Do winglets produce thrust?

In my country, our gliders move forward because the wing produces
thrust, and our sailboats move over the water because the sail produces
thrust. Whether we should rule the world is causing much controversy.


PLEASE....Readers of the World! This is not in our textbooks! Did
someone in the USA write the above???

Wings produce Lift!! A by product of lift is drag! Winglets do also
produce lift, and therefore drag. Possibly less than the wing? But
you canot call it thrust!.......

This sounds like I am in the middle of some ski instructors!

Skiing is great in Aspen!

Think Snow!

The Redtail Hawk

soarski wrote:
In my country, our gliders move forward because the wing produces
thrust, and our sailboats move over the water because the sail produces
thrust. Whether we should rule the world is causing much controversy.



PLEASE....Readers of the World! This is not in our textbooks! Did
someone in the USA write the above???

Wings produce Lift!! A by product of lift is drag! Winglets do also
produce lift, and therefore drag. Possibly less than the wing? But
you canot call it thrust!.......

"Thrust", for the winglet question and my remarks about gliders and
sailboats, was used to mean "force in the direction of motion".
Apparently, that was an unusual use of the word for some people.

Here's an expanded expanation:

Gravity is pulling straight down, and so can not propel the glider
forward; drag is pulling the glider back, and so can not propel the
glider forward. So, what is left to counteract the drag? Lift, produced
by the wings. This forward force comes from the lift, which is not
vertical, but tipped forward a bit. Look at any diagram showing the
forces on a glider, and you will see how the lift, drag, and gravity
forces accomplish this.

It is not common to call this force moving the glider forward (without
it, drag would bring it to stop) "thrust", but the word is sometimes
used that way.

I still can't answer the original question about the winglets, though.

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Eric Greenwell
Washington State
USA

On Sat, 29 Nov 2003 11:32:36 -0800, Eric Greenwell wrote:

Here's an expanded expanation:

Gravity is pulling straight down, and so can not propel the glider
forward; drag is pulling the glider back, and so can not propel the
glider forward. So, what is left to counteract the drag? Lift, produced
by the wings. This forward force comes from the lift, which is not
vertical, but tipped forward a bit. Look at any diagram showing the
forces on a glider, and you will see how the lift, drag, and gravity
forces accomplish this.

It is not common to call this force moving the glider forward (without
it, drag would bring it to stop) "thrust", but the word is sometimes
used that way.

Sheesh! So many words and so little knowledge... Here's how it works,
guys.

For any aircraft in balanced flight, there are four forces acting on it.
All forces except gravity act only along the chord or perpendicular to it.
Gravity not only produces a force in opposition to lift, but a resultant
vector force which can be either thrust or drag, depending on the angle of
the chord in respect to earth (gravity). in other words; Gravity is the
'engine' in a glider that produces thrust.

For those that don't understand vector force components (or flunked trig),
don't worry 'bout it. Simply believe they exist.

As for the winglets, they only reduce drag. At the point where the
airfoil ends, air rolls to the other side of the wing due to the pressure
difference. The rolling air produces a vortex that kinda acts like vacuum
cleaner hoses grabbing the trailing tips of the wings. The winglets
interfere with the creation of the vortex(s) thus reducing drag. Smaller
vortex (smaller vacuum cleaner) means better L/D (slicker ship).

LittleJohn
Madison, AL

"soarski" schreef in bericht
om...

In my country, our gliders move forward because the wing produces
thrust, and our sailboats move over the water because the sail produces
thrust. Whether we should rule the world is causing much controversy.


In my country (Holland) students will be disqualified from their examination
when they make an "interesting" remark like this. Reducing induced drag is
what winglets do and gravity is the engine of our gliders.

Karel Termaat

K.P. Termaat wrote:
"soarski" schreef in bericht
om...

In my country, our gliders move forward because the wing produces
thrust, and our sailboats move over the water because the sail produces
thrust. Whether we should rule the world is causing much controversy.


In my country (Holland) students will be disqualified from their examination
when they make an "interesting" remark like this. Reducing induced drag is
what winglets do and gravity is the engine of our gliders.

And what produces the "thrust" that moves your sailboats? Gravity?

This may be a simple confusion over the word "thrust", which I used (as
did the original question) in the sense of "force in the direction of
motion". Both the glider and the sailboat are propelled in a forward
direction by lift from the wing or sail.

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Replace "SPAM" with "charter" to email me directly

Eric Greenwell
Washington State
USA

Keith W wrote:

That's against the laws of thermodynamics.

No.

Provided the thrust of the winglets is not higher than the drag of the
other part of the glider, that's not (and of course the winglet thrust
is only a few % of the glider drag)


--
Denis
Private replies: remove "moncourrielest" from my e-mail address
Pour me répondre utiliser l'adresse courriel figurant après
moncourrielest" dans mon adresse courriel...

Bob Salvo wrote:

Anyone?
Bob

Yes

--
Denis
Private replies: remove "moncourrielest" from my e-mail address
Pour me répondre utiliser l'adresse courriel figurant après
moncourrielest" dans mon adresse courriel...

Not thrust in the same way as a propulsion system,
but winglets generally do produce a lift vector that
has a spanwise and a chordwise component. Since the
flowfield at the wingtip is angled inward, the winglet
has an incidence angle that is slightly outward-facing
-- while still producing a positive angle of attack
(look at your winglets from straight ahead to see that
this is true). This means that the 'lift' produced
by the winglet is directed mostly inwards towards the
fuselage, but also forwards.

I don't know what lift coefficients winglets fly at,
but I suspect the actual magnitude of the 'thrust'
is very small.

9B

At 19:54 28 November 2003, Bob Salvo wrote:
Anyone?
Bob

If winglets produce thrust, at what angle of attack does its thrust/drag ratio
maximise?


Bob

Now, I'm confused! An airfoil cannot produce thrust
-- only 'lift.' But if an airfoil has a reverse counterpart,
the two are joined at the center and rotated about
an axis in a vertical plane, they are then a propeller;
this produces 'thrust.' But if their pitch is differentially
variable and they rotate in a horizontal plane, they
are then helicopter blades; they produce 'lift.'
Why don't we just combine the two words in one concept
and call it 'thrift?'


At 20:36 29 November 2003, Bob Salvo wrote:
If winglets produce thrust, at what angle of attack
does its thrust/drag ratio
maximise?


Bob