How to determine the cg of Nose cone?
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Ironnerd88
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I like the dangle-from-a-string method.
I want to do a bunch of math or I need the formula.
As I've to design my rocket which will work properly, I need to be sure before building one. In our country, there's no oppurtunity for buying kits or engines.
GregGleason
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If you have the nose cone, tape and string is all you need.
Attach and remove tape until the centerline axis of the nose cone is perpendicular to the floor. The intersection of the imaginary line that goes from the string into the nose cone and the centerline axis of the nose cone is the center of gravity. This is true regardless of a solid or hollow nose cone.
To approximate the center of gravity of a nose cone that you do not have, you calculate volumes in sections of length increments (say from 1 mm to 1/4", depending of the accuracy desired). Assuming a homogenous and solid nose cone, the center of gravity is where the sum of the volumes from the tip to point "x" equals the sum of the volumes from point "x" to the base of the shoulder of the nose cone. If the nose cone is hollow, then you have to add a step of removing the volume of the hollow portion for each section.
Greg
Attach and remove tape until the centerline axis of the nose cone is perpendicular to the floor. The intersection of the imaginary line that goes from the string into the nose cone and the centerline axis of the nose cone is the center of gravity. This is true regardless of a solid or hollow nose cone.
To approximate the center of gravity of a nose cone that you do not have, you calculate volumes in sections of length increments (say from 1 mm to 1/4", depending of the accuracy desired). Assuming a homogenous and solid nose cone, the center of gravity is where the sum of the volumes from the tip to point "x" equals the sum of the volumes from point "x" to the base of the shoulder of the nose cone. If the nose cone is hollow, then you have to add a step of removing the volume of the hollow portion for each section.
Greg
bobkrech
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https://openrocket.sourceforge.net/ openrocket is a free rocket design program that you might find useful.
You need to know the CG/CP relationship of your rocket for stability, so the CG of a rocket component is less important than the CG of the complete rocket.
For stability, the CG should be at least 1 airframe diameter ahead of the CP, so you really want to calculate the CP of your rocket. It is really easy to measure the CG of your assembled rocket because it's the balance point.
This thread discussed how to calculate the CP which is determined only by the shape of the rocket https://www.rocketryforum.com/showthread.php?t=23915
Bob
You need to know the CG/CP relationship of your rocket for stability, so the CG of a rocket component is less important than the CG of the complete rocket.
For stability, the CG should be at least 1 airframe diameter ahead of the CP, so you really want to calculate the CP of your rocket. It is really easy to measure the CG of your assembled rocket because it's the balance point.
This thread discussed how to calculate the CP which is determined only by the shape of the rocket https://www.rocketryforum.com/showthread.php?t=23915
Bob
redsox15
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The rule of thumb I use is from an article written by James Barrowman. He uses very simple math to find the CG of a standard Conical, Ogive and Parabolic Nose Cone. I have attached the page of the article below. Hope this helps.
Matt
Matt
