Aerodynamics Flashcards
What is CP?
Center of Pressure
AOA
Angle of Attack
What is the stalling AOA know as?
CL-Max
What proportion is lift to airspeed in an airplane?
The lift is the square of the airspeed. Written out CL • p • V^2 • S / 2.
If all factors remain constant, an airplane going 200 knots has 4x the lift of the plane going 100 knots.
What is (p)?
Air Density
What is (V)?
Airfoil Velocity
What is (S)?
Surface area of the wing
What is (C’L)?
Coefficient of lift for a given airfoil
How is the L/D Ratio determined?
Dividing the CL by the CD
In the lift and drag equations;
L=
D=
p=
CL=
V=
q=
S=
CD=
L= Lift in pounds
D= Drag
CL= Coefficient of Lift
p = Density
V = Velocity (feet per second)
q = dynamic pressure per square foot (q=1/2pV^2)
S = area of lifting body
CD = Ratio of drag pressure to dynamic pressure
What is the drag equation?
D = CD•p•V^2•S/2
What is form drag?
Portion of parasite drag generated by the aircraft due to its shape and the airflow around it. Ex- engine cowling, antennas, etc.
What is interference drag?
Comes from the intersection of airstreams that create eddy currents, turbulence, or restricts smooth air flow. Ex - intersection of wing and fuselage at the wing root has significant interference drag.
What is skin friction drag?
The aerodynamic resistance due to the contact of moving air with the surface of an aircraft.
To minimize the chances if flying through another airplanes wake turbulence:
• Avoid flying through another aircraft’s flight path.
• Rotate prior to the point at which the preceding aircraft rotated when taking off behind another aircraft.
• Avoid following another aircraft on a similar flight path at an altitude within 1,000 feet. [Figure 5-13]
• Approach the runway above a preceding aircraft’s path when landing behind another aircraft and touch down after the point at which the other aircraft wheels contacted the runway.
How long is the safe margin of time to wait for another aircrafts wake turbulence to dissipate?
3 minutes if you are unsure of where the wale turbulence could be.
Wind vortices travel with the wind. How fast would a vortex travel in 10 knots?
1,000 feet per minute
What advisor circular is about wake turbulence?
(AC) 90-23
What are the two types of stability?
Static & Dynamic
What is static stability?
The initial response of the aircraft when disturbed by a given pitch, yaw, or bank.
3 types of static stability
Positive
Neutral
Negative
On an aircraft what does static longitudinal stability depend on?
- Location of wing with respect to CG
- Location of horizontal tail surfaces with respect to CG
- Area or size of tail surfaces
What are the 4 design factors that make an aircraft laterally (roll) stable?
Dihedral
Sweepback
Keel effect
Weight distribution
Stability on the airplanes vertical axis is called __________ stability?
Directional
ROT
Rate of Turn
What force is the horizontal lift component also known as?
Centripetal force
What is an AOA Indicator and what is its use?
AOA indicators are a new initiative by the faa and general aviation joint steering committee (GAJSC) aimed at reducing accident rate. An AOA indicator gives the pilot better situational awareness pertaining to the aerodynamic health of the airfoil.
What items cam limit the effectiveness of an AOA indicator?
Calibration Techniques
Probes or Vanes not being heated
The type of indicator itself
Flap setting
Wing contamination
Describe how propeller thrust is calculated
Propeller thrust equals mass of air handled multiplied by slipstream velocity, minus velocity of aircraft.
Propeller slip is the difference between what two types of pitch?
Propeller slip is the difference between the geometric pitch of the propeller and its effective pitch.
What is torque?
The left turning tendency of the airplane.
What 4 elements make up the affect of torque?
- Torque reaction from the engine and propeller
- Corkscrewing effect of the slipstream
- Gyroscopic action of the propeller
- Asymmetric loading of the propeller (p-factor)
How is the torque reaction (on left tire) on takeoff adjusted for?
Proper use of the rudder or rudder trim by the pilot.
What is a “G”?
(Acceleration of gravity) a unit of force equal to the force exerted by gravity on a body at rest and indicates the force to which a body is subjected when it is accelerated.
Why is the load factor in a spin usually found to be the 1g of level flight?
- Airspeed in a spin is very low, usually within 2 knots of the unaccelerated stalling speeds.
- An aircraft pivots, rather than turns, while it is in a spin.
What is a Vg diagram?
Velocity versus G load diagram
What two principle reasons are planes certificated for weight and balance?
- The effect of the weight on the aircraft’s primary structure and its performance characteristics
- The effect of the location of this weight on flight characteristics, particularly in stall and spin recovery and stability
What is the most influential factor in determining the length of a turn?
airspeed is the most influential factor in determining how much distance is required to turn
Under standard temp. conditions of 15 degrees C the speed of sound at sea level is?
661 knots
At 40,000 feet altitude where temp. is -55 degrees C the speed of sound decreases to how many knots?
574 knots
What are vortex generators used for?
Vortex generators are used to delay or prevent shock wave induced boundary layer separation encountered in transonic flight.
Why do jet transport aircrafts have small ailerons?
The ailerons are small because much fo the trialing edge of the wing is needed for flaps. Also conventional size ailerons would cause wing twist at high speeds.
