What happens to flight time when payload weight increases?

A multirotor stays airborne by generating thrust equal to its weight, so adding payload directly increases the thrust required for every second of flight. More thrust means higher rotational speed, higher motor current, and faster depletion of a battery whose stored energy is fixed. The relationship is not linear — power required rises faster than weight, because the motors also move further from their efficient operating point — so a payload increase of twenty percent typically costs rather more than twenty percent of endurance. Two secondary effects follow from the same physics and matter operationally: the aircraft carries more momentum, so it decelerates more slowly and needs greater standoff from obstacles, and the reduced margin between available and required thrust erodes performance in wind and at altitude. None of this changes at the rated payload limit; the limit is where the manufacturer stops guaranteeing behaviour, not where the cost begins.

Additional weight requires additional thrust throughout the flight, so the motors draw more current and the fixed battery energy depletes faster.

Multirotor thrust must equal weight for level flight, so payload increases power required and reduces endurance, with power rising faster than weight. Added mass also increases momentum and reduces performance margin in wind and at altitude.

More Weight, More Thrust, Less Time. The battery holds what it holds.

Remember the two companions: longer stopping distance and reduced margin in wind. Payload questions often test them together.

• •Assuming the endurance penalty is proportional to the weight increase
• •Treating the rated limit as the point where costs begin
• •Keeping obstacle standoff unchanged after adding payload