Posted on 06/12/2007 6:48:29 AM PDT by Freeport
When Boeing first considered extensive use of structural composites on the 787 Dreamliner, its engineers knew intuitively the epoxy/carbon fiber matrices would reduce weight significantly, allowing fuel savings and extended flying range. But after an intensive early look at composites, they realized fundamental design changes were possible that would allow functional systems integration, as well as changes in lamellar flow that would improve aerodynamics From a materials point of view, the 787 Dreamliner is one of the most revolutionary leaps in the history of manufacturing.
But in order to meet an ambitious delivery schedule the first delivery is scheduled for May 2008 there were tremendous hurdles to jump:
- No one ever attempted to mass produce very large carbon-reinforced plastic structures, which are thermoset materials with significantly slower processing times than thermoplastics,
- The critical tooling for such large sections was still very much in the development stage and, in fact, represented one of the few, small stumbles in the development program,
- New coatings had to be developed to deal with the crack propagation issues, which are not a factor with aluminum. Engineers had to devise different systems to deal with electrical shorts because composites are not electrically conductive.
One area that was not new was the materials technology. When we made the decision on composites use in the wings, fuselage, floor beams and so on, we went down a path based on a material that we had already had a significant amount of production experience with on the Triple 7, says Dr. Alan G. Miller, director of technology integration on the 787 and former chief engineer for all materials technology at Boeing...
(Excerpt) Read more at designnews.com ...
When Boeing first considered extensive use of structural composites on the 787 Dreamliner, its engineers knew intuitively the epoxy/carbon fiber matrices would reduce weight significantly, allowing fuel savings and extended flying range. .............................. Hmmmmmmm? No wonder the Russians and Chinese ordered them. A little reverse engineering potential?
—high school physics-—gravity wins again!!!
They've accounted for that and Boeing has a lightning lab for testing.
Early composite airplanes like the Beech Starship had a layer of lightweight conductive material imbedded into the composite. It was similar to honeycombed aluminum foil. Lightning strikes left a hole no larger than a quarter, and a few scorch marks. Lightning strikes were easily repaired and basically harmless. I imagine the 787 will use something similar.
Implanted in the Carbon-Fiber is a very thin mesh layer of copper(?) that would conduct away ant electrical discharge from any contact points.
That is another question, repairing the carbon fiber vs. aluminum skin. Since it is baked and essentially one big solid piece lets say some moron runs the forks of a forklift through the body of the plane, what is the repair cost and structural integrity afterwords compared to just replacing and re-riveting the aluminum skin of aircraft now?
Don’t forget to get permission to post comments from her... We wouldn’t want to get her in trouble.
Not much of an aviation expert, but will this be a better alternative for airlines than the new Airbus behemoth that doesn’t even work right?
Boeing will respond at some point after the 787 gets going with a larger 747 in a similar way that they did with the 737-800 (Really a new airplane flying under the type certificate of the existing airframe... Which Airbus REALLY hates.).
I’d say in 5-7 years the 747x (650-750 passengers) will resurface as more airport infrastructure is built to handle the larger aircraft.
After that, Boeing will have the kinks worked out of their cargo variant of a blended wing-body aircraft. Say in 10-15 years expect an aircraft that can haul 1,000 people, yet able to fit into the infrastructure of a 747...
Bet that'll be a comfortable ride...NOT!
I already insist that only people weighing less than 110 pounds can be truly comfortable in coach class as it is.
Not only less than 110 pounds -- but also less than 5'10" in stature.
Their biggest issues are:
- Loading & Unloading
- No Windows
- Non circular pressure vessel (Elliptical)
- “Different” factor - People don’t like different...
I find it interesting that the 787 can defer repair to the damage from a lightning strike, but an aluminum skinned aircraft has to be repaired right away.
Also remember that Boeing has experience with the composite tail on the 777.
Well, there are several 380's flying, and are route qualified on most routes early delivery customers will use.
If that's not working, I don't know what is.
As for composites, it wasn't long ago that the Airbus bashers were throwing a fit about it's use of composites, and praising Boeing for not.
They have completely reversed their positions now, convinced that composites are wonderfuuullll.
Infrastructure. As in:
- Runways
- Jetways
- Maintenance Bays
- etc.
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