If there’s a coyote strapped to the outside, then you probably need a lot! But many short, fat rockets don’t need much nose weight, if any.Is that not the key to short fat rockets?
It depends on the length. the shorter the fins and tube, the more weight is needed.If there’s a coyote strapped to the outside, then you probably need a lot! But many short, fat rockets don’t need much nose weight, if any.
The algorithms used by most sim programs don’t give a good idea of the real stability of the rocket. They don’t account for “base drag” or other stabilizing forces. You can use the zero-mass cone trick to get a better idea of the stability of a short, fat rocket. My rockets often show a seriously low stability margin of .3 cal or sometimes even less, but when you do the cone trick, it increases quite a lot. I’ve never added any weight to my Warlock, foam rocket, or other shorties, and they fly great.
Right. Instead of taking the difference between the CP and CG, and dividing by the diameter to get calibers, you can divide the difference by the length of the rocket. The rule of thumb in that case is that the CG should be ahead of the CP by about 10% of the body length.Another school of thought that is generally accepted and also debatable:
The standard of 1 CAL stability is derived from "normal" rockets in the neighborhood of a 1:10 diameter:length ratio. Meaning a 4" rocket that is 40" long will need 4", or 1 CAL stability. Shrink the rocket down to 20" and it will only need .5 CAL to be reliably stable. Stretch it out to 80" and and now you need 2 CAL.
The longer a rocket is relative to it's diameter the more CAL of stability it needs.
Like many things, it's a rule of thumb.
I regularly fly short stubbies well below 1 CAL as well, many below .5.
The balsa in that kit is ridiculously fragile, a lot more than current Estes balsa. Broke mine trying to build it. Gave up eventually.
Reminds me of the time my dad and I drove around the Nurburgring in our VW microbus in 1962-63? at the 1000km race.