Red somewhere that EF was the only aircraft in Singaporean contest that managed to take out 3 F16s and fly away, but later lost due the lack of A/G.
Obviously F15SG has been inaugurated politically, although it didn’t even passed the AA requirement.

Halo Dork Matter.
I’ve recompiled some answers, for easier reading, but tried not to loose context. If I left something out, I apologize, since there’s was really a lot of (good :)) text.

COMPILED STEALTH TOPIC:
-It’s a combination of shaping characteristics that makes newer VLO aircraft look more continuously “dull” to radar rather than spiky. In turn, the spikes (concentrated by planform alignment) are larger but fewer in number. The idea is that you’re less likely to be able to detect the newer stealth planes from a useful range, even momentarily. It’s not that the F-117 was designed according to different principles, but in a sense its finite facets are a lower-resolution version of the smooth contours used on the B-2, F-22, and F-35.
-You’d want to be able to calculate the RCS of a design from many angles before building it, which is limited by computer power.
-The B-2’s (and the F-22’s and the F-35’s for that matter) curved surfaces can be viewed as an infinite number of individual facets (approximated by a large number of facets or by formulas that work with curves directly).
I think you’re right, but the true average RCS doesn’t matter as much as what works best for most combat scenarios.
-It’s kind of a mystery to me, too, but basically it’s a matter of finding shapes that exploit how radio-frequency electromagnetic waves are converted into electrical currents that flow on the surface. The aircraft’s skin is a large antenna, really, that will convert waves into currents and create waves from these currents that form the reflection. What stealth designers do in a faceted design, for example, is carefully place the facets–which are each a planar antenna individually–in certain angles relative to others that somehow affects how their combined currents finally form the reflection. Curved shapes could simply be viewed as having an infinite number of such facets. This may be a fancy way of saying nothing new, or maybe when looking at this issue in this way, there is some kind of secret method for ensuring that radio waves do not return from the direction they originally came.

All of those are valid points 🙂 and I’d just like to add a few things.

In my previous post I used the example with sphere and cube. The sphere has all aspect equal RCS. The cube is radar invisible at all aspects, except those six perpendicular on it’s flat sides. The overall refection by cube and sphere is the same, although differently distributed.
Now, it’s also true that the sphere (as a consequence of curvature) has lower RCS compared to cube’s flat side, because of smaller reflecting area, which is infinitely small for a sphere.
However, the actual reflection surface is determined by radio wavelength as well and although sphere has, theoretically, infinitely smaller RCS compared to flat surface, in reality it isn’t so.
Let’s take a common X-band (GHz) aircraft radar. It has a wavelength expressed in centimeters. If such radar illuminates a nonLO aircraft, the reflecting surfaces, best qualified to return the echo, will be in order of a half the pulse’s wavelength (same principle as for antennae) and a nonLO (slick curved airframe optimized for performance) aircraft has plenty of them. In the end the return isn’t actually a single return, but the sum of all small (centimeter order) perpendicular surfaces of targeted plane, that returned the radio energy.
So, the current radar operating band has been chosen on a basis of shape of aircraft it is required to detect and the level of precision it’s been required to maintain. Now, if F117 is that unlucky to manages to return the signal, that return won’t be all that stronger (if at all) than common reflection from curved surfaces.
In all other cases, the F117 won’t return anything and will, just slip by. I assume here, the RAM will pick up parasite harmonics and that’s common feature even for nonLO aircraft.
The only case in which F117’s flat belly is in worse position than fractured one, is when it gets illuminated and seen by a longwave radar. This is because it has larger surfaces and therefore reflects less scattered signal back.
Serbians exploited that and used NEVA’s 144MHz (~2 m wavelength) radar to find it and shoot it down, back in 1999.
However, F22 has large belly and wings shape as well and maybe even larger than F117 (in total figure), so it’s difficult to to say how well it would go against VHF radar.

