Moderator, check the thread title again…I think “comtemplate” should actually be “contemplate”. 😀

Cheers, Cola

Waves don’t get “disintegrated”, just weaker.

True.
English isn’t my native tongue, so I may have expressed myself somewhat clumsy. For all intents and purposes the carrier wave cease to perform its function and by that, I ment “disintegrate”.

Cheers, Cola

Halo.

It’s a bit OT, but I was wondering whether European nations have the ability to transport tanks (MBTs) by air?
It seems the A400M is too light for that purpose and I don’t know if any other European nation actually fielded a plane in C-17 class, apart from Russia…

Thx, Cola

LPI is nothing else than different techniques to lower probability of interception (not no interception) of RF systems (not limited to radars only). There are indeed even MSA and PESA systems such as the Captor or RBE2 which provide LPI characteristics as well, though not to the same extend as it is the case with the AN/APG-77. AESA simply provides the greatest potential here due its inherent advantage of beam agility and flexibility. Spudman’s point about the APG-79 is indeed a valid one. Many seem to believe that AESA = LPI, but that’s not the case, albeit every AESA provides the potential for comprehensive LPI characteristics, not every AESA system exploits them or at least not to the same extend as the APG-77 for example.
While LPI might work against several RWRs currently fitted it has to be taken into account that modern ESM systems become more and more capable and sensitive and that latest computer technology isn’t just used by radars but also EW suits. Believing that LPI will perfectly work against latest ESM systems is quite optimistic and relying on the hope it does is somewhat naive. It might or might not this can differ from system to system.

Exactly.

The AESA made possible for each pulse to be emitted at different frequency at variable PRF and with different power setting.
Now, other radars can accomplish the same principle, but with different results (usually reduced).
When I said, AESA made LPI possible, I ment LPI, as is known and called today. You just can’t achieve ALL of those 3 operating aspects, by using conventional antenna, IN THE SAME DEGREE as AESA can.

Cheers, Cola

LPI is a functioning part of the F-22 program, not a “concept”.

I think that part of you misconception comes from your perception that AESA = LPI. This is a wrong concept. I have not seen any docs that equate any European or Russian AESA with LPI (not even the APG-79 on the F-18E/F either).

Additionally, because the LPI signal is broken into hundreds of beams, the workload of the RWR is overloaded and cannot try and process all the low-strength beams.

The F-22 has been doing it for years without a problem against current gen RWRs.

Well, AESA made LPI possible and there’s no reason why other nations wouldn’t include it into its own radar programs, so F22 may have pioneered it, but it doesn’t mean others won’t use it.

Cheers, Cola

LPI is not new, it has been flying on the F-22 for years and is better in the F-35.

The F-35’s APG-81 has newer T/R AESA modules and a better backend than the LPI AESA APG-77 of the F-22.

The F-35 will maintain it’s LPI modes throughout it’s engagement and will not have an increased risk of detection just because it’s getting a vector.

Look at this Youtube vid that shows the APG-81 doing a scan out to 80nm. Bear in mind how fast teach target’s full vector is determined and that this is with hardware from 3 years ago.

Agreed. LPI is more of a concept than technology.
TWS in APG-63 is a granddad of modern LPI. You could have fired AMRAAM without CW illumination warning. However, the target would still see your emissions, but wouldn’t react thinking it’s been just ranged. That trick has worn out today, so a need for the new one rises.
Now, I don’t argue that today’s LPI is a step forward in radar development. I’m just trying to point out its shortcomings, because, like every other system, it has it’s weak spots too…and that goes for either American, Russian, or European LPI radars.

The thing with real (shooting) war is, that the enemy finds our weaknesses much sooner than we hope he would and once he does that, he hasn’t nobility or chivalry not to exploit them to the full extent.

Cheers, Cola

…LPI, LPI…the magic words…

No one really knows, what does it do, though.

From what material is available, it seems the general idea of LPI is to spread frequency and PRF over a wide range, thus disabling short-memory RWRs to detect it’s patterns.
Now, this is very useful when the stealth aircraft “pings” the space and helps the given radar avoid detection, indeed. That said, it’s obvious choice for LO aircraft.

However, to calculate the target’s flight vector, without which a missile can’t be launched and feed it to missile’s INS, a radar must establish a steady contact, no matter how short. So, this rules out “pinging”.

Now, the frequency agility and variable PRF of the LPI mode, sure reduces, or even makes impossible the emitting radar’s identification, BUT can’t hide the fact that something is “out there” operating within X-band (or border Ku or C band).
The chance of detection, rises with emitting time and tracking needed for mid-course trajectory update is more than likely to warn the target of impending danger.

To conclude, the LPI (from what has been published) presents an advantage in “search” operating mode and indeed helps a radar to see without being seen. However, in tracking mode it’s still required to reveal itself, at reduced probability of being identified, but not intercepted.

Finally, keep in mind that the RWRs, the LPI has been measured against, aren’t the latest technology, but rather pre-LPI era. The “answer” in RWR technology is yet to come.

Cheers, Cola

The JSF had considered the use of canards, but due mass balance issues, and aerodynamic balance problems, canards were rejected, so i really doubt having canards affect the RCS of a design, actually there is no hard evidence for that, just usual rumors
The ATF designs rejected canards most likely due supercruiser/drag issues

Well, I don’t know whether this is true or not, but this was the ONLY comment issued by DoD(?) regarding canards, that I’ve managed to find. If someone has more elaborate discussion of this matter, plz post a link. Thx.

In drag terms…well, EF has foreplanes and yet is able to fly Mach 1.5 with 4xAMRAAM and with 0.4 engine bypass opposed to F22’s “clean” Mach 1.72 with 0.2 bypass.
From this example it doesn’t appear the drag is a decisive element in EF’s configuration, but it may well be the “one too many” for F22.

Cheers, Cola