Winglets
Winglets
Joined: Apr 2002
Posts: 11
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From: UK
mainwheel,
I'm thinking it must be primarily to reduce drag.
It is possible to dispatch a 747-400 with 1 winglet removed if the fuel uplift is increased. I cant remember the amount of fuel but if this is the case then no winglet must mean more drag so more fuel burn.
I'm thinking it must be primarily to reduce drag.
It is possible to dispatch a 747-400 with 1 winglet removed if the fuel uplift is increased. I cant remember the amount of fuel but if this is the case then no winglet must mean more drag so more fuel burn.
Moderator
Joined: Feb 2000
Aviation Qualifications: CPL
Posts: 14,480
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From: UK
They are there to reduce vortex generating swirl over the tips from the high pressure underside to the low pressure underside. This effectively increases the aspect ratio of the wing, and so should reduce induced drag.
Designed right, the increase in profile drag should be rather less than the reduction in induced drag.
G
Designed right, the increase in profile drag should be rather less than the reduction in induced drag.
G
Fleet Manager
Joined: Apr 2001
Aviation Qualifications: ATPL
Posts: 7,447
Likes: 310
From: various places .....
..another important concern with the big birds is the existing airport apron infrastructure.... I have no doubt that Mr Boeing would have far preferred to go for an increased wingspan .. but the bird then wouldn't fit into the gates without a major (read super expensive worldwide) rework ... so the only effective way to get a reduction in induced drag is to go for something more brutal ....
I suspect that, for many of the smaller aircraft, marketing has had a say in the way drag reduction is approached .....
I suspect that, for many of the smaller aircraft, marketing has had a say in the way drag reduction is approached .....
Joined: Feb 2001
Posts: 80
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From: Sandpit
Ghenghis is right. They reduce the flow of air outward over the wing tip which causes drag.
Didn't Mc Donnel Douglas have to fit them on the MD11 to get the fuel burn and range quotes on the aircraft they sold to Swissair.
Didn't Mc Donnel Douglas have to fit them on the MD11 to get the fuel burn and range quotes on the aircraft they sold to Swissair.
Joined: Jan 2000
Posts: 453
Likes: 0
From: ???
For Winglet Off ops, I think the fuel load is increased on the wing with the missing winglet to make up for the weight difference. will check MEL next time at work. Air Canada operated a B744 for a few days minus a winglet.
Joined: May 2002
Posts: 173
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From: somewhere near an airport
boeing put them for airlines to put their logos on...just to remind their pax who they are flying on(also so they know who to blame for delays due to atc/weather/security etc etc
but i will check the mel and let you know unless denzel gets there first
but i will check the mel and let you know unless denzel gets there first
Joined: May 2002
Posts: 173
Likes: 0
From: somewhere near an airport
ok th e mel says (for major us airline)but is prob a boeing std
1 may be missing
reduced performance limited weights by
20,800 lbs from the t/o runway,climb limit,and approach limit weight and
10,000 lbs from the etp/terrian clearance weight
also surprising is there is no time limit
but i expect with those restrictions any long flt will not happen
hope this helps
1 may be missing
reduced performance limited weights by
20,800 lbs from the t/o runway,climb limit,and approach limit weight and
10,000 lbs from the etp/terrian clearance weight
also surprising is there is no time limit
but i expect with those restrictions any long flt will not happen
hope this helps
Joined: Apr 2002
Posts: 11
Likes: 0
From: UK
screwdriver,
BA's CDL states that aswell as some performance limitations the planned trip fuel should be increased by 2.5%. I didn't notice anything about where the fuel should be put on the aircraft as Denzil mentioned.
BA's CDL states that aswell as some performance limitations the planned trip fuel should be increased by 2.5%. I didn't notice anything about where the fuel should be put on the aircraft as Denzil mentioned.
Joined: Jul 2000
Posts: 733
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From: The Daylight Saving Free Zone
I guess the size of the vortex is proportional to induced drag.
More info here.
BTW I saw a VirginBlue -800 a couple of weeks ago.
More info here.
BTW I saw a VirginBlue -800 a couple of weeks ago.
Joined: Sep 2001
Posts: 1,030
Likes: 262
From: Blighty
Winglets are there primarily for induced drag reduction.
However,
By increasing the efficiency of the wing outer section they also increase lift by making the wing "virtually" longer and also therefore increasing the aspect ratio.
Also, I read an article when I was an apprentice about wing "sails", these were described as long thin winglets which reduced drag on smaller slower a/c and were more efficent than winglets over short distances. Somewhat like the B737-800 BBJ.
However,
By increasing the efficiency of the wing outer section they also increase lift by making the wing "virtually" longer and also therefore increasing the aspect ratio.
Also, I read an article when I was an apprentice about wing "sails", these were described as long thin winglets which reduced drag on smaller slower a/c and were more efficent than winglets over short distances. Somewhat like the B737-800 BBJ.
