Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
Boeing Nut
Topic Author
Posts: 5078
Joined: Fri Feb 23, 2001 2:42 am

Wingtip Vortices Question, Winglets (with Pic)

Wed Mar 01, 2006 2:54 am

Take a look at this photo...


View Large View Medium
Click here for bigger photo!

Photo © Steve Morris



First of all, my compliments to the photographer for such a remarkable shot.

It got me to wondering though. We know how winglets work in dealing with wingtip vortices. In the pic, you see a very compact vortex coming off the flaps. My question is, what would the benefits be of installing a louver type of system connecting the flap to the wing which would eliminate the gap but not affect the lift from the flaps? The best description of the mechanism I am envisioning is like a Japanese Fan. One edge connected to the flap and the other to the wing. I realize that it would be a complex set up as the flaps not only move down, but out as well. At any rate, I am wondering if such a thing would work.

Regards.
I'm not a real aeronautical engineer, I just play one on Airliners.net.
 
miles_mechanic
Posts: 132
Joined: Sat Sep 08, 2001 4:30 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Wed Mar 01, 2006 3:21 am

Hi Boeing Nut
If I understand the way you envision your device, if you could attach it in such a way to allow it to blend back up into the outer part of the wing it would effectively increase the surface area of the wing and be more efficient. Of course that vortex you see off the flap, is basically the same as the one coming off the end of the wing, as it is the high pressure air under the flap flowing around the end and up over the top.
If you could come up with a material that would be able to withstand the pressure on it, as well as the repeated cycles that it would have to endure in its lifetime. I am sure you could sell it to the airplane companies. My guess is any such device if someone has thought of it already was either going to be expensive to encorporate into the airplane, or not able to withstand the repeated use in operation.
It definitely sounds like a interesting idea, I hope you can find a way to make it work.

Regards
Miles
 
Mir
Posts: 19491
Joined: Mon Jan 05, 2004 3:55 am

RE: Wingtip Vortices Question, Winglets (with Pic)

Wed Mar 01, 2006 3:22 am

Tech/Ops is probably the right place to ask this, but I'll give my answer anyway:

Vortices are always going to happen because of the differences in pressure on different sides of the wing. One could possibly lessen the intensity with a louver system, but would the cost and added complexity be worth it? I think not.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
rendezvous
Posts: 542
Joined: Sun May 20, 2001 9:14 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Wed Mar 01, 2006 4:52 am

Seeing as flaps are only deployed on take off and landing, which is relatively a very short time compared to the flight, I don't really see many commercial benefits.

Nice idea though!
 
meister808
Posts: 924
Joined: Sat Jan 01, 2000 11:45 am

RE: Wingtip Vortices Question, Winglets (with Pic)

Thu Mar 02, 2006 12:04 am

What gap are you speaking of? The vortex coming off of the flaps has nothing to do with the gap between the wing and the flap, it is there because of the difference in lift between the wing with flaps and the wing outboard of the flaps.

I might not understand what exactly you are getting at, though...

-Meister
Twin Cessna 812 Victor, Minneapolis Center, we observe your operation in the immediate vicinity of extreme precipitation
 
User avatar
Starlionblue
Posts: 20700
Joined: Fri Feb 27, 2004 9:54 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Thu Mar 02, 2006 12:08 am

Quoting Meister808 (Reply 4):
What gap are you speaking of? The vortex coming off of the flaps has nothing to do with the gap between the wing and the flap, it is there because of the difference in lift between the wing with flaps and the wing outboard of the flaps.

I might not understand what exactly you are getting at, though...

Yes but if you placed a membrane that went from the flap corner to a point a bit further out on the wing, you could (theoretically) harness the flap vortex like a winglet does the wingtip vortex.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Boeing Nut
Topic Author
Posts: 5078
Joined: Fri Feb 23, 2001 2:42 am

RE: Wingtip Vortices Question, Winglets (with Pic)

Sat Mar 04, 2006 12:23 am

Quoting Starlionblue (Reply 5):
Yes but if you placed a membrane that went from the flap corner to a point a bit further out on the wing, you could (theoretically) harness the flap vortex like a winglet does the wingtip vortex.

