Drag Flashcards
3 main types of drag
- Profile drag
- skin friction
- form drag
- interference drag
- induced drag
What is skin friction drag
Drag created from the roughness of the skin effecting the flow of the boundary layer
What is interfenerence drag
Drag created by airflow from one part of the a/c interacting with the airflow from a part adjacent on the
a/c
What is induced drag
Induced drag is the main bi-product of the production of lift
It can be directly related to the AoA of a wing
drag from the two pressures around the wing combining together (pressure drag)
Factors affecting form drag
Finesse ratio (thickness chord ratio) Shape of aircraft
Outline relationship between loft and drag
Lift is directly related to drag. The more lift created the more drag also created (induced drag).
There is a sweet spot where the coefficient of lift is maximized with drag minimized. This will depend on AoA, speed and other factors
Factors effecting lift/drag ratio
Aerofoil shape
Angle of attack
Wing surface condition
How do planforms effect drag
Different plan forms will either help reduce or create more drag. Some platforms cuase lift to stall at wing roots first while others at the wing tips.
This is due to the angle, shape, aerofoil shape or surface area of the wing
Types of wing platforms (6)
Rectangular Tapered Elliptical Cresent Delta Sweptback
Which plan form reduces the most drag
Elliptical reduces the most drag however it is the most complicated to make
List the advantages and disadvantages of swept back wings
Advantage is it increases the chord line. With the same wing area as that of a non swept back wing. The swept back will produce more lift.
Dis. It stalls at wingtip first so pilot gets no buffeting indications. Secondary stall warning are in place
