Week 19: Modern Motors

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The rocket motors we fly in Club Rocket today are direct descendants of decades of propellant chemistry improvement — which is also exactly why motor classification exists.

History

Modern composite propellants (ammonium perchlorate combined with a rubber-like HTPB binder) largely replaced older, simpler propellant chemistries, offering more consistent, higher-performance burns — a big part of why today's hobby motors are so reliable.

Forces

Motors are classified by their total impulse, and each letter class represents roughly double the impulse of the class before it.

Math

each class letter ≈ 2× the impulse range of the prior letter

Worked example (metric): a B motor covers 2.5–5.0 N·s, a C motor covers 5.0–10.0 N·s, so a D motor tops out around 20 N·s of total impulse.

Safety Note

Only fly motors that are NAR or Tripoli certified — certification means the motor's performance has been independently tested and verified as safe and consistent.