Parachutes & Shockcord:
Wildman recommends the Recon Recovery 40inch chute for the DS-3 or a Topflight 50in.
Recovery is 9/16 tubular nylon or 3/8 Kevlar.
These sizes are a good match for the weight of this rocket, which will be in the 9-11lb range built and flown. You figure the weight with largest motor,[ fuel weight matters not, cause it will be burnt for recovery] and ready for the pad configuration.
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Ok, my opinion only here:
Kelvar...Kevlar...Kevlar.... what's with this stuff? It has it's place,but is so overkill in most sport flying applications. It has no give [or very little] and can cut through an airframe like hot knife through butter! [zippers].
While were at it, what knot to use for Quicklinks? Boy here's a volatile subject. Well I did my own testing. I used 15ft of both Kevlar & TN....tied between my trucks bumper & a telephone pole.
I used 3 different knots. Bowline...Water...and fly tie.
Left about 4-5ft. slack in line and put truck into gear. Rolling under power, taking up slack and accelerating till line snapped. Where do ya think it broke EVERY time?
Not at either end or knot.....Right in the middle or close to middle....where the severest stretch occurs. Maybe not to scientific, but answered all my questions. For me knot strength is no longer an issue.
I use a bowline to attach shockcord to recovery Y-harness in fin can, & also to attach upper cord to NC. No need for Q-link, ya gotta tie a knot on it, so what do ya gain?
Bowline is easily undone anyhow & ya save a tad of weight.
I use a water knot for the 2 links at av-bay. I DO want Q-links there, easier prep.
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27ft of 9/16 tubular nylon for my apogee event. It's more forgiving than K. and wider so less chance of zipper on fincan should things go foul. I also will wrap tape around it where it meets airframe when deployed to keep from fraying.
27ft.[1500lb rated] for several reasons.
You will find during ground testing a shorter cord may work [if your REALLY good at it, you CAN make it work] I want the X-factor for dynamics of flight. Sometimes the apogee event will be early or late, rocket is moving at higher speeds. Extra cordage negates the possibility of shaking out the main, cause it comes to the end of a shorter shockcord violently, popping shearpins & NC.
Another reason is I fly around trees, longer cord give me a better chance of getting a rocket back..
15ft of 1/4in Kevlar[1200lb. rated] for my main. Takes up less space[easier to pack in my cut down payload]
Your already down close to ground[400-700ft] when main deploys & the 4-5ft of parachute risers make the total length = 19-20ft.
You have to be coming in ballistic to zipper a payload[usually], & by then you got bigger problems anyhow. I've flown many 3in rockets & this amount works, so why re-invent the wheel.
So there's some of the reasoning behind the madness!
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So I cut 27ft from my roll of TN. This will give me about 25ft usable after losing 1-2ft for tying knots.[another thing often overlooked].
Burn/melt the ends to keep from fraying.
17ft of Kevlar to give me 15 usable for same above reason. [knots]
If you wrap some tape around line before cutting, then cut in middle, both ends can't unravel like Kevlar is prone to doing.
Borrow the bone cutting scissors, from the kitchen knife set. They cut Kevlar & TN like butter!