So I watched a video where a guy built his own rocket from scratch. I noticed he used some F15-0 rocket engines* to get this thing as high as 300m (he's built other rockets too, where he used the same rocket engine and got up to 700m).
My question is, what if you expanded the diameter of the rocket to about half a meter and filled it full of F15-0 rocket engines? If a single F15-0 can get a small rocket to about 300m, what altitude can a 0.5m diameter rocket reach if it's full of these rocket engines? Obviously this depends on the aerodynamic engineering of the rocket, but considering the efficiency of the cylindrical shape of the rocket (maximum area for the minimum circumference (mass)), will adding a big amount of rocket engines make much of a difference, or not at all?
*In another video, he shows how to create your own $17/piece F15-0 rocket engine "clone" for just 50c/piece, which seems to have identical results.