Aerodynamics Flashcards
What are the 4 left turning tendencies?
- Torque
- P-Factor
- Corkscrew Effect
- Gyroscopic Precession
Explain how torque effects L turning tendencies?
- The right side of the prop has a higher AoA as it rotates and takes a bite out the the air
- Although the left side of the prop still produces thrust, it’s much smaller than the right
- Newton’s 3rd law of physics says that for every action there’s an equal and opposite reaction. So the crankshaft that’s attached to the prop reacts in the opposite direction of the prop taking a bigger bite as it’s rotating to the right
- Most powerful at high power settings, low airspeed, and high AoA
Explain how Spiraling Slipstream effects L turning tendencies?
- When the rotation of the prop is fast and the airplane is moving slow, it’s most prominent
- The air produced by the prop spirals around the fuselage, and as it does it hits the left side of the vertical stabilizer and pushes the tail to the right, causing a yawing motion to the left
- Increase in airspeed increases the length of the slipstream.
- So corkscrew effect is strongest at slow airspeed and high power setting
What is P-Factor?
- The bigger bite taken out of the air causes a yawing motion to the left
- Strongest at high angles of attack (climbs)
Explain how gyroscopic precession effects L turning tendencies?
- The prop acts like a gyroscope as it’s moving to the right
- When we _pitch down_ the force is felt from the top initially. Because of precession it’s felt 90° in the direction of the turning prop. Meaning the _force is actually applied and felt on the left_ therefore yawing the aircraft to the left (mostly felt with tail draggers as they push the nose down to raise the tailwheel
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What is the lift formula, and which components can we control in the lift formula?
L = CL + 1/2p* V2 + S
- In this formula we, in general aviation, have mostly the ability to control CL by pitching up/down and changing our AoA.
- We can also control V2 by adding throttle to control our TAS
What are the components in the lift formula?
CL: Is the coefficient of lift. This includes wing shape, AoA, camber
1/2p: Is the environment, air density, humidity
V2: Is the airspeed which we have control of with the throttle
S: Is the surface area. The bigger the area the bigger the lift that can be generated.
- If we can increase anything within the formula, we can increase our lift we produce
What occurs when power is increased, and thrust is increased?
- Thrust become greater than drag and the airspeed increases
- As long as thrust continues to be greater than drag, the aircraft will continue to accelerate
- When drag equals thrust, the aircraft flies at a constant airspeed
How would I manipulate the aircraft aerodynamics in order to maintain a given altitude with a slow or high TAS?
- If TAS is slow, I would need a higher AoA to maintain the same amount of lift at a given altitude
- Because thrust is decreased (due to the slower TAS) a higher AoA would be required generate a lift force to equal to the weight
If in straight and level flight you increase the power setting. What would happen to lift?
Lift formula is L=Cl+(1/2p*V2)+S
- If we increase any of the variables in the Lift equation, lift will be increased
- Since we’ve increased velocity (TAS) we’ve now increased one of the variables and therefore lift is increased. We would need to decrease AoA to maintain the relationship between weight and lift
What are the laws/principles that dictate lift?
- Bernoulli’s Principle
- As velocity increases, pressure decreases
- Newton’s third law of motion:
- For every action there is an equal and opposite reaction
- Air is a viscous fluid
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What is the formula for force?
mass x accelration = force
What is drag?
- The force that resists movement of an aircraft through the air
- 2 Types of Drag
- Parasite: Does not aid flight
- Induced: The result of an airfoil developing lift
What are the different types of parasite drag?
- Form:
- Generated by the shape of the aircraft and its components as it splits the air it travels through.
- Reduced when designing the aircraft; i.e. streamlining the parts as much as possible
- Interference:
- Formed when 2 surfaces meet at perpendicular angles
- Fairings used to reduce this drag
- Skin Friction:
- The aerodynamic resistance due to contact of moving air with the surface of an aircraft
- Smooth skin reduces skin friction drag, improving performance and fuel efficiency
- Similar to swimmers using swim caps
What is induced drag?
- Created whenever a wing creates lift
- 2 Key Factors
- Lift acts perpendicular to the airflow
- Wingtip vortices bend the airflow downwards
- The more lift we generate, the more stronger the induced drag
- Due to the vertical rearward component of lift, it acts backwards opposing thrust
