Earliest Plausible Manned Moon Landing

Angle information to Earth and Sun can actually be semi-automatically read with photomultiplier tube sensor (with 1935 tech, you would realistically need to turn two dials until the pair of balance galvanometers reads zero, and then read angle from dials). And stars angle could be taken with sextant.
Then feed the angle data to corresponding nomogram to get the navigation solution..
Nomograms are the very powerful computation tool for specific tasks, including orbital transfer calculations. Slide-rule is a special case of nomogram. For computer-less manned space capsule, the recipe for accurate guidance would be just "add more nomograms affixed to walls of capsule".

Was the manufacturing precision good enough to be useful?

Like the Soviet Lunokhod rovers, or their plan for LK manned lander, didn't have computers, just fancy autopilot, a crude computer, but still counts

The Soviet Lunar plans were a bit too dangerous for humans IMO.

There were many more things that if they broke, they'd have a dead crew.

Wasnt the guidance computer more of a luxury item? They were doing the calculations on the ground as well to compare what the computer on board of the capsule was doing because no one trusted that thing. Communications delay was 2 seconds or so, they could have done everything on the ground except the landing, which the pilots could and did do by hand.

In a sense. But some of the manoeuvres needed to be very precisely calculated and if communications DID fail, then the computer might be necessary for keeping the crew alive.

You could consider that extra margin of security a "luxury", but given the enormous costs that a dead crew would have carried... One could also consider it a very necessary piece of kit.

And for the sake of this WI, yes, maybe you could dispense with the computer and instead opt for a different backup. But I really can't see anyone starting a moon shot without similar capabilities to provide backups as the Americans were able to do for Apollo. Given the very public nature of the stunt and the extreme cost involved, no-one wants to lose people up there.

(And for those who say "what about the Soviets", I have a hard time seeing them actually taking a punt on the mission plan the cobbled together in the late 60s.)

fasquardon
 

trurle

Banned
Was the manufacturing precision good enough to be useful?
Nomograms can typically achieve precision of 0.2% to 1% (larger sheet is more accurate). Not as good as you accustomed with computers, but with 4-5 correction burns you still can get into reasonable Moon orbit even with nomograms.
 
If it's simply about the computer... there's lots of PODs to speed up development of those, like Charles Babbage getting the funding and managing to build his analytical engine in the 1860s. Other countries follow and businesses adopt, and as soon as vacuum tubes are available they would be used to leave the mechanical computing era, you can have an ENIAC style in 1910s if you have the funding and experts. Integrated circuits could follow soon after as semiconductors and why they work the way they do had been discovered decades ago, someone just needs to have the idea to use it, and more people working with computers means more people who can have the idea.
There's still the problem that despite being revolutionary it might simply be ignored...
https://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld
 
like Charles Babbage getting the funding and managing to build his analytical engine in the 1860s.

Victorian materials science wasn't up to building his full-scale analytical engine.

And even if larger mechanical computers were built, where does that lead to? There's no way they can ever be as good as vacuum tube computers, let alone transistor computers and the advances that push forward mechanical computers don't really help transistors and semiconductors at all. It's not going to help a space program.

There's still the problem that despite being revolutionary it might simply be ignored...
https://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld

It was ignored for good reason though.

If we had a PoD for advancing semiconductor materials science in time for Lilienfeld's FET, then we might see transistor computers appearing in the 30s and 40s. I have no idea what could push forward the materials to make Lilienfeld's invention useful so early though.

Nomograms can typically achieve precision of 0.2% to 1% (larger sheet is more accurate). Not as good as you accustomed with computers, but with 4-5 correction burns you still can get into reasonable Moon orbit even with nomograms.

That's pretty cool.

fasquardon
 
Victorian materials science wasn't up to building his full-scale analytical engine.

And even if larger mechanical computers were built, where does that lead to? There's no way they can ever be as good as vacuum tube computers, let alone transistor computers and the advances that push forward mechanical computers don't really help transistors and semiconductors at all. It's not going to help a space program.
The mechanical ones can solve problems, but more importantly they get more people into computing engineering and research, and once they're available the same thing like OTL will happen - the immediate need for a faster one. Earlier mechanical ones imo lead to earlier adoption of vacuum tubese for computing, there's no reason to wait until the early 40s for that.

It was ignored for good reason though.

If we had a PoD for advancing semiconductor materials science in time for Lilienfeld's FET, then we might see transistor computers appearing in the 30s and 40s. I have no idea what could push forward the materials to make Lilienfeld's invention useful so early though.
There were claims made much later by people that he demonstrated a tubeless radio in the 30s. The truth is lost to history most likely. I'm not talking about integrated circuits, just simple packaged single transistors, the packed multiple transistors OTL followed shortly after, and the integrated circuit just put all of them into one package when it became possible to shrink it down sufficiently.

