Perfect symmetry is not magic; it is math with gunpowder. Over a bridge, each bloom begins life as a shell obeying the same projectile motion equations that define artillery, its arc set by launch angle, muzzle velocity, and gravity alone.
The uncomfortable truth is that the romance of a mirrored chrysanthemum depends on brutally strict control. Designers start with classical kinematics and the ballistic trajectory equation, then lock in a narrow range of launch angles so shells crest above the bridge span rather than beside it. Inside each aerial shell, stars are packed in radial arrays around a central burst charge, so when the timed fuse triggers at apogee, the expanding gas pressure pushes pellets outward in a near-perfect sphere. Short fuse. Long flight. One mistake, and the pattern smears or clips the structure.
The more daring claim is that choreography, not chemistry, does most of the visual work. Digital firing systems compute time-of-flight from initial velocity and desired burst height, then stagger electronic ignitions by fractions of a second to stack concentric rings or alternating colors over the same point in space. Yet underneath the show control software and artistic sketches sits the same parabolic arc an artillery officer would recognize, proving that aesthetic precision still kneels to gravity and the equations of motion.
