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Old 10-13-2009, 01:05 PM   #61
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Trawlers 101 - Part 1

Quote:
nomadwilly wrote:

There is the unquestionable inference that "just bolted on" inferes* that no other action is necessary to incorporate them. Any fool can see that increased loads on the wingtip will result, hence the wing must be especially designed for the fences and "just bolted on" dos'nt cut it.
Sorry Eric, you lose. The 737's wing from the outset was strong enough to accept the added loads of the winglets, so they truly are "just bolted on."**This was actually a*design requirement for the winglets--- they could not require any structural modification*of the wing but had to be able to be installed on the existing 737 wing.*

The Airbus A320 wing, on the other hand, was built much lighter from the outset and when they tried to install large blended winglets similar to the ones developed by APB for the 737, the wing couldn't take it.* Airbus talked about beefing up their wing structure to accept the larger winglets as they reduce drag a lot more than the little end plates Airbus puts on the A320 but I have not heard if they have pursued this idea.

*


-- Edited by Marin on Tuesday 13th of October 2009 01:09:30 PM
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Old 10-13-2009, 11:20 PM   #62
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RE: Trawlers 101 - Part 1

OK Marin I'll eat crow but I'm surprised Boeing would build a wing heavier and stronger than it needs to be (safety factor assumably included). Why do that? I was under the impression that winglets increased L/D mostly at slow speeds and high angles of attack. Are they worth the parasite drag at high cruising speeds or do they just make the AC able to operate off shorter runways?

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Old 10-14-2009, 01:38 AM   #63
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RE: Trawlers 101 - Part 1

The benefits of winglets are best realized at cruise speeds over longer flight times. That's why airlines like Southwest and Alaska resisted them for so long (they ain't cheap). Their flights tended to be shorter, regional flights and they felt the fuel savings from the winglet on such short flights would not justify their cost. However when Alaska started offering coast-to-coast service with their 737s they began installing winglets on the 737s that flew those routes because that's where they really realized the savings (up to six percent drag reduction at cruise). As fuel prices went up, 737 operators began to realize that even the lower fuel savings on shorter flights was becoming worthwhile. So now almost every 737 we make and almost every existing 737 than can accept them has winglets. APB has since adapted the same basic winglet for the 757--- American and Delta have retrofitted a number of their 757s with them. And APB now has a blended winglet that can be applied to 767s.

However you are correct in that the winglets do improve takeoff and climb performance, but that's not why they were developed for the 737. And you are also correct in that winglets can make the difference between being able to operate into some airports and not being able to. When GOL in Brazil wants to operate a 737-800 in and out of Rio de Janiero's smaller and more convenient airport, the plane must be equipped with winglets.

I can't answer your wing design question, other than to say that Boeing has traditionally built very strong wings. The original 737 wing was designed in the 1960s and was probably overbuilt but the current 737 models have an all-new wing design. But it's still obviously very strong.

The 737 winglet was developed for the BBJ (Boeing Business Jet). Many aerodynamicists at Boeing at the time did not believe in winglets and there was quite a fight over them until the president of the BBJ program told the nay-sayers to screw off and had them designed, installed, and tested anyway. The efficiency increase the BBJ was experiencing was undeniable and some airlines began pressuring Boeing to put them on the commercial 737s. Boeing has since changed its tune on winglets, and we have also designed a wing feature for our larger planes that accomplishes the same thing in a somewhat different way that we now use on some models of the 777, the 747-8, and the 787. This is the raked wingtip.

More than you wanted to know, I'm sure, but there you have it.
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Old 10-14-2009, 06:35 AM   #64
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RE: Trawlers 101 - Part 1

How did we get to talking about airplanes?
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Old 10-14-2009, 09:13 AM   #65
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RE: Trawlers 101 - Part 1

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How did we get to talking about airplanes?
*For several folks here, they "float our boats"* so to speak.
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Old 10-14-2009, 10:34 AM   #66
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Trawlers 101 - Part 1

ZZZZZzzzzzzzzzzzzzzzzz (What? Are we on yet?)

-- Edited by SeaHorse II on Wednesday 14th of October 2009 10:34:57 AM
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Old 10-14-2009, 12:44 PM   #67
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RE: Trawlers 101 - Part 1

I'm sure the statements are only pilot talk, but in the G3,4and 5s I've flown in the winglets discussion comes down to less turbulent air flow/wind vortexes and resultant improving fuel economy. A SW pilot says the same -*BS or not???
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Old 10-14-2009, 12:52 PM   #68
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RE: Trawlers 101 - Part 1

I'm surprised this discussion hasn't migrated over to winged keels.* What, no ex-sailors here?
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Old 10-14-2009, 02:11 PM   #69
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RE: Trawlers 101 - Part 1

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I'm sure the statements are only pilot talk, but in the G3,4and 5s I've flown in the winglets discussion comes down to less turbulent air flow/wind vortexes and resultant improving fuel economy. A SW pilot says the same -*BS or not???
Basically, you've got it right.* Air flows out spanwise around a wing, not just straight back.* This spanwise flow spills off the end of the wing and generates the wingtip vortices you hear about--- rotating turbulent air.* This creates drag which has to be overcome by burning more fuel.* The winglet*reduces the power of the wingtip vortices.* If you reduce the power of the*wingtip vortex, you reduce the drag, which means you burn less fuel.

