earliest moon landing

Henry Spencer wrote:
Mind you, the crash-program timing I noted above is unfortunate, in
that it may put your first lunar expeditions during the nasty solar
maximum of the late 50s.

Wasn't the 1972 maximum, which was in the middle of the Apollo
program, even larger? I remember marveling at the August 1972
auroras. Fortunately there didn't happen to be an Apollo aloft that
day. If there had been, how much radiation would they have gotten?
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.

Derek Lyons wrote:

Pat Flannery wrote:


And when you need 30 motors per first stage of each individual N-1
rocket, you are turning out large numbers of motors that you can't be
sure of until the first launch is attempted and then you get a few
successful launches under your belt.



sigh Pat... You keep repeating this as fact, and it is not.

It is possible, nay fairly straightforward, to produce a large number
of motors *and* to be sure of their performance. That the Russians
screwed it up by making the wrong choices doesn't change this.

I'm not outright condemning the use of multiple motors on spacecraft,
but am stating that all things being equal in the reliability
department, you are more liable to have a motor fail the larger the
number of motors you use on a individual booster; the upside of the
multiple motor argument is that if you use enough, you can afford to
have one fail and still have a successful flight by increasing the burn
time of the other motors, such as on the second stage of Apollo 13;
that's an advantage. And smaller motors are easier and cheaper to design
than large ones; that's also an advantage. but once you start getting
beyond ten motors or so, you have to consider that your chances of
having one of them fail on a flight are starting to increase; as long as
the motor fails in a benign manner (sensing that it's function is going
outside of specification and shutting itself down) there isn't any
problem- but if the motor fails in a destructive manner- say by having
its turbopump disintegrate- then it is liable to damage other motors
that are near it, and you end up with a multiple motor failure at best,
and a potential chain reaction failure mode at worst, causing loss of
the vehicle.


Problems easily resolved with a proper design, qualification, and
production process. That the Russians chose not to follow this well
trodden path is no indication that the job is impossible.



I'm not saying it's impossible, I am just saying that beyond a certain
point you are probably going to end up with more problems from multiple
engines than the benefits you going to get from them, and thirty motors
to me sounds like it's beyond that point. if they had wanted to, von
Braun's Saturn team could have just taken a lot more of those H-1 Saturn
I motors, and built something very much like the Collier's ferry rocket
instead of the Saturn V...they didn't because they preferred a lesser
number of large engines over a large number of smaller ones.

Pat

Derek Lyons wrote:

Again, not an issue. Start your production early enough with one
line, then 'twin' it (I.E. move experienced workers from the first
line to the second, then filling both with less experienced). Repeat
as needed. (Or start a bunch of lines at once and be prepared to
scrap a lot of early motors.)


What exactly is the advantage to having to use a larger number of
workers and production facilities to get the same amount of thrust?

Pat

Pat Flannery wrote:

Derek Lyons wrote:

Again, not an issue. Start your production early enough with one
line, then 'twin' it (I.E. move experienced workers from the first
line to the second, then filling both with less experienced). Repeat
as needed. (Or start a bunch of lines at once and be prepared to
scrap a lot of early motors.)

What exactly is the advantage to having to use a larger number of
workers and production facilities to get the same amount of thrust?

The only possible advantage is if the motors are already proven and in
production. (I.E. Cluster's Last Stand.) That was the Russians first
mistake in the N-1 design.

I'm by no means advocating the design, only pointing out that your
repeated assertion that it was 'impossibly difficult to make work'
isn't quite true.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Pat Flannery wrote:

I'm not saying it's impossible, I am just saying that beyond a certain
point you are probably going to end up with more problems from multiple
engines than the benefits you going to get from them, and thirty motors
to me sounds like it's beyond that point.

The problem Pat, is that is *exactly* what you keep saying. That it's
an impossible job to tune/test that many motors.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Derek Lyons wrote:

The problem Pat, is that is *exactly* what you keep saying. That it's
an impossible job to tune/test that many motors.

I said it was going to be difficult and time consuming to do it; I
didn't say it was going to be impossible to do...and I was specifically
referring to the N-1 program in this regard- I said I thought the
Soviets would have had a very hard time making enough NK-15 motors to
sustain a high launch rate, while assuring that each motor had been
thoroughly checked out. This would take a lot of workers and a lot of
construction infrastructure to accomplish.
It's not impossible, but I think it isn't a good way to go about things
by any means.

Pat

Bull scheis.


"Greg D. Moore (Strider)" wrote:

wrote in message
oups.com...
I was arguing with a friend that the lunar landing required very little
new science but merely extrapolations of existing technology. This
leads to: If it had been necessary, and cost was no object, what would
be the earliest time that a lunar landing would have been possible. I
argue that the Germans could have done it with their 1940s technology.

"It depends".

You can look at the Saturn V as a scale-up of the V-2. Just a much bigger
rocket.

That is of course an extremely simplified look at things. Getting the F-1
engines to burn stablely was itself a large task.

