> I'm preparing to launch the Onyx at ROCSTOCK V. I did the CP/CG calc, and
> found that the CG need to be moved forward approx. 3 inches to a point
> 15.55 inches from the tip. This required the addition of allot of ballast
> (modeling clay) weight. The plan is to fly the Onyx on a G75 reload. Can
> anybody tell me if I really need to add the ballast weight, or is the "out
> of the kit" design aerodynamically stable as is?
My 7 year old table (that I've posted here at least twice before) has the
Onyx CP at 18.33" from the nose tip or 1.166 forward of the fin leading
edge. SOunds like we're in pretty close agreement.
With a G75, you probably need the weight. I'm sure this motor isn't on LOCs
"recommended" list for this rocket, as he doesn't recommend any reloads for
his kits. Of course, that doesn't mean that it won't work, if you add enough
nose weight to preserve stability. Try balancing it with an F50, and keep
the CG inthe same place.
Bob Kaplow NAR # 18L TRA # "Abort, Retry, Fail?"