1. Unit 2 Unmanned Aircraft
Module 5 – Small Unmanned Aircraft Loading

2. Module 5 – Small Unmanned aircraft loading
5.1 – Weight
Consideration before flight
Weight and balance restrictions are established by the manufacturer or the builder
Should be closely followed
Compliance with the manufacture’s weight and balance limit is critical to flight safety
Must consider the consequences fo an overweight aircraft if an emergency arises
Conditions that affect takeoff and climb performance:
High elevations
Hot air temperatures
High humidity (high density altitudes)
These may require a reduction in weight before flight
Weight changes during flight effect the aircraft performance
Most common weight change is fuel burn
As fuel burns the aircraft becomes lighter and the performance of the aircraft improves
Could cause negative effect due to balance shifting
Weight change in small UAS operations may be due to expendable items on board being used

3. Module 5 – Small Unmanned aircraft loading
5.1 – Weight
Center of gravity (CG) may be established by the manufacturer
CG is not a fixed point, location depends on the distribution of aircraft weight
Remote pilot should determine how the CG will shift and the effects on the aircraft
If CG is not within allowable limits for safe flight, the remote pilot needs to relocate or shed some weight before flight
Gravity, the pulling force, draws all bodies to the center of the earth
CG is the point at which all weight of the aircraft is concentrated
If supported at CG the aircraft will balance in any attitude
CG is a small UAS has a great bearing on stability
Location of the CG is determined by design of each particular aircraft
Designers determine how far the center of pressure (CP) will travel
Important to understand
Aircraft’s weight concentrate at the CG
Aerodynamic forces of lift occur at the CP
When CG is forward of CP tendency to pitch nose down
When CP if forward of CG nose up pitching moment
Designers fix the aft limit of CG forward of the CP to retain flight equilibrium

4. Module 5 – Small Unmanned aircraft loading
5.1 – Weight
Issuance of a remote pilot certificate with a small UAS rating.
An applicant for a remote pilot certificate with a small UAS rating under this subpart must make the application in a form and manner acceptable to the Administrator.
(a) The application must include either:
Evidence showing that the applicant passed an initial knowledge test. If applying using a paper application, this evidence must be an airman knowledge test report showing passage of the knowledge test; or
If a person hold a pilot certificate issued under part 61 of this chapter and meets the flight review requirements specified in 61.56, a certificate of completion of a part 107 initial training course.

5. Module 5 – Small Unmanned aircraft loading
5.1 – Weight
Weight
Weight has a definite relationship to lift
Lift is the upward force on the wing, acts perpendicular to relative wind and the lateral axis
Lift is required to counteract weight
In stabilized level flight the lift force equal the weight force
In state of equilibrium plane neither accelerates upward or downward
If lift becomes less than weight vertical speed decreases and if greater than the vertical speed increases

6. Module 5 – Small Unmanned aircraft loading
5.1 – Weight
Stability
Stability I the inherent quality of an aircraft to correct for conditions that may disturb its equilibrium, and return to the original flight path
Affects two areas significantly:
Maneuverability
Quality of an aircraft that allows it to be maneuvered easily
Withstand stresses imposed by maneuvers
Governed by:
Weight
Inertia
Size
Location of flight controls
Structural Strength
Powerplant
Controllability
The capability to respond to the Pilot’s control, in regard to fligh path and attitude.
Quality of the aircraft’s response to the pilot’s control application, regardless of the stability caracteristics

7. Module 5 – Small Unmanned aircraft loading
5.2 – Load Factors
Load Factors
Measured in Gs, acceleration of gravity
A unit of force equal to the force exerted by earth’s gravity
Indicates the force a body is subjected to when it accelerates
Any force applied to a aircraft to deflect it flight from a straight line produces a stress on its structure
The amount of the force is a load factor

