Ground Effect

Question 1

Where does ground effect occur

Answer 1

Within one wing span to the ground closer the more it is noticeable

Question 2

Advantages of high wing a/c with ground effect

Answer 2

Wings further from ground so less impact from ground effect
Drag does not decrease nor does lift
Short runway operations easier

Question 3

What causes Ground effect?

Answer 3

Ground reduced wing tip vortices
Wing therefore sees a flatter EAF
Smaller Induced AOA/Bigger EAOA
Decrease in drag “float”
Increase in CL “ballon”
Stall angle reduces as clmax reached quicker (risk of stall in ground effect)

Question 4

Entering Ground Effect

Answer 4

Reduced vortices = less induced drag
EAF will be shallower
Induced AOA reduces (float)
EAOA increase (ballon)
Lift increases
A/C pitches down
Airspeed underreads

Question 5

Airspeed in ground effect

Answer 5

Due to being close slight rise in static pressure reading compresses instrument showing dynamic pressure falling (under read)

Question 6

Pitching In Ground effect

Answer 6

Less tail force in ground effect so AC will pitch downwards

Question 7

Leaving ground effect

Answer 7

Downwash increases
Induced drag increases
Induced AOA increase
Effective AOA decreases
Lift decreases
Airspeed will rise
A/C will pitch up (more force on tailplane)

Question 8

Ballooning is

Answer 8

Uncommanded climb with no nose up input on round out

Question 9

Risk of stall in ground effect increases because

Answer 9

EAF is shallower
Effective AOA increases
Stall angle reduces

Question 10

Why does A/C pitch down in ground effect

Answer 10

Reduces downwash
Tailplane EAOA increases
Downforce from tailplane reduced
Pitch down at the nose

Question 11

What is the consequence of decreasing wings upwash and downwash

Answer 11

Decreased induced drag since effective aoa increases