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Nov 28, 2017
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Hello All! Been reading this forum for a long time but this is my first post. I am looking at doing a scratch build or maybe adapting a current rocket in order to have interchange motor mounts. I love the idea if having options of motors. After doing some research, I think I am going to do a 66mm (or BT-80) motor mount in order to have the following motor combos:
7x or 5x 18mm
1x24mm and 4x 18mm
4x 24mm
3x 29mm
2x 29mm and 2x 24mm

Looking around US rockets website I've seen a couple rockets that already have a 66mm mount I could base my design on.

Mu question is, how will these various mounts change the center of pressure and gravity of my rocket and what might I have to do when changing to different mounts in order to maintain stability?

Sent from my XT1585 using Rocketry Forum mobile app
More weight in the tail will pull the center of gravity towards the back; if needed, this would usually be compensated by additional weight added to the nose, to keep the center of gravity safely ahead of the center of pressure. Your best bet for something like what you're planning is to grab OpenRocket and put together a simulation for it. That'll tell you where your CP and CG are and you can proceed from there.

I recommend the self-contained installer.
Got ya.... So already started some design work in open rocket. I'm hoping to design a retention system like semroc uses on the Brighton and laser SLS models. Think this is do-able?

Sent from my XT1585 using Rocketry Forum mobile app
Nah.... That's way overdone to me. I like multistage clusters. I'd really like to build one of the US rockets high test models. Either 4x29mm to 4x29mm, 3x29mm to 3x29mm, or 3x24mm to 3x24mm 2 stage rockets. Have to be an awesome launch..

Sent from my XT1585 using Rocketry Forum mobile app