Plastic 737?

[PA-44Typed]

WASHINGTON: Plstic is the future, at least for the aircraft industry. It won't be long that we have to forget big metal birds of steel, aircraft of the future will be constructed out of plastic, reported CNN on its website.

That is according to American plane-maker Boeing who says new technology will soon enable us to take flights in carriers largely constructed from non-metal materials.

Alan Mulally, president and CEO of Boeing Commercial Airplanes, said the company was looking to replace existing 737 models with newer models made from materials called composites.

A composite is formed when two or more materials with very different properties are combined together. They are already used in items such as tennis rackets and bicycle spokes.

Boeing's new 787-Dreamliner is built from composites and will set a precedent for future Boeing models, Britain's Press Association reported ahead of the Farnborough Air Show, held in England this week and one of the biggest events on the aviation calendar.

The 787 is expected to make its first flight in mid-2007 and deliver the first models to customers in 2008.

The aircraft is made from a combination of non-metal carbon fiber composite materials, which is lighter than the aluminum normally used. This reduces the weight of the aircraft and leads to better fuel efficiency. Boeing predicts the 787s will be 20% more efficient than its 767 planes.

Mullaly said composite material would be used to build up to 50 percent of each aircraft and would significantly reduce the cost of building and maintaining them.

Mulally predicted that the technology needed to build the new Boeing 737s would not be ready until the middle of the next decade.


http://timesofindia.indiatimes.com/articleshow/1773466.cms

 

[V-1]

How many steel airplanes have been built?

 

[propsarebest]

One, the MIG 25.

 

[stearnst]

Now I'm certainly no engineer, but when I hear composites, plastic isn't the first word that comes to mind. It's my understanding that the manufacture of composite material is worlds away from plastic injection molding, right?

 

[AerroMatt]

Mulally predicted that the technology needed to build the new Boeing 737s would not be ready until the middle of the next decade


WTF does this mean? after 40 years plus of production, boeing isn't going to shift to a new design for the medium range market? they take all this time and effort on the 787, and just stretch the 737 a little further. how much longer will they continue with the venerable 737 design before they have to do a clean-sheet approach?

 

[Turkey Shoot]

Does this mean we'll be flying the, "Big Composite," or "Heavy Plastic" now?

 

[Alamanach]

Now I'm certainly no engineer,

I am.

...but when I hear composites, plastic isn't the first word that comes to mind. It's my understanding that the manufacture of composite material is worlds away from plastic injection molding, right?

From Materials Science and Engineering by Dr. William Callister:

Generally speaking, a composite is considered to be any multiphase material that exhibits a significant proportion of the properties of both constituent phases such that a better combination of properties is realized. According to this principle of combined action, better property combinations are fashioned by the judicious combination of two or more distinct materials. Property trade-offs are also made for many composites.

Composites... include multiphase metal alloys, ceramics, and polymers. For example, pearlitic steels have a microstructure consisting of alternating layers of (alpha) ferrite and cementite. The ferritic phase is soft and ductile, whereas cementite is hard and very brittle. The combined mechanical characteristics of the pearlite (reasonably high ductility and strength) are superior to those of either of the constituent phases. There are also a number of composites that occur in nature. For example, wood consists of strong and flexible cellulose fibers surrounded and held together by a stiffer material called lignin. Also, bone is a composite of strong yet soft protein collagen and the hard, brittle mineral apatite...

Many composite materials are composed of just two phases; one is termed the matrix, which is continuous and surrounds the other phase, often called the dispersed phase. The properties of composites are a function of the properties of the constituent phases, their relative amounts, and the geometry of the dispersed phase. "Dispersed phase geometry" in this context means the shape of the particles and the particular size, distribution, and orientation.

You know those reinforced glass winows that have a metal mesh embedded in them? You could think of the glass as a matrix and the mesh as a dispersed phase. Then you have a macroscopic idea of what composites can look like microscopically. I'm tempted to say something like "Yeah, we're a little bit beyond injection molding here," but I'm sure some wiseguy would come back with an example of an injection-molded composite. However, your basic intuition is correct; this is sophisticated stuff, and a lot stronger than your G.I. Joe Skystriker.

 

[mzaharis]

Completely off-topic, but injection-molded composites are actually quite common (sorry if this labels me as a wiseguy). Usually short strands of glass or, sometimes, carbon fiber, composites are included in the plastic (normally polypropylene, I think), for additional strength without high manufacturing costs. The slide on my kids' playgym is made this way (glass fibers).

As you noted, though, this is not common for aerospace (except maybe for things like food trays and such). Usually, aerospace structures consist of either hand-lay or machine-laid fabrics and tapes (or filament wound, like the 787 fuselage), which are "Pre-preg" (already impregnated with the resin). The resins certainly are considered plastics, although as mentioned earlier, they are much more sophisticated than the usual polyethylene or polypropylene seen in most consumer applications. Usually, aerospace-specific high performance epoxies, polyimides, or bismaleimides are used for aircraft applications.

Here's more than you ever wanted to know about the plastics used in aerospace composites:

http://www.angelfire.com/ma/ameyavaidya/c_matrix.htm

 

[stearnst]

Thanks for the insights. As usual, I know just enough about a subject to prove that I'm a complete idiot concerning them. It's always good to learn something new.

 

[mzaharis]

If you're interested in learning more about composites, the site that I listed with the resins information has lots of good information on fibers, resins, manufacturing techniques, and uses. Of course, being an angelfire site, you will need to deal with pop-ups if your browser doesn't block them.

http://www.angelfire.com/ma/ameyavaidya/mod.htm