Anhedral and ducks
Thread Starter
Joined: Nov 2001
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From: Norfolk
Anhedral and ducks
OK guys, here is an odd one to exercise the aerodynamic brains. My wife breeds ducks and wildfowl (as well as driving helicopters). She asked me: "Why do ducks when they are making a glide approach to their water ski landings, and before they lower the undercarriage, sweep their wings forward and carry considerable anhedral. Surely anhedral is laterally destabilising and unlikely to increase lift". Er.....right.
Joined: Jan 2001
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From: The Burrow, N53:48:02 W1:48:57, The Tin Tent - EGBS, EGBO
Originally Posted by rotorfossil
Surely anhedral is .......unlikely to increase lift". Er.....right.
Joined: May 2005
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From: Blackflies and Snow
Total guess work, but I'll have a stab at this. I suspect they are using their tip feathers to detect the change in local airflow as the ground effect kicks in. This allows them to judge the flare which could be a challenge otherwise given the difficulty judging height over water.
Dog Tired
Joined: Oct 2001
Posts: 1,686
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From: uk
well, where do we start?
gaxan should be banned for a start. failing to mention that one should be 'feathered'. also failed to mention Vmc beak.
DX W knows better, I am certain. even a duck needs lift at rotation as well as the flare.
AP is clearly mad; who would use feathers rather than eyeballs to judge the flare?
I am the only sane one here. not for the first time...
gaxan should be banned for a start. failing to mention that one should be 'feathered'. also failed to mention Vmc beak.
DX W knows better, I am certain. even a duck needs lift at rotation as well as the flare.
AP is clearly mad; who would use feathers rather than eyeballs to judge the flare?
I am the only sane one here. not for the first time...
Joined: Oct 2003
Posts: 1,300
Likes: 0
From: Canberra Australia
To maximise lift and drag close to the stall making best use of ground/over water effect contribution. Flicking the odd feather would probably be enough to control the roll instability from the anhedral.
Similar to the technique used by paragliders and to a lesser extent by hang gliders on landing.
Do the ducks always touch down directly into wind?
Wouldn't it be great to be able to do that!
Does anyone know the rest of the words to that old WW2 aviators song -
"Be kind to your web footed friends
Because a duck may be somebody's mother
Well you may think that this is the end
Well it is."
Similar to the technique used by paragliders and to a lesser extent by hang gliders on landing.
Do the ducks always touch down directly into wind?
Wouldn't it be great to be able to do that!
Does anyone know the rest of the words to that old WW2 aviators song -
"Be kind to your web footed friends
Because a duck may be somebody's mother
Well you may think that this is the end
Well it is."
