I've recently gotten into High Power Rocketry (HPR). These are not the Estes model rockets I launched as a kid. The FAR's define a Class 1 rocket as a "Model Rocket" which can't weigh more than 1500 grams nor use motors with more than 160 newton-seconds of impulse. Class 2 is High Power Rockets which are pretty much only limited by the power of the motor that can be used - up to 40,000 newton-seconds impulse. Notice the lack of the term "model." These are serious machines ranging from a few pounds to hundreds of pounds with some capable of Mach 3 speeds and edge of space (100,000'+) altitudes.
Certification is required to fly High Power Rockets. There are 3 levels of certification allowing use of bigger and bigger motors. For Level 1 the requirement is to build and fly a rocket using a Level 1 size motor. Level 2 adds a written test and the the flight must be with a Level 2 size motor. You can use the same rocket for Level 1 and 2 if it can stand the stress of the bigger motor. Level 3 requires a purpose-built rocket that is pre-approved and supervised along with redundant electronic deployment.
My attempt at Level 1 will use a modified Apogee Zephyr kit which I have named the "Wile E. Special"