should space shuttle be cancelled?

On Wed, 03 Aug 2005 01:54:31 GMT, Joann Evans
wrote:

The biggest flaw is being a vehicle that even *needs* a crew escape
system.

True, but rocket launches are considerably more dangerous than
aviation. Ignoring this current fact would be unhelpful.

We only do this in aircraft where some outside force may actively be
trying to destroy you. (fighters and bombers) Almost everything else is
sufficently robust that we don't consider it, we expect 'intact abort'
in virtually all cases.

Maybe you have not noticed, but in the case of both Challenger and
Columbia, they were both destroyed by outside forces. So the very
environment that they are in is the thing that is trying to destroy
them.

Now had the Shuttle came with an escape system built in, then both of
these crews may have survived. I am thinking of a detachable cockpit
that forms into a crude craft.

Certainly the case of the CEV is a whole different safety concern,
where simply mounting this craft on top provides a huge advantage over
the Shuttle.

That rocket goes and does it's worst during flight, then with only a
little luck they should survive with only getting a little cooked. I
can only say that it would be helpful if the CEV could detach itself,
should the rocket go way off course. Like straight down.

Anyway, it would simply be wrong to ignore that launching and reentry
does carry a high level of risk. Ignoring it won't make it go away,
which is why they should certainly plan for what can go wrong.

Cardman.

Cardman wrote:

On Wed, 03 Aug 2005 01:54:31 GMT, Joann Evans
wrote:

The biggest flaw is being a vehicle that even *needs* a crew escape
system.

True, but rocket launches are considerably more dangerous than
aviation. Ignoring this current fact would be unhelpful.


Tell me why this is necessairily so?


We only do this in aircraft where some outside force may actively be
trying to destroy you. (fighters and bombers) Almost everything else is
sufficently robust that we don't consider it, we expect 'intact abort'
in virtually all cases.

Maybe you have not noticed, but in the case of both Challenger and
Columbia, they were both destroyed by outside forces. So the very
environment that they are in is the thing that is trying to destroy
them.

What anti-aircraft weapon destroyed either ship?

Challenger was lost because of a failure of its own SRB. (Unless you
consider a cold morning to be an outside force. If so, it was absolutely
not an unknown one. Neither were potential leakage issues at the
joints.)

Columbia was lost because a piece of the ET insulation damaged a
critical part of the TPS. This wasn't a lightning strike (and even
Apollo 12 survived one of those)

By your 'environment' definition, we should eject every time the
weather gets bad. Weather has certainly destroyed aircraft, as recently
as the other day in Toronto. (and all survived without a 'crew escape
system,' unless you count the inflatable slides...one of which didn't
work, and those at that exit merely jumped)


Now had the Shuttle came with an escape system built in, then both of
these crews may have survived. I am thinking of a detachable cockpit
that forms into a crude craft.

Those have typically not worked well in aircraft, either.


Certainly the case of the CEV is a whole different safety concern,
where simply mounting this craft on top provides a huge advantage over
the Shuttle.

That rocket goes and does it's worst during flight, then with only a
little luck they should survive with only getting a little cooked. I
can only say that it would be helpful if the CEV could detach itself,
should the rocket go way off course. Like straight down.

I prefer a vehicle robust enough that it's no more likely to have a
catastropic failure than a commercial aircraft.

And as the shuttle doesn't pull more than 3 gees, and fighters
typically do much more, it's clear that, at least in terms of
acceleration, we know plenty about building to withstand the 'worst.'

All this proves is that the *shuttle* is a fragile design. Nothing
says all orbital spacecraft designs must also be so.

Anyway, it would simply be wrong to ignore that launching and reentry
does carry a high level of risk.


The degree of risk depends entirely on vehicle design. One can easily
have winged or (preferably, at least to me) semi-ballistic vehicles that
have less loading and heating on their entry surfaces. Low enough that
metals, rather than ceramics can be used.


Ignoring it won't make it go away,
which is why they should certainly plan for what can go wrong.


It won't go away, but there are ways of addressing it that aren't
like the shuttle.


--

You know what to remove, to reply....

