shear pins....

is three 3-52 shear pins in the nosecone of a 4 inch rocket too much? I did a ground test today with 3 grams of blackpowder, and it barely seperated the nosecone, yet there were still black stains all over the nomex from the BP burning.....

Can anyone help?

Only you can decide what is too much, just right and not enough....

I use three 2-56 nylon screws for shear bolts in a 4.5" fiberglass rocket with a fiberglass nosecone. That seemed just right for me with 3g of FFFF BP in a payload bay about 26" long x 4.375" ID.

You have 44% more area in each 3-56 versus a 2-56.
If you check Drake "Doc" Dramerau (sorry if I butchered the spelling) - and interpreting the data as he only tested #2 and #4 screws - you will need approx 100 lbs of force to break three 3-56 nylon screws.

3g of FFFF in a 24" (just a guess) by 3.9" ID payolad bay should give you 242 lbs of ejection force. I would suspect that is enough. Are you shearing the bolts cleanly? Are they "mushing" into the tubes and thereby the tubes are absorbing some of the force?

Black residue from Black Powder burning?? Yes - black powder burning leaves black powder residue and "stains" on everything it touches.

Hope this helps. I suspect your NC is either too tight or the energy is being absorbed/vented somewhere other than being applied to the NC ejection.

Cool, thanks gregzo, I'll go check it and see if any of those were the causes, and sorry, that was a typo, they are 2-65 shear pins....I'm terrible with these keyboard thingies.

As for the black stains...I know blackpowder leaves black stains silly, this isn't my first time doing this, I've just found in past results that a faster cleaner seperation will leave less of a stain than one that doesn't seperate as well.....I should have been more clear I guess.

case in point...not 2-65....2-56, maybe I need a class or something....