Model Rockets
Do you remember the old Estes model rockets that you used to fly as a kid? They're still out there! Not only that, but the "D" engine is no longer the largest engine available.
The impulse (average thrust * time - think if it as the actual "power" of the engine) is doubled each time the designation goes up one letter. That is, a "D" engine has twice the power of a "C" engine.
The biggest engine I have heard of being used is a "P" engine. This brute is plenty big enough to give you a ride - if you are foolish enough to trust your life to such a thing.
The only "man rated" solid fuel rocket engine available is the Space Shuttle's Solid Rocket Boosters. They are "AE" engines.
