Is there such a thing as ground effect ? - RC Groups
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Feb 06, 2003, 04:01 AM
Registered User

Is there such a thing as ground effect ?


I did a forum search and could not find an answer.
Thanks in advance.
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Feb 06, 2003, 05:17 AM
Registered User
Yes. For info about the extremes of this effect see

http://www.se-technology.com/wig/
http://home.mira.net/~radacorp/ground_effect.html

Did you have any particular reason for asking ?

Steve
Feb 06, 2003, 09:32 AM
Registered User
Pelicans are in the habit of saving energy by using ground (water?) effect. When flying over relatively smooth water a pelican will flap 7 to 10 times to gain an altitude of about 10 or 12 feet over the water. Then the bird goes into a shallow dive, pulling out inches above the water. It glides along for about 50 yards skimming the surface. The wing tips are arced downward slightly so that they sometimes penetrate the water briefly without the body touching the surface. As the speed gained in the dive bleeds off and a stall is about to happen the bird starts flapping again to repeat the cycle. When the bird glides this close to the surface its induced drag is approximately halved and its total drag is reduced by about 25%. That constitutes a significant energy saving for the bird.