low tide at the range again

compact PVC rocket - launch 3


the third attempt at a lower snug altitude record was made on the 20th of feb, '08, which was a wednesday. low tide was at 2:30pm, and it was LOW. sand was firm and not too bad at all really, must remember this for next time. this is actually the first page that isnt written in heavy retrospect regarding this long-suffering cylinder.



the rocket itself had been rebuilt from the middle down, after the successful but violent second launch, with no significant changes. HOWEVER the motor that would hurl it skywards was a flight of fancy, illustrated below:



call it what you like but i still reckon its got legs. it was a bit fidly to make the two opposed moon grains and then stick them together as one continuous lump, and then get them snugly into the casing, but certainly nothing a spartan would complain about. the idea is that both moons are inhibited with a couple of layers of masking tape on their outsides, and fit snugly into the casing. igniting the bottom one pressurises the casing, but gasses cant ignite the second core because its sealed at both ends and across its face by the not-so-flamable waxy tape. the first grain burns from its core upwards and across, untill its almost exhausted, and it uncovers the second core, which ignites immediately with the pressure and flame still present from the first core. the solid bit at the top is a standard delay, sealed at the top edges and held in with 5 min. epoxy.

SO how did it go then?



about half as well as it should have =( all credit to cameraman dennis for the insightful commentary. the ignitor goes off, followed like clockwork by the cackling of the plovers. the motor stuttered once before igniting properly, a sign of too low a Kn. though this propellant batch is a little slower burning [7.2s / inch], fuel rich and maybe harder to ignite or something.

but then, after the quite pleasing liftoff, the first moon waned. cue moon two.. come in moon two.. instead, more stuttering, a few flips and then touchdown, right on the newly repaired fins. you can hear them shatter in the video if you have a vivid imagination =(
then, after nigh on forty years of stuttering and chuffing and smoking, the ejection charge ejected.. nothing. but it ejected nothing PERFECTLY! and, the PVA / putty method of putting a machined nozzle in a plain bit of tube is proven at high pressure, AND complete heat saturation! SUCCESS!! mission control went to investigate...



broken fin bits, bugger. two fins mashed, booster end all soft and deformed. BUGGER!
the bottom end was a total writeoff, but i managed to salvage the piston and tether after cutting it all apart. the top end is mostly ok, the joiner is unstuck again but not bent, and the bottom of the chute lines are a bit melted after catching the ejection blast and will need shortening.

i wont rebuild this right away, but i will rebuild it eventually. with ANOTHER fin design, one which wont break. and even more motor space >:E.

in the meantime, these wild motor ideas need MOAR DOCUMENTS! **[put a link to them here]**

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