Upscaling towards Saturn V performance?

"Tkalbfus1" wrote in message
...
They did that because they understood little/nothing about orbital
rendezvous and assembly, and they were in a race with time. The
situation is different today.


So you want to do orbital assembly for the sake of doing orbital assembly?
We
still are in a race against time. I expect to die sometime in the 2050s.
It
seems possible to build such a spaceship in low orbit as to take longer
than
that.

Orbital *assembly*, in the sense of bolting things together, and then
hooking up electrical connectors and fluid lines in pressure suits is
generally to be avoided. But LEO *refueling* is a perfectly viable
alternative. A Mars ship would be something like 3/4 - 4/5 propellants for
the initial mass in LEO, so the hardware could be launched dry on one
flight, and the propellants could be launched on 3 or 4 additional tanker
flights. The payload of the launch vehicle would need to be only 1/4 to 1/5
of the payload of the HLLV required to do it all on one flight, as with Mars
Direct, which would put it in the range of a medium lift, 2-stage, VTOL RLV.
An RLV would have many other uses than Moon/Mars flights, which would help
spread the costs, and Congress couldn't shut down the Moon/Mars program by
shutting down the launch vehicle production line like they did with Apollo
and AAP.

Tom

JRS: In article , dated Mon, 27 Dec
2004 15:06:08, seen in news:sci.space.policy, Dick Morris
posted :

Orbital *assembly*, in the sense of bolting things together, and then
hooking up electrical connectors and fluid lines in pressure suits is
generally to be avoided. But LEO *refueling* is a perfectly viable
alternative. A Mars ship would be something like 3/4 - 4/5 propellants for
the initial mass in LEO, so the hardware could be launched dry on one
flight, and the propellants could be launched on 3 or 4 additional tanker
flights. The payload of the launch vehicle would need to be only 1/4 to 1/5
of the payload of the HLLV required to do it all on one flight, as with Mars
Direct, which would put it in the range of a medium lift, 2-stage, VTOL RLV.
An RLV would have many other uses than Moon/Mars flights, which would help
spread the costs, and Congress couldn't shut down the Moon/Mars program by
shutting down the launch vehicle production line like they did with Apollo
and AAP.

Orbital construction is to be avoided.

But orbital joining of vehicles is well-established.

The only connection really needed between the Trans-Mars injection
stage, if it is "not wanted on voyage", is a mechanical one capable of
handling of the order of a MegaNewton of thrust, and a few Newtons of
drift-apart force.

If units such as the cruise habitat, the lander, and each stage of the
propulsion can be launched, largely unfuelled, independently, they can
be docked in orbit - after all, Progress does that much nowadays, and
has done for years.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

"Dr John Stockton" wrote in message
...
JRS: In article , dated Mon, 27 Dec
2004 15:06:08, seen in news:sci.space.policy, Dick Morris
posted :

Orbital *assembly*, in the sense of bolting things together, and then
hooking up electrical connectors and fluid lines in pressure suits is
generally to be avoided. But LEO *refueling* is a perfectly viable
alternative. A Mars ship would be something like 3/4 - 4/5 propellants
for
the initial mass in LEO, so the hardware could be launched dry on one
flight, and the propellants could be launched on 3 or 4 additional tanker
flights. The payload of the launch vehicle would need to be only 1/4 to
1/5
of the payload of the HLLV required to do it all on one flight, as with
Mars
Direct, which would put it in the range of a medium lift, 2-stage, VTOL
RLV.
An RLV would have many other uses than Moon/Mars flights, which would
help
spread the costs, and Congress couldn't shut down the Moon/Mars program
by
shutting down the launch vehicle production line like they did with
Apollo
and AAP.

Orbital construction is to be avoided.

But orbital joining of vehicles is well-established.

The only connection really needed between the Trans-Mars injection
stage, if it is "not wanted on voyage", is a mechanical one capable of
handling of the order of a MegaNewton of thrust, and a few Newtons of
drift-apart force.

(Plus a redundant set of electromagnetically coupled data buses for
monitoring and control.)

If units such as the cruise habitat, the lander, and each stage of the
propulsion can be launched, largely unfuelled, independently, they can
be docked in orbit - after all, Progress does that much nowadays, and
has done for years.

