The competition that I am participating requires a min stability of 1.5 cal during boost and to satisfy this my static margin is 2.2 cal. Is this normal? It’s a 130 mm dia rocket of length 219cm with an L class SRAD motor. What stability is too much ? What factors would it depend ?
One factor is, “what is the goal/target for the competition?”
If the goal is max performance, usually either altitude or duration, generally you are going to tend toward pushing the lower margin of stability envelope as from the center of pressure (CP) aspect, fin surface area (larger fins or increased number of fins) is one of if not the most important method of pulling CP favorable tailward (outside of outside the box stuff like dynamic gas stabilization), and larger fin surface area usually equates to higher drag. So if it’s performance you want, I’d shoot for the minimum required of 1.5.
But if it’s something like TARC where the “target” is to get a various number of eggs safely to a certain altitude and then return to earth in one or more rocket pieces in a specified time, I’d say your goal for the rocket is likely to optimize for reliability and durability and consistency (and if required “egg protection”).
So what are the rules/goals/targets for your competition? If it isn’t altitude or duration, I’d shoot for “average” rocket stability, make the trailing edges of the fins perpendicular or forward swept and terminate them FORWARD of the tail of the body tube (think opposite of the Estes Alpha) to reduce breakage, and then mess with motor size and rocket mass to meet the other parameters, if any.
Kind of just hit me, you say this requires an L motor, so unless this is a paperwork exercise, at least in the U.S. SOMEBODY on your team must be level 2 certified (I’m a proud L-0, BTW). People on this forum are always glad to help, but seems like you ought to have a resource on your team that can easily answer questions like these.