On Sat, 06 Aug 2005 03:49:18 GMT, Joann Evans
wrote:

Cardman wrote.
True, but rocket launches are considerably more dangerous than
aviation. Ignoring this current fact would be unhelpful.

Tell me why this is necessairily so?

Greater acceleration / inertia, friction, pressure changes, and
thermal.

What anti-aircraft weapon destroyed either ship?

A non-applicable question.

Challenger was lost because of a failure of its own SRB. (Unless you
consider a cold morning to be an outside force. If so, it was absolutely
not an unknown one. Neither were potential leakage issues at the
joints.)

A couple of years ago I had a long discussion over Challenger. As to
begin with I had always assumed that Challenger was destroyed due to
an explosion in its ET. Apart from this being pointed out as being
combustion and not an explosion, then it was discovered that
Challenger broke up due to a sudden air maneuver.

So the environment causing stress on the shuttle caused the break-up.

Columbia was lost because a piece of the ET insulation damaged a
critical part of the TPS.

No. Columbia survived for several days in this damaged state. So that
did not directly destroy Columbia. Instead what it was destroyed by
was a combination of the heating caused by friction on reentry,
following by a mach 16 break-up due to the pressures involved.

And thus this proves that when something breaks, then the extreme
environment that they are in is what kills them. You could say that
every shuttle flight is balanced on a knife edge.

By your 'environment' definition, we should eject every time the
weather gets bad. Weather has certainly destroyed aircraft, as recently
as the other day in Toronto. (and all survived without a 'crew escape
system,' unless you count the inflatable slides...one of which didn't
work, and those at that exit merely jumped)

The environment involves much more than bad weather.

Now had the Shuttle came with an escape system built in, then both of
these crews may have survived. I am thinking of a detachable cockpit
that forms into a crude craft.

Those have typically not worked well in aircraft, either.

Well, they could certainly have done something. The extra mass
involved is why they have not.

I prefer a vehicle robust enough that it's no more likely to have a
catastropic failure than a commercial aircraft.

You seem very blind today. No space launch system has ever come close
to modern commercial airline travel. Since the two simply cannot
compare, then the dangerous space launch system needs additional
safety considerations.

NASA has not yet owned a manned space vehicle that could be considered
even reasonably safe. Simply because of the dangerous environment that
does not accept mistakes and failure.

And as the shuttle doesn't pull more than 3 gees, and fighters
typically do much more, it's clear that, at least in terms of
acceleration, we know plenty about building to withstand the 'worst.'

The fragile tiles and wing edges clearly highlight how fragile the
Shuttle is. And don't get me started on the SRBs and SSMEs.

All this proves is that the *shuttle* is a fragile design. Nothing
says all orbital spacecraft designs must also be so.

All NASA's plans to date involve manned vehicles that require launch
and reentry. Those are the more dangerous areas, but I am sure that
given time NASA will also find something in your safe space to kill
their astronauts as well.

Anyway, it would simply be wrong to ignore that launching and reentry
does carry a high level of risk.

The degree of risk depends entirely on vehicle design.

We do not yet have the technology to make a safe design. Manned space
vehicles have all killed some of the people who ride them. And I
should point out at a rate much higher than commercial travel.

I recall a recent story comparing the Shuttle to the B-18. The one
aircraft that was shot down the most during WWII. Apparently the B-18
is a lot safer to fly on.

So the Shuttle is less safe than the world's most shot down aircraft
when in combat against one of the World's most dangerous enemies.

One can easily
have winged or (preferably, at least to me) semi-ballistic vehicles that
have less loading and heating on their entry surfaces. Low enough that
metals, rather than ceramics can be used.

I have yet to see a vehicle design that would not kill some of the
people who ride it.

Cardman.

Cardman wrote:

On Sat, 06 Aug 2005 03:49:18 GMT, Joann Evans
wrote:

Cardman wrote.
True, but rocket launches are considerably more dangerous than
aviation. Ignoring this current fact would be unhelpful.

Tell me why this is necessairily so?

Greater acceleration / inertia, friction, pressure changes, and
thermal.


