Spin-stabilized artillery shells rely on gyroscopic rigidity to stay nose-forward through flight. Spin also creates a small sideways Magnus lift force, causing a real phenomenon called "spin drift" — the shell curves slightly in the direction of spin.
Sg ∝ spin² / v0 (gyroscopic stability factor)
F_magnus ∝ spin × v (sideways, ⟂ to velocity)
drift accumulates as ∫F_magnus/m dt
- Spin rate — revolutions per second imparted by the rifled barrel; higher spin increases stability but also drift.
- Muzzle velocity — initial shell speed, sets overall range.
- Launch angle — elevation angle, trades range for flight time (and thus drift accumulation).
- Magnus lift factor — scales how strongly spin translates into sideways aerodynamic lift, for exploring "what if" shell shapes.
Real use: Ballisticians compute the Miller stability formula and Magnus-induced spin drift to correct real artillery and sniper-rifle aim points for crosswind-like curvature caused purely by spin.