Forum: F-35 Design & Construction

Lockheed Martin reveals F-35 to feature nanocomposite structures By Stephen Trimble DATE:26/05/11 SOURCE:Flight International

http://www.flightglobal.com/articles/20 ... osite.html

"Lockheed Martin has revealed the F-35 Lightning II will be the first mass-produced aircraft to integrate structural nanocomposites in non-load bearing airframe components.

A thermoset epoxy reinforced by carbon nanotubes will replace carbon fibre as the material used to produce F-35 wingtip fairings beginning with low rate initial production (LRIP)-4 aircraft, said Travis Earles, a manager for corporate nanotechnology initiatives.

Meanwhile, the same carbon nanotube reinforced polymer (CNRP) material is being considered to replace about 100 components made with other composites or metals throughout the F-35's airframe, he said.

The shift to CNRP as an airframe material has been anticipated ever since carbon nanotubes were discovered in 1991. It is widely considered one of the strongest materials ever invented - several times stronger than carbon fibre reinforced plastic (CFRP), yet lighter by about 25-30%.

CFRP has come to rival aluminium and steel as a material for primary structures: for instance, Boeing is building 787 fuselage barrels entirely from CFRP material.

But the widespread usage of CFRP for load-bearing components of commercial and military airframes only happened after two decades of development work.

That development cycle began in the early 1970s, when manufacturers began experimenting with glass and carbon fibre-based composites for secondary control surfaces.

Similarly, the introduction of CNRP in non-load bearing structures in the current decade, starting with the F-35, could lead to wider usage in airframe structures as the technology matures.

According to Earles, there is no technical reason the material could not be used in load-bearing structures. However, to reduce certification requirements of a structural material, carbon nanotubes are only being considered in non-load bearing components.

In the meantime, the use of carbon nanotubes is already widespread in industries ranging from semiconductors to golf clubs. The high cost and complexity of producing the structures means they have so far had limited applications in aerospace programmes.

Lockheed, however, has invented a process that dramatically reduces the cost to build carbon nanotube composites for aircraft structures, Earles said. The new wingtip fairing is being made for one-tenth of the cost of the equivalent CFRP component, he said.

Earles declined to describe details of Lockheed's low-cost manufacturing process for carbon nanotube composites. Such particulars are considered trade secrets within the company, he said.

But it is clear that the cost-saving process is a relatively new invention within Lockheed. Earles said it has evolved within the past four years. During the same time period, Lockheed has been active in developing new, low-cost methods for manufacturing airframe structures.

Lockheed was selected by the Air Force Research Laboratory in 2007 to build and demonstrate the X-55 advanced composite cargo aircraft (ACCA), which modified a Fairchild Dornier 328Jet. The fuselage was rebuilt with a new kind of carbon fibre resin that can be cured outside an autoclave, avoiding one of the most costly steps in the production of CFRP materials.

It is possible that the X-55 airframe also benefited from the development work that produced the carbon nanotube composites, which are now being applied to the F-35.

The company is only now publicising the first details about the rapid progress in manufacturing nanostructures for airframes.

A display inside Lockheed's energy solutions centre in Crystal City, Virginia, shows off the F-35's new wingtip fairing derived from nanotechnology.

The material is identified as "advanced polymers engineered for the extreme - first generation", or APEX. It is described within the display as "best-in-class ultra-lightweight and affordable structural thermoplastic enhanced with nanoparticles that delivers increased mechanical properties, thermal stability, electrical conductivity and processability over currently available projects".

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Those would be the same carbon nano-tubes that in the words of Lockheed are, "particularly effective, for example, in the L- through K-band as described herein further below" aren't they?

http://www.google.com/patents?id=E0jYAA ... mp;f=false

Yep, thought so. So much for 'leading edge L Band AESA's' and other such fantasy stories...

Heating Pinpoints Internal Cracks in NanoEngineered Composites
http://nanotechweb.org/cws/article/lab/46092

Has been reported by 5.26.2011 Nanotechweb.org

Recently, engineers at Massachusetts Institute of Technology (MIT), US, embedded such a sensing network made of carbon nanotubes (CNTs) into a traditional fibre-reinforced laminate architecture, by placing aligned CNTs throughout the architecture to create a hierarchical nanoengineered material.

When electrical current flows through the CNT network, the temperature of the material increases from Joule heating. If damage that disrupts this conductive network exists somewhere in the material, a localized change in electrical current results, which, in turn, manifests as a localized change in temperature

tomtom22 http://midgetechnology.com/default.aspx

Adm. Venlet was quoted as being very, very pleased with the results of RCS testing, implying that the F-35 met and most likely exceeded design objectives. The article states however that only the wingtip fairings utilize the new nano material. With up to 100 more components possibly being converted to the new stuff, the F-35 may wind up being more radar-stealthy than even the Raptor. Amazing.

popcorn wrote:

Adm. Venlet was quoted as being very, very pleased with the results of RCS testing, implying that the F-35 met and most likely exceeded design objectives. The article states however that only the wingtip fairings utilize the new nano material. With up to 100 more components possibly being converted to the new stuff, the F-35 may wind up being more radar-stealthy than even the Raptor. Amazing.

Which then begs the question- can Raptors also benefit from this material?

wrightwing wrote:

popcorn wrote:

Adm. Venlet was quoted as being very, very pleased with the results of RCS testing, implying that the F-35 met and most likely exceeded design objectives. The article states however that only the wingtip fairings utilize the new nano material. With up to 100 more components possibly being converted to the new stuff, the F-35 may wind up being more radar-stealthy than even the Raptor. Amazing.

Which then begs the question- can Raptors also benefit from this material?

I'd love for the F-22 to get a new skin to go with a new brain but it will always come down to money.

Conan wrote:

Those would be the same carbon nano-tubes that in the words of Lockheed are, "particularly effective, for example, in the L- through K-band as described herein further below" aren't they?

http://www.google.com/patents?id=E0jYAA ... mp;f=false

Yep, thought so. So much for 'leading edge L Band AESA's' and other such fantasy stories...

Not trying to be rude but does it strike you as odd at all that LM would publish (publicly) a method to build RAM coating materials that are as effective as they claim against all radar bands?

By the sounds of it the materials side of this equation is well know by material scientists. It is the application part (putting it on the airplane) that is the difficult part. To put it another way, just because you have access to paint and a paint brush doesn't mean you going to turn out a Michelangelo.

jeffb wrote:

Conan wrote:

Those would be the same carbon nano-tubes that in the words of Lockheed are, "particularly effective, for example, in the L- through K-band as described herein further below" aren't they?

http://www.google.com/patents?id=E0jYAA ... mp;f=false

Yep, thought so. So much for 'leading edge L Band AESA's' and other such fantasy stories...

Not trying to be rude but does it strike you as odd at all that LM would publish (publicly) a method to build RAM coating materials that are as effective as they claim against all radar bands?

They didn't publish it. They patented the technology. Through whatever patent laws they have in America, they usually end up published and then online.

Again, knowing the theory is one thing. Physically producing it and being able to employ it on an aircraft is something else entirely.

As I've said before you and others are so certain of Carlo's claims, but without seeing the test data it's just sheer speculation.

popcorn wrote:

...I'd love for the F-22 to get a new skin.....

Not only the F-22 but also the B-2 and the Bone. Imagine the B-2 with its persistence and a durable skin. The lighter Bone with its speed and a smaller RCS; both on existing (paid for) airframes. Cool

neptune wrote:

popcorn wrote:

...I'd love for the F-22 to get a new skin.....

Not only the F-22 but also the B-2 and the Bone. Imagine the B-2 with its persistence and a durable skin. The lighter Bone with its speed and a smaller RCS; both on existing (paid for) airframes. Cool

Yeah, but the bill for facials will be a killer. Very Happy

Conan wrote:

jeffb wrote:

Conan wrote:

Those would be the same carbon nano-tubes that in the words of Lockheed are, "particularly effective, for example, in the L- through K-band as described herein further below" aren't they?

http://www.google.com/patents?id=E0jYAA ... mp;f=false

Yep, thought so. So much for 'leading edge L Band AESA's' and other such fantasy stories...

Not trying to be rude but does it strike you as odd at all that LM would publish (publicly) a method to build RAM coating materials that are as effective as they claim against all radar bands?

They didn't publish it. They patented the technology. Through whatever patent laws they have in America, they usually end up published and then online.

Again, knowing the theory is one thing. Physically producing it and being able to employ it on an aircraft is something else entirely.

As I've said before you and others are so certain of Carlo's claims, but without seeing the test data it's just sheer speculation.

Well, technically, patenting something means publishing it…

Quote:

A patent is a set of exclusive rights granted by a state (national government) to an inventor or their assignee for a limited period of time in exchange for a public disclosure of an invention.

http://en.wikipedia.org/wiki/Patent

Also technically, a patent has to include enough information about the process that a person familiar with the field can see it actually does represent an innovation that isn’t just an obvious extension of some other product or technique (although the USPTO has been pretty slack about this recently). Necessarily, someone familiar with manufacture of carbon nano tubes (CNTs) will see and understand immediately the innovation inherent and understand the techniques being described in this patent to manufacture this material.

The patent does say that the material can absorb wavelengths ranging from 0.1mhz up to 60ghz but it doesn’t say it can absorb them all simultaneously and there seems to be some language circling around selectively improving the materials response to certain wavelengths. It also seems to imply that orienting the panel towards the source of the radar emissions will improve the “reduced reflectivity” so its effectiveness does appear to be sensitive to the panels orientation with relation to the radar source.

But you are right, without seeing test results, it’s impossible to say how effective any of it is.

Again though, the fact that this patent has been made public is odd. The US government has the means to classify patents if they feel that the invention represents a threat to US security. Obviously in this case, they don’t.

So this patent describes the manufacture of (according to you) highly effective and efficient RAM coatings, but the free and public distribution of this information isn't considered a threat to US security. Weird. And I’m sorry, your suggestion that it’s all about the way you apply it is just speculation and we know how you feel about speculation.

Of course the good news is that if the material is as good as you say, we can re-skin the F-111s with a top-notch RAM material at a fraction of the cost of replacing them with 100 short range tactical stealth fighters.
Wink

Of course the good news is that if the material is as good as you say, we can re-skin the F-111s with a top-notch RAM material at a fraction of the cost of replacing them with 100 short range tactical stealth fighters.

Thanks for outing yourself as an APA fan. We can point to this post in perpetuity to show where you're coming from.

how similar is this to the thermoplastic Boeing tried to make the X-32 out of I wonder??

sprstdlyscottsmn wrote:

how similar is this to the thermoplastic Boeing tried to make the X-32 out of I wonder??

Probably not at all. Themoplastic is just a different type of plastic. Thermoplastics are things like polycarbonates, acrylics, and such.

Forum: F-35 Design & Construction

F-35 Features Nanocomposite Structures