As noted, we do aircraft that deal with more acceleration. Pressure
change is hardly an unknown, and can't be more than from 1 atmosphere to
zero. We know what fatigue from those changes is, though admittedly only
the X-15 has come close to working in this thermal environment on more
than a one-time basis.


What anti-aircraft weapon destroyed either ship?

A non-applicable question.


That's my idea of an 'outside force,' not faiure of the launcher
technology in the face of understood and predictable environmental
conditions.


Challenger was lost because of a failure of its own SRB. (Unless you
consider a cold morning to be an outside force. If so, it was absolutely
not an unknown one. Neither were potential leakage issues at the
joints.)

A couple of years ago I had a long discussion over Challenger. As to
begin with I had always assumed that Challenger was destroyed due to
an explosion in its ET. Apart from this being pointed out as being
combustion and not an explosion, then it was discovered that
Challenger broke up due to a sudden air maneuver.


Um, an SRB failure that leads to destruction of the ET and an orbiter
wing, will destroy vehicle symmetry, yes....


So the environment causing stress on the shuttle caused the break-up.

Columbia was lost because a piece of the ET insulation damaged a
critical part of the TPS.

No. Columbia survived for several days in this damaged state.


So the fact that it didn't destroy Columbia immediately during
ascent, changes my point...how?

The Titanic remained afloat for hours as well, but doesn't change the
fact that the process began with an iceberg collision.

No additional environmental factors need be invoked to accept that a
foam strike damaged TPS material on a wing leading edge. An orbiter is
always presumed to eventually land.


So that
did not directly destroy Columbia. Instead what it was destroyed by
was a combination of the heating caused by friction on reentry,
following by a mach 16 break-up due to the pressures involved.


Pressures and tempratures acting on a portion of the structure that
was compromised by a foam strike.


And thus this proves that when something breaks, then the extreme
environment that they are in is what kills them. You could say that
every shuttle flight is balanced on a knife edge.


And even bird strikes sometimes bring down otherwise functioal
aircraft, typically in the process of takeoff/climbout, where things are
somewhat more 'critical' than straight and level flight at cruise
altitude. But we don't refer to that period as an 'extreme environment.'
Or credit the accident to something other than damage caused by a bird
strike at signifigant speed, on an engine, windscreen, or other critical
component.


By your 'environment' definition, we should eject every time the
weather gets bad. Weather has certainly destroyed aircraft, as recently
as the other day in Toronto. (and all survived without a 'crew escape
system,' unless you count the inflatable slides...one of which didn't
work, and those at that exit merely jumped)

The environment involves much more than bad weather.


And Columbia underwent nothing unusual or unknown 'environmentally'
that its design could not normally handle. (Challenged *was* obviously
outside of its low temprature envlope, as far as O-ring flexibility was
concerned.)

Of course, you can argue that vibration/acceleration causes all foam
detachment...how does that translate to designs that aren't stacked
paralell, or use no ET?

Now had the Shuttle came with an escape system built in, then both of
these crews may have survived. I am thinking of a detachable cockpit
that forms into a crude craft.

Those have typically not worked well in aircraft, either.

Well, they could certainly have done something. The extra mass
involved is why they have not.


Which matters, if you indend to carry signifigant cargo.


I prefer a vehicle robust enough that it's no more likely to have a
catastropic failure than a commercial aircraft.

You seem very blind today. No space launch system has ever come close
to modern commercial airline travel.

None flown so far. And make not the assumption that if it could be
done, NASA would already be doing it. Even the current shuttle design is
not what NASA originally wanted. Politics and funding were as much a
factor as engineering.


Since the two simply cannot
compare,


Now and forever?


then the dangerous space launch system needs additional
safety considerations.

NASA has not yet owned a manned space vehicle that could be considered
even reasonably safe.


Phrased that way, I'm more inclined to agree.


Simply because of the dangerous environment that
does not accept mistakes and failure.


The definition of 'dangerous environment' is subject to debate. All
air travel could once have been described as such.


And as the shuttle doesn't pull more than 3 gees, and fighters
typically do much more, it's clear that, at least in terms of
acceleration, we know plenty about building to withstand the 'worst.'

The fragile tiles and wing edges clearly highlight how fragile the
Shuttle is. And don't get me started on the SRBs and SSMEs.


