Loading of the Small Unmanned Aircraft
Weight and Balance Basics
Every sUA has a maximum takeoff weight, and Part 107 caps the whole system at less than 55 lb. Loading includes the airframe, battery, payload (camera, gimbal, sensors), and any attached accessories. Adding payload shifts the center of gravity (CG), which affects stability, control authority, and endurance. Manufacturers publish CG limits and payload limits; stay inside them.
Practical Loading Considerations
Battery placement is a common CG tool - moving the battery forward or aft changes balance. External payloads such as lights, speakers, or delivery mechanisms add weight and drag and may change the aircraft's handling. Secure everything: an unsecured payload can shift in flight and cause loss of control. Remember that payload weight reduces available thrust margin, so climb performance and wind penetration degrade.
Regulatory Loading Rules
You may not carry hazardous material for compensation or hire. You may not carry property for compensation or hire unless the operation meets the applicable operating rules (Part 107 permits carriage of property only under specific conditions, and external load operations have their own limits). Do not exceed the manufacturer's maximum weight or the 55-lb Part 107 ceiling, whichever is lower.
Traps
Questions often ask whether a heavier payload improves stability (it does not; it reduces margin) or whether the 55-lb limit applies to the aircraft alone (it applies to the aircraft at takeoff including everything onboard and attached). Another trap: confusing CG with total weight - both must be checked.
Rule of Thumb
Before flight, weigh the aircraft with everything attached and confirm it is below both the manufacturer's max takeoff weight and 55 lb, then verify the CG falls within the published envelope with the battery installed.