Helmet Shenanigans, part 02

With the entire helmet now lined internally with additional layers of foam, I’ve added a bit of detail to the back of the helmet, where I intend to attach a external life support tube that follows the back of the spine down to the life support system. I also performed a first round of smoothing the outside of the helmet by carefully trimming away edges with a sharp knife and filling in seams and small gaps with hot glue using a trick described by Andrew DFT in his youtube tutorials. You can use hot glue to fill in small gaps (under 5mm -ish, larger ones will be trickier due to noticeable surface tension of the liquid glue) then flatten the surface of the glue using the tip of your glue gun (or any other hot item). This can also be done to old ho glue seams, since those will melt easily. Sharp edges can also be filed away in certain cases, but this seems to only work for already gentle angles and small surface (such as uneven surfaces left by a bad trimming cut).
This gave me a significantly rounder, though still far from properly shaped helmet:

At this point I find myself unable to smooth out the helmet’s shape any further, so I went ahead and applied a VERY generous layer of PVA to the outside of the helmet. The idea here is that if I wait for ~10 minutes (that’s for my particular brand of “fast drying” PVA) for the glue to start getting a bit more viscous, I can smooth it over uneven surface features, improving the helmet’s shape. It will also cover every foamy surface, replacing the rough texture with a smooth finish. The helmet will now look painted white for a few hours. Due to the very thick coating, the PVA did not get distributed evenly (and even started streaming down the sides in a few places ?), as you can see i the second image below.

Given my relative inexperience with all these processes, I expect to do 2 or maybe 3 more PVA coatings, waiting a day to let it dry fully every time so that I can do some filing of uneven places. In hindsight a lot of these problems come from the lack of curves in my cad design. *facepalm*

Engine Unit Frame, part 01

Having left the PVA to dry, I’ve started making the base structure for an engine unit. I purchased some stock aluminium angles at 15mm x 15mm and 1.5mm thickness, in huge 5m long pieces. Here my recent hours pulling weights at the gym actually came useful, since the rest of that day was spent sawing and drilling aluminium, and I would not have been able to do so much of it in one day a year ago X).

While my cad models show the outer section of the engine units as a contiguous piece, my plan is to actually make that shape as a frame only, leaving all the internals exposed. The design logic here would be to keep the engine units as lightweight as possible (since inertial is the enemy of high thrust), bu the main reason is to give them a “complex rocket-sciencey” look, with fuel feed lines, wires and bolts/rivets all in sight.

Since all of this would take too long to model in Fusion, and I mainly use CAD as a size reference and high level designing tool, how any of this detail is supposed to look like will have to wait until I get around to making it ;).

Having cut up 98% of one of the 5m pieces, I’ve started bolting together the shape of the engine unit. My original plan was to use M5 bolts, but the heads on those are too big and prevent me from placing 2 bolts adjacent to each other on different surfaces of the same angle piece (aka they’re too big to fit into corners), so I will be using M4. This is as far as I’ve gotten thus far:

In terms of work I am maybe 1/4 of the way to completing the barebones external structure. Given that it took me about 1.5 hours, and I want to eventually make 4 engine units, this does not bode well for my sanity a this project progresses ?. I do however think that I can speed the process up a bit for the other 3 engine assemblies, since I’ll have a fully assembled example to use as reference, and most of the mistakes I’m making right now, such as bolting pieces the wrong way around, will hopefully not happen twice ^^. The main timesinks in this process is the time it takes to do a proper cut or hole. Carefully measure and mark; clamp piece; saw/drill; file excess; use new cut/hole to mark out one on a corresponding piece; repeat. All the shiny dust around that clamp is from me cutting/drilling ?.