Cost of slowing down?

I was pondering last night... very dangerous, I know.. Well, I was wondering
why the CEV was a larger version of Apollo type re-entry techniques.
I eventually realised that it is in fact lighter and cheaper on all sorts
of fronts.

To get a Shuttle style heat dissipation working for the higher speeds of
coming in from the moon, would be not only more difficult, but heavier, cost
more to launch in the first place because of that, and presumably more
vulnerable, as it will be exposed throughout the flight.

Also, if you wanted to slow down before re-entry, you would need more
fuel...

Brian

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Brian Gaff....Note, this account does not accept Bcc: email.
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Brian Gaff wrote:
I was pondering last night... very dangerous, I know.. Well, I was wondering
why the CEV was a larger version of Apollo type re-entry techniques.
I eventually realised that it is in fact lighter and cheaper on all sorts
of fronts.

To get a Shuttle style heat dissipation working for the higher speeds of
coming in from the moon, would be not only more difficult, but heavier, cost
more to launch in the first place because of that, and presumably more
vulnerable, as it will be exposed throughout the flight.

Also, if you wanted to slow down before re-entry, you would need more
fuel...


The tiles on a Shuttle type of vehicle would be exposed to danger of
breakage in Outer Space. This is a hazard for the entire vehicle as
well, however. Even an Apollo type of vehicle would suffer from this
hazard, and it will have some sort of heat shield that could suffer
damage besides.

Air brakes -- split ailerons or sliding Corelle slabs -- are the most
efficient method of slowing down, requiring no fuel expenditure. If
the spaceship is large enough the extra fuel shouldn't be a problem for
retrofire or reverse thrust.

The argument for a SSTP (Single Stage To the Planets) spaceplane is
that it keeps things simple -- and resuable. Too many drop off tanks,
too many rendezvous, too many vehicles, too many orbital maneuvers, and
sooner or later Murphy's Law gets involved. The old "if something can
go wrong, it will" seems to work most of the time.

In the long run it saves money to keep things simple and reusable.
Everytime an explosive bolt is fired, it might misfire. Everytime a
rocket is burned, it might fail. Having one set of equipment that
works is worth many separate sets of equipment where any bolt or motor
might fail.

Would you want to ride in an airplane that did a rendezvous with
another airplane after takeoff, where you transfer to this other
airplane on a rocket sled which, in turn, would have to be 'captured'
by a mechanical net that is reeled into the other aircraft?

Then, add to this, yet another airplane rendezvous -- just prior to
landing -- where explosive bolts explode and another rocket sled
propels you to this new airplane . . . but "whoops!" . . . you miss the
mechanical net and . . . fall to your . . . Murphy's Law fate!

One nice simple spaceplane with good SSME engines and a large cargo
capacity is preferable to the above scenario, whether for sub-orbital
passenger flight or a SSTP trip to the Moon.


tomcat

"Brian Gaff" wrote in message
.uk...
I was pondering last night... very dangerous, I know.. Well, I was
wondering
why the CEV was a larger version of Apollo type re-entry techniques.
I eventually realised that it is in fact lighter and cheaper on all sorts
of fronts.

To get a Shuttle style heat dissipation working for the higher speeds of
coming in from the moon, would be not only more difficult, but heavier,
cost
more to launch in the first place because of that, and presumably more
vulnerable, as it will be exposed throughout the flight.

Also, if you wanted to slow down before re-entry, you would need more
fuel...

Very well thought out and correct! That's also why there's so much
interest, at least outside the US, in Ballutes--inflatable reentry shields.
Coming into Martian orbit from a long high speed approach (needed to keep
overall mission time lower) yields similar thinking.

I'm giving this idea for free.. Set into returnorbit back asswords into
high planes of statospheric? Oh yeah, the Defense Dept already does it..

Maybe NASA and DOD should not be inside each others peaches and prunes.

The USA is the new NAZI threat to the free world they are attempting to
control within their wickedness of crap and death methods.

H

One nice simple spaceplane with good SSME engines and a large cargo
capacity is preferable to the above scenario, whether for sub-orbital
passenger flight or a SSTP trip to the Moon.


tomcat


I agree but you might want to keep your head down. When I suggested
essentially the same thing I got rubbished in here!

Katipo

Katipo wrote:

One nice simple spaceplane with good SSME engines and a large cargo
capacity is preferable to the above scenario, whether for sub-orbital
passenger flight or a SSTP trip to the Moon.


tomcat


I agree but you might want to keep your head down. When I suggested
essentially the same thing I got rubbished in here!

