Raptor … or Turkey? (Part Two)

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, thus announcing its location to everyone in the vicinity with a Radar Warning Receiver.
15led.JPGUnder these circumstances, a Raptor is no better than any late-model fighter such as the Sukhoi Su-27 series, which is considerably cheaper.
Not so, said the Raptor jockeys of the 27th Fighter Squadron at Langley Air Force Base, Virginia.
“I’m going to be able to see him before he sees me,” Captain Phil Colomy assured me. He was refering to radar detection, not visual.
How so? I asked. If you radiate, everyone’s going to know where you are. To use Sprey’s analogy, it’s like using a flashlight in a dark room. Sure, you can see the bad guy, but he can see you too.
Colomy just smiled. 1st Fighter Wing commander Brigadier General Burton Field spoke up:
“Enemy RWR can’t detect radiating F-22s,” he said. “We haven’t had a problem with that.”
I asked if that had something to do with the Raptor’s Raytheon APG-77 Advanced Electronically Scanned Array (AESA) radar, which uses many tiny nimble radar beams instead of one big, slow beam.
Field just smiled. This is classified, but widely known to be true.
Basically, here’s how it works. RWRs are like any sensor: they operate at a certain fidelity lending a certain degree of dependability. If you radiate only briefly or only a little, RWRs aren’t going to be able to pin you down. A small, smart, well-directed beam — such as that from any new AESA — is too fleeting for a firm fix. It’s like using a flashlight in a dark room, but snapping it on then off in a fraction of a second.
One day RWRs will catch up to the new AESAs. But for right now, the radars have the advantage. What this means is that the F-22 can use its radar without entirely sacrificing stealth. That’s on top of the other advantages of the AESA.
—David Axe

  • Kolya

    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.

  • CardEE

    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).

  • Eric Hundman

    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.

  • Robot Economist

    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.

  • CardEE

    The F-22

  • pedestrian

    >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.

  • Byron Skinner

    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.
    Byron Skinner

  • Moose

    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.

  • Andy

    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.

  • TrustButVerify

    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!

  • Eric Hundman

    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?

  • Nicholas Weaver

    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…

  • Eric Hundman

    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.

  • Aaron

    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…

  • Big G

    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?

  • mon

    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.

  • Benjamin Fan

    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?

  • CC

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

  • Arthuraria

    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?