That's exactly the theory I am am getting at. It seems to me that if this energy could be harnessed some how, maybe there could be some aerodynamic beneifts. (Slower approach speeds, etc)
I'm not a real aeronautical engineer, I just play one on Airliners.net.
 
474218
Posts: 4510
Joined: Mon Oct 10, 2005 12:27 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Sat Mar 04, 2006 1:17 am

Quoting Boeing nut (Reply 6):
Quoting Starlionblue (Reply 5):
Yes but if you placed a membrane that went from the flap corner to a point a bit further out on the wing, you could (theoretically) harness the flap vortex like a winglet does the wingtip vortex.

That's exactly the theory I am am getting at. It seems to me that if this energy could be harnessed some how, maybe there could be some aerodynamic beneifts. (Slower approach speeds, etc)

Have you given any thought to the effect on the wing structure. The reason the flaps do not extend all the way to the wing tip is because of the bending stresses that would be exerted on the outer wing. You would have to increase the wing strength to accommodate the extra bending which would increase weight and may negate the extra lift your aerodynamic benefits.
 
Boeing Nut
Topic Author
Posts: 5078
Joined: Fri Feb 23, 2001 2:42 am

RE: Wingtip Vortices Question, Winglets (with Pic)

Sat Mar 04, 2006 1:31 am

Quoting 474218 (Reply 7):

I believe it to be feasible because I know at one point, McDonnel Douglas was considering "flaperons" for the MD-11 upgrade some years back.

Just keep in mind my signature, I am just curious about this.
I'm not a real aeronautical engineer, I just play one on Airliners.net.
 
User avatar
Starlionblue
Posts: 20700
Joined: Fri Feb 27, 2004 9:54 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Sat Mar 04, 2006 1:56 am

Quoting 474218 (Reply 7):
You would have to increase the wing strength to accommodate the extra bending which would increase weight and may negate the extra lift your aerodynamic benefits.

Granted. But maybe this would enable airframers to make the flaps smaller and lighter.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
meister808
Posts: 924
Joined: Sat Jan 01, 2000 11:45 am

RE: Wingtip Vortices Question, Winglets (with Pic)

Sat Mar 04, 2006 3:10 pm

I see what you are talking about now, and all the references to Japanese Fans make sense. I agree that something like that might work, but like 474218 said, if you want any of the benefit of the extra part realized, there is probably going to have to be strengthening of the wing involved. It is probably worth a look though.

Quoting Boeing nut (Reply 8):
McDonnel Douglas was considering "flaperons" for the MD-11 upgrade some years back.

I do think that this has to be a fairly compelling idea... putting something on the outboard trailing edge of the flap would keep the flow off of that end a little more in check, and would serve to improve efficiency on the flap without too much increase in parasite drag.

The complexity required to make such a system work is most likely what killed any previous incarnations of it, though.

-Meister
Twin Cessna 812 Victor, Minneapolis Center, we observe your operation in the immediate vicinity of extreme precipitation
 
amtrosie
Posts: 273
Joined: Thu Jan 06, 2005 6:44 am

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 12:06 am

Excellent post and very interesting responces. This is why I read this board ONLY! Keep it up!!
 
Grbld
Posts: 349
Joined: Tue Dec 06, 2005 9:25 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 12:22 am

Quoting Boeing nut (Reply 8):
I believe it to be feasible because I know at one point, McDonnel Douglas was considering "flaperons" for the MD-11 upgrade some years back.

The 777 has flaperons, namely the inboard ailerons also function as flaps but still move as ailerons as well.

The idea here has to be: Is it really beneficial?

What's the purpose of reducing this little vortex? Is it to increase efficiency (by decreasing drag) or to decrease wake turbulence?

