This is looking great Judy! I cant wait to see it fly. Are you going to fly this monster at ECOF? LDRS would be a great venue for this project too. One thing that you have failed to mention is the motor you will be using. Will this get another one of those sweet M3700's? I regret missing that flight of your Darkstar. From the TWA photos it looks like there were about 4 or 5 M's that day. I like the looks of those winglets, how are you attatching them to the fins? Just west systems and a big old fillet? Good luck with this project! Talk to you soon.
Manny
Eat Cheese or Fly is the official unveiling day for all of the recycling bottle rockets. Well have to hustle to make it, with Jacksons busy summer schedule, but were doing what we can.
Thanks, Manny, for giving me the opportunity to brag about the M3700 flight. It was a good one. For those who were not there, team JLRockets launched our Ultimate Dark Star on a Cesaroni M3700, in honor of Jacksons birthday. That white thunder propellant has a very sweet kick off the pad. Heres a link to the on-board video from the flight:
https://www.youtube.com/watch?v=3RirTkRh7-Y
If youre going to use the M3700 - and I do recommend this - dont forget to get hold of a copy of the double secret instructions the hidden addendum to the instructions that is not included with the motor, but nonetheless contains essential information for a proper build. Im not sure why Cesaroni is hiding this little gem, but JLRockets will not be stopped. We were able to thwart their impeccable security to obtain the classified information, thus ensuring the proper use of glue in the build. Where theres a will, theres a way.
https://www.pro38.com/pdfs/Pro75_notes_V1.4.pdf
We wont be using the M3700 in the bottle, because it is too long, especially since we own the 6XL case and not the 6 grain case, so we used it with a spacer. We have, however, considered the smaller M3100 and the bigger M3400. Jackson wants to use a Skidmark to get that sparkling soda affect, but I dont think well build light enough for a sparky.
After the results of the test flight, were leaning towards a greater than 5 to 1 ratio. The scale model did poorly with just under a 5:1 ratio, but great with a 7:1 ratio. The 75s are longer and distribute the weight up into the rocket, thus helping with the stability. So, were looking at 75s with good initial thrust, but not so many newtons so as to launch this giant garbage can into outer space. The M2250 C-star is a strong contender, as is the L2350 or the M3100. But with either white thunder or c-star, well have to build strong. These are powerful propellants.
Which brings me to your last question. The primary attachment for the fins will be the poured or injected internal fillets between the motor tube and the fins (both fiberglass) and the internal tube and the fins. Well do this with pour-able epoxy, so it will be Pro-line mixed with chopped carbon fiber. All of the strength will be internal. The bottle will be something like a dress that the rocket wears to the launch for appearance sake. However, it will have to be firmly attached as well. We will attach the centering rings to the bottle with the black tar epoxy that comes with Wildmans blackhawk rockets. I tested it, and it does attach to the bottle. But, just to be sure, we will also bolt the centering rings into the bottle. Well also use the Blackhawk epoxy to make external fillets between the bottle and the fin. Our chief engineer is skeptical, but Im asking him to consider plywood struts along the side of each fin on the interior wall of the bottle (attached to the centering rings). Then, we could add one more internal fillet that attaches the fin to the backside of the bottle that would hold with a high degree of reliability.