Amiga500“I can’t see the [expletive deleted] thing,” said RAAF Squadron Leader Stephen Chappell, exchange F-15 pilot in the 65th Aggressor Squadron. “It won’t let me put a weapons system on it, even when I can see it visually through the canopy. [Flying against the F-22] annoys the hell out of me.”
No doubt being totally taken out of context.
Probably cannot get a radar lock when able to see it coming in straight on (i.e. F-22’s lowest RCS).
To suggest that the F-22 cannot be tracked by an AIM-9 is simply ludicrous.
Amiga500It’s already been explained to the extent it can be without going into classified techniques. Rapid change of freqs and PRF waveforms(and multitudes of simultaneous beams with all of these characteristics), very narrow beams(i.e. 2 degrees by 2 degrees or less), lower power, etc…
Leaving aside narrow beams (as the wave is going to have to be directed at the target aircraft to get a return).
Fundamentally it reduces to frequency and amplitude – two ways to manipulate those are frequency modulation and phase modulation. No power = no range – that is still a fundamental, the power is there, it is just hidden.
Applying various higher order spectral analysis techniques solves the problem as the numerical patterns and manipulations used to hide the LPI radar waveform stand out.
Yes, a (4th gen aircraft) wideband RWR will be entirely useless. But, an example of an already marketed solution to the LPI problem is the Thales Vigile system.
Anyone continuing to advance the notion that an LPI radar will operate with impunity against a future technically advanced opponent (or even the likes of the current Rafale) is simply detached from reality.
Amiga500And I also think that LPI works both ways – the carrier’s LPI radar will be likely detected at shorter disstance due to varying frequency and varying outpout power) but the radar’s detection range should also be considerably reduced.
That is the case. 🙂
Amiga500Yes, you do know these things. In the AESA radar each T/R module sends a ping with a certain frequency to a specified location. So there are two options:
There is no return from X direction, Y freq. and at Z time.
or
There is a return from X direction, Y freq ad Z time.If you know what, where and when to expect you can easily filter it from the surrounding noise.
Each T/R module sends a ping at a certain frequency… at what amplitude?
As I said before, power is a function of the amplitude squared (at a given frequency).
No power = no range.
That is a fundamental issue you have yet to explain the solution to.
[Of course, there are ways and means, but you have yet to explain them – then you have to explain how you hide the characteristics of the solutions to limited power from a modern RWR]
Amiga500Or anywhere else apparently.
Usually 😀
Amiga500Er, if you’re unaware of this basic fact, why are you even bothering to comment? Anybody could google and discover it does have navigation in about 3 seconds. I have to wonder if you’ve ever actually read anything at all about the missile.
‘cos I couldn’t be arsed googling.
Some of us don’t get our knowledge from google. 😉
Amiga500So on RWR it may look like a noise, but when you know that a noise of X frequency, from Y direction and on Z time is coming – you know that’s your radar ping comig back to you.
The “noise” will need to be of very similar amplitude to the rest of the frequency range.
Thus, it will be very, very hard to get a decent return with such a low power wave (power/irradiance being a function of the amplitude^2).
A series of lower power waves can be used to extend range, but you then are increasing a series of frequencies above background levels.
If the LPI radar used identical frequencies and amplitudes to background noise, then it would be swamped by white noise, with absolutely no way of discerning what was real and what was not. It works both ways.
Amiga500The amount of ignorance packed into this post on how AMRAAM works makes any reply I could make redundant.
None of that post was talking specifically about AMRAAM. There was hypothetical talk about what AMRAAM could do if it has navigation.
It was talking about missiles, and their historical methods.
People on here like to throw out things like data link and mid-course updates, without any consideration for what they might actually be. Is it a vector relative to the missiles current orientation? Is it 2 3d points in space and the missile does the calculations for intercept?
To provide info without using the missile seeker head, you need 3 pieces of data, the target location, the missile location and the missile orientation.
To reduce that to a relative vector the guiding aircraft needs to know where the missile is mid course. Now, unless the missile is emitting and can be picked up with RWR, then the launch/guide aircraft needs to use its radar.
With navigation, it can be done passively. Without, it cannot.
