Ground Effect Flashcards
What is Ground Effect?
Ground effect alters the aircrafts aerodynamics close to the ground. The aircraft may float along the runway during landing or prematurely lift off during take off.
What is the effect on LIFT when entering ground effect?
Due to the reduction of induced drag and the decrease in induced angle of attack it results in INCREASED lift (and CL)
Increased pressure under the wing means more air is forced over the upper surface. This also increases lift.
Stalling speed is reduced
What is the effect on DRAG when entering ground effect?
Due to the early stagnation of vortices on the ground, the induced drag (and Cd) is DECREASED.
The induced angle of attack is decreased.
Thus, rate of descent is also decreased.
Why is there a nose down moment when entering ground effect?
A nose down moment is caused by the increased downward lift created by the elevators increased angle of attack.
This is caused by the reduced angle fo the downwash.
What happens to LIFT when leaving ground effect?
Lift is REDUCED as the drag increases.
> downwash angle increases
> induced drag increases
What happens to DRAG when leaving ground effect?
Induced drag INCREASES as the downwash angle increases. Parasite drag always increases with speed.
What action do we need to take to leave ground effect when taking off?
Pilot much reach the proper climb speed before leaving ground effect.
A trim change may be necessary to counter the change in AOA on the tailplane.
