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  (Source: Boeing)

  (Source: Boeing)
Boeing glides along with Dreamliner development

Boeing has a lot riding on its 787 Dreamliner program, and after a two-year delay, things appear to be panning out nicely for the Seattle-based company. The first 787 Dreamliner made its maiden flight on December 15, 2009 and stayed aloft for roughly three hours.

The second 787 Dreamliner took to the air a week later featuring the markings of the first customer which will receive the new planes: All Nippon Airways (ANA). In total, 15 flights (totaling nearly 60 hours) have been made so far using the first two aircraft.

Another milestone was reached late last week; the 787 Dreamliner achieved "initial airworthiness" status. This milestone allows Boeing to open up the testing phase to more aircraft. Boeing flight engineers will also be allowed on the flight deck now according to the Associated Press.

"This is an important step forward," said Boeing Commercial Airplanes VP Scott Fancher. "We are very pleased with the results we have achieved so far. The airplane has been performing as we expected."

The previous test flights have seen the 787 Dreamliners reach a top speed of Mach 0.65 and an altitude of 30,000 feet. In the coming weeks, Boeing test pilots will take the aircraft to Mach 0.85+ and in excess of 40,000 feet.

"The pilots have told me the results we are seeing in flight match their expectations and the simulations we've run. That's a real tribute to Boeing's expertise and the international team that helped develop and build the airplane," Fancher added.

ANA is expected to receive its first 787 Dreamliners during the fourth quarter of 2010. The Japanese airliner has ordered 55 of the aircraft.



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RE: Conventional looking now
By Hieyeck on 1/19/2010 8:24:05 AM , Rating: 0
COMPLETELY off-topic. Why are people throwing around the word 'composites' like 'alloy' was back in the 80s... It's not some magic word that makes you sound smarter... or maybe it is.

I give up.


RE: Conventional looking now
By Flunk on 1/19/10, Rating: 0
RE: Conventional looking now
By Kurz on 1/19/10, Rating: -1
RE: Conventional looking now
By theapparition on 1/19/2010 12:00:57 PM , Rating: 4
Plastics and composites are not the same thing. The definition of composite is using 2 or more materials (composite). A typical composite uses a base material surrounded by a epoxy matrix.

Talking about generalizations, when you say plastics, it's generally thought of as injection molded (or blow molded). Yes, there are other methods, and not all plastics are thermoplastics either, but close enough. Melted plastic pellets are pushed under high pressure into mold cavities to form a part.

Composites on the other hand, generally speaking, refer to hand made layups that orient the fiber of the base prepreg in the direction of interest. They have to specially cured usually under pressure. They can't be mass manufactured, can't be injected, and have signifigantly better strength to weight ratios than other competing materials.

Yes, you can add fillers to conventional IM plastics such as fiberglass, steel (wool), and many others. However, even though they fit the technical description of composites, they are generally not considered as such. The science of composite engineering is actually quite difficult since they have rather non-linear material properties. For example, in a typical carbon fiber body, the tensile strength comes almost exclusively from the carbon fiber, but it's compressive strength comes from it's matrix material.

Base materials for most composites are either fiberglass, carbon fiber or Kevlar. All three materials are actually classified as ceramics. So techically, they are most commonly a ceramic-plastic composition of 2 materials. Instead, the industry chooses the term "composite".

However, your assumption of them being anywhere remotely close to being the same is incorrect.


RE: Conventional looking now
By 91TTZ on 1/19/2010 12:42:32 PM , Rating: 2
quote:
Composites on the other hand, generally speaking, refer to hand made layups that orient the fiber of the base prepreg in the direction of interest. They have to specially cured usually under pressure. They can't be mass manufactured, can't be injected, and have signifigantly better strength to weight ratios than other competing materials.


This isn't accurate. You can definitely mass produce composite parts. Tennis rackets, fishing poles, tent poles, RC car chassis, surf boards, boats, and various other things are commonly mass produced and made of composite materials.

The reason you see composites being made by hand so often is because it's very workable and lends itself to that type of work. While a worker isn't going to be able to bend a plate of titanium with his bare hands he can easily cut and lay carbon fiber fabric in a mold and apply resin to it.


RE: Conventional looking now
By theapparition on 1/20/2010 8:15:15 AM , Rating: 1
Again, I was talking in generalizations and in context of aircraft manufacture. I thought I made that clear.

Some things, particuarly fiberglass, can be made by more conventional means. Keep in mind though, the round objects are manufactured by spin weaving composite threads. The other objects you mentioned (and as I mentioned) are technically composite, but are not continuous weave fabrics. So while they have some of the benefits of composites due to scrim reinforcement, those manufacturing processes would in no way be acceptable for airframe manufacture.