Wouldn't dream of it. (Hell, I already have some doubs about CRV.)
But those are shuttle-specific issues, that may have little to do with
past and future manned launchers.


All this proves is that the *shuttle* is a fragile design. Nothing
says all orbital spacecraft designs must also be so.

All NASA's plans to date involve manned vehicles that require launch
and reentry. Those are the more dangerous areas, but I am sure that
given time NASA will also find something in your safe space to kill
their astronauts as well.


You seem to assume that operating in those regimes inherently can
never be made as safe as commercial aircraft operations, in *any*
launcher design. I do not.


Anyway, it would simply be wrong to ignore that launching and reentry
does carry a high level of risk.

The degree of risk depends entirely on vehicle design.

We do not yet have the technology to make a safe design.


Or perhaps no one (espically NASA) has seriously tried?


Manned space
vehicles have all killed some of the people who ride them. And I
should point out at a rate much higher than commercial travel.


Which, I submit, says more about the designs, than the environment.


I recall a recent story comparing the Shuttle to the B-18. The one
aircraft that was shot down the most during WWII. Apparently the B-18
is a lot safer to fly on.

So the Shuttle is less safe than the world's most shot down aircraft
when in combat against one of the World's most dangerous enemies.

One can easily
have winged or (preferably, at least to me) semi-ballistic vehicles that
have less loading and heating on their entry surfaces. Low enough that
metals, rather than ceramics can be used.

I have yet to see a vehicle design that would not kill some of the
people who ride it.


Of course. I'm sure that 'some' people have died in the same
make/model of car that I drive. Despite one spectacular fatal accident
(arguably caused by the 'outside force' of runway debris), even the
Concorde had a very good safety record, by commercial standards, yet it
functioned every day in the same Mach 2+ regime that was strictly the
realm of relatively fragile rocket powered X-planes, decades ago.
(Concorde ultimately failed *commercially,* but that's another debate
for another time. Everyone who boarded one, could assume they'd safely
step off at the other end.)

The point is, there's no inherent reason that human access to LEO
can't be brought up to a safety level close to those things we think of
as common risks today.

But no, they aren't going to be shuttle orbiters, any more than
British Airways and Air France flew people in something like the X-2.

But they will learn the *lessons* of those earlier vehicles....


--

You know what to remove, to reply....

On Sun, 07 Aug 2005 17:31:48 GMT, Joann Evans
wrote:

Um, an SRB failure that leads to destruction of the ET and an orbiter
wing, will destroy vehicle symmetry, yes....

Yes, where it was that last step in the process that killed them.

No. Columbia survived for several days in this damaged state.

So the fact that it didn't destroy Columbia immediately during
ascent, changes my point...how?

If they had been previously aware of this possible problem, and had
taken prior steps, then the Columbia crew may have lived on. So it was
not the foam that directly killed them, but the dangerous process of
reentry that does not tolerate faults.

The Titanic remained afloat for hours as well, but doesn't change the
fact that the process began with an iceberg collision.

Certainly. And had they adequate lifeboats, then all the passengers
could have lived on. So it was the environment of the cold ocean is
what really killed them.

No additional environmental factors need be invoked to accept that a
foam strike damaged TPS material on a wing leading edge. An orbiter is
always presumed to eventually land.

Then had Columbia spent it's life in orbit, then this hole would not
have been a concern. So it is easy to conclude that the environment of
reentry is a lot more dangerous than the environment in LEO.

Pressures and tempratures acting on a portion of the structure that
was compromised by a foam strike.

And had an aircraft wing suffered the same damage, then the odds are
that the aircraft could have landed safely. In fact it may have
continue on not even aware that there was a problem.

So proof enough that the reentry environment is a lot more dangerous
than the normal environment for flight. Therefore, additional safety
concerns need to be considered, when dealing with this more hostile
environment.

And even bird strikes sometimes bring down otherwise functioal
aircraft, typically in the process of takeoff/climbout, where things are
somewhat more 'critical' than straight and level flight at cruise
altitude.

