Loading and performance — weight, balance, battery
**Maximum takeoff weight (MTOW)** includes airframe, battery, payload, and anything attached to the aircraft. Exceeding MTOW reduces flight time, degrades maneuverability, and in severe cases causes motors to overheat and fail. Part 107 caps MTOW at 55 lb; anything heavier falls under 14 CFR Part 137 (agricultural) or requires Section 44807 exemption.
**Center of gravity (CG)** is maintained by the airframe design, but aftermarket payloads (cameras, gimbals, delivery packages) shift CG. CG forward of limit causes nose-down trim demand that reduces power efficiency; CG aft causes instability in pitch. Most consumer drones have integrated gimbals that place the payload CG near the aircraft CG.
**Battery performance** degrades with: • Temperature — LiPo capacity at 0°C is ~80% of 25°C baseline; at -10°C it drops below 60%. Always pre-warm batteries in cold weather. • Age and cycle count — capacity degrades ~3-5% per 100 cycles; internal resistance rises. • Depth of discharge — consistently running below 20% state-of-charge accelerates degradation. • Storage state — LiPos stored at full charge for months develop dendrites; store at 50-60% for long-term.
Plan for 20-25% battery reserve at landing. Low-battery return-to-home (RTH) behaviors vary by manufacturer; verify RTH altitude is above all obstacles along the path home.