The process to create silicone crystals has been discovered in 1915 already and tolerances for early ones were nowhere near as important as they are today. There's plenty youtube videos of people producing their own transistors at home and testing them to prove they work (etching 20µ structures into silicone with a home projector and a simple lens, that's late 60s era). It's of course questionable how comparable an educated amateur today is to an expert 80 years ago.
https://en.wikipedia.org/wiki/Czochralski_process
Maybe i'm being too optimistic but shaving off 10 years of development could easily be done without the Victorian computer. I blame the world wars.
 
Maybe i'm being too optimistic but shaving off 10 years of development could easily be done without the Victorian computer. I blame the world wars.

Without the world wars, absolutely computing would have advanced faster.

I'm pretty sure the USSR would be building its first mainframe at least 10 years earlier without WW2, so without WW1 or WW2, you could probably shave off 20 years.

Also, there are ways to build better vacuum tubes which could plausibly be invented earlier, so one doesn't necessarily need transistors early to accelerate computers.

fasquardon
 
Without the world wars, absolutely computing would have advanced faster.

I'm pretty sure the USSR would be building its first mainframe at least 10 years earlier without WW2, so without WW1 or WW2, you could probably shave off 20 years.

Also, there are ways to build better vacuum tubes which could plausibly be invented earlier, so one doesn't necessarily need transistors early to accelerate computers.

fasquardon
They were dramatically miniaturized and still have their uses today, and there was also something inbetween a vacuum tube and transistor, i dont remember what it's called though.
 
If it's simply about the computer... there's lots of PODs to speed up development of those, like Charles Babbage getting the funding and managing to build his analytical engine in the 1860s. Other countries follow and businesses adopt, and as soon as vacuum tubes are available they would be used to leave the mechanical computing era, you can have an ENIAC style in 1910s if you have the funding and experts. Integrated circuits could follow soon after as semiconductors and why they work the way they do had been discovered decades ago, someone just needs to have the idea to use it, and more people working with computers means more people who can have the idea.
There's still the problem that despite being revolutionary it might simply be ignored...
https://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld

It isn't necessary to use either mechanical or vacuum tube based computers.
How's this for a POD: fluidic computing is developed 150 years earlier, around the same time Babbage is working on the Analytical Engine. Suddenly, instead of requiring several seconds to get a result, several thousand computations can be performed per second. The resulting increase in number crunching capability would have large economic impacts, but assuming everything remains more or less unchanged in the grand scheme of things, then the computational wherewithal will exist in the early 50s to plot correction burns for at least a circumlunar trip. Of course, a large enough rocket would be required...
 
They were dramatically miniaturized and still have their uses today, and there was also something inbetween a vacuum tube and transistor, i dont remember what it's called though.
Resistor - Diode Logic? you can make logic gates with Diodes, and that output to work with relays to invert signals when needed.

Anytime after 1886 Selenium diodes could have been made commercially, rather than OTL 1930s.


Clunky, yes, but a number of '50s 'Big Iron' mainframes used diode logic
 
Trurle wrote:
Yes, i tend to agree what workable space suit was the bottleneck of moon landing.

Well, being ‘technical’ it’s more an issue if you actually plan on doing anything you know, useful once you get there J I am still surprised to read stories even into the early 1960s where authors whom you would assume KNOW better make assumptions that the Moon has an atmosphere or some such making it ‘easy’ to get around without a space suit….

Effective rockets can be developed about 1916 if some perceived military application for them would exist (for example, delivery of biological warfare warheads).

Key issue is the phrase “military application” because while they were available and in fact used, (a Royal Navy ship launched rocket aimed at trying to knock down Zeppelins was deployed with limited success) the ‘rocket’ wasn’t actually very useful to the military when compared to any type of shell artillery. Now having said that bio-warfare delivery and some chemical use IS possible since you don’t really need accuracy as much as a specific “benign” delivery method. On the other hand we ‘almost’ had gas/bio delivery by ‘cruise missile’ with the Kettering Bug (https://en.wikipedia.org/wiki/Kettering_Bug, https://en.wikipedia.org/wiki/Hewitt-Sperry_Automatic_Airplane) and getting that deployed operationally in WWI would actually be pretty easy. “Rocket” propelled not so much.

Life support was not much different from models used on submarines.

Very limited though since till the mid-50s it pretty much consisted of whatever air was inside when you closed the hatch and how much CO2 absorbing chemical you could carry if any. “Stored” air wasn’t a thing because you had no way to ‘dump’ the air you already had to add new. This of course is less an issue when in a vacuum but air storage is still by compressing it into a cylinder and lugging that along and large containers of CO2 absorbing material.

For reentry, bakelite (which make a passable heat shield) was invented in 1925

Well with enough surface area you might not need what one considers a ‘normal’ heat shield. (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660027566.pdf)

Guidance..well, with full-manual control and a stock of experienced ICBM pilots (yes, WWI-epoch ICBMs must be piloted to have a decent probability of hit, with pilot may be jettisoning at final stage of reentry) i can imagine a hundred of qualified "rocket aces" lining up the space program premises by 1930.

Something like a ‘rocket-powered’ version of this “Spider Plane” concept? (http://blog.modernmechanix.com/diving-spider-plane-to-hurl-big-bomb/) But again what’s the ‘motivation’ for the development?