Amiga500The AN/ALR-94 provides passive information on a target which can be passed on to the radar to perform more precise targeting
Yeap. Cue the radar, which cues the missile.
or passed on to the missile itself to perform a ‘passive’ shot. As I stated before, passive shots can be done but their pk is much lower than with a proper target lock.
Can it?
Assuming the AMRAAM can track its movements after launch (navigational guidance), so can calculate where it is relative to the launch aircraft… then from the info provided via the datalink it can orientate itself to actually head toward the target, then there is no reason a passive launch cannot be made.
However, the reason radar has traditionally been used is to avoid all that, and give the missile radar head a return (using the launch aircraft radar as a transmitter and the missile head as a reciever), so it just has to worry about moving to that dot.
But the former adds a helluva lot of complexity to the missile… complexity = added weight. Probably a trade-off that is worth making, but I dunno if they have or not. (Anyone?)
Amiga500An AMRAAM shot can be made several ways- the F-22 can illuminate the target until impact, it(or a third party) can provide datalink info until the missile is close enough to go active, a third party can provide the guidance, it can be fired using HOJ,
Yeap. That is all common knowledge.
and it can be fired using information from the ALR-94.
But can it be fired exclusively on information from the RWR….?
That is what I mean by “cue”.
To date, there is absolutely nothing that would support the notion it could be fired using ONLY the ALR-94.
The -C7 AMRAAM is by no means a short ranged missile, and the -D will be even longer ranged.
Who said it was? I was talking about IR AAMs.
Amiga500No one is saying LPI is undetectable, but the probability is low.
Yeap… low.
Various above-background pulses coming from a one direction… oh, and that direction is above the horizon, and its position is moving supersonically. 🙂
LPI is a marketing gimic used by LM etc to get more money from Congress. It is something that “differentiates” the F-22 and F-35 from the teens, i.e. another reason to pay out for the ‘latest and greatest’.
It will have its uses, against old aircraft (as used by say the Serbians or Iraqis… i.e. the last enemies in air wars that the USAF has had to fight in the previous… 20? years). But it will not be much use against an opponent on a similar technical level.
Amiga500Even if the radio waves look like a noise, a background radiation?
It cannot by definition be of identical amplitudes to background noise.
If it was, then there would be no signal for the receiving radar to pick up on… apart from background noise.
Amiga500The similar size Su-47 was ~19 tons empty equipped. The present T-50 is still without radar, weapons and some other features missing may reach 22 tons in NTOW with a modest fuel load. Maybe forced by the lower thrust engines to get a more realistic behavior.
Surely they will be using various forms of ballast to evaluate performance!
No point looking at stability & control if your short 200kgs in the nose!!!
Amiga500yes it can:
High-priority emitters — such as fighter aircraft at close range — can be tracked in real time by the ALR-94. In this mode, called narrowband interleaved search and track (NBILST), the radar is used only to provide precise range and velocity data to set up a missile attack. If a hostile aircraft is injudicious in its use of radar, the ALR-94 may provide nearly all the information necessary to launch an AIM-120 AMRAAM air-to-air missile (AAM) and guide it to impact, making it virtually an anti-radiation AAM.
Of course, there are some targets that do not emit signals. “We prefer it that way, because he’s dumb,” remarked one Boeing engineer. In this case, the F-22 can use its LPI features to track the target — which is not a threat unless another radar is tracking the F-22 and datalinking information to the “quiet” aircraft — and can, if necessary, identify it.
Was all going well until the follow-on paragraph (bolded).
Bill Sweetman is a journalist I respect, but if he really thinks LPI is non-detectable…
(He is probably just regurgitating what Boeing/LM/whomever said)
Oh, and what are the implications of the underlined bit? A quick active pulse directed to the target… then launch?
Amiga500Not true. Even the mighty AN/ALR-94 is intended to CUE the radar rather than be the actual targeting device itself. Of course if you are willing (or feel the need to in order to reduce the propability of being detected yourself) you CAN go for a “passive” shot but expect your pk to be rather poor compared to a proper ‘active target lock’ shot.
Of course, the AN/ALR-94 cannot cue a radar guided AAM.
IF the F-22 had IRST, and IF the F-22 had long ranged IR AAMs… like say a R-27ET… then cues can be made from passive sensors.
Be careful applying sweeping generalisations. 🙂
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