FYI: I'm the guy in photo holding DarkStar Xtreme in the instruction link above. I built & fly the prototype & wrote the instructions for this and 31 other Wildman kits. Just a few helpful [I hope] hints to help you finish this ...so far wonderful...build of yours. Great job so far, BUT you are overthinking all this a bit.
Mine has flown to 16,600 ft. no issues, built as described.
1 vent per airframe section is all that's needed. 1/8 hole in payload and 1/8 in fincan. If it makes you sleep better... up it to 5/32. Anymore is overkill! Yeah you can fiddle all day with calculations, but I assure mine are based on years of flying experience with airframes of this size. Flying all types of motors with various thrust curves, especially high thrust motors where you need to vent fast, due to speeds.
Vent band holes [for altimeter reading] were determined by discussion with Jim Amos of missleworks. Hole sizes for various altimeter bays can be found on his site under RRC3 manual. 2 years of testing, on top of usual calculators determined actual sizes. Recommended to use odd # of holes when ever possible. That reason is cause for a whole 'nother thread. Suffice to say it has to do with airflow around a tube and the negative pressure on downwind side of tube equalizing with positive side. This comes into play with wind shears you may pass through on the way up & gusts on the pad over 20mph that can drop pressure on negative side quickly triggering a false apogee detect.
This can fire a charge on pad. Well that issue has been corrected, but some altimeters will still do it.
3 holes 3/16 or 1/4 can be used.
I use 2.25 grams bp on main.
Often overlooked is apogee charge. IT SHOULD VARY, depending on size of motor flown.
A 2.5 g charge is perfect for a mid to long 54 motor, but when flying a long 75mm M - motor there is very little space left between top of motor with 25ft of shock cord/nomex/chute stuffed on top. Then only a 1.5 g charge is needed, you're only pressurizing a 10 in space.
Most flyers over look this item and just use same size charge no matter what motor is flown. As always ground testing is recommended, due to variance in build technique and tightness of parts fit. Mine are based on a nice snug fit.
As stated in manual I use 3 pins 2-256 nylon, which have a shear break of 24lbs @ on average.
I use a Topflight 84 or 96inch chute depending on wind conditions. What ever Blake sells in a similar size, I'm sure, will suffice.
When finished & painted The DarkStar & your OZZ version [virtually identical by the way] make for one sexy looking rocket & great sport flier! My favorite motor pick is any of the CTI 2-grain 75mm loads. Little known fact.....they sell for less than their 54mm counterparts and are a better value. Over here in US prices they are 30-45 dollars cheaper than a 6xl 54mm!
Mine flies 8600-9200ft on those 2-grain loads. I love the L-910 C star, it's tailor made for this rocket.
Have fun and good luck finishing your project.
PS when you get tired of flying this..... just change DarkStar vinyl to Katana, it will look fantastic
I can have Blake send you parts to build a bigger one....LOL
PPSS: Rocket Trivia..... by the way at the top of this page, flying sideways, is the "Drama Queen" flying on a sparky "O" motor. 7.5in diameter 14ft tall .
I built that in 3 days and delivered it to Blake at BlackRock.....Lol
"Crazy Jim's Gone Bananas"
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Rocketry..........an exact science......but not exactly!