On my return to London in the UK from Gothenburg in Sweden the
aircraft I was in, during landing, sucked up a bird. This aircraft
design, already aware of this problem, proceeded to initiate an
automatic process, where the engines where revved for a couple of
seconds in order to clear out the debris.

In other words aircraft can now handle this situation.

But we don't refer to that period as an 'extreme environment.'

Birds are a part of this environment. The problem has been solved in a
way that does not benefit the birds. You could also label this under
one of your "being attacked by outside forces".

Mostly all aircraft who hit birds survive, when this problem has been
solved in the design.

And Columbia underwent nothing unusual or unknown 'environmentally'

Mach 16+. Large G-Forces. Extreme friction. To name a few. Aircraft do
not have these "environmental concerns" to worry about.

that its design could not normally handle.

On a knife-edge. This goes to show what one small hole can do.

Of course, you can argue that vibration/acceleration causes all foam
detachment...how does that translate to designs that aren't stacked
paralell, or use no ET?

NASA is just being crazy. They could certainly solve this foam problem
quickly and cheaply in just a few weeks. The reason why they do not do
so is because this would increase the mass of the ET.

Since NASA spends a lot of it's time removing mass from the ET, then
they don't want to put it back on again. As had they done so, then the
shuttle launching some of those ISS components would not even make it
into the ISS orbit.

So other people's designs do not have to deal with a shuttle that is
largely over the design weight due to previous safety upgrades.

NASA's best option is to launch and install the most heavy ISS
components, then to do a *real* fix of this foam problem.

Also just what are they doing launching a 10 ton cargo module that can
carry 3 tons of cargo? Sounds like someone screwed up that design,
when 10 tons of cargo in a 3 ton module sounds a whole lot better.

Maybe in the future NASA should stick to packing supplies into their
lighter ISS components, when their Italian build cargo module is a fat
ugly pig.

Well, they could certainly have done something. The extra mass
involved is why they have not.

Which matters, if you indend to carry signifigant cargo.

If they really want to launch large cargo in the future, then NASA
really does need to upgrade their engines. Maybe to enlarge their SRB
size a bit, or to add on some mini-SRBs.

Had they done that, then they could both do a "real" foam fix, and to
get their large cargo mass into orbit. Removing further mass from the
ET is simply not an option, when they now need to add mass back on.

Their failure to solve this foam problem, despite the $200 million
spent on it, clearly highlights that they are barking up the wrong
tree. Foam will always fall off simply because it is foam. And them
trying to work out why the foam falls off, is simply a case of trying
to understand an unsolvable problem.

So the only solution is increased thrust on launch.

I prefer a vehicle robust enough that it's no more likely to have a
catastropic failure than a commercial aircraft.

You seem very blind today. No space launch system has ever come close
to modern commercial airline travel.

None flown so far.

Certainly. And that explains my point of why they need to consider
additional safety steps. They have not yet mastered this environment
by a long way.

And make not the assumption that if it could be done, NASA would already
be doing it.

Fair enough.

Even the current shuttle design is not what NASA originally wanted. Politics
and funding were as much a factor as engineering.

Yes, but NASA is also responsible. They accepted it and they had it
built.

Since the two simply cannot compare,

Now and forever?

In the future, it seems highly likely, that they could do safe designs
that deal with all safety considerations.

The definition of 'dangerous environment' is subject to debate. All
air travel could once have been described as such.

Yes, it would have been. NASA is a long way behind that of aircraft
dealing with flight. They even make better ships these days.

All NASA's plans to date involve manned vehicles that require launch
and reentry. Those are the more dangerous areas, but I am sure that
given time NASA will also find something in your safe space to kill
their astronauts as well.

You seem to assume that operating in those regimes inherently can
never be made as safe as commercial aircraft operations, in *any*
launcher design. I do not.

No, I am simply saying that it won't be nearly as safe any time in the
near future. I am already sure that their CEV will go on to kill their
astronauts.

The CEV will be like 100 times better than the shuttle, but 1000 times
less safe than commercial aircraft travel.

You also have to accept the serious future problem of lack of fuel. Or
more correctly at the current time they only get places by "drifting"
there, through minimal fuel use.

