Back when flashbulb ignition was new (about 1976 or so) At one of the first GLRM meets, I successfully launched a 25 engine cluster that was still legally, at that time, a model rocket (Weighed under a pound, had less that 4 ounces of propellent) It had, if I recall correctly, a D12 and 5- B14's (to get it off the ground) and the rest were either 1/4 or 1/2 A's, to keep the propellent weight down, yet give me the number of engines I wanted. The previous record was 19 engines. I followed that up a year later with a 37 engine cluster. We're in the process of moving (and starting a rocket company....which will have to wait 'til after the move) but I know I have at least 2 or 3 pictures of the rocket and it's flight packed away in my office stuff. I'll post 'em when I find them.
Al