Two separate limits
Part 107 applies to aircraft weighing less than 55 pounds at takeoff, including everything onboard or attached. The manufacturer may impose a much lower maximum takeoff weight, payload, wind, or temperature limit. The stricter applicable limit controls the operation.
Moment and center of gravity
A simple loading moment equals weight multiplied by arm. Moving a payload farther from the datum increases its moment. Center of gravity moves toward added weight. An off-center payload may force motors to produce unequal thrust, increase heat and power draw, and reduce control margin.
Example: a 2-pound payload placed 8 inches from the datum creates 16 pound-inches of moment.
Endurance is not the advertised maximum
- Use actual measured performance with a similar payload, battery age, wind, route, temperature, and flight mode.
- Plan a reserve for headwind, go-arounds, traffic, route changes, battery imbalance, and landing delay.
- Do not plan to land at absolute minimum charge.
- Remember that cold, heat, high density altitude, heavy payload, aggressive flight, and wind increase risk.
Payload integration checklist
- Secure the payload against movement and vibration.
- Keep propellers, cooling paths, GPS, compass, antennas, obstacle sensors, and landing gear clear.
- Verify center of gravity and total weight.
- Conduct a controlled test in a safe area before the operational mission.