Henry Spencer wrote:

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.

Right up till they got to their 30 engined N-1 Moon rocket it worked,
then it didn't work.
There is also a great deal of propellant feed plumbing weight associated
with such an approach.


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


And the figures on the number of rocket launches to build the space
station, Moon and Mars ships are staggering, Jeffrey Bell (Cut to scene
of Bell applying wax to his handlebar mustache, moth-eaten stovepipe hat
set at a jaunty angle, as he prepares toss a young Hawaiian single
mother into the fiery crater of Mauna Loa after foreclosing on her
mortgage.
"And after you, NASA! Hahaahaahaaa!"
He reaches down and lights his cheroot on a handy piece of freshly
ejected lava.)
Pointed out just how unrealistic von Braun's space plans were, based on
the proposed launch rate alone- as huge V-2 technology based ships put
small payloads into orbit at the rate of four launches per day:
http://www.spacedaily.com/news/rocketscience-03zzf.html







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).


The landing approach would have been interesting if you flew it by the
seat of your pants; Armstrong had a "fun" landing after getting the LM
into hover mode. Trying to do it with a bigger lander would have been
even more fun.... particularly figuring out exactly where you are going
to land at once you started your descent. You could probably do fairly
well on a direct ascent approach, but descending from lunar orbit would
be a whole other ball of wax, especially given the Mascons.

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.


But also heavy...one of the big problems would be the weight of the
lander; the LM was fairly small and had robust landing gear to take a
less than perfect landing, trying to get landing gear and spacecraft
structure that could handle a fairly rough landing on a far larger
lander would be challenging, to say the least. Years ago I read
someone's comment about the direct ascent Apollo variant where the whole
spacecraft was to land on the Moon, the gist of it was that the lander
was going to weigh about as much as an Atlas ICBM, and we couldn't get
one of those to take off reliably, much less have it gently touch down
without exploding.





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.


Getting a heat shield to take those reentry heats would have been a real
problem given the state of technology at the time, and Titanium and
Inconel metallurgy for spacecraft structure wasn't nearly as finessed as
it later became. The biggest problem though would have lack of space
experience; you'd still need something like the Mercury and Gemini
programs to get a handle on how to work in space.
IMHO, if you had gone gung-ho at the project at the end of W.W.II, you
might have been able to shave 5-10 years off of the timeline, at the
price of far more failures and lost lives, and far, far, higher expense
than what really happened.


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.


One could have used the Soviet automated docking technique, something
that we still should develop- but won't- because of the perceived threat
to manned spaceflight.



(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...)


You mean the _von Braun_ belts in this scenario; the lack of experience
with solar storms would also be a problem.

Pat