This is by far the simplest practical breakdown of the rocker bogie mechanism that's easy to understand. It's one thing to read papers with angle calculations, pressure delta etc... but another to actually see just the moving components

I think this platform would work quite nicely for the simplest practical rover

https://wpirover.wordpress.com/2011/11/15/rocker-differencing-kinematic-suspension/

And then there's this guy who built an entire rocker bogie car for his kid

https://www.youtube.com/watch?v=E_6e71BJOzM

There's a lot of reading involved when it comes to starting your own space program

https://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.21

Personal hygiene is important under the DIY space program. Of course, a spinning habitat would make things a lot simpler, but in the meantime, we'll probably go with the no-rinse shampoo too

https://www.reddit.com/r/Damnthatsinteresting/comments/jp76rj/washing_hairs_in_space/

I was looking at the engine detail of the Redstone rocket engine, the heart of the PGM-11 missile. It occurs to me that this particular geometry lends itself quite well to the expander cycle

This particular engine had a turbopump powered by decomposed high-test peroxide

In theory, H2O2 is a pretty neat way to power a turbopump (also used by Copenhagen Suborbitals is using it for their engines) and as a monopropellant for RCS thrusters, but it's kind of a pain to handle and store safely

Fiber optic cables don't seem to fare well without special shielding and different methods of construction in a high radiation environment. While they're resistant to transient EM spikes, they do tend to break down and attenuate more of the laser light over longer distances

This is a bit of a dilemma. Either go with copper lines for signaling and sensors and risk spikes and have them acting as antennas in a EM field, or go with fiber. Alternatively, I may have to make my own

Also, I may have accidentally landed myself on some kind of list by searching for "radiation sources" too many times

I'm both heartened and terrified that some of you are genuinely interested in this backwater space program

Please be patient about the first several (dozen?) explosions

Speaking of explosions...

The number of accidents in rocketry is too damn high!

Some of that is the inherent danger of the fuel + oxidizer and the complicated plumbing involved. I have neither the intelligence or patience to grasp all of that mess so if I build a rocket, it will probably use the expander cycle

The plumbing is *far* less complex with fewer moving parts. Which means fewer places for things to go wrong and fewer areas of concern to monitor (less work for the computer)

I know the new hotness is Methane right now, but I'd go with Dimethyl Ether as the fuel instead. It's very cheap and can be made from biofuel (possibly on Mars via a different process as well)

As the oxidizer, I'd use Nitrous Oxide. Laughing gas, basically. It's also very cheap and made by the millions of tons. Best of all, it can be decomposed into a very hot gas at 577 C

Dimethyl Ether auto ignites at only 350 C so there's the startup process solved. No need for pyros, sparks, etc...

No nonsense that can fail explosively. Just a tiny electric pump to get the N2O going over the catalyst, which is more than hot enough to ignite the mixture

Also, the expander cycle limits the maximum size of an engine, which means you have to build more smaller ones anyway. While that's extra work, you get spares if one or two shutdown mid-flight

And expanders don't have complicated turbopumps which need high temp/high speed moving parts and seals so they're cheaper to build

Hmm...

An expander cycle rocket engine with a radiation resistant computer and sensors will probably cost more than the $2.41 I found in my couch this morning

I'm gonna need to engineer this to within an inch of its life

Going with Dimethyl Ether and Nitrous Oxide as fuel and oxidizer also because they can be kept liquid at similar temps

-141 C To −24 C for Dimethyl Ether and −90.86 C to −88.48 C for Nitrous Oxide. Which means, they can share a bulkhead in the tanks

This significantly cuts complexity and reduces weight

Also, both have enough expansion at warmer temperatures that I can use "Autogenous pressurization". Same as SpaceX's Starship (though mine will probably be made of glue and aluminum foil)

Hypgergolic propellant as praxis

ProTip: The oils on your skin can be just as bad as battery acid depending on the material you're touching. Especially if you can't clean it ever again and will remain in operation for years or decades

Also, welding gloves are better than oven mitts for everything you'd need ovens mitts

Technically, there's no rule that you can't use a turbo charger used for a typical small block V8 in a rocket engine as a turbocharger (with a few modifications)

As long as it doesn't blow up immediately, it should work

This plan is flawless and brilliant

My kitchen is too small to build a rocket engine :(

Apparently a turbocharger from a V8 isn't actually designed to funnel liquid propellant at -89 C at turbopump tolerance. Or survive reentry down from orbital speeds (because reusable rockets or GTFO)

My plan to use a rice cooker to make homemade high-temp composites is probably gonna have issues too

I hope lockdowns lift a bit so I can go trash diving. I'm sure someone's thrown out an orbital grade turbopump somewhere

ProTop: Always separate utensils used in your rocketry experiments separate from your food cooking stuff

Graphite tastes terrible and epoxy is toxic

I think I'll also be using stainless steel for my rockets so there's basically no difference between me and SpaceX

Oh wow. Titanium is kinda expensive. Like much more than I thought it was. Well, it's probably OK to use plain ol' steel as long as it doesn't reach softening/melting temperatures

2 girls 1 cup

Although there are significant drawbacks with a multi-nozzle rocket engine design, I think for small scale development, the benefits outweigh them. Biggest benefit being combustion stability, which is greater in smaller combustion chambers (see Apollo's F1 issues). The biggest drawback is the additional manufacturer of nozzles and chambers, but once you get the design finalized, they're relatively straightforward to do repeatedly

