I have a question for anyone who can accurately answer. In A2A combat, which is the superior aircraft, the F-22 or the SU-30MK?

Posted by: Arthuraria at March 13, 2008 10:28 AM

Big G: Please don't try to act knowledgable about technology you don't understand.

Posted by: CC at June 9, 2007 02:17 AM

What role would AWACS play in such a situation? Wouldn't an AWACS, with illuminating radar, allow the F-22 to see the enemy without the F-22 having to turn its own radar on?

Posted by: Benjamin Fan at November 1, 2006 01:45 PM

Can some-one explain how you can be sure of seeing what's out there by turning on your narrow-beam flashlight for a millisecond in a darkened warehouse?
In other words, the F-22's radar is fine if you already know where to point your beam, but a problem if you don't.
And am I alone in finding it fishy that the Air Force finds a brilliant new role for the F-22 every time the previous one is disproven?

That's the advantage AESA radar provides over previous tech. A F-15 could take up to 15 seconds to scan a patch of sky in front of it, making its radar emissions easy to detect.. by comaprison, a raptor can scan the same patch of sky nearly instantaneously using relatively low-powered radar frequencies that are much more difficult to detect.

Posted by: mon at September 10, 2006 07:35 PM

Can some-one explain how you can be sure of seeing what's out there by turning on your narrow-beam flashlight for a millisecond in a darkened warehouse?
In other words, the F-22's radar is fine if you already know where to point your beam, but a problem if you don't.
And am I alone in finding it fishy that the Air Force finds a brilliant new role for the F-22 every time the previous one is disproven?

Posted by: Big G at August 18, 2006 11:56 AM

I think its more important to imagine the next war. Our enemies are smart and if there is a simple fix to the detection of f22 radar problem, I think they will find it and it will be common quickly. In addition RWR is a cheaper technology readily deployable to existing fighters. Imagine if china develops an advanced rwr and it costs $150,000. it will be deployed..

However in the next major airwar, Im imagining AWACS dominating the battlesky..and f22's not needing to radiate...well maybe briefly before final targeting solution...
sounds worth it...

Posted by: Aaron at August 16, 2006 01:33 AM

I'm no expert on this, btu I think that both spread-spectrum and UWB radars transmit on multiple frequencies; the frequency spread for the former is just vastly narrower and therefore much easier to find. I believe frequency-hopping radars send strong, very narrowly tuned pulses at different frequencies for each pulse (or something along those lines).

Finding noise sources directionally would certainly counter UWB noise radars. The processing requirements would be heavy, though (making it hard to track fast-moving sources) and it is unclear how powerful the noise signals would have to be compared to background sources, natural or otherwise. If our processing capabilities are good enough, the cross-correlation in UWB noise radars could allow low power signals that would be very hard to find. If not, then looking for loud noise sources would work well.

Posted by: Eric Hundman at August 15, 2006 02:57 PM

As far as my (admittedly ignorant) understanding goes:

Spread spectrum frequency hops with a pseudo-random permutation. Its hopefully cryptographically strong, so its unpredictible. From the point of view of other spread spectrum receivers/senders, congestion just increases the noise floor.

The ultra-wide-band stuff adds two things: operates over a wider frequency range, and you start to send on multiple frequencies at the same time. Both make you look more like noise.

But both improvements STILL make you a "point noise source".

Given an antenna array rather than a single antenna, and signal processing magic, you should be able to see that "this is a point noise source". and it has to be a pretty high power point-noise source.

And if you see a point noise source pulsing on and off, moving at mach 1.5 and 40,000 feet, it might be a good candidate...

Posted by: Nicholas Weaver at August 15, 2006 12:33 PM

Nicholas, a question:

My research on noise radar indicated that spread spectrum was several orders of magnitude narrower (in frequency spread) than ultra-wideband "noise radars." The latter are actually modulated to be random, but this incurs some significant costs in processing time.

This leads me to believe that traditional radar detectors (which look for powerful, relatively focused peaks) could still detect spread-spectrum radars relatively easily. I agree that a switch to directional radar detection would be necessary if truly noiselike radars became widespread (though even the proponents of noise radar say it is very difficult to put on fast-moving platforms right now), but I'm not sure that would be required for current spread-spectrum radars. What do you think?

Posted by: Eric Hundman at August 15, 2006 10:21 AM

A possible problem is with the F22, both on the radar side and the stealth side, is its vulnerable to computation...

