Loading and performance is 7-11% of the Part 107 test. The questions come from the FAA's Remote Pilot Study Guide and Advisory Circular 107-2A.
Weight
A small unmanned aircraft must weigh less than 55 pounds at takeoff, and that counts everything on board or attached, so payload and batteries are included. Weight changes in flight directly affect performance: a lighter aircraft performs better, but losing weight, as when a drone drops an item, can upset its balance.
Load factor
Load factor is the force on an aircraft when its flight path bends from a straight line, measured in Gs. A load factor of 3 means the structure carries three times the aircraft's weight.
- In a coordinated level turn at 60 degrees of bank, the load factor is 2 Gs.
- Stalling speed rises with the square root of the load factor. At a load factor of 4, stalling speed doubles, for example from 30 to 60 knots.
Density altitude
When air density falls, density altitude rises and performance drops. Four things raise density altitude:
- High elevation: higher places have lower pressure and density.
- High temperature.
- Low pressure.
- High humidity: water vapor is lighter than air, so moist air is less dense. Humidity is a smaller factor than the others.
Wind shear
A tailwind suddenly changing to a headwind increases airspeed and performance; a headwind changing to a tailwind decreases them. In a microburst a drone may meet a performance-increasing headwind, then downdrafts, then a strong tailwind that can drive it into the ground.
Before takeoff
Check the launch area's length, surface, slope, surface wind and obstacles; any of them may call for less weight. Read the manufacturer's performance data on takeoff, climb, range, endurance, descent and landing.