Tuesday, April 3, 2018

Alternative Stealth

How do you make an aircraft stealthy?  We all know the answer to that, right?  You carefully shape the aircraft and then apply low observability (LO) coatings.  The only problem with that answer is that today’s radars are becoming more and more capable of detecting stealth aircraft.  The radars operate at different frequencies and networked radars can compare returns and scatter (to put it simplistically) to pick out stealth aircraft.  Add to that the improvements in infrared detection (IRST) and stealth aircraft are becoming less and less stealthy all the time.

For ships, it’s a similar case of stealth being achieved by shaping and, to a lesser extent, coatings.

We’ve invested huge amounts of money into stealth and we’ve based our entire military on it.  For a relatively brief period in the 1990’s we had a monopoly on effective stealth and a major battlefield advantage.  Today, however, everyone has stealth and everyone is developing stealth detection capability.  Our advantage is disappearing.

In the near future war, two stealth aircraft are going to meet and their air-to-air weapons, having only small, relatively simple radars, will be unable to lock on to their opposite number.  At that point the engagement becomes a dogfight, no different than our WWI forefathers and the better aerodynamic aircraft will win (hmm… that F-35 isn’t looking so good now, is it?  But, I digress …).

So, is our stealth advantage permanently gone?

No.  There are alternate means of achieving stealth – something the military seems slow to recognize.  Here are some alternate means.

ECM – This is an easy one to implement and can be highly effective.  Electronic countermeasures (ECM) such as jamming, disrupting, creating false signals, etc., for the enemy’s sensors is effective and efficient.  If the sensor is disrupted, our asset gains a measure of stealth – in this case a bestowed stealth rather than an inherent one.  The challenge lies in staying current, given the pace at which the electronic signals world changes, and covering the massively broad range of signals.  Even more challenging, many weapons are built with frequency agility meaning that the ECM has to be able to counter almost the entire spectrum!  On the plus side, ECM is easily upgraded in terms of hardware and software and is small enough to be carried by almost any platform.  If the threat changes, we can upgrade the ECM of the entire force with relatively simple software changes.

IR – One of the ways stealth is being countered is through alternate detection methods like IR.  IRST sensors are one of the “hot” technologies, at the moment.  Thus, IR signature suppression offers another form of stealth.  Of course, like radar stealth, this is difficult to achieve and nearly impossible to upgrade over time.  Still, it is well worth the initial effort.  Ships, especially, need more attention paid to IR signature reduction.  The ubiquitous gas turbines that power ships generate immense IR signatures and while they offer obvious operating benefits they also impose survivability disadvantages.  Thought should be given to alternative power sources and to minimizing their IR signatures through careful design.  Measures such as utilizing the washdown systems can provide a degree of IR signature reduction.

Decoys – Simple decoys create stealth, too. Decoys can take the form of chaff, flares, floating radar-reflective targets, towed aerial decoys, towed Nixie anti-torpedo decoys, submarine noisemakers, dummy visual targets (fake tanks or aircraft, for example).  If incoming missiles "see" dozens or hundreds of fake targets (decoys) then the real ones have become stealthy, barring the bad luck to be the one "fake" target that a missile zeroes in on.  Decoys are generally cheap and easily deployed.

Obscurants – Smoke is a great visual obscurant but today there are multi-spectral obscurants – multi-spectral smoke, if you will.  We now have obscurants that can cover the spectral range of visual, near/mid/far infrared, centimeter/millimeter wave, and ultra high frequency. (1)  Laser weapons, laser ranging, laser spotting, and laser imaging can all be disrupted thereby providing “laser stealth” protection.

And so on.

We see, then, that stealth can be provided by means other than the shaping and exotic coating of the individual ship or aircraft. With the foregoing in mind, consider a giant commercial 747 or a commercial cruise ship. They're about as unstealthy as possible - easy detections and kills in a war zone, right? But, they can be made stealthy by other means. For example, if we could disrupt the terminal guidance of incoming missiles (ECM, IR signature suppression, frequency obscurants, etc.) or supply alternate targets in the form of decoys then the 747/cruise ship would be "unseeable" to the missiles and, thus, stealthy even though it contains no inherent stealth characteristics of its own.  Thus, a “stealthy” 747/cruise ship is achieved via other means!

The point is that there are multiple ways to achieve "stealth". We don't have to always go for the most expensive method. In fact, stealth shaping/coating is becoming less and less effective as technology develops multi-frequency radars, back-scatter analysis, multi-node radar networking, IRST, and other technologies designed to defeat stealth shaping.