It is fundimentally hard to detect a spread-spectrum radar, but doable. Spread spectrum signals, unless you know the key, look like noise radiators.

So what the opponent needs to look for is a wide-band, point noise source which goes from "off" to "on" very quickly and back off. Annoying, but its JUST signal processing.

Additionally, the radar detector has a huge advantage here. The power of the radar signal dissipates at O(R^2) to the radar detector. But the received power back at the radar dissipates at O(R^4).

The chinese haven't done it yet because they haven't needed to, but my bet is that as the F22 and, more importantly, future AWACS successors come online, you will start seeing phased antenna arrays designed to detect wideband noise sources: voila, an F22 radar detector/locator/targeter. Most of the problem is just computation, and parallel computation at that.

Spending a good 1/4-1/3 of a billion dollars an airframe, based on a system where the countermeasures just involve more computing can be a problem.

The solution is, of course, passive radar. Well, the solution for the other guys.

Rather than using the transmitter and receiver at the same place, use multiple transmitters which are broadcasting their location, have the receiver(s) know where they are, and then receive the signals, use a bunch of DSP processing to understand the reflected signals: multipath radar. There have been prototypes which use cellphone towers to track aircraft AND CARS.

This has a huge advantage as all the smarts that you care about, the receiving radar, is not broadcasting at all.

But the big problem, this technique is anti-stealth. There are actually three different kinds of radar stealth: Absorbtion, scattering, and transparency.

Absorbtion and transparency are robust against multipath radar. And there are such stealth aircraft: the piper cub, for one, doesn't show up very well on radar.

And US stealth aircraft rely somewhat on absorbtion: special paints with iron beads and other technologies. But the key to US stealth is scattering.

There are no concave features on something like the F22, F117, B2, SR-71, etc. They are all designed to reflect radar signals away. And it is very effective as long as two conditions hold:

a: No external stores. This is one of the factors which really limits the F22's capacity as a ground pounder, you can only fit two bombs in the internal bays. If you ever wanted to haul more (e.g. Ferry mode), you have to give up on stealth.

b: The radar receiver and the sender are co-located. WHich is true of conventional radar, but not true for multipath radar. Thus multipath radar can potentially detect modern stealth aircraft extremely well.

Posted by: Nicholas Weaver at August 15, 2006 09:18 AM

Data links in the style of JTIDS/Link 16 have led to established techniques for using one aircraft as a "designated radiator" and sharing its tracks with distant "shooter" aircraft. Mr. Skinner has a point- existing airframes can already do this. I think the advangage of the F-22 lies in stealthiness; can remain undetected much longer than F-16s or Tornados. LPI radar on the radiating aircraft can only improve the odds!

Posted by: TrustButVerify at August 15, 2006 12:46 AM

Sounds like many have no idea how RWR's work. At best they provide a rough estimate of the direction and distance of a threat radar. The RWR is designed to give threat warning and cannot provide the kind of accurate targeting information required to employ a weapon in response. That's provided the RWR is able to detect and discriminate the radar's characteristics. The APG-77 is almost certainly a LPI radar (http://en.wikipedia.org/wiki/Low_probability_of_intercept) which makes RWR detection difficult.

So, assuming the threat aircraft has a very advanced RWR that can detect the APG-77, the pilot will still have to use his/her own radar to search for the Raptor. By the time it does, one of the Raptor's missiles will probably be a few seconds away from destroying the threat aircraft.

With the Raptor's stealth features and unmatched mobility, it excels at ambushing and destroying other aircraft before they even realize the Raptor is there. Pierre Sprey is living in the 1980's - radar technology has come a long way.

Posted by: Andy at August 15, 2006 12:02 AM

Skinner,
Russia has produced several updated variants of it's fighters, and has had long-running programs to replace its current airframes with all-new fifth-gen fighters. Should funding be made available, they could be producing such designs in 3-5 years. China is developing fighters based on tech learned/bought/stolen from Russia and the West, including a stealth project I believe they call J-X. Both countries sell exstensively to countries whith a low opinion of our foreign policy.

Posted by: Moose at August 14, 2006 08:15 PM

Good Afternoon David,

Good stories about the F-22 Raptor, but I'm, still left with two nagging questiosn about the F-22 Raptor.

First: what can the F-22 do that current fighters can't do with the same electronics and weapons and why does it need dong?

Second: who is the F-22 ment to be used on? The Russians haven't produced a new fighter since they were the old Soviet Union, the Chinese are still stuck on cloaning the old Soviet Sukhoi SU-37 and the Indians are chaseing the Chinese in the race to make a better SU-37.