So in the future you just have to accept the fact that if one of their
CEV's goes flying out of orbit, in the wrong direction, then they
simply won't be getting them back. There are some missions that they
simply cannot do within the allowed time limit.

We do not yet have the technology to make a safe design.

Or perhaps no one (espically NASA) has seriously tried?

First they have to learn how.

One other problem is that; the further NASA goes in their exploration
plans, the more hostile the environment will get. The heat around
Mercury, the high pressure and acid rain on Venus, dust issues and
solar storms on the Moon and Mars, the radiation belts of Jupiter,
etc.

I am also sure that there are tons more space concerns that I have not
listed.

Once some bright spark solves all these problems, in an efficient
light-weight design, then you have your system as safe as commercial
air travel.

My point here is that since NASA is all onwards and upwards, then you
simply won't get your safe design any time soon. It may even get worse
some time in the future.

Which, I submit, says more about the designs, than the environment.

The design does not deal well with the environment. And for NASA that
will not change any time soon. You can use the MPL and MCO as examples
of how well NASA will do their CEV "parking" in the future.

I have yet to see a vehicle design that would not kill some of the
people who ride it.

Of course. I'm sure that 'some' people have died in the same
make/model of car that I drive. Despite one spectacular fatal accident
(arguably caused by the 'outside force' of runway debris),

Vehicle safety does need to accept human failings. This is why cars
now come with airbags, roll bars and side-impact bars.

NASA won't be building such concepts into their CEV.

even the
Concorde had a very good safety record, by commercial standards, yet it
functioned every day in the same Mach 2+ regime that was strictly the
realm of relatively fragile rocket powered X-planes, decades ago.

That it did.

(Concorde ultimately failed *commercially,* but that's another debate
for another time. Everyone who boarded one, could assume they'd safely
step off at the other end.)

Concorde was never really built to be that commercial, due to it's
high fuel use and limited passengers. Built by the French and the UK
governments. It was handed down when the airlines moved out of
government control and kept on as a status symbol.

Commercial reality eventually won out.

The point is, there's no inherent reason that human access to LEO
can't be brought up to a safety level close to those things we think of
as common risks today.

Given another 200 years then maybe so.

But no, they aren't going to be shuttle orbiters, any more than
British Airways and Air France flew people in something like the X-2.

But they will learn the *lessons* of those earlier vehicles....

And the whole point of this is that the CEV won't be this perfect
vehicle. It will be a great deal safer than the shuttle in doing all
those same tasks, but this will be partly offset with additional risk
now that NASA is sending it places where the shuttle has never gone.

Cardman.

Joann Evans wrote:
Cardman wrote:

On Wed, 03 Aug 2005 01:54:31 GMT, Joann Evans
wrote:

The biggest flaw is being a vehicle that even *needs* a crew escape
system.

I'm glad that someone is stating the obvious.

.....snip....

The degree of risk depends entirely on vehicle design. One can easily
have winged or (preferably, at least to me) semi-ballistic vehicles that
have less loading and heating on their entry surfaces. Low enough that
metals, rather than ceramics can be used.

This shouldn't need to be said--but well said, anyway.

However, with the right kind of design, I think winged can be
can be just as light as semi-ballistic--but better operationally.
Our current orbiters are basically ballistic at staging, but
definitely winged for reentry and landing. The key is to avoid
high dynamic pressures on the way out; that way, wings don't
have to be prohibitively heavy. And (cryogenic) tanks can be round
and structurally efficient. I find that cryogenic cylindrical tanks
can provide more reentry area per kg of tank mass than shaped tankage.

Best regards,
Len (Cormier)
PanAero, Inc.
(change x to len)
http://www.tourspace.com

"Len" wrote in message
ups.com...
Joann Evans wrote:
Cardman wrote:

On Wed, 03 Aug 2005 01:54:31 GMT, Joann Evans
wrote:

The biggest flaw is being a vehicle that even *needs* a crew escape
system.

I'm glad that someone is stating the obvious.

....snip....

The degree of risk depends entirely on vehicle design. One can easily
have winged or (preferably, at least to me) semi-ballistic vehicles that
have less loading and heating on their entry surfaces. Low enough that
metals, rather than ceramics can be used.