Then of course you have things like the IU and on-board computation. Even
with the advances there, much of the navigation was helped out by the
ground.

And of course things like fuel cells. While the science had been around for
I think about a century, making it work effectively was part of the problem.

Ultimately I think it comes down to, "how much brute force and money are you
willing to throw at the problem?"

wellyou were "arguing" total nonsense, so you were agruing nothing!
You like to argue! Go handle rattlesnakes next time and save us
some further nonsense.



wrote:

I was arguing with a friend that the lunar landing required very little
new science but merely extrapolations of existing technology. This
leads to: If it had been necessary, and cost was no object, what would
be the earliest time that a lunar landing would have been possible. I
argue that the Germans could have done it with their 1940s technology.

Ok a more polite reply. vonBraun wanted to go to the Moon from
the outset. That was one of his earliest dreams in youth. He considered
the V2 and all of its planned successors in Germany, totally inadequate to this
job. Later when the political climate turned in favour of realising
this task he and his team designed the Saturn V specific to this job.
So there is your answer.
John



"Greg D. Moore (Strider)" wrote:

wrote in message
oups.com...
I was arguing with a friend that the lunar landing required very little
new science but merely extrapolations of existing technology. This
leads to: If it had been necessary, and cost was no object, what would
be the earliest time that a lunar landing would have been possible. I
argue that the Germans could have done it with their 1940s technology.

"It depends".

You can look at the Saturn V as a scale-up of the V-2. Just a much bigger
rocket.

That is of course an extremely simplified look at things. Getting the F-1
engines to burn stablely was itself a large task.

Then of course you have things like the IU and on-board computation. Even
with the advances there, much of the navigation was helped out by the
ground.

And of course things like fuel cells. While the science had been around for
I think about a century, making it work effectively was part of the problem.

Ultimately I think it comes down to, "how much brute force and money are you
willing to throw at the problem?"

Henry Spencer wrote:

In article ,
Greg D. Moore (Strider) wrote:
...If it had been necessary, and cost was no object, what would
be the earliest time that a lunar landing would have been possible. I
argue that the Germans could have done it with their 1940s technology.

You can look at the Saturn V as a scale-up of the V-2. Just a much bigger
rocket.
That is of course an extremely simplified look at things. Getting the F-1
engines to burn stablely was itself a large task.

However, that was mostly a consequence of its very large combustion
chamber. When the Russians ran into similar problems, they responded
by clustering smaller chambers instead, which worked.

Von Braun's "Das Marsprojekt" -- published in 1952, but based on work done
somewhat earlier -- proposed going to *Mars* with essentially WW2 German
technology.

Nicht! Theis was a dream theory thesis, a science fiction story idea, not a
practical proposal and he intended nothing more by this. He had been
so impressed with the rate o technological advancement he now considered space
missions possible at some near time in the future
and so was trying to get public support 'through a fantasmic idea'
so political funding would continue to grow in support of the growing
technoloigcal base. Werner was a consumate successful politician of ideas. He had
won his way with Hitler finally! Had he been younger we might never have seen the
Shuttle but kept with a rocket program?

John






Then of course you have things like the IU and on-board computation. Even
with the advances there, much of the navigation was helped out by the
ground.

Apollo could have gone to the Moon without ground help, using the on-board
optical navigation system. In fact, completely autonomous navigation was
originally a design requirement, and the capability was retained for abort
cases. (The ability to fly a lunar landing solely on optical navigation
was eventually sacrificed to free up some memory in the computer.) Tests
on Apollo 8 confirmed navigation accuracy comparable to ground-based radio
navigation.

Doing without the on-board computer would have been a bit less easy, but
Gemini demonstrated computerless LEO navigation (including rendezvous).

And of course things like fuel cells. While the science had been around for
I think about a century, making it work effectively was part of the problem.

Alternative approaches would have been used -- either solar-dynamic power
(concentrating mirrors supplying steam for turbogenerators), or possibly,
for the shorter lunar mission, gas turbines tapping propellant from the
rocket tanks. Heavier and involving moving parts, but quite workable,
especially on a larger scale than Apollo.

Ultimately I think it comes down to, "how much brute force and money are you
willing to throw at the problem?"

Quite so. I can't immediately think of any technological issues that
couldn't be finessed by just throwing mass at the problems.

The one area where von Braun's original concepts might have hit a serious
technological snag would be the extensive reliance on orbital assembly
work done in spacesuits. 40s and 50s concepts were (in hindsight) grossly
over-optimistic about both working in free fall and getting adequate suit
flexibility. It wasn't until the mid-60s that we really understood how
big a headache this all was. The discovery of this might have required
replanning around either modular concepts or development of much larger
launchers to minimize dependence on orbital assembly.

(Well, and there would have been the small matter of his favored assembly
orbit -- the "two-hour orbit" -- being right in the middle of the inner
Van Allen belt...)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |