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A Defense Technology Blog
JSF News 2 - Stealth Questions Raised

The Air Power Australia team have produced an unprecedented report which asserts that the F-35 Joint Strike Fighter is much less stealthy than the F-22 - and in fact is comparable in radar cross-section (RCS), under some circumstances, to a conventional fighter in clean condition. APA's updated surveys of modern Russian radars - which are most likely to form the basis of the threat systems that it would encounter from the late 2010s onwards - have set the scene for this analysis.

The report is unprecedented because it's the first "civilian" use of radar scattering models to take a first-order look at an aircraft's RCS. It was the development of computer-based RCS models that opened the way to the development of stealth in the 1970s:  the theory of scattering was well known but was too hard to apply to a 3-D shape without those tools.

The APA analysis will no doubt be countered by the JSF team in several ways. They'll argue that the APA team has an agenda. They will argue that the analysis is too crude to reflect reality;  that anything it does show is not operationally relevant;  and that the true picture is much more complex and (of course) secret.

The APA team does have an open agenda (as does the JSF team) but that does not mean that their data is bad.

The analysis is crude insofar as it doesn't make any detailed estimates of the effects of radar absorbent material (RAM). On the other hand, the doctrine laid down by Stealth pioneer Denys Overholser still stands:  the four most important aspects of stealth are shape, shape, shape and materials.

On the other hand, the APA analysis is a lot more detailed than the cartoon representations in Lockheed Martin briefings. And more realistic than the claims of total invisibility made on JSF's behalf.

The APA team also makes the point that the F-35 doesn't look as much like an F-22 (or the X-35) as you might think. Those two aircraft both reflected a refined version of the F-117 shape - they are basically faceted designs, although they incorporate large radius curves and the lines between facets are smoothed. But the F-35 has acquired some very conventional-airplane-shaped lumps and bumps around its underside, not to mention the hideous wart that covers the gun on the F-35A. It's enough to raise questions.

blog post photo

Of course, it's possible to argue that the F-35 meets its stealth requirements (which may or not be the same for all F-35s), and that it will be stealthy enough to survive - combined with situational awareness and tactics.

But that in turn depends on what the requirements are, and what threats it was designed against. (That's why stealth air vehicles are as diverse as they are, from the DarkStar to the AGM-129, while submarines look pretty much the same.)  In the design of the F-22, for example, features such as 2-D nozzles, edges swept at 42 degrees, and high-altitude, high-speed flight were required to address that threat set.

More recently, the Northrop Grumman X-47B and Boeing X-45C designs have clearly been aimed at all-aspect, wideband stealth - although that's particularly important for an unmanned vehicle, which may not be as flexible in its response to a pop-up threat.

The worst argument against APA, though, is that of secrecy. Implemented on an experimental airplane 30 years ago, stealth is no longer covered by Arthur C. Clarke's principle that "any sufficiently advanced technology is indistinguishable from magic." Competitors and potential adversaries around the world have assuredly run F-35 models in simulations, in RCS chambers and on open ranges. So if APA has got their models wrong, it probably wouldn't compromise security to explain why.

Tags: ar99jsfstealth
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BDF wrote:
I figured that APA's analysis would make to Ares. It was a very interesting read. I still think that Kopp does himself a disservice by not illustrating how the other VLO platforms  and the F-22 in particular  possess a superior signature in the same manner he did with the F-35. That being said I believe his analysis has some merit to it but I suspect that the actual signature of the jet would in all probability be better than he's postulating simply because of the material variables. What's interesting is that now we can start to see  if he is indeed correct -- why the F-22 has been restricted form export and the F-35 available to anyone who wants it. Now lets have some fun; any wagers how long this thread will get? Im going to go big and say 5+ pages! :^)
1/7/2009 8:54 AM CST
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I gotta check out the report, though with a jaundiced eye, as APA has been generally hostile, though less hostile than I am, to the F-35.
1/7/2009 10:14 AM CST
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Marcase wrote:
To me, stealth is a relative thing, because it all depends on your mission. As long you are stealthy ENOUGH and able to put steel on target it doesn't really matter what kind of stealth you use - be it shape, active jammers, terrain masking, mission planning or a combination of all.

It is NOT, and never was, intended to go deep into a "first day" up and running S-400/SA-11 IADS; smart planners fly around those or skirt the edges of detection ranges where its limited stealth comes in handy.

The F-35 is no super plane, trade-offs are made to design a reasonable (affordable) next-gen aircraft with stealth characteristics. That's it. My beef is that LM shouldn't sell it as an equal to the F-22 or mini-B2 at a bargain price.

Combined with stand-off weapons, under guidance of AWACS/JSTARS and supported by other assets the F-35 is to play its part in future conflicts, and will make a real decisive impact operating from amphibs and small carriers.

