Questions tagged [ground-effect]

The increase in lift experienced by wings in close proximity to the ground.

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29
votes
10answers
9k views

What is ground effect?

We've all heard the "acts like a cushion of air" explanation tossed casually around by CFIs. There's also plenty of books and reference materials that give a detailed, accurate, and complete ...
17
votes
4answers
8k views

How high does the ground effect last?

Up to which height is the ground effect still significant enough to be taken into account? Would this height be sufficient to actually fly above the ground, overcoming at least trivial obstacles like ...
11
votes
2answers
708 views

Can ekranoplans (GEV) be more efficient than traditional airliners?

Ekranoplans or Ground Effect Vehicles (GEV) fly low enough to the ground that their wings stay in the ground effect. This increases lift and efficiency. But GEV fly in the lower atmosphere (...
32
votes
2answers
9k views

Why don't helicopters always takeoff from a hover out of ground-effect?

I've read enough crash reports to see that helicopters discovering too late in takeoff that they lack the power to fly out of ground-effect is a serious problem. I am wondering why the following isn'...
31
votes
6answers
6k views

Why the ground effect has such a different outcome for wings and cars?

I have some confusion concerning the ground effect. If we take two applications: Aircraft and Cars, they seem to have completely opposite effects. Aircraft From Ground effect (aerodynamics), we can ...
8
votes
2answers
309 views

Does ground effect scale 1:1 with wingpsan?

The rule I have been taught is that ground effect begins within 1 wingspan of the ground. What is the derivation of this measurement? Is it actually true, or just an urban-legend/rule-of-thumb style ...
18
votes
1answer
2k views

Why is there a plateau in helicopter H/V diagrams?

The "dead-man's curve" in a typical helicopter height/velocity (H/V) diagram is commonly referenced to indicate that "towering flight" is dangerous and avoided in general practice. (Simon explained, "...
9
votes
1answer
3k views

What is the effect of uneven ground on ground effect vehicles?

I understand ground effect as far as Wikipedia explains it. There are two ways to ask my question; A ground effect vehicle flies along and encounters an obstacle (say a big wave) that's maybe about ...
1
vote
0answers
57 views

What were the L/D ratio of the A-90 Orlyonok at its different operational atlitudes?

The A-90 Orlyonok was designed to operate in ground effect (altitude significantly lower than its wingspan). If I understand correctly, when in ground effect, the L/D ratio is better due to induced ...
0
votes
3answers
226 views

Could an airliner be as efficient lower and slower?

Could an airliner ever be as efficient at 15 or so meters using ground effect as it is at 50,000 km even if it has to go slower and be shaped differently?