So here's the data with the new rates. Keep in mind that the speeds are with a 6 foot rod which the club does not have. They only have 3 foot rods.
View attachment 411387
I am thinking I need to look at this rocket again and consider adding some rail buttons because the rails are longer than the 3 foot rods.
I did put vent holes in my two stage Citation Patriot build and my two stage Tempest design. Those boosters are basically the same as this booster
-Bob
Other than MindSim, I don’t do simulator stuff (most of my rockets are square or otherwise weird.).
I do a decent bit of black powder staging, and my experience has been that multistagers seem to have a strong propensity to weathercock. I think this is because they require either more plumage in the tail or more nose mass to counter the extra mass of two engines in the rear. Weathercocking is generally not a good thing, and particularly bad on multistage as (at least with black powder staging) the sustainer is presumably going to light whether it is vertical or not. Definitely not a mode of Rocketry you want to have marginal speed off the rod or rail.
Suggestion. For first flight, go with the lowest rated engine you can in the SUSTAINER. Even consider putting in an adapter and going down a motor size (try a D12). Remember, the sustainer rocket at separation is already in flight therefore presumably stable. So you don’t NEED much in the sustainer to make it a successful first flight. Part of a successful first flight IMO is FINDING the sustainer.
first advantage is that the less mass, the faster your rocket gets off the rail.
Second is the less mass in the tail, the more stable the rocket.
Third is safety (probably should have put that first.). If indeed you encounter fecal turbine interaction and the sustainer goes off non-vertical, the smaller the motor the less the potential energy if the nose encounters something other than sky (generally bad and potentially the badness is proportional to the velocity).
Fourth is convenience. Staging is cool. Long hikes to find rockets that went really high (or weathercocked and went sideways).... not necessarily so cool.
Once you have proven the rocket flies well with a smaller sustainer, you can always go back and try something larger.
Hoping you get two straight trails on this puppy.