Load factor is the ratio of lift to weight and can be expressed as:
In straight and level flight, lift is equal to weight – so the load factor is 1.
When a pilot is flying a level turn, the total lift increases in order for the vertical component of lift to remain equal to weight. However as total lift is now greater than weight, the load factor increases in a turn.
The aircraft is now creating a greater force perpendicular to the wing (the lift) and the pilot feels this as a force pushing them down into their seat. This is commonly referred to as ‘g-force’.
The load factor can be calculated using the formula:
If a pilot wants to fly a level turn at a bank angle of 45°, the angle of attack will need to increase until 41% more lift is being generated. Since lift has increased by 41% and weight remained the same, the load factor is 1.41 and the aircraft will experience 1.41g.
Increasing the bank angle to 60° requires twice as much lift to be generated. Lift will need to double while weight remains the same, so the load factor will be 2 and the aircraft experiences 2g.