One other problem with UHF/VHF is that it has so large wavelength that it resonates with the today’s combat aircraft sized object, regardless of LO. This is why B2 has been given anechoic chambers. Unfortunately, you cant fit one (for VHF wavelengths) on smaller fighters, due space constrains.
Now, you mentioned a skin acting as antenna. (digression: I believe it is a next step in RWR tech development).
Actually, the skin induction is unavoidable in VHF/UHF bands and that’s called “resonance/Raleigh scattering region”, when the plane starts to “glow”, etc,…
Anyway, you’re right that such phenomenons must be investigated and eliminated properly, since they may actually add five times more RCS than the aircraft actually has!

Finally, I find it difficult to agree with USAF/DoD claim the F22 is more stealthy than F117, per se.
In reality, that may well be true, because the F22 will fight according to a pattern that gives it a best chance of success and some, less stealthy, features will be visible in unimportant (design estimated) number of occasions.
However, such aspects aren’t non-existing and those are the milestones of anti-LO measures.

-True, but I think that the designers made the F-22 as stealthy as they could for a fast, agile fighter.

Precisely. It’s always a trade off.

…there’s a big difference between designing all of these features together cohesively from the start and either retrofitting stealth later or not taking it into consideration at all. With careful design and a lot of work, you might be able to get the first 90% of the benefit of one feature at the cost of only 10% of the other, just as an arbitrary example.

Agreed. You can’t really “retrofit” a plane to make it as stealthy like the one shaped for stealth in the beginning.

COMPILED LPI TOPIC:
-I realize that this is not a strong statement by any means, but that’s only because I’m not privy to the secrets of stealth technology. I’m just trying to get people to open their minds a little bit to the possibilities, like when I compared CDMA cell phones and LPI radar earlier. Now, an LPI radar would not spread its signal in the same manner at all, but broadly similar principles apply. Read up on CDMA if you’re not familiar with this widely-used yet little understood (among the public) technology–it may astound you with what can be done in seeming defiance of physics (it does not defy physics, of course–it’s just a different way of looking at information).
-…but if you think about it, that’s how LPI radar, for example, would work–send out a signal that looks like low-powered, jumbled noise across many frequencies. To other receivers, it looks like random noise, but the radar knows exactly how to extract meaningful, accurate information using mathematical techniques and parameters that are specific to both the radar and each individual pulse. It’s like a form of encryption! Now that we’re all somewhat familiar with how physics can seemingly (to the uninitiated) be worked around with mathematics, maybe we can be a bit more open-minded about other technologies that may seem impossible because of something we don’t know but a few other people do, such as stealth technology.

I did some more research on LPI topic and here’s what I found…
The LPI’s most prominent operating mode is low-power tracking. This mode, once it measured the distance to the target, switches to minimal required power to track the given (measured) RCS.
Now, we know that RWR antennae and operating protocols of the last (not today’s/future) generation, have been conceived back in 80s with appearance of TWS. So, such an RWR is designed to monitor radio traffic in somewhat broader bandwidth than the radar. Moreover, there are usually, just four antennae used to cover 360° of space around the aircraft. Such broadband and wide-angled antennae have lower gain, compared to radar. The LPI radar exploits this and the fact that it always has maximum gain (focus), while a single RWR antenna must cover a quarter of a sphere at once. So, LPI can indeed lower it’s power output to descend below ALR-56 (F15) threshold and remain undetected and that’s the basis of LPI’s working idea.
However, during such LPI tracking, radar can’t change power output (can’t go below it’s own threshold and can’t risk entering RWR’s threshold) and pulse frequency (because different frequencies at same power setting, measure different ranges) and constant PRF would be preferable too (in order to keep things as simple as possible).

Ok, so what we have here is a constant, but weak signal, tracking unsuspecting RWR.
First and foremost, such LPI tracking is based on a premise the RWR antenna is insufficiently sensitive to detect radar’s emissions, due whatever reasons. That may well be true for 70s/80s RWRs, but since radar evolved, it’d be unrealistic to assume the RWR didn’t. You can always put more sensitive antenna, but it’s a matter of filtering (hardware and software) how successfully you’ll be able to extract information.
Second, such weak signal is much more easy to jam than the strong steady one (it’s like flying on the edge of detection range all the time). It may be even possible to jam in short bursts to prevent HOJ tracking, etc,…
Third, designer can always include more high gain fixed antennae in an EW suit, or can make “active” RWR layout, with fewer high-gain antennae, but with small servos, which actively scan the given quadrant of space.

