Composites Machining for the F-35 Aug? 8/3/2010 Article From: Modern Machine Shop, Peter Zelinski, Senior Editor
Composites Machining for the F-35 : CompositesWorld
"...The F-35 features “supportable” VLO. That is, the VLO on this plane comes with very low maintenance cost. Stealth aircraft of the past couldn’t make that claim. Because radar detects sharp edges, even small mismatches between exterior parts on past VLO planes were smoothed out using epoxy. The epoxy would dry, harden and separate in the field—meaning it had to be frequently inspected and replaced.
By contrast, adjacent parts of the F-35 match so fluidly and precisely that no epoxy is needed...."
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THE F-35 LOW OBSERVABILITY’S LIFELONG SUSTAINABILITY: A REVOLUTIONARY ASSET FOR 21ST CENTURY COMBAT AVIATION
http://www.sldinfo.com/?p=6065
"...Performance-wise, it is a very aggressive capability. From a design standpoint, it is a radical change from legacy systems. In legacy stealth, the stealth in effect is a parasitic application of a multiple stack-up of material systems done in final finish after the actual airframe is built and completed. In the case of the F-35, we’ve incorporated much of the LO system directly into the air frame itself. The materials have been manufactured right into the structure, so they have the durability and lifetime qualities. It makes them much more impervious to damage. It is a much simpler system with fewer materials to contend with....
...From day one, the supportable LO has been a key entity on the program and has had a profound influence on the very design of the airplane. In fact, the element that is manufactured into the skin was an initiative brought about by our LO maintenance discipline....
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SLD: The F-35 program is built around global partnerships and a globally deployed capability. What is the role of partners in the LO repair facility?
Bill Grant: The partners weren’t involved from the very beginning because our technology transfer agreements didn’t permit that for a while. But as of November of 2008, they have participated in what has become a real institution here. We have quarterly two-day hands-on familiarization courses where members from maintainers from all of the services and several partners come in and get some experience with the tools and the processes affecting the restorations and the repairs. That’s been a tremendous plus in terms of their input and shaping our understanding of what works and what doesn’t work, and we’ve modified our designs and our concepts accordingly. But mostly, they’ve provided a
high-level validation that these tools and processes do, in fact, work for them, for both experienced and inexperienced LO maintainers, and that it’s doable in their environment.
SLD: So a lot of the LO maintenance will be done by the services and partners in the field?
Bill Grant: Yes indeed: we have no recognized need for any kind of return to depot or return to manufacturer for doing any type of LO maintenance. Our system requirement was for end of life, which means that throughout the 8,000-hour service life of the jet, it is to remain fully mission-capable. So we anticipated that the amount of maintenance that would be done over the life of the airplane and anticipated that in the design. So when we deliver the jet, it’s delivered with a significant margin of degradation that’s allowed for all of these types of repairs over the life of the airplane, again, without having to return to the depot for refurbishment. There may be some cosmetic-based reasons why the jet might go back to a facility to get its appearance improved, but from a performance-standpoint we recognize no need to do that. The unit-level maintenance will be adequate for maintaining the full-mission capability of the jet.
SLD: In entering the facility, I noticed you have a “door mat” of stealth that’s been there for some time. Can you comment on this “door mat?”
Bill Grant: Oh, the slab of stealth? That’s our welcome mat. Yes, we actually have one of the test panels that we use for assessing the stealth of the various materials. It represents a stack-up that’s consistent with the upper surface or the outer surface of the jet. It has the exact same structure and the primer and the topcoat system that you’ll find on the operational jets. And that gets walked upon every time somebody comes in or out of our lab area out there, the repair development center.
Occasionally, we take it up to test to see if there’s any electrical or mechanical degradation to the system and with around 25,000 steps across that system we have not seen any degradation whatsoever. So we have a great deal of confidence, however anecdotal that may be, that we have a very robust system."
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The F-35’s Race Against Time Nov 2012 By John A. Tirpak Executive Editor
http://www.airforce-magazine.com/Mag...12fighter.aspx
"...The F-35’s radar cross section, or RCS, has a "maintenance margin," O’Bryan explained, meaning it’s "always better than the spec." Minor scratches and even dents won’t affect the F-35’s stealth qualities enough to degrade its combat performance, in the estimation of the company. Field equipment will be able to assess RCS right on the flight line, using far less cumbersome gear than has previously been needed to make such calculations....”
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F-35 Stealth Coatings Applied to F-22 Shane McGlaun (Blog) April 7, 2011
DailyTech - F-35 Stealth Coatings Applied to F-22
"..."Some of the [low observables] coatings system and gap-fillers that the F-35 had an advantage on, we have incorporated into the Raptor," said Jeff Babione, vice president & general manager of the F-22 program for Lockheed Martin. Defense News reports that Babione claims that the new coatings don’t change the radar cross section of the F-22. The coatings according to Babione are simply to reduce maintenance costs. He said, "[The F-35 program] had some more robust materials that were more durable & we were able to pull those back on to the F-22. So our system is better, & the life-cycle cost of the F-22 is reduced."..."
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USAF praises early performance of Lockheed Martin F-35 06 Nov 2012 Dave Majumdar
US Air Force praises early performance of Lockheed Martin F-35
"...Additionally, the F-35's stealth coatings are much easier to work with than those used on the Raptor. Cure times for coating repairs are lower and many of the fasteners and access panels are not coated, further reducing the workload for maintenance crews...."