for the Estes 36 d squared kit. This is my first time actually attempting this mod while using the Rocksim demo version so I'd like some input as to the new shape. I did this because I hate the original fins but love the rest of the rocket! Thanks guys, Jeff

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Attached Files

estes_36d_FINStest.rkt (125.7 KB, 64 views)

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"That's considerably more than minor, David"

Jeff, the only thing I see of real importance with this shape is to watch out for the bottom-edge tips, they will be the first to break off after a few landings - good or bad.

You might want to play some more with the shape. The deployment velocity is still on the higher side of comfortable, and the shape/size/thickness can affect the final Dv numbers. Always try to keep the Dv below 15 FPS for really comfortable deployments, below 10 FPS for gentle deployments, and below 5 FPS for soft-as-a-feather deployments.

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Craig McGraw

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Craig:
Thank you very much for taking the time in both reviewing the design and making excellent suggestions! I believe than this may turn out to be a very longgggggg night. Take care, Jeff

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"That's considerably more than minor, David"

Well, this software is becoming addictive! I just may need to ask for it as a bday present

Anyway, I've made a few design changes and hopefully the DV rate has lowered but this is my second time around the block so....... Also, I've recently become a NAR member and plan to contact folks in my area soon for launches-I'm a complete newb since 20 years ago. I've found that the D-12's land well but the E-9's crash land every time-I'm I missing something? I though that the number designates the ejection charge time and with this thing soaring to 1900ft the chute would have plenty of time to open up, right? Or is the decent Vel too high which will produce too much pressure against the NC? Thanks again! Take care, Jeff

Attached Files

	estes_36d_FINStest Mk3.rkt (220.0 KB, 61 views)
	estes_36d_FINStest Mk2.rkt (194.3 KB, 57 views)

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"That's considerably more than minor, David"

We don't call this place "The Asylum" for nothin'!!!

E-9s don't have the kick off the pad as the D12 - about half the power, but for a longer period of time. Try something like an E15 (composite). It could also be saying the deployment is occurring after it "core samples". Try the shortest delay above zero and see if you get any altitude.

The Dv is the "Velocity at Deployment". Deployment can occur before, at, or after apogee. Typically, you want the deployment at or just after apogee. Getting the Dv number lower means you're getting closer to the apogee point. Some designs just never will reach that "sweet spot" without electronics; that's the reason we have to tweak these designs to achieve the best compromise through aerodynamics.

It takes a bit of playing with the software to get the best use of it. RockSim generates TONS of data which most of us never pay attention to - until it's too late. Thirty days is just enough time to get frustrated, not comfortable, with the program.

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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