8. Module 5 – Small Unmanned aircraft loading
5.2 – Load Factors
Load Factors in Steep Turns
Example: a load factor of 3 means the structure is three times its weight
Expressed as Gs so a load factor of 3 is 3Gs and 4 is 4Gs
Aircraft structures are designed to withstand only a certain amount of overload
Important for two reasons:
Pilot can impose a dangerous overload on the aircraft structures
Increased load factor increases the stalling speed, making stalls possible at seemingly safe flight speeds
At constant altitude, during a coordinated turn the load factor is the result of two things:
Centripetal force
Weight
For any given bank angle, the rate-of-turn varies with airspeed
The higher the speed the slower the rate of turn (ROT), the compensates for added centripetal force allowing load factor to remain the same.
After 45º – 50º the load factor increases at a terrific rate
Wings must produce lift equal to load factors if altitude is maintained
Load factor rises geometricly as it nears 90º, constant altitude at 90 is not mathematically possible
At slightly more than 80º the load factor exceeds the limit of 6Gs

9. Module 5 – Small Unmanned aircraft loading
5.2 – Load Factors
Load Factors and Stalling Speeds
Aircraft within limits of its structure, may stall at any speed
With sufficient AOA, smooth flow over an airfoil breaks up and separates
This produces an abrupt change of flight characteristics and sudden loss of lift resulting in a stall
Stall speed increases in proportion to the square root of the load factor
Pilots should be aware of inadvertently stalling the aircraft by increasing the load factor, ie. Steep turn or spiral

10. Module 5 – Small Unmanned aircraft loading
5.2 – Load Factors
Issuance of a remote pilot certificate with a small UAS rating.
An applicant for a remote pilot certificate with a small UAS rating under this subpart must make the application in a form and manner acceptable to the Administrator.
(b) If the application is being made pursuant to paragraph (a)(2) of this section:
The application must be submitted to a Flight Standards District Office, a designated pilot examiner, an airman certification representative for a pilot school, a certificated flight instructor, or other person authorized by the Administrator;
The person accepting the application submission must verify he identity of the applicant in a manner acceptable to the Administrator; and
The person making the application must, buy logbook endorsement or other manner acceptable to the Administrator, show the applicant meets the flight review requirements specified in of this chapter.

11. Module 5 – Small Unmanned aircraft loading
5.3 – Weight and Balance
Weight and Balance
Operating above maximum weight limitation compromises the structural integrity
Adversely affects the performance
Operation with CG outside of approved limits results in control difficulty
Weight Control
Weight is the force of gravity attracting a body toward the center of the Earth
It is a product of mass of a body and the acceleration acting on the body
Weight is a major factor in aircraft construction and operation and demands respect from pilots
Force of gravity constantly attempts to pull an aircraft down toward Earth
Force of lift counteracts weight and sustains an aircraft in flight
Airfoil lift is limited by the airfoil design, AOA, airspeed, and air density
To insure enough lift, loading beyond recommended weight must be avoided
If weight is greater than lift, aircraft is incapable of flight

12. Module 5 – Small Unmanned aircraft loading
5.3 – Weight and Balance
Effect of Weight
Any item that increases the total weight is undesirable for performance
Aircraft are as light as possible without sacrificing strength or safety
Should always be aware of consequencies of overloading
Overloaded aircraft many not be able to leave the ground, or have unusually poor flight characteristics
Initial indication of poor performance usually takes place during takeoff
Excessive weight reduces flight performance and may result in:
Higher takeoff speed
Longer takeoff run
Reduced rate and angle of climb
Lower maximum altitude
Shorter range
Reduced cruising speeds
Reduced maneuverability
Higher stalling speed
Higher approach and landing speed
Longer landing roll

13. Module 5 – Small Unmanned aircraft loading
5.3 – Weight and Balance
Effect of Weight
Pilot must be knowledgeable of the effect of weight on the performance
Excessive weight reduces the safety margins available
Becomes more hazardous when other performance-reducing factors are combined with excess weight
Consequences of overweight aircraft must be considered if an emergency condition arises