Small Unmanned Aircraft Loading and Performance
Weight, balance, and the 55-pound ceiling
The aircraft's weight at takeoff - airframe, batteries, camera, gimbal, and anything else attached - must stay under 55 pounds. Payload changes are never free. Multirotors balance by driving motors asymmetrically, so an off-center camera forces the flight controller into constant corrections: control authority shrinks, motor temperatures climb, and endurance falls. Fixed-wing UAS respond to center of gravity as manned airplanes do - a forward CG buys stability at the cost of a higher stall speed and longer takeoff, while an aft CG erodes pitch stability and can make the aircraft uncontrollable. Compute the new weight and balance and recheck the manufacturer's maximum takeoff weight before adding equipment.
Performance factors
Climb rate, maximum speed, endurance, and controllability all degrade with added weight. Density altitude compounds the problem: thin air means less rotor thrust or wing lift, a higher true airspeed for the same groundspeed, and less battery margin. Cold temperatures cut usable battery capacity. A heavy aircraft also flies a different profile in gusty or hot conditions, and a payload that shifts in flight changes the CG in real time.
Traps
Items offer "55 pounds of fuel" or "55 pounds without payload" - both wrong. Others tempt you with "a heavier camera improves stability." It does not; it moves the CG and shrinks margin. Hover time, route, and reserve all need recomputation.
Rule of thumb
Any change to the payload means a fresh weight, balance, and endurance calculation - three numbers, every time.