So far, I've been unsuccessful in finding an appropriate spacesuit design that I can make with my own sewing machine and materials from the craft store. Probably will have to settle for a pressure suit made of heat resistant material for now, until I get better at it

I'd like to investigate non-pressurized suits, particularly compression types which use "lines of non-extension". The materials will still be expensive, but at least this will be old research

Today in gloriously-impractical-yet-want, here's an actual core memory unit including the Gerber files for the circuit board and schematic

http://mikesmods.com/mm-wp/?p=556

Spacecraft don't use these anymore since there are better options, but part of me feels like there's still some value in here

I also wonder if it's feasible to have core memory backed SRAM

So the system reads/writes to SRAM in normal use, as a fast buffer, while it slowly updates the core memory

Might just be crazy enough to work

I thought I was being very clever when I thought of combining PCBs with core memory

Basically, you include an iron coated ring in one of the inner layers (or maybe several rings) while a via through the middle takes care of the connections to sense and address leads

Well, someone already thought of it before

Back in 1961

But it does mean this may be a feasible way to create modern core memory without resorting to fiddling with tiny ferrites. Maybe even mass-produce it by iron-plating rings

If we take "ring" or "ferrite" to just mean "iron loop", then printed core memory may actually be fairly straightforward (hah!)

The iron loop can actually be printed as two iron-plated half loops on either surface of a 4 layer, double-sided PCB, with vias through the middle and on each half end of the loop to the one the opposite side

4 layers is also ample to handle addressing, sense, and inhibit lines

Coincidentally, 4 layers are the cheapest multi layer PCB type available from most vendors

I think this is a Crew Return Vehicle concept. There's a lot of space dedicated to provisions and maybe experiments, but not a lot for fuel. I'm guessing there's just enough for a bit of maneuvering and a deorbit burn and nothing else

But that also makes it a feasible build of an orbital spacecraft for a DIY space program that's a bit more exciting than a simple capsule. Geometrically, it's actually an elongated capsule than a "spaceplane", unlike the Shuttle

And you can mount it atop a rocket

Oh that's actually not a Crew Return Vehicle, but a full on space shuttle replacement concept by Lockheed. And it's a lot bigger on the inside than the concepts imply. Which means, it's probably not going to be built any time soon (if at all)

The problem with larger Shuttle* concepts is that they're always going to be semi-reusable as long as rockets are involved

Ironically, the SpaceX Starship is probably the way to go as it's the least "plane-like" of all the reusable systems

This is a pretty nice video of on building a solar cooker with a parabolic reflector. The form is actually made of concrete so you can make many reflectors repeatably with very good accuracy

If I'm building my own radio observatory, I'd probably also use this technique to build hundreds of parabolic dish antennas

https://www.youtube.com/watch?v=9Q_VzJ3P4wc

Going back to the idea of DIY core memory, I came across this page many moons ago, but lost it. Sadly, the original page is gone, but luckily the Internet Archive has a snapshot

It's a very good primer on the operation of core memory and has a set of demo circuits to operate a small grid of cores (expandable to as many as is practical)

https://web.archive.org/web/20061205234134/http://cs.ubc.ca/~hilpert/e/coremem/index.html

This is an interesting preview of an orbital space station structure (the basics of assembly) from The Gateway Foundation

Their goal is to send an assembly robot with the raw material to build a rotating habitat in space. They'll start with the skeleton structure and the rest can be brought up with subsequent launches

https://www.youtube.com/watch?v=85MItNr0rBk

Large scale production of chemicals still require very expensive permits. I know it's to ensure that a large chunk of a neighborhood suddenly doesn't become uninhabitable, but I can't help but feel some of it is just run-of-the-mill bureaucracy

The good news is that I won't need an alcohol permit if I don't produce ethanol

Bad news is that storing several tons of Nitrous Oxide(oxidizer) and Dimethyl Ether(fuel) is a pain and I still need permits

Er... and I need to get said chemicals first

Hmm...

The asteroid belt is actually farther away from Earth than I remembered 🤔

Gravity is so weird

Every object, not acted upon by a force, is still a traveling in a straight line from an object's own perspective. No matter how curved it looks to an outside observer

Even when it's about to hit something

OK, I've had my fill of math for the rest of the decade

Now I actually have to figure out orbital mechanics to the point of being able to model it in the Doom engine, running on a laptop I found on the street back in 2007

Should be good enough to get a spacecraft to the nearest asteroid if I wrap it in some aluminum foil and Silly Putty to protect it from the radiation

This is a concept to incrementally append modules to the ISS with the intention of private use (likely "space hotel", but that idea has its own issues)

The idea itself seems interesting and I think it might be viable now that bigger payloads will soon be possible without the Space Shuttle thanks to SpaceX

This is an animation from a company called Axiom Space

I was looking at the A6/7 Redstone rocket engine and, while the design is decades old, it's one of the simpler variations that can be copied

Probably explains why Copenhagen Suborbitals use it as a reference for their own designs

Also, since the original engine used alcohol + liquid oxygen, it's a tad safer to operate than toxic hypergoic substances. The bigger danger was the high-test hydrogen peroxide used to drive the turbopump