If it's to decrease drag, well, at higher flap settings, the flaps are designed to create more drag. The 757 you see in the picture is very slippery. If you fly a normal ILS in one, you'll have a touch time bringing your speed down to final approach speed during the final glideslope descent, if you didn't have the extra drag. Furthermore, you need "engine spool-up" which is a higher thrust setting, during the final part of the approach. This is required in case of a go-around. Big jet engines take a long time to spool-up to high thrust, and if your thrust was at or just above idle, the engines would take TOO long. It's a legal requirement. So the drag is needed.

If it's to reduce wake turbulence, well, the wing vortices are much more significant than the flap vortices. With current separation minima, there are no problems at all regarding flap vortices. Minimum separation on final is usually 3 nm, cutting that any shorter would increase risk of go-around if the preceding aircraft wasn't able to clear the runway. So the 3 nm seperation is just fine.



Grbld
 
2enginesonly
Posts: 91
Joined: Mon Jun 13, 2005 11:08 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 8:00 am

Quoting Grbld (Reply 12):
The 777 has flaperons, namely the inboard ailerons also function as flaps but still move as ailerons as well.

On the B767 these inboard ailerons have this 'droop' function as well, however they are not called flaperons....just inboard ailerons.
McDonnell Douglas stopped the flaperon upgrade project but they did provide an upgrade for ailerondroop during flap selections on ALL ailerons....also the outboard ailerons.
They called it an 'aileron deflect' system and is only active between 6.5 and 31.5 degrees flaps....more then that and the ailerons move to their regular position.

Just some extra info  Smile

Arjan
 
User avatar
Starlionblue
Posts: 20700
Joined: Fri Feb 27, 2004 9:54 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 8:26 am

Quoting 2enginesonly (Reply 13):
Quoting Grbld (Reply 12):
The 777 has flaperons, namely the inboard ailerons also function as flaps but still move as ailerons as well.

On the B767 these inboard ailerons have this 'droop' function as well, however they are not called flaperons....just inboard ailerons.

They may call them that, but technically they are in fact flaperons  Wink


Gratuitous list of other hybrid surfaces:
- Ruddervator - found on V-tails.
- Elevon - found on fighters like the F/A-18 and the Su-27.
- Flapevon - Do these exist in reality? A delta wing trailing edge flap/elevator/aileron hybrid.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
2enginesonly
Posts: 91
Joined: Mon Jun 13, 2005 11:08 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 9:00 am

Quoting Starlionblue (Reply 14):
They may call them that, but technically they are in fact flaperons

Alright, you win  Smile

Quoting Starlionblue (Reply 14):
Gratuitous list of other hybrid surfaces:
- Ruddervator - found on V-tails.
- Elevon - found on fighters like the F/A-18 and the Su-27.
- Flapevon - Do these exist in reality? A delta wing trailing edge flap/elevator/aileron hybrid.

How about 'ailevator'?

Arjan
 
User avatar
Starlionblue
Posts: 20700
Joined: Fri Feb 27, 2004 9:54 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 9:17 am

Quoting 2enginesonly (Reply 15):

How about 'ailevator'?

That would be an "elevon". Much easier to speak and spell.  Wink
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
vikkyvik
Posts: 12621
Joined: Thu Jul 31, 2003 1:58 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 1:04 pm

Quoting Meister808 (Reply 10):


how many farting hamsters wearing pressure suits would it take to make sense of this thread

Sorry to post completely off-topic, bu Meister808, your signature cracked me up for a good 5 minutes.

Isn't there a such thing as a spoileron? Is that what you call a spoiler that assists the ailerons? It sounds familiar, but I might be making it up.

~Vik
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
Grbld
Posts: 349
Joined: Tue Dec 06, 2005 9:25 pm

RE: Wingtip Vortices Question, Winglets (with Pic)

Mon Mar 06, 2006 6:22 pm

Quoting Vikkyvik (Reply 17):
Isn't there a such thing as a spoileron?

Correct! Pretty much all airliners have them. They aid in rolling and counteracting adverse yaw (which is caused by the aileron on the outside of the turn creating more drag and causing the plane to yaw to the wrong side).

Who is online

Users browsing this forum: GloomyDe and 10 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos