Winglets and Wake Turbulence

[labbats]

After hearing about the AA 757s getting winglets, I started wondering if that will ease up on the wake turbulence they create. Anyone have a guess?

 

[minitour]

I'm gonna say no....but that's coming from a Cessna driver (172s)....

Why they going to winglets? Fuel efficiency?

-mini

 

[scoreboard]

I'm gonna say no....but that's coming from a Cessna driver (172s)....

Why they going to winglets? Fuel efficiency?

-mini

Well, I'd say the winglets increase aspect ratio and reduce drag as a result of vortices, so they reduce the vortices...

 

[Knob]

They may reduce the drag, look @ the difference between the 747-100 & the -400 though. Even with the winglets you better be a dot high on g/s when behind a -400!

 

[scoreboard]

They may reduce the drag, look @ the difference between the 747-100 & the -400 though. Even with the winglets you better be a dot high on g/s when behind a -400!

Well sure, but even though they redeuce vortices, still pay them head as I do. Winglets save 3-5% on fuel, so easy math says they reduce drag by that or less and hence the vortices are reduced by ONLY that 3-5%, so still be careful.

 

[PolarTwins55]

they will reduce the wake turbulence. wake turbulence is a function of weight and wingspan. If you increase the wingspan(add winglets), then the vortexes will be reduced.

 

[minitour]

Well, I'd say the winglets increase aspect ratio and reduce drag as a result of vortices, so they reduce the vortices...

yes, but the question "will it ease up on the wake turbulence?" I still say no.

Again, coming from a Cessna guy....my 172 isn't gonna just go "oh...winglets....smoooooooth flyin" I'm still gonna have to be (as was said) a dot higher on approach.

-mini

 

[AirBud]

There was an article about this 3 or 4 months ago. The wake on the 757 is reduced by something like 30% with the winglets.

Check out

http://oea.larc.nasa.gov/PAIS/Concept2Reality/winglets.html

 

[MarineGrunt]

yes, but the question "will it ease up on the wake turbulence?" I still say no.

Again, coming from a Cessna guy....my 172 isn't gonna just go "oh...winglets....smoooooooth flyin" I'm still gonna have to be (as was said) a dot higher on approach.

-mini

Vortices = Wake Turbulence. As mentioned, winglets are designed to dampen vortices to give the effect of an increased aspect ratio, which means less induced drag. Less vorticies = less wake turbulence because they are the same thing. Now is it enough to make a difference to your 172 if you fly through the wake of a 757? I seriously doubt it....

 

[MarineGrunt]

There was an article about this 3 or 4 months ago. The wake on the 757 is reduced by something like 30% with the winglets.

Check out

http://oea.larc.nasa.gov/PAIS/Concept2Reality/winglets.html

Aw! No fair! How come we don't have winglets on our 135's??? Those would look totally sweet with my Oakleys and overly-gelled spiked hair!

 

[minitour]

Now is it enough to make a difference to your 172 if you fly through the wake of a 757? I seriously doubt it....

That was my point....I was trying to make a very very tongue-in-cheek comment.

-mini

 

[MarineGrunt]

That was my point....I was trying to make a very very tongue-in-cheek comment.

-mini

Ah. I thought you were speaking in broader terms. I can be slow somethimes.............. (to the surprise of many!)

 

[minitour]

Ah. I thought you were speaking in broader terms. I can be slow somethimes.............. (to the surprise of many!)

slow is a relative term.....take that 135.....slow in that would be Vne + ??? in the 172....so see...its not so bad :beer:

 

[drinkduff77]

There was an article about this 3 or 4 months ago. The wake on the 757 is reduced by something like 30% with the winglets.

Check out

http://oea.larc.nasa.gov/PAIS/Concept2Reality/winglets.html

This is from the same article in the "Wake-Vortex Hazard" chapter:

Langley researchers were constantly challenged by the complexity of the wake flow field for representative transports. Many concepts that appeared to affect the wake properties in the immediate roll-up area behind the generating aircraft were found to have little impact on the magnitude of roll upset at downstream distances representative of the location of trailing aircraft. Furthermore, it was found that numerous interacting vortices were shed by the typical transport in the landing configuration. For example, in addition to the vortices expected at the wingtips, strong vortices were also shed at the edges of wing trailing-edge flaps, and aft fuselage. As a result of these types of interactive vortex effects, some wingtip vortex control concepts that were known to provide beneficial effects for cruise drag (such as winglets) had little or no effect on the wake vortex hazard when the aircraft was in the flaps-down, landing approach configuration.

I'm not sure where you got that 30 percent number from. Seems kind of high and conflicts with the paragraph above.