The other problem is the actual development of the needed materials and industrial methods is still lacking for such a vehicle. Even something as ‘simple’ as the Sanger sub-orbital bomber would need some pretty hefty materials science advances. (And we’re talking ‘mearly’ intercontinental not antipodal here!)

Then come the space suit problem. First space suits were developed for stratosphere jumps in 195x, and earlier models were extremely crude, likely not survivable in vacuum over 30 minutes even if not failing outright.

Some of the 1920-ish models of “stratosphere” suits were possible but not very comfortable or really practical once ‘pressurized’ but again it depends on what one plans on doing with them.

Landing ‘might’ be possible with some early light based reflector devices but really you’d be ‘eyeballing’ it before the advent of a good radar.

Swiffness wrote:
Well, if you mean land a man on the moon as a ONE WAY TRIP, that should knock a few years off eh?

Sure if you can ‘justify’ it PR and acceptability wise. Both the US and USSR gave the concept some passing glances, (https://www.wired.com/2012/04/one-way-space-man-1962/) but the chances of failure are higher as is the chance of failing DURING the mission. (And no, nobody considered an outright ‘suicide’ mission for the same reason no on seriously considered launching a person on a V2 ‘just because they could’ )

Turtle wrote:
Nomograms can typically achieve precision of 0.2% to 1% (larger sheet is more accurate). Not as good as you accustomed with computers, but with 4-5 correction burns you still can get into reasonable Moon orbit even with nomograms.

Nomograms and Pork Chop Plots are wonderful items to have around and you can ‘pre’ do them for a mission. (http://www.projectrho.com/public_html/rocket/astrodeck.php#nomograms,http://www.projectrho.com/public_html/rocket/mission.php#porkchop) heaven help you if you have to make changes though… Then again you CAN use an abacus if you have to J

Ddtim wrote:
It isn't necessary to use either mechanical or vacuum tube based computers.
How's this for a POD: fluidic computing is developed 150 years earlier, around the same time Babbage is working on the Analytical Engine. Suddenly, instead of requiring several seconds to get a result, several thousand computations can be performed per second. The resulting increase in number crunching capability would have large economic impacts, but assuming everything remains more or less unchanged in the grand scheme of things, then the computational wherewithal will exist in the early 50s to plot correction burns for at least a circumlunar trip. Of course, a large enough rocket would be required...

A ”plumbers nightmare” computer? It’d work of course but I’ll note (again) Arthur C. Clarke pointed out that we’ve had significant ‘computing’ power for centurires if you think about it the ‘right way:

“Into The Comet”
...‘This,’ said Dr Martens three days later, ’isn’t my idea of a joke.’ He gave a contemptuous glance at the flimsy structure of wire and wood that Pickett was holding in his hand.
‘I guessed you'd say that,’ Pickett replied, keeping his temper under control. ‘But please listen to me for a minute. My grandmother was Japanese, and when I was a kid she told me a story that I'd completely forgotten until this week. I think it may save our lives.
‘Sometime after the Second World War, there was a contest between an American with an electric desk calculator and a Japanese using an abacus like this. The abacus won.’
‘Then it must have been a poor desk machine, or an incompetent operator.’
‘They used the best in the US Army. But let's stop arguing. Give me a test — say a couple of three-figure numbers to multiply.’
’Oh — 856 times 437.’
Pickett’s fingers danced over the beads, sliding them up and down the wires with lightning speed. There were twelve wires in all, so that the abacus could handle numbers up to 999,999,999,999 — or could be divided into separate sections where several independent calculations could be carried out simultaneously.
‘374072,’ said Pickett, after an incredibly brief interval of time. ‘Now see how long you take to do it, with pencil and paper.’
There was a much longer delay before Martens, who like most mathematicians was poor at arithmetic, called out 375072.’ A hasty check soon confirmed that Martens had taken at least three times as long as Pickett to arrive at the wrong answer.
The astronomer's face was a study in mingled chagrin, astonishment, and curiosity.
‘Where did you learn that trick?’ he asked. ‘I thought those things could only add and subtract.’
http://www.projectrho.com/public_html/rocket/astrodeck.php

Figuring out HOW to get there is in essence pretty simple, the ‘technology’ to do so it vastly more difficult to accelerate.

Something to keep in mind is that (as I noted above) “military” applicability of rockets are marginal at best over other options and the ONLY reason Germany pursued them (to the tune of what amounts to a couple billion dollars currently in at-the-time money) was to go around the proscriptions on artillery production in the Versailles Treaty and WHICH for the most part was a significant money and resource sink of limited value! Sure they got ‘some’ good systems out of the deal but those were literally ‘side’ projects of the main work which ended up in a very limited and arguably non-effective weapons system. They got ‘vastly’ more ‘value’ out of the V1 and those aforementioned ‘side’ projects than the main liquid rocket program.

The POD to anything earlier than a late 60s landing possibility requires an earlier and more extensive use of rockets as a plausible weapons system.

Randy
 
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