This shouldn't need to be said--but well said, anyway.

However, with the right kind of design, I think winged can be
can be just as light as semi-ballistic--but better operationally.
Our current orbiters are basically ballistic at staging, but
definitely winged for reentry and landing. The key is to avoid
high dynamic pressures on the way out; that way, wings don't
have to be prohibitively heavy. And (cryogenic) tanks can be round
and structurally efficient. I find that cryogenic cylindrical tanks
can provide more reentry area per kg of tank mass than shaped tankage.

It seems possible to build a ship in such a way that the tankage provides
the primary structure for both ship and lifting surfaces. Space ship
design is largely that of propellant tankage with auxillery components.
Designs need to be explored that use efficient tank shapes, that effectively
accomodate the auxillery components like engines, pilots, payloads,
lifting/control surfaces and such.

I am against conformal tanks or wrapping some sort of ship around
normal tanks. Toroid tanks could use a bit of investigation. There
appears to be an aerodynamic solution for flying them as primary
structure and aero surfaces with a light structure turning the donut
hole into crew and cargo area.
Best regards,
Len (Cormier)
PanAero, Inc.
(change x to len)
http://www.tourspace.com

"redneckj" wrote in message
...

It seems possible to build a ship in such a way that the
tankage provides the primary structure for both ship and
lifting surfaces. Space ship design is largely that of
propellant tankage with auxillery components. Designs
need to be explored that use efficient tank shapes, that
effectively accomodate the auxillery components like
engines, pilots, payloads, lifting/control surfaces and such.

I am against conformal tanks or wrapping some sort of
ship around normal tanks. Toroid tanks could use a bit of
investigation. There appears to be an aerodynamic
solution for flying them as primary structure and aero
surfaces with a light structure turning the donut hole into
crew and cargo area.

I eventually found toroidal tanks to be a little restrictive in their
aerodynamics. I now suspect one can do better with many cylindrical
shapes stacked side by side, (long tanks probably require composite
construction). Reasonable aspect ratio and L/D should be possible,
considering hypersonic constraints, the subsonic aerodynamic shape can
be very crude indeed. I even considered sliding or pivoting outboard
tanks for aerodynamic control. Basically building control surfaces out
of common tank shapes.

Intertank structures also seem something that might be avoidable. One
might use multiple full length tanks, with internal end caps for
lengthwise CoG management. In this fashion each tank can be
structurally supported directly from the engine mounts, or by direct
attachment to the tank next to it. This also eliminates a lot of
propellant feed lines.

Obviously I am against independent aeroshells, TPS, etcetera, could be
directly applied to tank surfaces. Even for a winged vehicle I suspect
that an aeroshell over the fuselage is not justified. The L/D is so low
that the tanks, engines, etcetera may as well be fully exposed, no
streamlining. Being behind the wing they should be relatively protected
during re-entry and specific areas could be individually protected as
required. This would also make maintenance access much easier.

Another possibility is that horizontal landing on water with such tank
shapes might be practical, avoiding potentially heavy and problematic
landing gear. The guidable parachute systems I have been looking at
would enable a gentle vertical landing on a soft surface, tankage
providing an extra crumple zone in an emergency.



One configuration I had considered was a capsule with re-entry shield
supported by a ring of long tapered cylindrical tanks, flared out in a
conical shape. Engines at the base with access to the capsule from
behind, perhaps through the centre of the tanks from the base. The
capsule might be easily detached for abort modes and better access.
Alternatively, or additionally, the space with in the ring of tanks
might be pressurized and used as cargo/person volume.

Another possibility was a crude delta wing of cylindrical tanks with TPS
suitably applied and the cargo/person cylinder mounted on top. One
might also place three full length tanks on top of a standard delta wing
with a capsule at the nose, there is a shielded area between the three
tanks through which cables, etcetera, could pass.

Anyway, I too like the idea of building space transports from tanks, and
further using those tanks as additional shielding.

Pete.

Pete Lynn wrote:
"redneckj" wrote in message
...

It seems possible to build a ship in such a way that the
tankage provides the primary structure for both ship and
lifting surfaces. Space ship design is largely that of
propellant tankage with auxillery components. Designs
need to be explored that use efficient tank shapes, that
effectively accomodate the auxillery components like
engines, pilots, payloads, lifting/control surfaces and such.