Your hypothetical manufacturing enviroment is not anywhere close to being correct either. Cheap fiberglass work does not equal carbon fiber or kevlar manufacture. You need an autoclave to properly cure the resin under pressure to eliminate voids. Why you see people doing hand layups is simple, because they don't have too many machines that can take the fiber and properly orient and apply in a custom situation. They do have machines that cut the fiber in the propper pattern. But actual assembly is still mainly a hand operation, especially in a custom enviroment.

BTW, a stamping machine to form metal is far cheaper in the long run than a team of skilled composite technicians.


RE: Conventional looking now
By drewidgho5t on 1/20/2010 3:06:33 PM , Rating: 1
@ theapparition

in defense of you I would like to tell 91ttz to STFU. Try learning instead of arguing.

@ 91ttz Those "mass produced parts" you speak of are usually fab'd as FRP--fibre re-inforced polymers. There is very little control regarding the orientation of the fibres. They are dumped into a big batch of molten polymer.

theapparition was kind enough to share knowledge with us, you included. You are rude enough to argue the minute details of semantics. See the part about additives-steel wool, fibreglass, etc??

Read the part where theapparition breaks down the difference in terminology. Resin impregnated fibre cloth is almost always laid by hand. That is how the fibre orientation is assured.

What a shame that the concept needs to be explained TWICE.

@theapparition--your explanation of terminology is eloquent and accurate. Just tell 91 titties to STFU and go rub some of his 91nplz.


RE: Conventional looking now
By 91TTZ on 1/20/2010 4:09:34 PM , Rating: 3
Wow, you seem overly upset over a non-issue.

The apparition was able to explain his case clearly while you come across as being an emotional 15 year old whose mom just took his XBox.


RE: Conventional looking now
By drewidgho5t on 1/20/2010 10:37:12 PM , Rating: 1
So if the case was explained clearly why did you attempt to find an inconsistency with what theapparition posted? CLEARLY, you chose to find whatever point you thought could be argued and emphasize the innaccuracy.

That is much more indicative of "the 15yr old" than someone berating a man-child for choosing to ignore an exceptionally informative post. Getting upset over nothing? No, I got upset over you choosing to argue instead of learn. Now STFU, read and learn.

BTW, have you noticed that none of the other clearly knowledgable people in this field have taken the same position as you.

theapparition did you (and me) a favour and you took a pass. You sure you want to discuss who is coming across as a 15 yr old?


RE: Conventional looking now
By 91TTZ on 1/21/2010 9:03:09 AM , Rating: 2
You clearly behave like an adolescent. You were either beaten up too much as a child or maybe you weren't beaten up enough. I'm not really sure.


RE: Conventional looking now
By 91TTZ on 1/19/2010 12:36:25 PM , Rating: 4
Composites are slightly different than pure plastics. A composite is a, well, composite of a stiff fabric and a plastic binder. If you made a part of only plastic it would be plastic. If that part was fiberglass or carbon fiber binded together with plastic, it would be a composite.


RE: Conventional looking now
By Amiga500 on 1/19/2010 9:06:07 AM , Rating: 2
Yes, it is quite funny.

Not many would believe you if you pointed out an isotropic lay-up Carbon Fibre composite will be heavier than an equivalent strength titanium component.


RE: Conventional looking now
By Spacecomber on 1/19/2010 10:26:08 AM , Rating: 2
I assume the advantage is in ability to more easily shape the part to a specific purpose. This makes it easier to make do with less; so, you may end up with a weight savings in the final product. Carbon fiber composite bikes have pretty much replaced everything metal at the high-end, for example. (On the other hand, I'd never trade my titanium frame for a composite, in part, because of its durability. No one will be giving a me new frame if I break this one, unlike for the professional riders.)


RE: Conventional looking now
By stromgald30 on 1/19/2010 12:18:29 PM , Rating: 2
Yes, most people don't know the details of composites and would make that mistake.

However. . . who uses isotropic lay-ups? I doubt more than 5% of composites on the 787 are isotropic. You're basically comparing one of the structurally weakest composite designs with a metal that's good in any direction. Of course it'll be inferior.


RE: Conventional looking now
By Amiga500 on 1/19/2010 3:22:14 PM , Rating: 2
You'd be very surprised at how close everything is to a balanced laminate. It has to be for a myriad of other reasons (which I'm guessing you are somewhat familiar with).

Orientate more than 30-40% of your lamina in any one direction and your laminate will start to become weaker, not stronger. That it accentuated when a hole exists (such as bolt hole).

