Mike, Dale and Jono prepare for the 3rd launch, temperature="34c".
sometime in january, 2008, my mates decided it was simply too hot to hide inside
and so we all went to the beach. i'd researched this beach as it had vast sand dunes and
looked like a suitable launch site, seeing as we were on our way out there anyway.
first though, destination: moon got new fins. the old ones were goofy and worse they were pulling away from the fuselage and taking some green paper with them! so they must DIE! i still liked the idea of having them support the rocket upright, even if it was guided by a rod. after all, its a rocket not a missile. these new ones are made from corrugated cardboard and PVA glue'd to the fuselage via super lovely brackets made from heavy grey archival paper. the fragile-tape edging was an afterthought. avant-garde!
i decided to test a new motor design, which was mostly an end-burner, but with a short cored section for pressurisation and lift-off. i reasoned that the motor was huge, the propellant fast-burning, and the rocket lightweight, so it would fly with the minimal end-burner thrust...
the nozzle was held in with a couple of bits of cardboard and some silicone gasket goo,
so it blew out and hit the carport rafter, and then all the fuel came out too - its very fast burning.
this was all very entertaining but i was quite lucky not to mangle and melt the household scales. i
was really lucky that the nozzle suffered barely a scratch, so i figured i'd just make another motor, a bit
bigger of course, EPOXY that nozzle in and hope for the best...
above you can see the little mark on the nozzle exhaust cone rim. after M00N II [and other things] i knew it was time for a sensible ignition system. so i made the below one from some old tupperware, a very second-hand relay, a red toggle switch, lots of colourful scavenged wiring, an ancient bicycle light, and a 7.2v Tamiya RC car battery, which JUST fits inside the container.
red means on and safe, so you connect the igniter leads to the two bolts behind the light. ignition can be affected from practically any range - since the control lead is fitted with an australian 240v/10amp mains plug, you just add extension leads and then short the terminals once a satisfactory distance has been achieved. ubiquitous!
i also changed the chute after the "simple" two-lined one wouldnt open. i just cut the bottom of the bag in a wide arc around the apex hole, and used 3 lines instead of two. this is at least a billion times more reliable and stable, remains easy to pack, and only falls slightly faster <('.'<) ^('.')^ (>'.')>
SO it was launch tiems finally. the beach launch was not attempted after i found the sand dunes to be incredibly uneven, covered in spiky grass and trampled trees, and most bizzarely, populated by rednecks on motorbikes and naked old men. hrrmph.
instead it went back to Gav's farm again, which is grassy and wonderful. Gav threw the switch:
ALMOST! the rocket took off well but appeared to get upset about 10m up,
did a couple of flips and floped back down in the grass, hissing madly.
the motor worked as intended except the ejection charge didnt fire.
i suppose it was lucky that it only had half as much thrust as it needed,
or the nice new fins would probably be nice and bent.
as it is, the nozzle didnt come out and the foil inhibitor was largely intact. one fin is a bit looser, and thats yer bloomin' lot.
next time: MOAR BOOST. [GO BACK TO INDEX.HTML]