Soviet Lunar Lander- Rushed into production?

[Weaver]

Spherical shapes is what I expected when I saw the title.
I suppose Soviets found it a good shape for containing pressure differences.

A sphere is supposed to be the best type of pressure vessel... something all deep submergence vessel makers should know...

Actually, there is some footage on the Tube of how they make spherical vessels, using a welded construction, water and high explosives... fascinating and really cool.

https://www.youtube.com/shorts/yheJXYbk-QI

A sphere is the best pressure vessel for a given weight of material, but it's often not practical or easy to make, so the next-best shape is a cylinder with hemispherical end-caps. A torus is also pretty good but pretty impractical (except for a fuel tank), but I'm not sure where it sits relative to the cylinder. Part of this is the avoidance of stress-raisers which occur at sharp changes of section or shape, such as a square corner.

It's worth remembering that the pressure difference across the hull of a spaceship is WAY less than that across the hull of a submarine. Subs have to take thousands of psi and are thus pretty constrained to "pure" pressure vessel shapes. When a sub has an irregular outer shape, that's usually an unpressurised fairing outside the actual pressure hull. A spacecraft only has to take, at most, 14.7psi (one atmosphere) and with an increased oxygen percentage it can get away with less than that.  The Apollo CSM used pure oxygen at 5psi, switching to and from normal gas mix and pressure during ascent/descent. The LEM, which only ever had to operate at 5psi, was anything but a "pure" pressure vessel shape.

[Rick Lowe]

True. 

[Andrew Gorman]

The blue plastic 20 mule team tank is immune to any solvent cement, including my ultimate acrylic cement with methylene chloride.  It was also warped and not circular at the cut end.  I found part of a built up Strombecker Explorer 1, but it is very thick walled.  I HAD some appropriate tubing, but it went away in the late purge. I did strip the paint off of some recycled parts and beads, cleaned up the future landing legs  and am thinking about a jig to hold the spherical tanks in position to be glued.  I also moved the parts I'm actually using into their own small box and dug out a pearl drilling jig I picked up at a flea market decades ago for its first ever use.

[Old Wombat]

... and dug out a pearl drilling jig I picked up at a flea market decades ago for its first ever use.

The fact that you remembered you even had it is impressive in its own right!   

[Andrew Gorman]

The Pearl Drilling Jig has been rattling around in the jewelry box drawer of "tools of minimal utility" so it's often in sight.  And it proved to be of minimal utility, not grabbing the plastic beads tight enough to hold while drilling a #14 drill in a hand held chuck, leaving a mark.  It did work fine with smaller bits in a Dremel. For making the ring of tanks I just glued them around a narrow ring of tubing, big enough that another bead can slip through for the ascent engine.  Then added two or three more points of support by sticking some craft store "Sequin Pins" to connect two adjacent beads and the ring. Yep, they look like tanks for something. My stretched sprue adventure has been limited to filling the holes in the beads.  Pictures will follow when there is more to look at.  Sequin pins are great for tiny spheres and antenna spikes. Balls are about 3mm in diameter and read as round:
https://www.amazon.com/Assorted-Thumbtacks-Christmas-Ornaments-Accessories/dp/B0816H3TQC

[Leading Observer]

Hey, Old School still works... and it's cheaper, and keeps the State Industries going... 

How much did NASA spend developing a ball pour that would work in Zero-G? Soviet solution - the mighty pencil😀

[Rick Lowe]

Hey, Old School still works... and it's cheaper, and keeps the State Industries going... 

How much did NASA spend developing a ball pour that would work in Zero-G? Soviet solution - the mighty pencil😀

True.
But then there's the issue of loose bits of graphite floating around and getting into the circuitry...

[Weaver]

Hey, Old School still works... and it's cheaper, and keeps the State Industries going... 

How much did NASA spend developing a ball pour that would work in Zero-G? Soviet solution - the mighty pencil😀

Except it's all an urban myth. The Fisher Space pen was a private venture development that didn't cost NASA a dime other than the purchase price of a few thousand, and the Soviet space program bought them as well, because it turns out that having flammable wood shaving and conductive graphite dust floating around in zero gravity in a spacecraft isn't the best of ideas.

[Andrew Gorman]

I spent some time looking at actual Soyuz ships, so am more comfortable where bits pieces and holes need to go.  This picture of a museum Luna 16 inspired me for color- some kind of bureaucratic office drab:
https://sciencephotogallery.com/featured/luna-16-lunar-space-probe-detlev-van-ravenswaay.html
Tamiya xf76 gray green seems close, but I'm open to suggestions.  Canadian Navy Ship Side Gray is another possibility but I can't find any model paint that color.

[kerick]

I spent some time looking at actual Soyuz ships, so am more comfortable where bits pieces and holes need to go.  This picture of a museum Luna 16 inspired me for color- some kind of bureaucratic office drab:
https://sciencephotogallery.com/featured/luna-16-lunar-space-probe-detlev-van-ravenswaay.html
Tamiya f76 gray green seems close, but I'm open to suggestions.  Canadian Navy Ship Side Gray is another possibility but I can't find any model paint that color.

Lots of great ideas on that site!

It made me imagine astronauts on the moon using jet packs to get around. It could work since the gravity is so much less that the jet packs would be much smaller and could carry more fuel.

[Andrew Gorman]

A quick root around in the basement turned up an appropriate diameter tube- or at least half a tube X2, but it is part of a "rare" model, a Geobra/Palmer/Renwal Vanguard rocket.  Of no use to me, but for some reason I am conflicted about cutting it up.  I'll dig around again tomorrow, but I think it will meet its doom!

[kerick]

Sell the kit and use part of the money to buy a proper tube?

[Rick Lowe]

Find a charity/hardware shop/one at a landfill and see if there's any tubing that will do the job instead?

[Weaver]

I spent some time looking at actual Soyuz ships, so am more comfortable where bits pieces and holes need to go.  This picture of a museum Luna 16 inspired me for color- some kind of bureaucratic office drab:
https://sciencephotogallery.com/featured/luna-16-lunar-space-probe-detlev-van-ravenswaay.html
Tamiya f76 gray green seems close, but I'm open to suggestions.  Canadian Navy Ship Side Gray is another possibility but I can't find any model paint that color.

Lots of great ideas on that site!

It made me imagine astronauts on the moon using jet packs to get around. It could work since the gravity is so much less that the jet packs would be much smaller and could carry more fuel.

It was looked at extensively for Apollo, which is why there are flying platforms and two-seat "hoppers" in the Airfix Astronauts set. It is, as you suggest, entirely doable, but it was rejected because:

a) Apollo was in a hurry and development and training time would have been significant,

b) the limited endurance of the Apollo landings meant they could do everything possible in the available surface time without travelling that far,

c) the risk of crashes was high and would almost certainly end a mission in tragedy, so they didn't take that risk

[kerick]

That reasoning is understandable. If there is ever a prolonged stay on the moon it might be a consideration. But this is whiff world so the possibilities are endless.