50% Scale ARCAS Build Thread

[MattD42]

After wanting to build an ARCAS for the longest time, I discovered that the random tube I have laying around is perfect for a half (ish, I'm not targeting perfection) scale ARCAS. It will be motor eject for the time being, however once motors become more available here in Aus I may convert it to DD for some spicier flights.

Some sources of info (for those interested):
https://ntrs.nasa.gov/api/citations/19700020646/downloads/19700020646.pdf
https://www.jcrocket.com/boosted-arcas.shtml#history

The av-bay and nosecone have already been 3D printed from PETG, though I would love to start making things from ASA, though some printer upgrades would be needed first.

For electronics, I'm running an Eggtimer Quantum (data-logging only here), Cris makes great stuff and I would highly recommend checking it out (if you're like me and love assembling tiny, fiddly things).

Up next will be cutting the fins, centering rings and bulkheads from 3mm ply on my universities laser cutter, hopefully tomorrow if all goes to plan.

 

[Hobie1dog]

 

[MattD42]

Today was a very productive day. Managed to laser cut the fins, rings and bulkheads, as well as 3D printing the coupler (slightly lengthened from the original CAD).

About the coupler, yes it is not the best idea to 3D print them, however university has access to Carbon Fiber/Nylon based filament and associated post processing equipment. After chatting at length with my materials professor (who has done some very cool titanium additive manufacturing work with Lockheed), we concluded that it should be strong enough for a small-ish rocket. Despite my initial apprehension surrounding layer lines, they are apparently not a weak point after chemical treatment, and it certainly feels that way. This material is very expensive - hundreds of dollars per kg -, but learning about the process (and the final part) was well worth the $15 imo.

After much messing about with AutoCad, I cut the fins and such from 3mm ply.

Unfortunately I forgot to grab any pictures of printing or cutting, but such is life sometimes.

The av-bay came together very nicely, though I will likely tighten up the coupler fit with some tape or a layer of clear coat.

Currently waiting on an Aeropack retainer, but in the mean time I'll begin work on the fin slots for a dry fit hopefully by next week.