[roc-chat] Re: Motor and Case Fitting
- From: Jack Garibaldi <jackgaribaldi@xxxxxxx>
- To: <roc-chat@xxxxxxxxxxxxx>
- Date: Sun, 16 Dec 2012 10:03:13 -0800
There is a setting to say the other way around I always just say measure
everything from the tip of the nose or I didn’t see your design maybe you had
something wrong or out of wack on it.
Jack G
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On
Behalf Of chris_coffee@xxxxxxxxxx
Sent: Sunday, December 16, 2012 12:39 AM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: [roc-chat] Re: Motor and Case Fitting
Thanks, Jack. This will help a lot. The only reason I said the CG was behind
the CP is because that's what openrocket has it at. That's what had me confused
because I knew it was suppose to be the other way around.
Sent from my Verizon Wireless 4GLTE smartphone
----- Reply message -----
From: "Jack Garibaldi" <jackgaribaldi@xxxxxxx>
To: <roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: Motor and Case Fitting
Date: Sun, Dec 16, 2012 12:23 am
I also noticed you said the CG behind the CP everything is measured from the
tip of the nose so the CG is forward the CP not Behind it.
Jack G
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On
Behalf Of Chris Coffee
Sent: Saturday, December 15, 2012 9:41 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Motor and Case Fitting
Hello everyone,
I am currently in the process of building a Madcow 4.0” Fiberglass Little John.
It has a plastic nose cone with a fiberglass wrap on the inside (not sure if
there is a actual nomenclature for that design) and a 10” long 54mm motor
mount. The instructions state the “estimated” CP is at 36”. I have put together
a simulation with OpenRocket to the best of my knowledge (I am certainly no
expert with the program) and I am seeing a slight problem.
According to O.R. the CP is at 34.508 in. and the CG is at 35.196 in.! When I
add weight to the nose cone, in order to get the CP at least 4.0” behind the CG
I have to add approximately 18 oz. of weight. To me that just seems a bit
drastic so I figured I would put it out here and see if I can get some advice
on what to do.
I have attached the copy of what I have done with O.R. to this point. As of now
the parachute is just a experimental size because I am not sure what size to
use. Was told to wait until I get the rocket built and then we could figure it
out, so I am just playing with ideas here when it comes to the chute.
Christopher L. Coffee
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