We have a rocket day coming in the next month or two at church, so I'm building a couple models size rockets for launching there. These are my first venture into clusters - and they are tiny clusters. The tall rocket is a Rhino and the shorter one is a Baby Bertha.
Both rockets use BT-60 size tubes, so I picked up a couple cluster mounts from a local rocket guy. The Baby Bertha will use 3 tiny A motors and the Rhino will use 4; this will give the Baby Bertha about 6.6 N-s and the Rhino 8.8 N-s of total impulse (equivalent of mid-C).