Katipo


I also advocate keeping the weight down on space vehicles. While I
believe it may be possible to go 0 weight or less, it is definitely
possible to keep it under 5% of GLOW (Gross Lift Off Weight).

How is it done? No aluminum because the meltpoint is just too low.
Use titanium rolled quite thin for practically . . . everything! Then
take either carbon fiber, or carbon nanotubes if available, and use
graphite epoxy (for the hull) or boron epoxy for the interior and make
a nice laminated composite over top of the thin titanium sheets.

This will add great strength to the metal. Turn everything into boxes
or, more accurately, closed shapes. This includes bulkheads, overhead,
deck, furniture, acceleration couches, control panels, areas betwixt
and between, and anyplace else that doesn't need human occupation or
air pressure. Then 'suck' out all the air creating a vacuum. The
cargo hold will also be a vacuum, except for loading.

Because of the very light metal -- titanium is about the weight of
aluminum but can be thinned down even more because it is stronger --
and the composite which is carbon fiber, quite light, or carbon
nanotubes, feather light, the overall spaceplane without fuel or cargo
should . . . float.

Well, we'll see what the 'heavies' have to say about this. Remember
guys, "you have to do more with less until you can do everything with
nothing."


tomcat

"Katipo" wrote in message
...

One nice simple spaceplane with good SSME engines and a large cargo
capacity is preferable to the above scenario, whether for sub-orbital
passenger flight or a SSTP trip to the Moon.


tomcat


I agree but you might want to keep your head down. When I suggested
essentially the same thing I got rubbished in here!

Katipo

Yeah, that happens when you can't back up your opinions with real
science/math/engineering...

Welcome to the real world.

"Brian Gaff" wrote:

I was wondering
why the CEV was a larger version of Apollo type re-entry techniques.
I eventually realised that it is in fact lighter and cheaper on all sorts
of fronts.

To get a Shuttle style heat dissipation working for the higher speeds of
coming in from the moon, would be not only more difficult, but heavier, cost
more to launch in the first place because of that, and presumably more
vulnerable, as it will be exposed throughout the flight.

Careful -- that line of thought might lead you toward the conclusion
that the Shuttle was a "failure" not because of this or that design
choice, but because bringing a sizeable vehicle rather than a capsule
back safely even from LEO is *hard* and *expensive* -- much more so
than we thought in 1969-1972, or than most have been willing to admit
ever since.

The Shuttle is not a failure because it blew up a couple of times.
That was out of a large number of flights and who said rockets and
space travel were safe?

Traveling in a rocketship is dangerous, but it is the road to Outer
Space. The Shuttle has made a real step in the direction of our final
frontier.

Now it is time for a SSTP (Single Stage To the Planets). The
reliability of the SSME (Space Shuttle Main Engine) and the new 'slush'
LH2 tanks have made the SSTP a possible next step.

Scarce resources await us. He3 which does not exist on Earth exists in
large quantities on the Moon. It makes nuclear fusion a cinch. It has
been done already using small amounts of He3 from nuclear weapons
production.

Let's not remember the Shuttle for it's two explosions, but rather for
the tremendous technological advances of waverider hypersonic flight,
the SSME, and hefty cargo capacity into orbit.

It pioneered in hypersonic technology proving, not that it is
impossible, but that it is possible. It did -- all but one -- reentry
successfully.

Don't throw the baby out with the bath water.


tomcat

in article , Monte Davis at
wrote on 10/23/05 9:58 AM:

"Brian Gaff" wrote:

I was wondering why the CEV was a larger version of Apollo type re-entry
techniques. I eventually realised that it is in fact lighter and cheaper on
all sorts of fronts.

To get a Shuttle style heat dissipation working for the higher speeds of
coming in from the moon, would be not only more difficult, but heavier, cost
more to launch in the first place because of that, and presumably more
vulnerable, as it will be exposed throughout the flight.

Careful -- that line of thought might lead you toward the conclusion that the
Shuttle was a "failure" not because of this or that design choice, but because
bringing a sizeable vehicle rather than a capsule back safely even from LEO is
*hard* and *expensive* -- much more so than we thought in 1969-1972, or than
most have been willing to admit ever since.

The concept of a flying reentry is a good one IMHO. While studying
Columbia's ill fated reentry I realized, from an aviation perspective, how
smooth and low stress a shuttle reentry *normally* is. It seems to be much
more comfortable than a capsule reentry.

A scaled down version of the shuttle, say of the size and weight of a CEV,
seems ideal and I wouldn't be surprised if that is where things end up.

The shuttle has been very useful. In science and engineering, failures are
as useful as successes.

George Evans