I’m rather convinced that actual EW suit designers of today, came up with more than one creative solution against today’s LPI, because if they didn’t LPI mode wouldn’t been made public. 😉

I apologize for rambling on a seemingly unrelated topic…

“Don’t” and your text isn’t rambling, but very good with appropriate parables for less imaginative :). It’s all related indeed and sometimes one needs to go far to prove the point.

As for the poor rearward view, perhaps they could have gone the “Clint Eastwood MiG-31 Firefox” way? Rearward facing cameras.;)

>>LOL

I think such intake position has problems with engine airflow at high AoA, as well. But then again, judging by the wing’s chord, I’d say P2107 didn’t have spectacular AoA abilities, anyway.
The wing reminds me of F-16’s wing, except it has angled trailing edge. It’s possible that the wing is the prime contributor to good sustained turn rate, since it less draggy (like F16’s wing too), than Gripen’s production delta.

It’s very interesting layout and if you manage to find any background data or design concept why did designers even bothered to build this layout, be sure to post it…:)

Shape isn’t everything, RAM and RAS which has evolved over the time, materials used in the airframe, antenna design, assembly accuracy etc. all matters.

Agreed. The trouble is I don’t know how much have those measures evolved and from reports I’ve red it seems it’s still a minor portion of a complete LO solution…

Being a flying wing with no draggy tail or control surfaces at work, i actually think B-2 is a better aerodynamic design then F-22 in subsonic plain flight, tho it is naturally totally out-classed in agility and can’t get supersonic.
The lack of tail or control surfaces at work also gives much less area that can reflect radar back, then it is coated with a huge amount of RAM and probably has RAS, probably giving it the best all aspect “stealth” characteristics of the lot, tho definitely giving it the worst maintenance and availability cost characteristics.
I wonder if it is of any particular use to compare the different designs tho, as they all have different missions-requirements.

Exactly.
B2 is probably the “slickest” (subsonic) LO plane operating today, indeed.
As for comparing different type aircraft, the trouble is there isn’t a line of stealth fighters, bombers, etc, but one of each and so we need to manage with what what we have :).

http://www.airandspacemagazine.com/ASM/Mag/Supp/AM97/Stealth.html
F-35A/B/C____-30.0db =0.001m²
PAK-FA ______-30.0db =0.001m²
F-117A_______-35.0db =0.0005m²
F-22A/B-2A___-40.0db =0.0001m²
Since then the USAF said the F-22A is more stealthy than the specifications called for.

Unfortunately, the link has been broken…

Anyway, I don’t argue the posted numbers. You see that difference between F22 and F117 is marginal. However, RCS isn’t a fixed number, but a dynamic value and the given figures, mean exactly what? Front RCS, rear RCS, or what RCS?? It most definitely isn’t an average RCS…

Now, you mentioned continuous curvature stealth. This is exactly the opposite to known principles of radio waves spread. However, designers may have well exploit some “blind spot” nobody was counting on and if you have some more insight into these techniques, I’d appreciate if you’d share them :). Thx.

The USAF has stated that the F-22A has less drag than ANY previous USAF aircraft! Technology moves on!

These are the most dreaded words for any self-conscious being. Yes technology moves on, BUT THE AIR DOESN’T :).

Precisely. You hit all the vital spots.
Each and every one of those people has some agenda and each and every one is telling just a piece of truth that suits his needs.

However, you’re right.
We do need data and I don’t mind quoting anyone (I watched Bessley’s materials over and over again, myself).
What I do mind however is, when some people “get into the battle gear” and interpret those quotes any way they like, with little or no argumentation, at all.
That’s all.

It’s really funny, how some people imagine weapon manufacturers :D…

Every manufacturer is a trader as well and tries to sell produced weapons.
Well, we all know who and what the traders are (no offense) and traders themselves know that too.

This is why they invented contracts!