(My bet, four pages ;)
1/7/2009 10:26 AM CST
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Bill Sweetman wrote:
Marcase - I agree. Also, note that nobody's saying that JSF doesn't meet its stealth KPPs, whatever they are. And the argument has to be, in the end, that stealth + mission planning + situational awareness will break the kill chain when it needs to be broken.
That said, if the claims were more realistic there would be less controversy - and I think that some of the overselling is to squelch support for the F-22.
1/7/2009 10:53 AM CST
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B.Smitty wrote:
If Dr Kopp's analysis is on the mark, and you project the F-35 program price increase trend out a few more years, one has to wonder at the business case for the F-35 for the USAF.

It may be the only "semi-stealth" game in town for the USN, the USMC and foreign air forces, but the Air Force already has the F-22, and its unit price is trending down.


1/7/2009 1:10 PM CST
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BigRocket wrote:
If the underbelly of the F-35 is as un-stealthy as APA claims, here's one solution: roll over and fly the plane upside down as you penetrate enemy airspace. Just remember not to drop bombs while doing this.

Seriously, this is what the APA is really saying: Under some conditions (read: the worst-case scenarios we could find that were the least favorable to the F-35), the F-35 (when fully loaded) was no more stealthy than an adversary flying clean (not carrying any missiles or bombs). I find that ironic, because a lot of folks (including APA) were harping on how little the F-35 can carry, and now APA is comparing it (and the few missiles it can carry internally) to an adversary with zero missiles and bombs. We are talking about an internal gun only for the adversary versus a small number of internal missiles for the F-35. Just how are you supposed to club a baby seal without a proper club, as the baby seal holds its own club to club you right back?
1/7/2009 1:23 PM CST
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Bill Sweetman wrote:
BR - I don't think that APA intended to get into a comparison of a JSF with (for instance) a Super Hornet, or with a conventional aircraft carrying RAM-treated external stores. (Although I'm sure Boeing would do so in a forum at an appropriate classification level.)

The F-35-versus-the-others, LO-versus-not-LO argument has no single answer. It's mission-dependent. For the F-117, B-2 or NGB, LO is the only way to go. For close air support, Afghan-style, LO is next to irrelevant. Other missions tend to be in between. As a Typhoon salesman, I'd tell you that if you want "going downtown" LO, hang a couple of Storm Shadows on the jet; otherwise, you are as well off with a bigger weapon assortment and jamming.
1/7/2009 2:32 PM CST
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ELP wrote:
Good points M. also.... the quote "It is NOT, and never was, intended to go deep into a "first day" up and running S-400/SA-11 IADS; smart planners fly around those or skirt the edges of detection ranges where its limited stealth comes in handy."

... is interesting.. because LockMart has stated that the F-35 can manage those high end threats in other briefings. Hard to believe when you consider "affordable" and "exportable" stealth with no high end altitude or significant super-cruise. Funny as they have used APA as a source of lethality of the threat in some briefing slides.

1/7/2009 2:39 PM CST
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B.Smitty wrote:
Which makes one wonder why the USAF can't do just fine with a hi/low mix of new F-22s, F-16s and/or F-15Es. That way we get a mix of high-end, all-aspects stealth, and proven affordability.
1/7/2009 2:41 PM CST
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BDF wrote:
"...one has to wonder at the business case for the F-35 for the USAF."


I agree with you 100% here. In my opinion the USAF has been continuing too long on the fighter-centric cold war/early post cold war force structure and hasnt come to terms with likely scenarios where even high intensity wars would be quick; where the US adversaries will not permit her to build mass prior to joining combat. This means the USAF needs to concentrate on long range force projection platforms: i.e. Bombers.

Move away from fighters for the traditional BAI/CAS roles and move towards cheaper persistent platforms such as a notional non-VLO UCAS platform (joint Army/USAF would be nice but thats a dream world solution) for the CAS role and a joint VLO UCAS platform with the Navy for the principal BAI strike platform. Incidentally, I drool over the potential of the X-47B and its addition to naval aviation. The carrier now becomes a legitimate deep penetration threat again.

With the notional $250 Billion development and procurement plan (from right now) for the F-35 you could extend F-22 production to the circa 400 needed (this could constitute the bulk of the traditional fighter force since fighters are still needed), accelerate the UCAS program, develop an inexpensive non-VLO UCAS, and fund the development and initial buys of the NGB.

The above is unlikely since it isn't politically palatable to cancel the F-35 now. I still think it'll be a good jet but I'm very concerned that we won't have an adequate balance in our future force structure to persecute a realist high intensity threat in the future where we are facing extensive anti-access threats. This kind of environment we'll need team approach for degrading and eventually destroying those threats and this will require more than a plethora of F-35s I'm afraid. I'm very worried that we are putting too much into the F-35 basket.
1/7/2009 2:50 PM CST
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