Oh, and the metal has good through thickness strength - a composite will never have that without 3D weaving - which isn't used in the aerospace industry.


RE: Conventional looking now
By Keeir on 1/19/2010 6:56:29 PM , Rating: 2
Err... I guess that all depends on your notion of "balanced laminate". Also, I am fairly sure your assertion is primarly true for tensile or axial compression type loads.

Even a "Balanced" Laminate is significantly less dense than Titanium. Also significantly less expensive. A Balanced Composite comes down as in general significantly stronger per dollar than titanium in all but a few applications.

Not that I like composites, expecially due to as you mentioned the through thickness strength


RE: Conventional looking now
By Amiga500 on 1/20/2010 5:41:35 AM , Rating: 2
A balanced laminate has the same density as an unbalanced laminate...

What I was saying is that you can make a lighter titanium component to do the same job as a isotropic composite lay. That is not the same as saying less dense. The component dimensions will be different, hence the different weights.


RE: Conventional looking now
By Solandri on 1/20/2010 4:46:59 PM , Rating: 2
It's been over a decade since I did directional strength calculations for composite lays. But for most applications a 0-60-120 lay ends up pretty close to isotropic properties (except perpendicular to the panel of course).

CF has about 7x the tensile strength of titanium
Titanium is about 4.5 g/cc, CF about 1.75 g/cc, epoxy about 1.0 g/cc
Figure a 60/40 ratio of epoxy to CF

For a load in the 90 degree direction (its weakest orientation), the 3 layers end up contributing 0%, 86.6%, and 86.6% of their strength, for an average of 57.7%, knocking the 7x down to 4.039x. The 60/40 ratio knocks this down further to 1.6156x.

The weight of the 60/40 composite would be .6*1+.4*1.75 = 1.3 g/cc.

So for the same weight, the isotropic composite lay would have 1.6156*4.5/1.3 = 5.6x the strength of titanium for the same weight. Obviously the composite is a weaker perpendicular to the panel (no fibers oriented in that direction). Which is why you use them where loads are primarily within the panels like aircraft skin.

For applications where true isotropy in all three axes is required, I could see titanium being superior. But I'm pretty sure that would be because your specifications are deflection-limited, not strength-limited. CF is so flexible that if you need it to stay within a specified maximum deflection, it often ends up being several times stronger (and heavier) than it needs to be to withstand the load.


RE: Conventional looking now
By Amiga500 on 1/21/2010 8:17:08 AM , Rating: 2
quote:
CF has about 7x the tensile strength of titanium


With regards aerospace, CF plies have at best around 2.75x the ultimate tensile strength of Titanium. The densities are around 1600 kg/m^3 (CF) and 4500 kg/m^3.

That is AS4-8552 compared to Ti-5Al-2.5Sn.

So you can recalc that. Using your approach CF will still work out lighter if you've managed to confine the loading to in-plane only.

[FYI, compared to Al2024-T3, aligned CF is about 6.25x stronger, and 1.75x lighter]

Although it is all irrelevant as best practice is to design CF for max strain allowable (typically < 0.4%), not stress. The equivalent max "stress" of that is only 560 MPa or so... quite a ways short of Ti's 830 MPa yield strength. That is before you start to consider ply alignment!


RE: Conventional looking now
By stromgald30 on 1/19/2010 12:23:08 PM , Rating: 2
Maybe some people are throwing it around to sound smarter, but the facts are that composites are the 'new' material technology being implemented in industry, just as alloys were in the 80s.

Alloys aren't a hot topic anymore because most of the possible gains from them have been achieved. Composites will fade away too once a new material technology comes out and/or composites have been mostly exhausted. (Yes, there's probably alot about alloys that we don't know of yet, but industry has pretty much caught up with cutting edge alloys right now).


RE: Conventional looking now
By 91TTZ on 1/19/2010 1:01:07 PM , Rating: 3
quote:
Maybe some people are throwing it around to sound smarter, but the facts are that composites are the 'new' material technology being implemented in industry, just as alloys were in the 80s.


Huh?

Composites started taking off in the early 1940's with the use of fiberglass composites on aircraft. By the 1960's carbon fiber parts were becoming popular on aircraft. Over time they got cheaper and cheaper and by the 1980's you had carbon fiber being used in cheap consumer items like fishing poles and baseball bats.

The use of alloys goes back thousands of years, ever since the ancients realized that you could mix metals together to get a stronger finished product. In fact pure elemental metals are rarely used since the metal usually performs better when you alloy it with something.


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