Boeing's F-15SE

[trax1]

This press release is from March but I just heard about it and saw that no one else posted about it, it's the new F-15 variant SE which stands for Silent Eagle, it's supposed to be a cost effective stealth fighter for international customers like Israel.

http://www.boeing.com/news/releases/2009/q1/090317a_nr.html

[shreck]

This press release is from March but I just heard about it and saw that no one else posted about it, it's the new F-15 variant SE which stands for Silent Eagle, it's supposed to be a cost effective stealth fighter for international customers like Israel.

http://www.boeing.com/news/releases/2009/q1/090317a_nr.html

(Image removed from quote.)
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Without modifying the "BIGMOUTH" intakes, how stealth could it possibly be ?

[eagl]

You'd be surprised at what some attention to detail can do to a radar cross section...

In any case, aviation week says that the prototype F-15SE is nearing flight test.  They have a handful of prospective customers so they're collecting requirements to put into the prototype before first flight.  The prototype will be a modded F-15E leased back from the USAF, and it won't have the canted vertical tails because those can be (relatively) easily tested in computer simulations.  The big test items will be the stealth treatments and the new conformal tanks with internal weapons carriage.  Things like AMRAAM and JDAM employment envelopes will be tested and proven before the package is offered for sale.

I personally think it's a great idea...  It would allow a relatively cheap yet proven and reliable airframe to participate in first-day strikes against full-up air defense systems.  Then once the IADS is beaten down a bit, you can swap out the stealthy conformals for the normal ones and double the weapons loadout after low RCS isn't needed anymore.

[Ack-Ack]

Is it just for export or will the USAF also be getting some of these planes?


ack-ack

[trax1]

Is it just for export or will the USAF also be getting some of these planes?


ack-ack

Haven't read anything that says will be using it, I think that USAF might feel that we already have fighters that do that role.

[Maverick]

Silent Eagle??? What, are they putting mufflers on that sucker? 

Having been around some fighter pilots I know they need one at times......        

[Babalonian]

I personally am really looking forward to this plane's debut.  Between the continueing development of the Super Hornet and the F-15SE, Boeing is doing very well for itself and its legacy.  If it lives up to expectations, it won't be any F-22, but pound-for-dollar it might be the best modern fighter given the economic climate of the world while still demanding the best weapon systems and competitive level of stealth technology from the aircraft manufacturers.

[eagl]

Is it just for export or will the USAF also be getting some of these planes?
ack-ack

Current USAF policy is to purchase no non-stealth manned combat aircraft.  I do not know if the F-15SE would count as stealthy under the policy, but I am convinced that once the shortcomings of the F-22 and F-35 with respect to deep strike are fully realized, we will be looking for something to purchase to fill that capability gap.  The F-15Es are going to wear out because we're using them quite heavily, and we will need replacements because nothing we are buying or developing right now comes even close to being a reasonable replacement.

[Sabre]

This varient can not be considered a "stealth" aircraft.  What they're applying here is "signature reduction"; i.e. reducing the range at which it can be successfully engaged, rather than trying to make it invisible to sensors.  About 85 percent of an objects RCS (radar cross section) is determined by shaping.  Shaping controls first-order specular reflections; put another way, the planform shape of the object is shaped in such a way that most of the radar energy striking it is reflected in a direction away from the radar transmitter/reciever.  There's little they can do for the F-15 in this regard, except for canting the tail fins (again, still minor compared to the planform) and storing ordnance internally (which will limit the striking power).  Second-order radar scattering comes from edges, seams, and cavities.  This is the other 15% of the RCS.  This is the area they can work on with the F-15.  What they're going for is reducing the signature just enough to allow the F-15 to deploy its own weapons against a target at a slightly greater range then it can be engaged at in return, or at least reduce the time an enemy has to engage it.

Of the second-order scattering features they can treated on the Eagle, the largest are the cockpit and the engine intakes.  The cockpit is the easier of the two to treat without affecting aerodynamic charactoristics (serrated window edges and metalizing the canopy, for example).  The intakes represent an order of magnitude more difficult problem; they are essentially giant wave guides that trap electromagnetic energy and then spew it back out in all directions.  The engine placement is something they can do nothing about, and there is not enough intake length to place effective radar baffels within it.  Cracks, gaps, and leading/trailing edges can be treated to attenuate their scattering somewhat.

