Wednesday, July 1, 2009

Wing and body

flightblogger gave a run down on the cause of the recent 787 delay and followed up with more information. That latter begs a question of how Boeing information can be out on the web with a flightglobal mark on it (this is only one example).

If flightglobal didn't protest so much about this, one would think that there was some conduit (yes, financial metaphor - remember? off the books) in place.

The plane that you sit in is essentially a tube being pulled along by the engines. So, believe it when they say that the wing-body join is crucial. If it breaks, ... This join has a very significant role. Too, it is a very difficult thing to design. Why?

It has serious aerodynamic requirements at higher speeds, and it has to be strong enough to handle the loads (meaning more than carrying around a bunch of sitting passengers and their luggage, okay?). The design for the first set of requirements (the external look) can be analyzed prior to flight (somewhat) but is something that flight testing (and lifetime performance) validates. The second set of requirements deals with the internal structures and seems to be where the current problem is found.

The design issues of the wing-body join have caused many to tear their hairs out. Higher speeds, minimizing efforts at material and weight, the computational sirens of modern technology, and other things make the design issues very difficult to solve. We will get into part of this further.

The associated knowledge, folks, is what is called a competitive advantage and usually is proprietary. For some reason, Boeing decided to farm this baby out to others (where is the soul of this thing?). Then, they seemed to have let the oversight of this crucial piece lapse. Why?

Was it relief at getting rid of the problem? Ah, how many Boeing engineers are sick at hearing about the current state?

Well, the middle-out issues apply here; we'll discuss that, too.


04/07/2012 -- Flightblogger ends, as least, Jon's watch. Some issues raised five years ago are still apropos. The context may have changed a little, yet, perhaps now is time to re-address the themes.

02/03/2011 -- The topic of this post can be used for a whole bit of discussion.

Modified: 04/07/2012

1 comment:

Anonymous said...

The aerospace bloggers (groupies like Sheth, Ostrower, and fleetbuzz) and the Aviation industry analists (read Hamilton, Aboulafia) seriously lack in technical accumen, and seem unwilling to cast a critical view at anything Boeing has to say.

Judging by the photo of the affected area of the center wing box, an in situ modification on a complete airframe is going to be neither cheap, nor easy, especially if the aircraft has been fueled.

Yet all of these poeple seem to give Boeing a pass and have adopted thier "what me worry?" attitude.

Then come the financial 'silver lining' articals which attempt to bolter the notion that cancellations are somehow good.

I really have to ponder why such attempts to bend the facts around an certain axis of opinion are occuring. The design engineering truths seem rather well established. Even if the models need refinement.

The "fix" is going to take longer than is being postulated. Much longer. A final, incorperated redesign is going to be much longer yet. Weight, already an issue is going to be an bigger issue.

The 800lb gorilla is the notion that the computer models are sufficently flawed to force the FAA to call for modification and lengthening of the flight test program.

The investment community seems to be catching on much faster than the "experts", as 787 continues to absorb vast amounts of capital for no payoff to speak of.