I am against conformal tanks or wrapping some sort of
ship around normal tanks. Toroid tanks could use a bit of
investigation. There appears to be an aerodynamic
solution for flying them as primary structure and aero
surfaces with a light structure turning the donut hole into
crew and cargo area.

I eventually found toroidal tanks to be a little restrictive in their
aerodynamics. I now suspect one can do better with many cylindrical
shapes stacked side by side, (long tanks probably require composite
construction). Reasonable aspect ratio and L/D should be possible,
considering hypersonic constraints, the subsonic aerodynamic shape can
be very crude indeed. I even considered sliding or pivoting outboard
tanks for aerodynamic control. Basically building control surfaces out
of common tank shapes.

Intertank structures also seem something that might be avoidable. One
might use multiple full length tanks, with internal end caps for
lengthwise CoG management. In this fashion each tank can be
structurally supported directly from the engine mounts, or by direct
attachment to the tank next to it. This also eliminates a lot of
propellant feed lines.

Obviously I am against independent aeroshells, TPS, etcetera, could be
directly applied to tank surfaces. Even for a winged vehicle I suspect
that an aeroshell over the fuselage is not justified. The L/D is so low
that the tanks, engines, etcetera may as well be fully exposed, no
streamlining. Being behind the wing they should be relatively protected
during re-entry and specific areas could be individually protected as
required. This would also make maintenance access much easier.

Another possibility is that horizontal landing on water with such tank
shapes might be practical, avoiding potentially heavy and problematic
landing gear. The guidable parachute systems I have been looking at
would enable a gentle vertical landing on a soft surface, tankage
providing an extra crumple zone in an emergency.



One configuration I had considered was a capsule with re-entry shield
supported by a ring of long tapered cylindrical tanks, flared out in a
conical shape. Engines at the base with access to the capsule from
behind, perhaps through the centre of the tanks from the base. The
capsule might be easily detached for abort modes and better access.
Alternatively, or additionally, the space with in the ring of tanks
might be pressurized and used as cargo/person volume.

Another possibility was a crude delta wing of cylindrical tanks with TPS
suitably applied and the cargo/person cylinder mounted on top. One
might also place three full length tanks on top of a standard delta wing
with a capsule at the nose, there is a shielded area between the three
tanks through which cables, etcetera, could pass.

Anyway, I too like the idea of building space transports from tanks, and
further using those tanks as additional shielding.

Pete.

Pete and John:

While I agree that the approaches that you advocate are promising,
I now feel that the penalty for adding wings, tail and TPS can be
held to less than about 14 percent of reentry mass--with an 80 tonne
(gross) orbiter and 400 tonne system and a payload nearly twice the
mass of the wing, tail, and TPS (excluding our usual 10 percent
contingency). An essential ingredient is low dynamic pressure ascent.
I think this penalty is worth it for landing with a good lift-to-drag
ratio, with a 75-knot stall speed. I would like an orbiter that I
am still capable of flying myself. That should make it suitable for
a lot of other pilots.

Best regards,
Len (Cormier)
PanAero, Inc.
(change x to len)
http://www.tour2space.com

"Len" wrote in message
oups.com...

Pete and John:

While I agree that the approaches that you advocate are
promising, I now feel that the penalty for adding wings, tail
and TPS can be held to less than about 14 percent of
reentry mass--with an 80 tonne (gross) orbiter and 400
tonne system and a payload nearly twice the mass of the
wing, tail, and TPS (excluding our usual 10 percent
contingency). An essential ingredient is low dynamic
pressure ascent. I think this penalty is worth it for landing
with a good lift-to-drag ratio, with a 75-knot stall speed.
I would like an orbiter that I am still capable of flying
myself. That should make it suitable for a lot of other
pilots.

If wings, tail and TPS are down to less than 14% of re-entry mass, then
it is probably time to move the design focus on to other areas where
there might be greater room for improvement. Going much below 14% is
probably getting into the realm of diminishing returns.

How long before this is up on your website?

Pete.