Is there a formula or "rule of thumb" for estimating the descent rate for
rockets without parachutes? I'm working on some spool rockets and I figure that
as I build larger ones at some point they will need a recovery system with a
parachute and everything. I'm trying to figure out where that point is. I
figure there should be some way to estimate the descent rate, say as a function
of the surface area of the convex hull versus the weight of the rocket. With
small spools (and other rockets) tumble recovery works fine, but at some point
they become too heavy to tumble safely. I figure this is may be a result of the
fact that as the rocket is scaled up the weight increases faster than the
surface area that produces drag.

Any insights on this issue would be appreciated.

Jonathan ----- Jonathan Sivier Secretary, Central Illinois Aerospace jsivier AT uiuc.edu NAR #56437 Tripoli #1906 CIA Web Site: http://www.prairienet.org/cia / Home Page: https://netfiles.uiuc.edu/jsivier/www / ----- "Remember to always keep the pointy end up."

Any insights on this issue would be appreciated.

Jonathan ----- Jonathan Sivier Secretary, Central Illinois Aerospace jsivier AT uiuc.edu NAR #56437 Tripoli #1906 CIA Web Site: http://www.prairienet.org/cia / Home Page: https://netfiles.uiuc.edu/jsivier/www / ----- "Remember to always keep the pointy end up."