If I were to take an educated guess (and I have that education ), I'd say they can get maybe a 20db reduction in signature.  That will reduce radar engagement ranges by about 40% to 50% against reasonably modern air defence/air-2-air systems.  Against some threats, that will be enough.  It then becomes a cost-benefit analysis to determine if the cost (production and maintenance) is worth it, given the reduced payload and (possibly) strike range of the modified aircraft.

[indy007]

Sabre, I've seen company claims the F-15SE RCS will be the maximum allowable by US export laws, same as the F-35 export models.

[Sabre]

Sabre, I've seen company claims the F-15SE RCS will be the maximum allowable by US export laws, same as the F-35 export models.

Hey there, Indy!  By design, the F-35 (even the export model) will beat the F-15SE in the stealth department. I've not seen the export law language covering this, so I can't speak to specifics.  I've also not seen the specs on the F-35 export model.  My guess is that the export control language doesn't simply state a single number (i.e. "Average RCS at X-band must be greater than or equal to XX.XXXXXdBm"), though there are probably some restrictions of that nature. It probably prohibits or limits specific items of low-observable technology (the technical term for stealth tech) that can be sold with the aircraft.  For instance, it probably limits what types of radar absorbing materials can be used, and perhaps prohibits the sale of various subsystems like the low-probability-of-intercept radar.

[eagl]

You are going to find that the people who know the details are the ones who will speak only in the broadest terms.  No offense to Sabre intended but while he is probably on the right track, if he *knew* he wouldn't have posted in this thread in the first place.  People who get even a taste of that world from an operational perspective are prevented from ever discussing it or even fairly loosely related topics, until they are specifically cleared.  And I know from experience that such clearance is almost never given even if a particular project becomes fully public.

Lots of guys in my line of work have entire weeks (months or years even) that simply never happened.  When any discussion in any forum (including the secure vault in the squadron) trends towards those events or topics, they shut up, pretend to be as ignorant as everyone else in the room, or if absolutely necessary they fall back on a pre-determined cover story and then report it as an incident to the security manager.  That's how it works, and that's why I quit visiting military forums like the strike eagle forums.

Personally, I'm willing to bet (in public) that the RCS reduction for the F-15SE is tactically significant, but I won't say why or how I think they'll achieve those objectives.  There are just too many technologies and techniques that can be applied, that may or may not be releasable.  And some things that are public knowledge have ramifications or applications that are not obvious, and of course that can't be discussed either.  So I think the plane will be worthwhile in a modern sort of aerial warfare environment including the F-15E's areas of specialty (deep conventional and nuke strike, interdiction, CAS, PGM employment in the worst environmental and threat conditions, etc), but I am not inclined to detail exactly why or how I think this will be true

[eagl]

Semi-funny story...

I met a 1Lt who came through pilot training here at Sheppard as one of my students.  After getting his commission, he had about a year of casual status before his pilot training class started and he was fortunate enough to be stationed at Nellis working with some of the flying squadrons there.  He was a smart kid straight out of school and still in an academic sort of mood, and he met another Lt there with the same sort of inclinations.  The two of them got their security clearances worked out so they could really dig deep into what their squadrons were doing, and they decided to use their time to write some research papers.  They wanted to be able to publish, so they thoroughly documented everything they did from multiple unclassified sources and tried to stay away from classified topics.

They wrote about 4 papers, each one more carefully crafted than the one before, and despite their best efforts all of their papers were immediately classified.  They published all right, but only a fraction of their intended audience would ever see their work because their analysis was significant.  They created new classified information from unclass information and some skull sweat.

Funny, this one student of mine still got a little worked up talking about it a year later because he really wanted to get his stuff published, and it never made it outside the classified journals.

[eagl]

Sabre, I've seen company claims the F-15SE RCS will be the maximum allowable by US export laws, same as the F-35 export models.

Sabre is right regarding the specifics we haven't read about, but also realize that certain technologies might themselves be export restricted no matter how effective they are on a particular plane.  Using some RCS reduction techniques on an F-15, even if not very effective, might spill the beans on how those techniques are used more effectively on other planes.  That could lead to a specific vulnerability in another system.

[Strip]

Funny, this one student of mine still got a little worked up talking about it a year later because he really wanted to get his stuff published, and it never made it outside the classified journals.

Not a bad thing to have on your resume though, even if the title reads "Classified" by John Doe in his jacket....

 

Strip