Ammonium Perchlorate Composite Propellant (APCP) (NH₄ClO₄ + Al + HTPB (composite)) is a composite solid propellant propellant used as a combined fuel/oxidizer. Excellent — 10-25 year storage life when properly encased. Typical ISP: 240–270 s seconds.
APCP is the dominant solid rocket propellant formulation, consisting of ammonium perchlorate oxidizer crystals (65-72%) bound in an HTPB matrix with aluminum powder fuel (16-20%). It powers the solid rocket boosters on the Space Shuttle, Ariane 5, and most modern solid rocket motors. The propellant is cast as a thick slurry and cured into a rubber-like solid grain.
Developed in the 1950s-60s at JPL and Aerojet. Became the standard solid propellant formulation for launch vehicle boosters and strategic missiles.
High thrust, simple design (no pumps), reliable, long storage life, high density impulse
Cannot be shut down, limited Isp, HCl exhaust pollution, difficult to manufacture large grains
