in ground testing) the ability to be restarted over 30 times.
> We just haven't been using them that way.
> Most booster engines, with the exception of upper stages for systems
> that will need to change orbit, like, say, an Apollo leaving parking
> orbit to go to the Moon, or a Mars Probe, or such, aren't restartable
> in flight. Once they are lit, you can turn 'em off, but there's not
> way to get them lit again.
>

Which in practise makes them one shot devices.

> I think there may be a bit of overstating the case here, too. It's
> not so much that a closed-cycle engine is _that_ much more difficult,
> but it does reflect a different design philosophy than most
> U.S. rocket manufacturers have used. The again, nearly all
> U.S. liquid fuelled rocket motor are either late 1950s designs, or
> derivitives of designs from the late 1950s and the 1960s. There've
> been plenty of incremental improvements, but not a lot of new
> development.
>

The US manufacturers concerned were clearly sold enough on the
case to license the design from Energomash and its was THEY
who made the claims referenced not the TV company (or me).

Keith

[Arie Kazachin]

In message > - Bradford Liedel
> writes:
>
>
>I find this stuff very interesting. I'm curious to see if (within the
>next 30 years) space travel actually becomes a consumer industry
>rather than a government only industry. With backstreet boys being
>launched into space, towers into the atmosphere, corporations
>competing on new shuttle designs, etc...who knows what this will all
>bring.
>

I often see this type of thinking: "if only we'll start launching on
commercial scale things will be cheap". Well, things are not that rosy:
physical limits come to play. The classical rocket equation:

dv = Ve * ln((final mass) / (initial mass))

where:

Ve = exhaust velocity.
dv = change in velocity

The exaust velocity is more or less constant for chemical fuels. In F-1
engines of the Saturn-V first stage it was around 2.9 km/Sec in vacuum
(2.6 km/Sec at sea level). The required dv is about 8 km/Sec (to LEO).
Substitute the figures into the equation and you'll get that final mass
is only about 5% of the initial mass. That means: 95% of the rocket mass
is fuel and the WHOLE structure and payload and engines has the meager
5% of the mass budget. That'll dictate you engineering decisions very
uncomfortable to live with:

1) You can't make the spacecraft "sturdy as a buttleship", in fact
you'll be forced to make its structure rather flimsy (forget
about "belly landing" with shuttle) and therefore you'll have
to very thoroughly inspect it before EVERY flight to make sure
absolutely nothing is damaged and probability of slight damage
requiring repairs will be quite high. Such inspection by an army
of technitians adds cost.

2) The cryogenic fuels (LH2+LOX or Kerosine+LOX or other similar stuff)
are much mode dangerous to handle than ordinary jet fuel, therefore
in almost any event of unexpected pre-launch maintenance you'll need
to drain the tanks and refill them again and it's not as simple
as dealing with jet fuel - again you'll need many more people
which again adds to the cost.

3) Because of the tight mass budjet (5%) every equipment must be
on the cutting edge in terms of mass (materials used) which makes
it expensive to build and maintain.

I'm not saying you can't make launches cheaper than NASA does (if Shuttle
launch costs $19,000/kg and is equal to Saturn-V launch cost per kg than
clearly NASA missed something implementing the "reusable cheaper than
expandable" attitude) but there are inherent technical problems which can't
be solved in a cheap way when you'rr constrained by the 5% mass budget.

However, if you'll use nuclear propultion - that really opens the road to
cheap space access. All you need is LOTS of R&D money to restart programs
USAF conducted in 50-s and 60-s (and got as far as having working prototype
of nuclear rocket on a test stand) and solve the problems of engine life,
radioactive exhaust, worst case launch failure survivability of the
reactor, etc. And of corse, you'll need to re-educate the public (voters)
to allow polititians to make such decisions.


************************************************** ****************************
* Arie Kazachin, Israel, e-mail: *
************************************************** ****************************
NOTE: before replying, leave only letters in my domain-name. Sorry, SPAM trap.
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