Drag Flashcards
Induced drag is caused by air at the bottom of the wing flowing?
Outwards
Induced drag is caused by air at the top of the wing flowing?
Inwards
Why does the wing tip vortices result in added drag(induced drag)?
Because the net direction of lift is altered to act rearward in the direction of drag.
Induced drag, relevant to airspeed, is?
inversely proportional to the square of the indicated airspeed
profile drag, relevant to airspeed, is?
proportional to the square of the indicated airspeed
Minimum drag can be found where?
Induced drag = Profile drag
Relevant to minimum drag airspeeds, Compared to a lighter aeroplane, a heavier aeroplane will have a ?
higher Vmd airspeed
Relevant to Vmd speed.
Compared to the clean configuration , an aeroplane with a dirty configuration will have a lower?
Vmd airspeed
Does total drag vary with altitude?
No, since aeroplanes are normally operated according to IAS, drag remains the same.
The drag formula =
Cd 1/2p v^2 S
Which provides better efficiency, an high lift/drag ratio or a low lift/drag ratio?
An high lift/drag ratio
The angle of attack for greatest economy is?
4 degrees
The airflow is altered when in ground effect because?
The upwash and downwash is substantially altered
Ground effect can be experienced within what distance above the runway?
Within one wingspan length.
Ground effect increases?
The coefficient of lift at a given angle of attack
Ground effect reduces the?
minimum speed of an aeroplane
Due to ground effect, the aeroplane will stall - ?
at a lower angle of attack
relevant to ground effect, the float sensation is caused by?
the increase in effective angle of attack
relevant to ground effect, the increased float distance is caused by?
A reduction in induced drag
The two types of drag -
And each sub-category
Parasite and induced drag
For parasite drag: Form drag, interference drag and skin friciton.
Form drag and skin friction fall under profile drag
Parasite drag is proportional to -
Induced drag -
The square of IAS
Inversely proportional to the square of IAS
the speed at which total drag is a minimum (VMD) occurs when the -
Induced drag and parasite drag is equal
The effect of altitude on parasite drag -
Parasite drag is proportional to the IAS. Unless IAS is higher, parasite drag will not be higher. Unless the IAS is not kept constant with altitude, parasite drag will not increase
The effect of altitude on total drag -
Again, drag is proportional to IAS. With a constant IAS total drag will be unchanged with altitude
Thrust required =
Power required =
Drag
Drag x TAS
Vmp and Vmd is (IAS or TAS)
Between Vmp and Vmd, which is higher?
IAS.
Vmd
Effect of weight on the glide distance -
Weight does not change the glide distance, but will change the endurance. Glide distance is dependent on L/D ratio.
If aircraft mass is increased, the result weight component will be balanced by drag.
