yeah okay, its silly.
from cupressus macrocarpa which was only half-dead and kinda horrible to turn.
roughed to a hexagonal cone with a little chainsaw, then hastilly trued on the lathe before something went ka-pwing!
almost famous, also quite some time later.
and the finished former next to a 60x420mm australia post mailing tube, which will be a section of the main body.
hopefully maybe more progress later...
paper-mache or bust! the first time, bust - i had to cut it off the former in my impatience.
i waxed the former and started off with some large vertical sweeps of newspaper brushed with
PVA glue thinned with water. starch paste seemed like it would be asking for trouble.
then i laid on longer, thinner strips spiralling up and back down on diagonals. this took hours.
then i bound it with garden twine, very tightly to get it to conform at the top better.
after that i fired it in a very low oven for a couple of hours, and took the twine off.
it wouldnt budge from the former again, so i put it in the fridge for an hour and it came off with ease =)
its springy like the tubes now =) next on the menu is an epoxy bath, extensive sanding, and something to make it shiny. current weight is 50g
the rocket fuselage parts were all taken to the upper franklin aero works for a lick of epoxy.
i spread the epoxy over the postpak tubes' surface and then worked it into the fibres a bit,
whereas the nosecone, being pretty rough, was iced in a cake-making manner with a thick epoxy/glass
microspheres mix. the leftovers went into the wooden nozzle forms, two inner cones and an outer profile.
oh dear too late now!
the nosecone isn't really smooth in profile, it has minor undulations. but it's glossy and plastic at least. i was going to sand and re-coat it but i think i will just have to see how it goes like this first :)
now i'm up to casting the motor nozzle. im aiming to turn those wooden forms into plaster moulds for the inside and outside of the nozzle, lock it all together and pour in porcelain clay slip to fill the de Laval void.
I've been making nozzles and working on the motor for this rocket mainly, so i havent made much progress,
OKAY any progress on the actual rocket. It needs to be fitted out with a framework first, and before that
it will need to be planned so i dont have to cut thrice. cutting thrice is lame. im building a 3d model so
i can figure out the basic layout in 3 dimensions and where the fuselage will come apart:
im also seeking a launch site. i have two already:
~= gav's orchard: closer, rocket freindly, quiet area. can be windy though, lots of neighbours and hilly.
~= dad's orchard: also rocket freindly, on a hilltop but flatter, generally calm and neighbours are cool. it contains a LARGE pond though, and its a hell of a long way away.
public sites need a lot of open space, which is by definition unlikely to be public, and need to be free of air traffic, and need to be somewhere accessible, so not in the styx.
an altitude wavier for +300ft is also a possibility, but this might lead to disclosure of propellant which might lead to refusal of wavier / being reported to Terrorism Australia LTD
stuff could then get Orwellian.
i finally downloaded AEROLAB and told it what i
knew about this rocket. it told me this:
obviously the fins arent exactly right, mach 4 isnt a consideration, and i dont have a center of gravity yet, though wild conjecture suggests it'll be right about the middle of the tubular fuselage section, at launch, moving forward quickly, and offering an okay-ish stability margin. maximum-diameter motors are going to require larger fins.
i have trimmed the fins to keep drag around 0.45, but the surface finish factor of this is hard to estimate, as it is both smooth and a bit irregular. a good surface keeps mid-subsonic drag down, but a "boat tail" between the nozzle and the fuselage would help the most as shown by the base drag plot. the nosecone is especially good through mach transition, if it will survive that structuraly...
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