Warren747sp From United States of America, joined Feb 2004, 1132 posts, RR: 0 Posted (4 years 8 months 3 weeks 18 hours ago) and read 6397 times:
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?
Flyf15 From , joined Dec 1969, posts, RR: Reply 1, posted (4 years 8 months 3 weeks 18 hours ago) and read 6388 times:
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.
Flighty From United States of America, joined Apr 2007, 7507 posts, RR: 2 Reply 4, posted (4 years 8 months 3 weeks 13 hours ago) and read 6286 times:
The thirsty engines -- and 3 man cockpit -- and large maintenance costs mean that the 747 classic is completely uncompetitive, with or without winglets.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 5, posted (4 years 8 months 3 weeks 10 hours ago) and read 6254 times:
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.
A342 From Germany, joined Jul 2005, 4656 posts, RR: 4 Reply 6, posted (4 years 8 months 2 weeks 6 days 15 hours ago) and read 6138 times:
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"?
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 7, posted (4 years 8 months 2 weeks 6 days 12 hours ago) and read 6089 times:
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.
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 9, posted (4 years 8 months 2 weeks 6 days 7 hours ago) and read 6036 times:
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.
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