FAA Part 107 Study Notes

Important References

Quad - Produced by the motors
Fixed - created by the wing (airfoil)
Applied as the Center of Pressure/Lift (CP/CL)
Counteracts the Weight
Relative Wind is parallel to the flight path in the opposite direction
- Pretend that the aircraft is fixed in position
Leading Edge (airfoil) where the wind hits the airfoil and splits the air above and below the surfaces
Trailing Edge (airfoil) where the wind remerges at the back of the airfoil
Chord Line (airfoil) the line drawn between the leading and trailing edge
Angle of attack (airfoil) the angle between the chord line and the relative wind
Lift is always perpendicular to the relative wind.
Proportional to speed of aircraft and angle of attack
- Faster speed or increase angle of attack = more lift
Lift is governed by Newton's 3rd Law and Bernoulli's Principle

Always perpendicular to the lift (basically, the relative wind)
Resultant Force (airfoil) the total lift. From vector math, subtract the drag from the true lift, I think
2 types of drag
- Parasite Drag by product of flying through the air
  - As speed increases, parasite drag increase.
  - Three types of Parasite drag
    - Form Drag the shape of an object (e.g. Truck vs sports car)
    - Interference Drag increased drag created by the junction between different objects
    - Skin Friction any imperfections on the surface of the lift generating object (propeller, wing, etc)
- Lift Induced Drag
  - As soon as lift is created for fixed wing
  - As soon as we have lateral movement for quads
  - LID becomes less as speed increases
    - proportional to angle of attack
Drag can cause stall based on Angle of Attack usually at low speed
- only a fixed-wing can stall
- only way to recover is to lower the nose of the aircraft
- Can occur when the critical angle of attack is reached regardless of airspeed

Result of gravity
Applied as center of gravity. This is different than the center of pressure/lift.
Always points to center of earth
Every aircraft has a maximum allowable weight to be able to leave the ground.
- If exceeded, no flight

Created by the propeller
A Propeller is just an airfoil and creates lift using the same principles as a wing.
In a quad, thrust is only created when the quad is banked, otherwise, it's creating only lift
Trust > Drag = Accelerating
Drag > Thrust = Decelerating
Drag == Thrust = Consistent speed
If Thrust == 0 then Drag == 0, meaning you aren't moving

It's the acceleration of gravity.
Increases with the bank/roll angle of the aircraft
Sometimes called the Resultant Force
Load is equal to the lift
Typical values of load factor at angles, not it's exponential
- 0° = 1
- 10° = 1.015
- 30° = 1.154
- 45° = 1.414
- 60° = 2
- 85° = 11.473
Also effects stall speed
- Load factor increases with bank angle
- stall speed increases with load factor
- fly at slow airspeed when doing abrupt maneuvers to avoid stalling

Ability to return to the original flight path after being disturbed
Static Stability - Initial ability to return to equilibrium.
- Positive static stability is returning back to equilibrium
- Neutral static stability is not returning but not getting worse
- Negative static stability is getting worse after disturbance
Dynamic Stability - Aircrafts response over time when disturbed
- Positive-Static-Positive-Dynamic - returns back to stability
- Positive-Static-Neutral-Dynamic - oscillates "forever"
- Positive-Static-Negative-Dynamic - oscillates with increasing amplitude "forever"

CG = The point at which WEIGHT is applied
CP = The point at which LIFT is applied
Arm = Distance between the CG and where a force is applied
Moment = Efficiency of the force = Arm × Force
There are limits to where the CG can go based on aircraft design. When mounting things to sUMAs you must take into account resulting CG
Make sure the loaded equipment does not negative impact the CG. Too forward or aft can cause crashes
A large arm between CG and CP will cause a large moment. The elevator help compensate for that. Taildown force is the force created by the elevator.
With an AFT CG - fixed wing
- Higher cruising speeds
- Increase Range
- Faster take offs
- Decreased Stability
- Maybe uncontrollable
- Over rotation on take offs and flaring on landing
- lower stall speed
With a forward CG - fixed wing
- mostly the opposite of everything above
- easier stall recovery
Exceeding CG Limits (envelope of the aircraft)
- Uncontrollable
- Too far forward, can't get off the ground - fixed wing
- Too far aft, stall immediately - fixed wing
- For quad - motors have to work harder in an imbalance
- Make sure weight is also within limits

increased temperature means decreased performance
though battery efficiency decreases at low temperatures too, which will decrease performance