Bank Angle & Load Factor

G Forces

When talking about bank angles and load factors, you first need to understand G forces. G forces measure the amount of added weight that is felt when centrifugal force is acting on an object. In our video, we give the example of a roller coaster. As you go through a loop or a steep turn, you feel as if you are being sucked into your seat. This added feeling of weight is measured in G force (or Gs for short). One G is the normal force of gravity, where 3Gs is three times the force of gravity.

Bank Angle

When an aircraft begins to turn, the lift from the wings or propellers is no longer lifting the aircraft straight up. Rather, the lift component is now distributed upwards and to the side. This causes the aircraft to start to lose altitude. To counteract the potential loss in altitude, the pilot (or flight computer) will need to increase the pitch of the aircraft. This increase in pitch causes increased G forces (similar to a tight turn on a roller coaster).

Load Factor

This increase in Gs places a heaver load on the structure of the aircraft. Some aircraft are only built to withstand a certain amount of G forces before they begin to experience structural damage. The FAA may want you to calculate how many Gs are associated with varying degrees of bank angles.

The chart below comes from the FAA supplemental test materials. To calculate load factor, start with the bottom of the chart and find the bank angle you are looking for. Follow the chart straight up until you hit the red line. Then, from that point, follow the chart directly to the left until you get to the vertical axis to measure the G forces.

The FAA may ask you: At what bank angle do the forces placed on an aircraft begin to substantially increase? As you can see from the chart, the load factor begins to curve up around 45 degrees. Remember that for the exam!

Here is another test question that is likely to appear on your exam:

If an unmanned airplane weighs 33 pounds, what approximate weight would the airplane structure be required to support during a 30° banked turn while maintaining altitude? (Hint: Refer to FAA-CT-8080-2G, Figure 2)

In this section, we need to locate 30 Degrees under the Angle of Bank section on the Load Factor Chart. You will then look over in the next table cell and see the load factor number 1.154. You will take this number and multiply it by the weight of the UAS to get the weight when the aircraft is banked 30 Degrees.

Example:

33 pounds x 1.154

= 38 Pounds

This means the aircraft would have to support the weight of 38 pounds during the bank to maintain altitude.