#11
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Agreed. I think I have a couple or more such designs in my folders right now. But the ones that really get my goat are those that proclaim their stability in bold numbers, then promptly perform cartwheels just above my head.
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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 |
#12
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Quote:
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Paul If we weren't all crazy, we would go insane - Jimmy Buffett NAR #87246 www.wooshrocketry.org |
#13
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Yup. Sometimes BARCLONE field looked a lot like Canaveral in the early days...
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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 |
#14
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Quote:
Been there, done that buddy!
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Gerald Wallace...BAR in Ky. BoRocks Rocketry Systems jonrocket.com "An armed society is a polite society." - Robert Anson Heinlein "Its a tale, told by an idiot, full of sound and fury, signifying nothing" - MacBeth |
#15
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Here is the "Dead Ringer". I actually built this years ago. It's the ultimate back yard flyer. On a 1/2 A your looking at 75 feet straight up/straight down with a streamer on board. But....it will really haul the mail on an A10! Sorry for the poor pic!
Bo
__________________
Gerald Wallace...BAR in Ky. BoRocks Rocketry Systems jonrocket.com "An armed society is a polite society." - Robert Anson Heinlein "Its a tale, told by an idiot, full of sound and fury, signifying nothing" - MacBeth |
#16
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I believe I'm going to build it, then swing test it the old fashioned way. If it seems like it's going to work, perhaps with some nose weight, I'll finish it as is. If not, I'll notch some regular fins (maybe just rectangles) and slide them over the rings to make it flyable.
... today I calculated the CP location of my Bandito using the Barrowman equations. Cost me fewer brain cells than I expected. But Jim didn't provide a method for calculating the effect of rings either... probably why RockSim can't do it. Do you suppose that the pressurized air in front of the first ring might act like a conical shoulder? That would yield a benefit to the CP, if it were true.
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NAR # 115523 Once upon a better day... SAM #0076 My site: http://rocketry.gonnerman.org |
#17
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I have no idea. I am not a RockSim user. I do the equations and swingtest...and I use cutouts if necessary...but most significant of all....I build em' and fly em'. The rocket pictured is one of the most stable critters I have ever flown. Matter of fact, after flying 4 times today (after it sat for at least 3 years) I decided it deserved a better paint job than simple silver. The "Dead Ringer" is now sporting a metallic green top fading to metallic purple on the bottom. Main body tube = T-50 @ 18" Nose Cone: PNC 50 1st ring: CR5060 2nd ring: CR5070 3rd and 4th rings: CR5080 13mm mount Streamer recovery. No nose weight required. Stable and able from 1/2A to A10. Bo
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Gerald Wallace...BAR in Ky. BoRocks Rocketry Systems jonrocket.com "An armed society is a polite society." - Robert Anson Heinlein "Its a tale, told by an idiot, full of sound and fury, signifying nothing" - MacBeth |
#18
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Hey Bo....distance between rings? Looks like an interesting build....
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Don NAR 53455 "Carpe Diem" |
#19
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New Plan -- Dead Ringer
Quote:
Bo, I worked up a simulation of Dead Ringer, using an invisible paper transition with no mass and no CG to simulate our suspicions about how the rings work. The components are not exactly as in your design, but they should be close. Nose Cone: BNC-50K Body Tube: BT-50 Ring 1: CR-5060, 3.50" from rear Ring 2: CR-5070, 1.75" from rear Ring 3: CR-5080, 0.63" from rear Ring 4: CR-5080, 0.10" from rear EM-59 motor mount (SEMROC package) 12" Parachute (or 2x20 streamer) SE-10 screw eye Snap Links SC-24 elastic SCK-24 Kevlar Length: 22.35" Diameter: 0.976" (BT-50) Span: ~2.80" Weight: 1.16 oz 1/2 A3-2T......90'......Dv 2 FPS.......requires 25" of guide length A10-3T........215'......Dv 10 FPS......requires 20" of guide length Margin with A10-3T motor installed: 2.29 (VERY STABLE!) Margin with 1/2A3-2T motor installed: 2.08 (VERY STABLE) CG with A10-3T: 15.54" from NC tip CG with 1/2A3-2T: 15.75" from NC tip Let me know if this comes close to your observed performance with the prototype.
__________________
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 |
#20
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Solo,
Your version using BT-20 simulated out to nearly 400'. Lighter design, but still highly stable. Both designs look like stable mates next to each other. Like minds thinking alike...
__________________
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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