I mean, it’s romantic to perceive LM as “altar of justice and honesty” and LM’s PR division, is working around the clock to make such impression, indeed.
In reality they’re just merchants trying to invest as little as they can and sell as expensive as they can get away with.

Now, I’m not anti-American here, but just repeating well known social facts. Make no mistake, same goes for Russian and other traders, too.

Here’s an example from Slovenia. Some years ago, they bought Galil 5.56 rifles from IDF. During the first live fire, rifles blew up and killed a few Slovenian soldiers! Further inquiry revealed poor material and haste assembly were the cause of that.
I doubt IDF put a declaration tag on rifles blowing up!, although they knew very well what they were selling and what MAY happen. Now, IDF didn’t kill those soldiers on purpose, but they hoped everything will go well and nobody will notice and they’ll earn themselves a few dollars more…

That’s who the weapon manufacturers are and Flex covered the topic very well.

Now, as for Mr.Beesley, he’s a test pilot and also an LM employee>if I understood correctly. He speaks what has been cleared by LM (I though that was a common knowledge, but it seems that it needs to be emphasized, after all).
As such (LM’s employee), his statements can’t be taken into account, since that would be a legislation category > “conflict of interests”, right?

However, it’s one thing to quote him, but it’s something completely else to imply what he “really” meant, without some serious scientific argument and especially since he isn’t here to clarify/explain.
The paradox is that he doesn’t even invent the things he says, but LM’s PR div, so F35 fanboys, should really stop dragging Mr.Beesley’s name around. It’s a distasteful, at least.

Worse than a cruise missile? Or an ICBM?

You have more time to call it back.

True.
But then again, guys with “joysticks” may get the ideas (Dr.Strangelove) and “take one, just in case” (and justify it with rapid response ability) on non-delivery flights…

Ok…Let’s repeat how does radio detection and ranging (RADAR) works in the first place…

1) Radar antenna emits a pulse in emitting portion of scanning

2) Radar antenna receives a pulse in listening portion of scanning (if there IS a reflecting surface/target) or doesn’t receive the pulse (if there ISN’T reflecting surface/target)

“The radar (radio) pulse always reflects out at the same angle it came in.” This is the fundamental rule around which the LO concept has been developed.
According to the law of energy-consistency, you can’t just evaporate ALL of radio energy and thereby hide your presence, so you need specific shaping.

So, what LO aircraft do is, they deflect and effectively disperse incoming radio waves at all angles, except perpendicular ones. This is because the radar that is currently illuminating the aircraft can’t hear echoes other than perpendicular ones, due it’s size limitations.
RAM material is being used for attenuating the remains of such deflected and dispersed radio emission and contribute to a small degree to overall LO profile.

So, what does it mean when it’s been said that F-22 (got no data on F35) has been built for “36°-39° angle”???

This means that the overall LO shaping has been done against an angle of 36-39 degrees below F22’s horizontal plane and this is the angle at which US DoD decided the SAMs and other aircraft are the most threatening. From this information, we can easily conclude that F22’s operating ceiling will be above anything else (exposing its LO belly), including other aircraft and that corresponds with F22’s official performance figures and flight tactics, etc, etc,…
However, this also means that, in order to maintain required performance (especially at high AoA), the F22 has reduced LO in the upper hemisphere of the aircraft. If we compare ALL ASPECT LO of F117 and F22, we’ll see the F117 is more LO overall, meaning it has smaller all-aspect RCS.
The consequence is, the F117 has poor aerodynamic performance.

RCS (radar cross section) isn’t a fixed number for a given aircraft, but the sum of perpendicular surfaces at given angle (also called aspect) and therefore dynamic by definition.

To conclude, F117 has more flat surfaces than F22, meaning it has less perpendicular angles and therefore reflects less radio energy at perpendicular angles, which makes it more LO.
EXAMPLE: a cube has 6 perpendicular angles, while a ball has infinite. That makes cube more stealthy, but it also makes ball more aerodynamic, because it offers less interrupted air stream.

So, it doesn’t matter if the F117 is older than F22. It’s not automatically more austere, in terms of LO.

…it’s good to keep in mind above stated, when discussing stealth/radar issues…

Cheers, Cola