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787 Wing Tanks  
User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Posted (9 years 6 months 1 week 3 days 2 hours ago) and read 3771 times:

Reading the other thread about wing tanks, a question came to mind. Does anyone here know how the tanks on the 787 will be sealed to hold fuel?
Fuel and composites don't exactly get along. Carbon fiber probably does the best of the aviation composites but over time problems do occur.
Will they have bladders? A special sealer applied to the inside of integral tanks? I can't really see that working too well as every sealer I've used in tanks fails eventually due to the flexing of the wings. Unlike composites, this isn't a structural problem in aluminum wings as the fuel doesn't adversely affect the metal. Perhaps they have developed a fuel proof resins?

Anybody have any insight or guesses?

Dl757Md


757 Most beautiful airliner in the sky!
10 replies: All unread, jump to last
 
User currently offlineWidebodyphotog From United States of America, joined Jun 1999, 917 posts, RR: 67
Reply 1, posted (9 years 6 months 1 week 3 days 1 hour ago) and read 3692 times:

The wing spar structure of 787 will not be made of composites so it will hold fuel just like any other modern airliner.

-widebodyphotog



If you know what's really going on then you'll know what to do
User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Reply 2, posted (9 years 6 months 1 week 3 days 1 hour ago) and read 3689 times:

The wing spar structure of 787 will not be made of composites so it will hold fuel just like any other modern airliner.

Widebodyphotog
I'm not trying to flame your post. I don't however understand the premise behind it.

From the Boeing website http://www.boeing.com/commercial/7e7/background.html

"Boeing has announced that the majority of the primary structure including the fuselage and wing on the 787 will be made of composite materials."

While it's not specific about the spars it does say the majority of the primary structure. Even if the spars are aluminum the skins, ribs, and stringers are the only other primary structure in the wing. If they are composite they will also be in contact with the fuel. The structure of the wings that forms the integral tanks in modern airliner's wings IS the primary structure of the wings. There are composite components of current wings but they are limited to flight control surfaces and secondary structure(closeout panels and such). If Boeing states that most of the PRIMARY structure of the 787's wings will be composite how do you figure it won't be. Is the Boeing site misleading us?

Dl757Md

[Edited 2005-02-14 11:59:24]


757 Most beautiful airliner in the sky!
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 3, posted (9 years 6 months 1 week 2 days 20 hours ago) and read 3631 times:
AIRLINERS.NET CREW
DATABASE EDITOR

Great question, Dl757Md. I look forward to hearing the answer.


2H4



Intentionally Left Blank
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3500 posts, RR: 66
Reply 4, posted (9 years 6 months 1 week 2 days 19 hours ago) and read 3610 times:

The A330 and A340 have used a composite H. tail as a fuel tank through out their production life. The B2 is essentially all composite and has used the wing as a fuel tank as it has no other option.

If it works on these aircraft, why should the 787 be any different?



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineAUAE From United States of America, joined Apr 2004, 296 posts, RR: 3
Reply 5, posted (9 years 6 months 1 week 2 days 19 hours ago) and read 3606 times:

I am only guessing, but given the weight penalties of rubber bladders I am sure it is some sort of coating on the inside of tanks.

Shawn



Air transport is just a glorified bus operation. -Michael O'Leary, Ryanair's chief executive
User currently offlineA350 From Germany, joined Nov 2004, 1100 posts, RR: 22
Reply 6, posted (9 years 6 months 1 week 2 days 18 hours ago) and read 3591 times:

Just a guess, but from a chemistry and engineering point of view I would suggest a teflon coating. Teflon (CxF2x) is very light and chemically extremely inert.

A350



Photography - the art of observing, not the art of arranging
User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Reply 7, posted (9 years 6 months 1 week 2 days 18 hours ago) and read 3588 times:

If it works on these aircraft, why should the 787 be any different?

Good point OldAeroGuy but I never said it wouldn't work. I merely asked if anyone knows how they will make it work. I have every confidence Boeing has addressed the issue, just was wondering how.

I didn't realize the A330 and A340 horizontal stabs are composite and wet. I forgot about the B-2. So I'm sure this has been addressed and somebody out here has the answer as to what methods are used in these aircraft.

To answer your question, one reason the 787 would be different from the B-2 is that commercial aircraft are utilized far more greatly than military aircraft. I'm sure that operational readiness is very important with the B-2 but I highly doubt that it could come close to delivering a 98% dispatch rate if it were operated 8+hrs every day as airliners are expected to. Basically it has much more ground time with which to correct the technical difficulties I envision with a composite integral tank.

AUAE I like your signature.
Air transport is just a glorified bus operation. -Michael O'Leary, Ryanair's chief executive
A point of view I'm sure a lot of airline CEOs have these days. They just don't have the balls to say it publicly.

Dl757Md



757 Most beautiful airliner in the sky!
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3500 posts, RR: 66
Reply 8, posted (9 years 6 months 1 week 2 days 15 hours ago) and read 3548 times:

DI757md,

I do appreciate the utilization differences between military and commercial airplanes, but the B2 has been around for a long time so I threw that in as example of how problems would have been recognized and corrected.

By the way, I agree totally with your thoughts on the 757. One of the best examples of "Looks Good, Flies Good".



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Reply 9, posted (9 years 6 months 1 week 2 days 15 hours ago) and read 3530 times:

OldAeroGuy

I guess where I was coming from in my remarks about the B-2 is that due to the military's lower utilization of the airframe, they might be more willing to repetitively maintain a problem inherent with an aircraft rather than demand a permanent solution as the airlines would because their planes need to fly more.
Put another way the military might accept 10% of a fleet down at one time for mtc. whereas the same situation would kill an airliner. I know it's a tough generalization to justify but it's how I feel.

I'm glad we share the same fondness for the 57. Just wish someday when I'm doing a takeoff power run at the run-up area at the end of the runway I could release the brakes and see what it's like to fly one!  Big grin

Dl757Md



757 Most beautiful airliner in the sky!
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 10, posted (9 years 6 months 1 week 2 days 4 hours ago) and read 3450 times:

Presumingly there must be a Coating application on the Insides of the tank to act as a barrier of the Fuel.
These question sure make me more eager to await the Flight of the B7E7.
 Smile
regds
MEL



Think of the brighter side!
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