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Narcon 2011
NARCON 2011
Tim Van Milligan gave an excellent presentation at NARCON on Rocksim from beginner to advanced in which I learned few things. I personally could have spent most of the day asking Tim question but had to settle for the 1-hour presentation. I personally never knew that in the flight sims screen that the parachute symbols has a black arrow on it. If the arrow is pointing up then chute deployment occurs before apogee and the opposite if the arrow is down. Something I never really noticed. Tim is also suggesting the Velocity at Deployment is best under 50 mph which seems to be a much higher than the 20 mph that most rocketeers use as a standard. Also Tim stated that the Velocity at Launch Rod Departure should be at least 30 mph to make the fins effective for stability. A little about decal simulations was given. Decals work best if the decal is made more like a complete BT wrap in size and completely covering the BT desired with decal and background colors. Also change the BT’s color in Rocksim to a white and diffused for the decal wrap for best results. I later had a chance to meet Tim and had a chance to ask him a few other questions. Yes I had the courage to ask about the Tube Fin/ Ring Tail drag calculation problem! Tim knows it is a problem and I am assuming it is on his list of thing to be improved at a later date. Respectfully submitted, James Pierson NAR# 77907 PS. How that for reportin' Jay-o |
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Good to hear from you, JP! Having that acknowledgement from TVM about something we've suspected is reassuring, really. We weren't just imagining it... Quote:
My standard for LPR, using thin plastic canopies and tape disk attachment points, is the slower the better. If you can hear the canopy "pop", the Dv is too high. Period. Quote:
Meaning we're stuck with calculating the exact diameter of the BT and making a flat 'decal sheet' with everything in place before applying it. Pi, anyone? (Pi R round, Cornbread R square!)
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Craig McGraw BARCLONE Rocketry -- http://barclone.rocketshoppe.com BARCLONE Blogsite -- http://barclone.wordpress.com BARCLONE Forum -- BARCLONE Forum BARs helping BARs SAM 0044 AMA 352635 |
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Inquiring minds want to know...
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James, you freakin' rock. *Again.* .
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Jay Goemmer "Centuri Guy"/"Tau Zero" YORF Member 28 Semroc SAM #0029 NAR 86131 "I think about organizing things all the time. Never seems to happen. I find something that piques my interest and I'm off on a quest. Or a Centuri. " --Bill Eichelberger, 02/22/2022 “Centuri fret buzz in an updated form.” Bill “Wallyum” Eichelberger re: Estes Flutter-By 03 Sept 2014 |
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My rule of thumb is that 1 mph is about 1.5 fps, so 50 mph -> ~75 fps. Bill |
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Doug .
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YORF member #11 |
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Seems to me it would be easier just to use bullet-proof chutes, shock cords and attachment methods than focusing too much on DV.
In this area a little can go a long way as delays for certain manufacturers motors are notoriously inaccurate.
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When in doubt, WHACK the GAS and DITCH the brake !!! Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't ! Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY. ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC ! |
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The damping allows the use of lighter shock cords and parachutes, which reduces the overall system stresses. The other key is making sure the shock cord is wide thru the opening of the rocket to minimize zippers. I've had so-called experts tell me the best solution is selecting the right delays, but I know better. Too much crap can happen, especially in the Texas wind, to get it out at the top with minimal DV every time. So a robust recovery system is needed, and is not overkill. This rocket is a great example. With a four-motor booster staged to a single motor sustainer, with the higher likelihood of one booster motor out, flying in the nearly perpetual cross wind here, high DV is almost unavoidable. It has to be built to tolerate the hard jerk that often occurs at deployment. Doug . .
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YORF member #11 |
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Is the heat wave distortion of the background hills due to the motors or the local temperature? Either way, it makes for a striking photograph!
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
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Doug .
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YORF member #11 |
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see: http://www.lulu.com/content/paperba...an-form/8075185 http://www.lulu.com/product/cd/what...of-2%29/6122050 http://www.lulu.com/product/cd/what...of-2%29/6126511 All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com. NAR #54895 SR |
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