Nobody in the aerospace world thought this up.* Watch any hawk, eagle, raven, or vulture in flight and you will see the world's most sophisticated winglets (particularly on*the vulture).* They are the big*primary (?) feathers that project from the ends of their wings that the bird can position at an almost infinite number of angles to vary the drag*as*necessary. When they are*soaring, you will see that these feathers are angled up quite sharply which yields the highest drag reduction.* While the bird is not concerned about fuel burn, it is concerned about drag and*gravity.* The more the bird can reduce the drag, the slower its rate of descent will be, which means the less it will have to flap its wings to maintain altitude, which means the longer its last meal will last.* So I guess it is concerned about fuel burn
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Old 10-14-2009, 03:16 PM   #70
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RE: Trawlers 101 - Part 1

Marin:
In your comparison of bird wings vs. aircraft wings, perhaps a better comparison would be that of a "crow" to a "ravin". The wing tip feathers you refer to are called "pinion feathers." The raven has 4 while the ordinary crow has but three. Obviously, the more pinions, the more efficient the wing. So the next time the subject of "winglets" comes up, let's be specific as to what kind of winglets we are talking about. After all, it's just a matter of "opinion." <grin>
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Old 10-14-2009, 07:05 PM   #71
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Trawlers 101 - Part 1

Walt--- Thanks for the correction on the name of the wingtip feathers. The number of feathers could make a difference as you say, and so would the bird's ability to angle them up. It's the angle that so affects the vortex generation. From watching both ravens and crows, it's apparent that the raven can angle its pinion feathers up at a much steeper angle. Which makes sense since a raven spends a good part of its time soaring.

One of the neat things about cruising up into BC waters (to move this back somewhat to boating) is that you are in raven territory. Fascinating birds from the little I've been able to learn about them. I've read that they are the smartest of all the wild birds. But it's really neat to be in an almost silent anchorage and hear them over in the trees running through their amazing variety of calls. The most characteristic sound is called a "bell."* It's the "sound of the Inside Passage" to many boaters. I'm sure Eric has heard it thousands of times on his cruises in SE Alaska.

While I realize you hate off-topic discussions, there is one thing I'd like to show you with regards to ravens. Probably my all-time favorite sculpture is this one, called "Raven and the First Men." It's in the Museum of Anthropology at the University of British Columbia in Vancouver. The sculpture is by Bill Reid, and I'd never heard of it until Carey Worthen of this forum told us about it and took us there to see it. The scale of the thing is impressive. It was carved from a single, laminated block of yellow cedar and is about seven or eight*feet tall. It depicts a coast Indian legend explaining where Man came from--- Raven was walking on the beach and heard noises coming from a large*clam shell. He pried open the shell and Man climbed out.


-- Edited by Marin on Thursday 15th of October 2009 12:08:31 AM
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Old 10-15-2009, 05:03 AM   #72
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RE: Trawlers 101 - Part 1

Nobody thought this up?

Guess the fact that tip tanks "paid for themselves" was only known to P2V7 drivers ,

and not the rest of the aircraft community?

Reducing tip losses and lowering induced drag was done on some of the Italian sea planes in the 30's.
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Old 10-15-2009, 05:16 AM   #73
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RE: Trawlers 101 - Part 1

Ya'll might want to take this airplane discussion to another forum with a title different than Trawlers 101.
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Old 10-15-2009, 05:34 AM   #74
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RE: Trawlers 101 - Part 1

Hiya,
** I agree Keith.***A brief reference to aircraft designs/similarites is OK but maybe such discussions should take place in "Other makes" section.
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Old 10-15-2009, 05:43 AM   #75
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RE: Trawlers 101 - Part 1

Quote:
Marin wrote:While I realize you hate off-topic discussions, there is one thing I'd like to show you with regards to ravens.
Did somebody mention Ravens?

Since we've strayed so far afield anyway .....
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Old 10-15-2009, 06:26 AM   #76
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RE: Trawlers 101 - Part 1

What was the original topic? I seem to remember Mike having a point somewhere.
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Old 10-15-2009, 08:51 AM   #77
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RE: Trawlers 101 - Part 1

Visit our website to view our selection of Used Trawlers and Motor Yachts.
We ship Used Yachts and Boats worldwide.

The string started with a commercial,
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Old 10-15-2009, 11:16 AM   #78
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RE: Trawlers 101 - Part 1

You guys don't know how good we have it here - go the The Hull Truth website and you'll find 100+ long pages of why Luhrs sucks or 80 pages of pit bull chest thumping nonsense.

8 pages on winglets is perfect, and it is pilot Baker's site!

Now for the more serious question. For a bow thruster cost -*how does $17K sound for a first*class shipwright doing the install? Not sure yet on tube size or whether my hydraulic PTO for stabilizers is big enough.
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Old 10-15-2009, 11:34 AM   #79
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RE: Trawlers 101 - Part 1

That sounds kind of high compared to the kinds of costs I've heard discussed in the past. On the other hand, if you're considering a large hydraulic thruster the parts and labor cost might be in line with reality. Most of the costs I've heard are for electric thrusters in 36-42 foot boats, and the cost is generally in the $10,000 or less range.
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Old 10-15-2009, 02:54 PM   #80
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RE: Trawlers 101 - Part 1

Not so much about the topics drifting, but think about the archive quality of the forum. Do you think anybody in the future will dig 9 pages into Trawlers 101 expecting to find a possibly valuable discussion of hydraulic bow thruster cost? Or even today do you think you might lose valuable input because folks have stopped reading that thread? By alll means, carry on the conversations, but I think it would be better to keep the subject matched to the header, somewhat.
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