Yes, we could do something like that. We could have done something like
that with Apollo and gone to the Moon using Saturn-I's (with LOR AND EOR)
and avoided the expense of developing the Saturn-V and LC-39. We could do
something similar to go to Mars.

What I actually propose is to launch all of the Mars-bound payload on one
flight. The Orbiter stage of the launch vehicle would use it's full delta-v
capability to inject the payload into orbit, arriving at the propellant
depot with only residuals. In the Mars Direct scenario, the first
Mars-bound payload would consist largely of the ERV. Two years later, the
Hab would be launched in a similar fashion. The Orbiter stage with it's
attached payload would dock to the propellant depot and the Orbiter stage
would be refueled. The vehicle would then undock and the Orbiter stage
would do the TMI burn. Mars-landing propellants (and seed hydrogen for
Earth return) would be loaded at the same time as the TMI propellants.

One could, of course, split up the Mars-bound payload into two (or more)
packages, such as the ERV hardware in one (or two) package(s) and the
aerobrake and lander stage in another. That would permit the use of an even
smaller launch vehicle (at the cost of a larger number of launches per Mars
flight). I would not object too strenuously to doing that.
--
© John Stockton, Surrey, UK. Turnpike v4.00
MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms &
links;
some Astro stuff via astro.htm, gravity0.htm ; quotings.htm, pascal.htm,
etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail
News.

"Dr John Stockton" wrote in message
...
JRS: In article , dated Mon, 27 Dec
2004 15:06:08, seen in news:sci.space.policy, Dick Morris
posted :

Orbital *assembly*, in the sense of bolting things together, and then
hooking up electrical connectors and fluid lines in pressure suits is
generally to be avoided. But LEO *refueling* is a perfectly viable
alternative. A Mars ship would be something like 3/4 - 4/5 propellants
for
the initial mass in LEO, so the hardware could be launched dry on one
flight, and the propellants could be launched on 3 or 4 additional tanker
flights. The payload of the launch vehicle would need to be only 1/4 to
1/5
of the payload of the HLLV required to do it all on one flight, as with
Mars
Direct, which would put it in the range of a medium lift, 2-stage, VTOL
RLV.
An RLV would have many other uses than Moon/Mars flights, which would
help
spread the costs, and Congress couldn't shut down the Moon/Mars program
by
shutting down the launch vehicle production line like they did with
Apollo
and AAP.

Orbital construction is to be avoided.

But orbital joining of vehicles is well-established.

The only connection really needed between the Trans-Mars injection
stage, if it is "not wanted on voyage", is a mechanical one capable of
handling of the order of a MegaNewton of thrust, and a few Newtons of
drift-apart force.

If units such as the cruise habitat, the lander, and each stage of the
propulsion can be launched, largely unfuelled, independently, they can
be docked in orbit - after all, Progress does that much nowadays, and
has done for years.

Yes, we could do something like that, but what I propose is to use the
Orbiter stage of the RLV to do both the orbital injection and the TMI burn,
after being refueled in orbit. The Orbiter stage of the launch vehicle
would use it's full delta-v capability to inject the payload into orbit,
then dock to the propellant depot, where it would be refueled. The vehicle
would then undock and the Orbiter stage would do the TMI burn. Mars landing
propellants - and seed hydrogen for Earth return - would be loaded at the
same time as the TMI propellants. (The Orbiter stage would be designed from
the start for the Mars mission, and the RLV booster stage would be sized as
required to get the Orbiter and its Mars payload into orbit.)

In the Mars Direct scenario, the first Mars-bound payload would consist
largely of the ERV. Two years later, the Hab would be launched in a similar
fashion. Instead of launching a Mars payload as a single unit one could,
for example, split the ERV payload into two packages, for each stage of the
ERV itself, and another package for the aerobrake and lander stage. That
would allow the use of a still smaller launch vehicle, but then the Orbiter
stage no longer has enought total impulse to do the TMI burn for the
complete stack. We would either have to develop a separate TMI stage or use
some kind of staging arrangement to do the TMI burn. I wouldn't object too
strenously to doing it that way, but prefer the operational simplicity of
the single docking operation.
--
© John Stockton, Surrey, UK. Turnpike v4.00
MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms &
links;
some Astro stuff via astro.htm, gravity0.htm ; quotings.htm, pascal.htm,
etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail
News.