the end of the beginning
i know i wrote last time that this rocket had had it's final launch but its winter now and im a liar -
THIS is more likely to be its last hurrah. and / or its first...
since every rocket i ever launched completely failed to deploy its parachute in the intended way, i made the decelerating air-speed switch pictured above. its based on richard nakka's ones and it triggers at somewhere between 150-100km/h. the power source to ignite the ejection charge is a "CR2" 3v. lithium camera battery.
other new things are:
-steel-cased 'moon' grained motor
-propellant packed straight into motor
-water putty [no PVA glue] attaching steel nozzle
-ignitor epoxied into the top of the motor core
-no ejection charge delay [duh]
-propper-ish centering rings, plywood bulkhead structure
-onboard electrics of any kind
-steel scourer wire in ignitors [HOT but unsolderable]
-gunpowder / sparkler lacquer pyrogen
-ignitor leads pull through power terminals
-single rubber band on chute instead of 3 at corners
-lots of un-aerodynamic holes
motor with slotted bulkhead to hold bottom of air-speed switch.
who cares, that be SLAMMIN'
i even got my parachute shroud back XD
the very late [but equally welcome] appearance of the parachute was quite puzzling - the air-speed switch should have released it on the upswing.
upon closer inspection of course, it became obvious that the 'switch bay' was 'well sooty' and 'smelt like hell', if hell smells like hot plastic, burnt carbohydrate and paper ash. obviously it was time to squirrel it off back home to the lab for a tear-down:
destruction and chaos in the bottom end, order and tranquility in the top.
the motor burst it's top closure, which was epoxy, burning around the ignitor wire and funneling really hot gasses into the fuselage. it must have happened late in the burn or there'd be NOTHING left, perhaps it was just the 'plug' of propellant the ignitor was set into burning up the wires under pressure. the last bit of smoke trail the rocket leaves in the video is dense and dark, this might have come from the aero-flap port instead of the nozzle.
the switch was pretty scratcy and need rebuilding, i think it was a bit of a miracle that it managed to close before it hit the ground. the bulkhead is torched through, insulation melted and the switch body has burns on the bottom. the onboard ignitor is definitely the way to go, but a more secure closure and more epoxy would be sensible.
having proven itself, Destination: Moon will quit while it's ahead and enjoy semi-permanent leave. though there is tempting clearance in the engine bay...
[GO BACK TO INDEX.PHP]
go forth unto the stars, we salute you!