Hi Bob,

Interesting that you should ask such a question  relatively soon after I
posted the URL for my rocket altimeter project (
http://www.rocket-roar.com/rap/alt.html )

The rule of thumb is that you want the center of gravity forward of the
center of pressure by at least 1, preferably 3, body tube diameters. So,
adding weight to the nose (without changing the shape or size of the
rocket) should actually make it more stable, not less. So, if you are
working with a rocket which can safely be assumed to be stable, you do not
need to do any further tests.

If you are designing from scratch, one method that is said to work well for
small rockets (less than 5 feet long or 4 inches diameter or so, would be
my guess) is to use a paper cutout of the silhouette of the rocket
(including fins), and find the cutouts's center of gravity. This usually is
a good approximation to the real rocket's center of pressure.

For more information, you can try searching Barrowman Equations, or center
of pressure. One link I got was:

http://www.execpc.com/~culp/rockets/Barrowman.html

Sean


At 12:02 PM 2/10/01 -0800, you wrote:
>Hi Everyone,
>
>Does anyone know what the rule of thumb regarding center of gravity on a
>model rocket? Specifically, if you want to add telemetry to a model rocket,
>is it OK to put it in the nose, or is it better to keep the weight low in
>the fuselage?
>
>Thanks,
>
>Bob
>
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