Winglet thrust
Thread Starter
Joined: Nov 2005
Posts: 87
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From: Canada
Winglet thrust
Winglets do the fallowing:
1. Reduce Drag
2. Increase lift
3. Increase thrust?
I dont dont understand #3 fully, I get that it increases thrust like a sail going into the wind but I dont know how.
HELP
1. Reduce Drag
2. Increase lift
3. Increase thrust?
I dont dont understand #3 fully, I get that it increases thrust like a sail going into the wind but I dont know how.
HELP
Joined: Jul 2005
Posts: 1,031
Likes: 0
From: エリア88
The reason you get "thrust" is because of the way the vortex coming off the bottom of the wing affects the winglet. It causes a small element of lift in the direction of flight thus, it adds to the thrust vector.
Probably not the best explanation, I hope someone can elaborate.
Probably not the best explanation, I hope someone can elaborate.
Joined: Jun 2005
Posts: 31
Likes: 0
From: Pacific Ocean
Here is how I understand winglets. Winglet thrust, in itself, is quite small. In fact, the "forward" thrust contemporary winglets generate by means of vortex interaction barely offset the induced and parasite drag they create themselves. So no increse in "overall" thrust like an engine will provide, so much as a net reduction of self induced drag (pretty clever though).
However, taking thrust aside, the lift and drag they do create as a supplement to the wing is clearly positive and beneficial
However, taking thrust aside, the lift and drag they do create as a supplement to the wing is clearly positive and beneficial
Joined: Sep 2002
Posts: 2,188
Likes: 6
From: La Belle Province
Aerodynamically, wings generate "lift" normal to the local flow and "drag" parallel to the local flow. (In fact, of course, "lift" and "drag" are just convenient ways to break down the total forces....)
Now, because of the tip vortex the flow which is hitting the winglet isn't parallel to the general airflow - it has a significant spanwise component, as the vortex "rolls inwards over the top of the wing".
That means that the local flow is such that when the winglet acts on it you get a "lift" compoenent from the winglet which is partially inwards, partially upwards and partially forwards.
Something like this:
DC-M is correct to say its minor, and its very much dependent on the conditions (which is why winglet optimisation is an art, and why winglets are much better on aircraft with a powerful single design point, rather than a range of design points)
Now, because of the tip vortex the flow which is hitting the winglet isn't parallel to the general airflow - it has a significant spanwise component, as the vortex "rolls inwards over the top of the wing".
That means that the local flow is such that when the winglet acts on it you get a "lift" compoenent from the winglet which is partially inwards, partially upwards and partially forwards.
Something like this:
DC-M is correct to say its minor, and its very much dependent on the conditions (which is why winglet optimisation is an art, and why winglets are much better on aircraft with a powerful single design point, rather than a range of design points)
