Forces in the Air
Thrust and Drag
Thrust is needed to ensure that the aircraft keeps moving in a forward direction. Drag is forces that keep the aircraft from moving forward.
Drag: byproduct of lift. This is resistance that slows the aircraft.
Drag causes: friction between the air and skin of the aircraft, and interference from components of the aircraft.
Ground Effect: results in less drag on the rotor during hovering close to the ground.
Thrust: caused by motors that push air in the opposite direction. An energy source is needed for this. Makes the aircraft go forward. Drones do this by tilting and vectoring.
Image Source: https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/four-forces-on-an-airplane/
Image Source: https://www.skytough.com/post/how-angle-of-attack-indicator-works
Lift and Airplanes
As mentioned previously, lift is needed for the aircraft to rise.
Weight: must be distributed throughout an aircraft to ensure a vehicle has a centre of gravity.
Angle of attack: the angle at which the chord of an aircraft's wing meets the relative wind (effects lift: greater the angle, greater the lift)
Forces against the airplane will produce different results (either by choice of the pilots or by accident).
If thrust is greater than drag: makes airplane go faster
If drag is greater than thrust: slows down airplane
If drag and thrust are equal: plane is in a constant state of motion
If lift is greater than weight: aircraft rises
If weight is greater than lift: aircraft descends
If lift and weight are equal: doesn’t climb or drop (stays steady)
Equilibrium: if drag and thrust are equal AND if weight and lift are equal
Factors that contribute to stall: angle of attack, air speed, load factor
Forces or objects on wings can affect the movement of aircraft.
Wing tip vortex: high pressure air trying to move from below a wing to the top of the wing. These cause drag and can cause RPAS to crash if they get caught in its flow.
If a wing is covered in frost: It disrupts the flow of air over the wing and can drastically reduce the production of lift. It also increases drag, which when combined with lowered lift production, can adversely affect the ability to take off.
Approved payload: a set amount of cargo/weight your drone can have added to it. Subject to Transport Canada regulations. Must not affect the RPAS centre of gravity.
Image Source: https://www.boldmethod.com/learn-to-fly/aerodynamics/how-winglets-reduce-drag-and-how-wingtip-vortices-form/
Image Source: https://aircrafticing.grc.nasa.gov/2_2_2_1.html
Lift and Helicopters
A helicopters blades are used to affect the forces being exerted on it.
Cyclic pitch: affects pitch and roll of a helicopter
Collective pitch: affects thrust / throttle helicopter
Helicopter Wake Turbulence: higher than turbulence since they travel at lower speeds
Helicopter Tail rotor: It provides a counteracting force to the helicopter's main rotor.
Without the sideways thrust produced by the tail rotor, the torque generated by the main rotor would spin the helicopter's body in the opposite direction.
Image Source: https://www.centennialofflight.net/essay/Dictionary/pitch/DI39.htm