Rohan737 From , joined Dec 1969, posts, RR: Posted (9 years 1 month 3 weeks 6 days 8 hours ago) and read 3644 times:
Heard a rumor today that Continental Airlines is going to install winglets on the 737 NG & 757-300's to improve their efficieny. I thought that winglets were not an option on 757's. Anyone else heard this rumor about CO and the winglet installation.
Spike From United Kingdom, joined Feb 2004, 1170 posts, RR: 6 Reply 10, posted (9 years 1 month 3 weeks 6 days 1 hour ago) and read 3181 times:
What gests me is why it took Airbus and particularly Boeing soooo long to work out that winglets make a plane fly further. Everyone used to incorporate them in paper aeroplanes at school! I think they are now the airliner equivalent of the old 'go faster stripes' of Essex fame.
KLM777 From Netherlands, joined Dec 2003, 372 posts, RR: 0 Reply 12, posted (9 years 1 month 3 weeks 6 days ago) and read 3005 times:
Winglets are not always more efficient. The advantage of them is that the induced drag is being reduced. Induced drag are the vortexes because of air flowing from underneath the wing (high pressure) around the wingtips to the upper side of the wing (low pressure). Winglets prevent most of this airflow.
Now the disadvantage is that they weigh a couple hundreds of kilos. And not only that, this weight is at the most uneconomical spot of the aircraft: the edge of the wings. This requires the structure as a whole, and particular the wing and wing attachment to the fuselage, to be reinforced to cope with the bending moment.
Whether to add winglets to the aircraft is a tradeoff between the advantages and the disadvantages. Some wings are efficient enough without winglets, adding winglets could still increase efficiency, but the weight of the winglets and extra structure would outweigh this increase in efficiency.
Take for example the wing of the 777. It is long and at the end it's relatively small (high aspect ratio [span*span/standard mean chord]), therefore reducing induced drag to a minimum. Winglets are not advantageous here. I'm not 100% sure about the 757, but I think I think it has a relatively high aspect ratio too. Apart from that, the aircraft is not build to carry winglets (would be possible though I guess).
Ckfred From United States of America, joined Apr 2001, 4650 posts, RR: 1 Reply 15, posted (9 years 1 month 3 weeks 5 days 19 hours ago) and read 2635 times:
Replacing the wingtip with a winglet on a 737NG is not horribly difficult, at least according to a Boeing publication that I read several years ago.
If the price of jet fuel remains high, I think almost every operator of the 737NG will look at the retrofit kits. Even Southwest is now taking delivery of 737NGs with winglets, and they to buy planes with fewer options that the legacy carriers.
I haven't heard of a Boeing-designed winglet to retrofit to the 757, but I know that Pan Am has installed winglets on its 727s. So, it wouldn't surprise me if someone did it within the next few years.
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 35 Reply 17, posted (9 years 1 month 3 weeks 5 days 16 hours ago) and read 2395 times:
I'm nitpicking a little, but preventing wingtip vortices from making it all the way around the tips of the wings isn't the only thing that winglets do. Rather than explaining it yet again, check out my reply (# 6) to this other thread here. I know, I always refer back to that post, but I can't be bothered to type it all again.
You're right that tradeoffs must be made when considering incorporating winglets into an aircraft design. The weight is the main negative, and so various things must be factored in to see if it's really worth adding them. Raked wingtips and increased AR (aspect ratio) also help reduce induced drag, and in some cases those methods are better to use, in some cases they're not.
Thrust From United States of America, joined Sep 2003, 2673 posts, RR: 11 Reply 18, posted (9 years 1 month 3 weeks 5 days 16 hours ago) and read 2363 times:
Why doesn't Delta put winglets on their 738s? Though they are low on cash...it would save money on fuel. And CO, given as many 737NGs as they have, would benefit greatly by adding winglets...hate to break to ya, but the 757 never had winglets, and never will for two reasons: 1, someone already said Boeing ended their studies of this in 1998, and 2, the 757 is no longer being produced after 2004, have all the remaining 757s to be built been built? Does anyone know?
Iahcsr From United States of America, joined Jun 1999, 3308 posts, RR: 46 Reply 19, posted (9 years 1 month 3 weeks 5 days 13 hours ago) and read 2229 times:
The main reason that kept CO from adding winglets to it's 738s right from the getgo was the manufacturer's pricing for their product. The cost/benefit numbers just weren't right at the time. Now however ....... Well, we will just have to wait and see.
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 35 Reply 20, posted (9 years 1 month 3 weeks 5 days 10 hours ago) and read 2099 times:
I just found the following from here, under "news." It simply confirms that Aviation Partners Boeing are certainly looking into 757/767 winglets. Enjoy...
Launch Customer Opportunity for Boeing 757-200 and 767-300ER Blended Winglet Fleet Upgrade
Who will be the first to fly Aviation Partners Boeing Performance Enhancing Systems?..."We're looking for a customer to partner with in the certification and launch of 757-200 and 767-300ER Blended Winglet Programs," says Aviation Partners Boeing CEO Mike Marino..."[Blended winglet] technology is particularly well suited to 757 and 767 series applications." Aviation Partners Boeing forecasts a potential Blended Winglet upgrade market for some 850 Pratt & Whitney and Rolls-Royce powered 757-200 and over 400 767-300ERs in both passenger and freight configuration.