Loading and Performance Flashcards
An airplane has been loaded in such a manner that the CG is located aft of the aft CG limit. One undesirable flight characteristic a pilot might experience with this airplane would be
difficulty in recovering from a stalled condition.
An aft CG means that the CG will be closer to the center of lift (or center of pressure), which in turns means that the aircraft will be less controllable, so more difficult to recover from a stall. See “Performane > Moving CG Location” for more information.
(Refer to FAA-CT-8080-2H, Figure 2.) 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?
38 pounds.
The information needed for this answer is found in the left column of the figure. At 30° of bank, the load factor is 1.154. If the object weighs 33 pounds, then at 30°, the load factor will be 33x1.154=38 pounds. See “Load Factor” video for more information.
When loading cameras or other equipment on an sUAS, mount the items in a manner that
does not adversely affect the center of gravity.
As seen in the videos in this chapter, mounting anything to the sUAS affects the location of the CG. So when mounting cameras or other equipment, be sure it doesn’t change the CG to the point where it is out of limits. While the other two answers are rather correct, the “most correct” answer is still “does not adversely affect the center of gravity.” See “Factors affecting performance” video for more information.
The term “angle of attack” is defined as the angle between the
chord line of the wing and the relative wind.
This is rote memory material. The angle of attack is always defined as the difference between the chord line and the relative wind. The chord line is the line between the leading edge and the trailing edge of the wing. The relative wind is the vector that represents where the airflow that “hits” the wing is coming from. The relative wind is always parallel to the direction of motion of the aircraft, but opposite in direction. See “Stalls” video for more information.
A stall occurs when the smooth airflow over the unmanned airplane’s wing is disrupted and the lift degenerates rapidly. This is caused when the wing
exceeds its critical angle of attack.
As explained in the aerodynamics video about stalls, the airflow starts to disrupt at a particular moment: when the critical angle of attack is reached. While the traditional wisdom dictates that this happens at slow airspeed, when the nose of the aircraft is high, this can happen at any speed. If you apply abrupt pitch-up controls, the angle of attack can reach the critical number where the airflow separates and the aircraft stalls. Remember also that the angle of attack is the difference between the chord line and the relative wind (or direction of motion of the aircraft). When the aircraft reaches maximum speed, the wing will still produce lift, but structural failure can occur (the aircraft wouldn’t be strong enough to go that fast). If the aircraft exceeds its maximum allowable operating weight, structural damage or failure is also a possibility. See “Stalls” video for more information.
What could be a consequence of operating a small unmanned aircraft above its maximum allowable weight?
Shorter endurance.
This is actually an interesting question from the FAA and one that could be worded better. The technical answer to this question is: if the aircraft is operating above its maximum allowable weight… well… it wouldn’t be operating because the wings wouldn’t be able to sustain its weight! But let’s assume they mean you are operating “near” the max allowable weight, in which case you will need to generate more lift, which means it will require more energy. More energy = less battery or fuel = shorter endurance. Maneuverability would be decreased and the speed would be reduced (imagine riding a 50 lbs bike instead of a 10 lbs bike, which one will give you faster speeds). See “Factors affecting performance” video for more information.
When operating an unmanned airplane, the remote pilot should consider that the load factor on the wings may be increased anytime
the airplane is subjected to maneuvers other than straight and level flight.
As seen in the videos, load factor increases in relationship with total lift. Total lift increases when the aircraft is turning or climbing/descending, aka “maneuvers other than straight and level flight”. The gross weight does have a detrimental effect on load factor as well but only when it increases (more weight = more lift = more load factor). Finally, the location of the CG does not have an effect on load factor. See “Load Factor” video for more information.
(Refer to FAA-CT-8080-2H, Figure 1.) The acute angle A is the angle of
attack.
The angle of attack is always defined as the angle between the chord line and the relative wind. This definition needs to be committed to memory. The angle of dihedral does not exist. The angle of incidence is the angle between the chord line and the longitudinal axis of the aircraft. It is a fixed number and does not change in flight. See “Stalls” video for more information.
According to 14 CFR part 107, who is responsible for determining the performance of a small unmanned aircraft?
Remote pilot-in-command.
The Remote pilot-in-command has many responsibilities before, during, and after a flight, including determining the performance of the aircraft prior to take off. The owner or operator also has responsibilities but not this one. See “Responsibilities & Forces of Flight” video for more information.
The angle of attack at which an airplane wing stalls will
remain the same regardless of gross weight.
The angle of attack at which an airplane stalls is defined as the critical angle of attack. Since the angle of attack is defined as the difference between the chord line and the relative wind, it is not affected by weight at all. See “Stalls” video for more information.
In a fixed-wing aircraft, yaw is controlled by
the rudder.
Yawing is controlled by the rudder in an airplane. See “Loading and Performance > Axes of Rotation” for more information.
In a fixed-wing aircraft, roll is controlled by
the ailerons.
Roll is controlled by the ailerons in an airplane. See “Loading and Performance > Axes of Rotation” for more information.
Which of the following increases load factor the most on fixed wing aircraft?
Level turn.
At which bank angle does the load factor increase dramatically
45-50 degrees.
During an approach to a stall, an increased load factor will cause the aircraft to
stall at a higher airspeed.
Stall speed increases as the load factor (and bank angle) increases.
