warren747sp
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Why No Winglets For Class B747?

Thu Oct 02, 2008 5:05 pm

I was in JNB recently and looking at all the 743 and 742 parked all over. I would imagine if winglets were installed planes like the 743 it could possibly be made competitive again on certain routes. any comments?
747SP
 
flyf15
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RE: Why No Winglets For Class B747?

Thu Oct 02, 2008 5:09 pm

I actually recall seeing a picture a while back of an ex-FedEx 747 with aviation partners winglets fitted. They were huge.

But, my guess is there simply isn't the demand. There aren't really that many 747 classics out there anymore, they're not a main component of the world fleet like 737s, 757s, and 767s.
 
A342
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RE: Why No Winglets For Class B747?

Thu Oct 02, 2008 6:34 pm

Aviation Partners developed a winglet solution for the 747 Classic and flight-tested them. The programme was shelved in 2000 or 2001.

I fear winglets alone aren't enough to make them compeitive again. Their time is slowly running out.
Exceptions confirm the rule.
 
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CrimsonNL
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RE: Why No Winglets For Class B747?

Thu Oct 02, 2008 7:58 pm

In front of the Seattle Museum of Flight, is a huge blended winglet for the 747Classic on display, I would have loved to see those in action!
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Flighty
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RE: Why No Winglets For Class B747?

Thu Oct 02, 2008 9:59 pm

The thirsty engines -- and 3 man cockpit -- and large maintenance costs mean that the 747 classic is completely uncompetitive, with or without winglets.
 
tdscanuck
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RE: Why No Winglets For Class B747?

Fri Oct 03, 2008 12:25 am



Quoting Warren747sp (Thread starter):
I was in JNB recently and looking at all the 743 and 742 parked all over. I would imagine if winglets were installed planes like the 743 it could possibly be made competitive again on certain routes. any comments?

In addition to all of the above, the 747 isn't a very good application for blended winglets. It's not span restricted and it's already got a very long wing. For the same reasons that you don't put winglets on a 777 or 787, you wouldn't want to on a 747. Raked wingtips maybe, if the wing has enough residual structural margin.

Tom.
 
A342
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RE: Why No Winglets For Class B747?

Fri Oct 03, 2008 7:36 pm



Quoting Tdscanuck (Reply 5):
In addition to all of the above, the 747 isn't a very good application for blended winglets.

IIRC, they achieved a fuel burn reduction of at least 5% on the 747.

Quoting Tdscanuck (Reply 5):
For the same reasons that you don't put winglets on a 777 or 787

Installing a blended winglet must be worthwhile on 787-3, otherwise they wouldn't do it. And isn't Aviation Partners studying a retrofit programme for the 777"Classic"?
Exceptions confirm the rule.
 
tdscanuck
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RE: Why No Winglets For Class B747?

Fri Oct 03, 2008 10:36 pm



Quoting A342 (Reply 6):

Quoting Tdscanuck (Reply 5):
For the same reasons that you don't put winglets on a 777 or 787

Installing a blended winglet must be worthwhile on 787-3, otherwise they wouldn't do it. And isn't Aviation Partners studying a retrofit programme for the 777"Classic"?

787-3 is span restricted, which is why they'd go for winglets over raked tips. For the early 777's they may not have enough margin to support a raked wingtip...that causes more additional load on the wing than a blended winglet.

Tom.
 
A342
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RE: Why No Winglets For Class B747?

Fri Oct 03, 2008 10:47 pm



Quoting Tdscanuck (Reply 7):

I agree. But my point was that having blended winglets on a 747 is better than no wingtip device at all.

BTW, what do you mean by "a very long wing"? The length of the wing measured along the main spar, as opposed to half the wingspan?
Exceptions confirm the rule.
 
tdscanuck
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RE: Why No Winglets For Class B747?

Sat Oct 04, 2008 3:42 am



Quoting A342 (Reply 8):
But my point was that having blended winglets on a 747 is better than no wingtip device at all.

Fair enough. It's not necessarily true that a winglet is always better than none (some wings can't support the shifted load without taking a hit on MTOW) but, in the 747 case, if it really gives 5% improvement then it's clearly aerodynamically advantageous.

Quoting A342 (Reply 8):

BTW, what do you mean by "a very long wing"? The length of the wing measured along the main spar, as opposed to half the wingspan?

The efficacy of a winglet, assuming that's it's designed properly, isn't proportional to the size of the winglet, it's proportional to the ratio of the winglet size to the wing size. So sticking a 737 winglet on a 747 gives you a lot less proportional advantage. The longer your wing is, the larger your winglet needs to be to realize the equivalent benefit. Since the 747 already has a very large wing, it needs a very large (i.e. heavy and expensive) winglet.

Tom.
 
A342
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RE: Why No Winglets For Class B747?

Sat Oct 04, 2008 5:11 pm



Quoting Tdscanuck (Reply 9):

Thanks for the answer.

I'll shamelessly steal Aeroweanie's picture, as I can't find it elsewhere.  biggrin 



Here are two articles:


http://www.flightglobal.com/articles...-737-classic-and-747-winglets.html

http://www.flightglobal.com/articles...ssic-winglet-flight-tests-set.html
Exceptions confirm the rule.

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