Aerodynamics Flashcards
Name the 3 axis of the airplane
Longitudinal (Roll)
Vertical (Yaw)
Lateral (Pitch)
What is parasite drag?
Skin friction drag
Increases as speed increases
Double airspeed and then parasite increases by 4Xs
Cut airspeed in 1/2 and then parasite drag will become 1/4
What in induced drag?
Drag caused by AOA as you increase lift
Slower you go the more AOA then more induced drag
What is Max L/D?
Lowest point of overall drag
Max range
Max distance glide
What are the 4 turning tendencies?
Torque- propeller turning to the right, tries to roll the airplane to the left
spiraling slipstream- propeller creates a spiral of air that contacts left of the tail causing yawing motion to the left
P-factor -right side of propeller, descending blade has a higher angle of attack, yaws to the left
Gyroscopic precession- propeller acts like a gyroscope
What are the 3 different types of parasite drag?
1) skin friction drag -smooth the surface the less drag
2) form drag -result of an objects general shape in relation to relative wind
3) Interference drag -generated by the mixing of airflow streamlines between the airframe components such as the wing and fuselage… as it flows around it interacts well or not well either minimizing or creating more drag
Why does induced drag decrease in ground effect?
Ground effect reduces the effectiveness of your wingtip vorticies… reduction in down wash, and allows you to maintain a slightly lower AOA which reduces your induced drag as well.
What is the lateral axis of the aircraft?
Pitch
What is the longitudinal access of the aircraft?
Roll
What is the vertical axis of the plane?
Yaw
What V speed is drag the lowest?
Vs
When does induced drag start to form?
When does parasite drag start to form?
What is adverse yaw?
Adverse yaw is the tendency of an airplane to yaw in the opposite direction of the turn. For example, as you roll to the right, your airplane may initially yaw to the left.
Keep coordinated to counter adverse yaw.
When are wingtip vortices the greatest?
Heavy, clean, and slow…
Clean b/c high AOA
What way do wingtip vortices move?
Airflow moves out from under the wing, swirled around the tip, and tries to enter low pressure regional at the top
What is Bernoulli’s principle?
Increase in the speed of a fluid occurs simultaneously w/ a decrease in pressure
What is Newton’s 3rd Law?
For every action in nature this is an equal and opposite reaction
What are the 4 phase of a spin?
Entry phase
Incipient phase
Developed phase
Recovery phase
aircraft spin is an aggravated stall that causes autorotation about the spin axis and a downward corkscrew path for the aircraft. The outboard wing is less stalled than the inboard wing when the aircraft spins around the vertical axis
What is our aircraft spin recovery?
PARE
Power back
Ailerons level
Rudder opposite of spin
Elevator/ nose down
What do we need for a spin to occur?
Airplanes wings uneven AOA is what causes the rotation at stall… wings are extended beyond their critical AOA
Adverse yaw
What’s the difference between Vs0 and Vs1?
Vs1 is stall speed in the clean configuration.
Vs0 is stall speed landing flap configuration.
Vs is stalling speed or min steady flight speed at which the airplane is controllable.
What is a standard rate turn?
360 deg turn completed in 2 min
360/ (2*60)= 3 deg/ sec
180 deg turn completed in 1 min
What is the difference between the forward slip and side slip?
Forward slip used to lose altitude by increasing drag. Lowered wing points toward direction of flight and nose points away…
Side slip used to keep the airplane aligned on the runway when landing in a crosswind. Nose points towards direction of flight.
What creates lift?
Higher pressure under wing
Lower pressure above wing
Pressure differential that creates lift
Angle of Attack (AOA)?
Angle between the chord line of the wing and the relative wind
Changing AOA controls lift, airspeed, and drag
Critical AOA is the high test angle of attack where the air flows smoothly over the wing
What is a stall?
Angle of Attack beyond the critical AOA
Loss of laminar flow over the wing
To maintain altitude there is…
Indicated airspeed for every angle of attack
Stalling angle of attack is the same regardless of:
Weight
Dynamic pressure
Bank angle
Pitch attitude
Stalling speeds affected by
Weight*
Load factor*
Power
*affects stalling speed the most
Stalling AOA is a fixed value
Stalling speeds are not
What is Va
Maneuvering speed
What is the impact of frost on the wing?
Will cause the airplane to stall at a lower AOA than normal
Why is a Rectangular wing form beneficial from a stalling perspective?
Stalls from the root to the wingtip which allows ailerons to remain somewhat effective
A left side slip is used to counteract a crosswind drift during the final approach for landing. A spin would most likely occur if the controls were holding the stick…
Too far back and applying full right rudder
What are the functions of flaps?
Provide same lift at slower airspeed
Increase lift and drag
What is the purpose of the trim tab?
Relieve control pressure
Servo tab -moves when you move the primary control surface. Purpose is to help you move the primary control surface. A servant that is there to help you… balance tab to help you.
Anti-servo tab -used when force to require primary flight controls is to little. Reduces the risk to over control or flutter…
What are spoilers?
Tops of wings of jets
Decrease lift
Increase stall speed
Increase drag
Speed brakes?
Primary purpose is to increase drag
