Aerodynamics Block 15 Flashcards
Which goes up when laminar flow turns into turbulent flow at the boundary layer?
Parasite Drag, particularly Form Drag
What form of drag goes down when vortex generators are put ON?
Form Drag goes down
What is pressure drag? What is another name for pressure drag?
Pressure drag is the difference in leading pressure, and the aft edge.
Pressure drag is known as FORM DRAG
What do wingtip vortices create by definition?
INDUCED DRAG
What are the two types of turbulent flow?
Burbling
Vortex Tubes
Dt is constant/not constant
Not Constant
Pressure Drag/Form Drag may aid in recovery of what?
Pressure/Form drag help recovery in a spin (ex . F-16)
Parasite drag is ________due to _______
Powerplant cooling
Air Conditioning
Leakage through access gaps
Poor construction
Skin Friction Drag AKA _________ is ?
.
High aspect ratio for induced drag changes the airflow
Minimal / Maximum
Therefore
High Aspect ratio = ____________
High aspect ratio for induced drag changes airflow minimally.
Therefore high aspect ratio = low induced drag.
REMEMBER THE SPHERE OF INFLUENCE
Induced Drag is influence mainly by (3)
- Lift
- Altitude
- Speed
When lift is double what happens to drag?
At a flight from 1 to 5 Gs then induced drag is ___?
If everything else is held constant induced drag varies as the _____ of _____
Di=L2
As lift is doubled, induced drag is 4 times as great.
At 1 g changed to 5 g’s induced drag is 25 times as great.
INDUCED DRAG AS SQUARE OF LIFT IF ALL ELSE CONSTANT IS IMPORTANT
What’s interesting about total drag?
ITS NOT CONSTANT
Induced drag In regard to ALTITUDE:
What has to happen to the less dense, thinner air at higher altitudes?
At 39,000 feet air is ___ the density of sea level, requiring ____ times the lift.
Thinner air must be deflected FURTHER to create the same lift.
At 39,000 feet - air is 1/4 the density at sea level, requiring 4 times the lift.
(des not increase Di by 4^2 due to increase in air density.
Induced drag in regard to SPEED -
Di varies ___ as the ____ of _____.
Low airspeeds mean ________
Double the airspeed means?
Cut airspeed in half and what happens?
As average relative wind changes, induced _____ changes and _______ change.
Di varies inversely as the square of airspeed.
Low airspeeds mean high Cl
Double the airspeed means 1/4 of the Di
Airspeed in half = 4 times the Di
As average relative wind changes, induced AOA
changes and lift vectors change.
Induced Drag Speed:
Slow an airplane from 300 - 150, dp is now 1/4 at ____the speed. This forces the airflow to be deflected ____ times greater.
Slow an airplane from 300 - 150, dp is now 1/4 at 1/2 the speed. This forces the airflow to be deflected 4 times greater.