Which payloads are NOT allowed in a high power rocket?

Payloads that are flammable or explosive are prohibited in high power rocketry due to safety concerns. High power rockets operate at significant altitudes and velocities, which can create conditions where flammable or explosive materials could lead to catastrophic failures during flight. The potential for ignition or detonation increases with the high speeds and pressures encountered, which could pose risks not only to the rocket itself but also to spectators and the environment. Therefore, to ensure the safety of all involved, regulations strictly forbid these types of payloads in the construction and launch of high power rockets.

Rocks and soil, electronic devices, and live plants, while they may have their own considerations, do not inherently present the same level of risk associated with flammable or explosive payloads. Each of these can be safely used within the guidelines provided, assuming they comply with other safety regulations set by rocketry organizations.