All that I can see is that the F-22 is setting the benchmark for the next superpower (whom ever and when that may be) who wants to get into a fighter race. Viewing the current political landsape when that happens the F-22 will be another aging warplane, with most of it's production sitting out in the desert at Davis Mt.

ALLONS,
Byron Skinner

Posted by: Byron Skinner at August 14, 2006 06:29 PM

>In a fight against other airplanes, the Lockheed Martin F-22A Raptor's stealth capabilities are
>useless, claims noted fighter designer Pierre Sprey, since the Raptor must radiate to detect
>the enemy

WAAAHAHAHAHAH! Tell this guy what the role of AWACS is. Why would F-22A always have to use its own radar.

Posted by: pedestrian at August 14, 2006 05:32 PM

The F-22’s radar isn’t integrated into the skin of the aircraft. The APG-77 is integrated into the nose of the aircraft, just like most other modern fighters. The only difference with the F-22 is that the nose cone acts as a bandpass filter, allowing only selective frequencies to pass. This lets the F-22 radar see out, but keeps enemy radar from entering and compromising the stealth signature of the airplane.

I don’t see why using two F-22s is a problem, as most fighters don’t operate by themselves anyway. If you use two aircraft as I described before, once the forward aircraft is out of missiles, you simply switch aircraft positions and repeat. You would only use this technique when AWACs data is not available. In defensive mode, where AWACs feed the F-22s radar data, you can utilize all of your F-22s in full stealth mode.

The F-22 is expensive at the 130 million mark (rough flyaway cost). New build F-15s for Singapore and South Korea are costing about 100 million each. Is the incremental cost of 30 million worth having both stealth and supercruise? In a shooting war with a competent adversary, I think these features could make a huge difference.

Posted by: CardEE at August 14, 2006 05:31 PM

Correct me if I am wrong, but don't most long range, deep penetrators most fly with their radar switched off anyways? Couldn't they just get targeting information from an AWACS (or in the future, an ISIS blimp) fed targeting information to them via their satellite link?

I've only sat through a few USAF strategic planning briefings, but my impression was that they are still interested in pursuing their Cold War-era vision: God-like mobile radars in the rear uploading pictures of the battlefield to wings of stealthy air-to-air fighters operating behind enemy lines. The F-22 would fit that mold pretty well.

Posted by: Robot Economist at August 14, 2006 05:22 PM

Re: Kolya's question

Multipath (many different artificial RF sources) and passive (using natural RF soruces) radars are in development, though I don't know much about how well-developed they are. So far as I know they are not ready for widespread use yet, which is probably why the F-22 does not incorporate them. Since the F-22's radar is integrated into the skin of the plane, my guess is it would be extremely difficult to rig it to detect other radar sources.

The tandem F-22 idea is interesting, though it seems silly to require TWO ridiculously expensive planes to give one of them true stealth capabilities.

Posted by: Eric Hundman at August 14, 2006 04:43 PM

I believe the F-22 uses the Northrup Grumman APG-77 AESA, not the Raytheon APG-79.

Even when RWR technology is able to reliable locate the APG-77, stealth is not useless. Since the F-22s share information over encrypted satellite links, two Raptors could work in tandem, one flying miles behind the other. The rear Raptor could searchlight its radar and pass targeting data to the front Raptor (which retains the full elements of stealth).

Posted by: CardEE at August 14, 2006 04:39 PM

Might it also be possible for another source to do the radiating - like a pilotless drone for example? I imagine the technology exists that if a reciever in a F22 (or another kind of aircraft) knows the coordinates of the source doing the radiating, it might be able to compute the coordinates of the targets radiating return signals. The drone could encode its location in an encrypted signal broadcast to the F22's. If the drones are cheap it does not matter if they are shot down by the enemy. Perhaps the same could be done with sonar.

Posted by: Kolya at August 14, 2006 04:27 PM

For now, it *may* be hard to detect frequency-hopping radars like those the F-22 uses, though I believe this is more due to the design of older radar detectors rather than technical difficulty. It would be cheap (compared with the cost of an F-22) to retrofit old jets with new detectors--and that will negate one of the biggest advantages of the F-22. The F-22 radar signals, even if short, still have to be powerful ("bright," in the analogy used above) and will therefore be relatively easy to detect.

Posted by: Eric Hundman at August 14, 2006 04:21 PM