The alternative methods of enhancing stealth also allow easier upgrades over time. It's very difficult/impossible to "upgrade" the shape of a ship or aircraft but it's easy to change the electronic warfare or decoy capability. We need to rethink where we're putting our "stealth" emphasis. This is not to say we shouldn't build stealth shaped platforms - we should because that's the minimal price of entry onto the modern battlefield - but that we should be emphasizing other approaches as opposed to the ever more expensive stealth shaping/coating path that produces less and less benefit and requires more and more exquisite care in manufacturing and maintenance.

At one point, I thought the Navy might be grasping this concept because they were looking at acquiring more electronic warfare aircraft (EA-18G Growlers) which could have been used to escort other aircraft and bestow stealth.  However, this does not seem to have happened.

Perhaps, in addition to our frantic effort to develop deep penetrating strike and aerial combat UAVs, we should be looking at developing basic, auxiliary electronic warfare UAVs – essentially, flying jamming pods controlled by EA-18G Growlers.  This would greatly extend the capabilities of the Growlers without requiring new, hideously expensive aircraft. 

I’ve mentioned in previous posts that it would be interesting to build a prototype, pure electronic warfare ship with, essentially, unlimited power and unlimited antenna size and numbers and see what it can do to provide area stealth just as Aegis provides area air defense.

We have been myopic about our stealth focus on shaping and coatings and we need to broaden our approach and recognize that there are alternative means of achieving stealth.



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30 comments:

  1. The Path that you suggests is the one followed by Dassault Rafale SPECTRA suite, with apparently good results. I think that because of a relative backwardness in conventional stealth other countries invested in electronic stealth and as result are agradezco of the US. At least France, and China is developing an electronic Warfare Flanker. This platform will be a beast of EW because its sheer size allows for adding up a lot of power generation and fuel for feeding that. I would considera adapting B1 bombers as offensive EW aircraft, and perhaps B52 or airliners as defensive EW platform.

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    1. Interestingly, the US Air Force once had fairly large EW aircraft, the EF-111A Raven (SparkVark) but they opted to drop it. I suspect that they believed that with the advent of stealth, they no longer needed EW - a prediction which is proving incorrect.

      The Soviet Union fielded electronic warfare versions of bombers such as the Tu-95.

      The US does use various larger aircraft for passive signals monitoring.

      The use of a US bomber as an EW aircraft is an interesting one and worth some consideration.

      Good thought!

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  2. The problems with these other techniques is what led us to stealth.

    To hit a single target, strike packages used to have to be large. SEAD/DEAD aircraft to shoot ARMs at missile sites, jammers to confuse and disrupt, aircraft carrying decoys to deceive, fighter CAPs to ward off enemy fighters, all to get a handful of strike aircraft through to the target.

    Decoys displace payload, only have limited life span and are susceptible to ECCM techniques. Jamming announces your presence (not stealthy), is also susceptible to ECCM, as well as home-on-jam missiles. Obscurants also announce your presence.

    The answer isn't either/or. It's both. Traditional VLO is not a silver bullet. But the same radars that claim to be able to detect stealth aircraft can be jammed or deceived with decoys, or destroyed with ARMs or bombs. It's far easier to jam for a B-2 than a B-52. Decoys can be smaller and lighter.

    As an aside, I personally dislike the dilution of the term "stealth". It used to mean something like "signature reduction to the point where enemy sensors have a low chance of detection at combat-useful ranges", aka VLO.

    Now we're lumping in all manner of deception techniques. Why not throw in anti-radiation missiles or even JDAMs used in DEAD strikes while were at it? If we destroy the enemy radar, they won't be able to see us, right?

    Anyway, rant off.

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    1. "The answer isn't either/or. It's both."

      Of course, it's both! As stated in the post,

      "This is not to say we shouldn't build stealth shaped platforms - we should because that's the minimal price of entry onto the modern battlefield - but that we should be emphasizing other approaches as opposed to the ever more expensive stealth shaping/coating path"

      Unfortunately, the U.S. military, and especially the Air Force, almost abandoned the other forms of stealth when shaping came along. Now, we only have shaping and it's being rapidly negated.

      "Now we're lumping in all manner of deception techniques. "

      Of course we are! It would be foolish not to use every form of stealth we can, as you acknowledged.

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    2. My problem is classifying these other techniques as "stealth". The words we use to describe things are important. I have a bunch of clubs in my golf bag, but I don't call all of them a "driver".

      Calling jamming "stealth" is the same type of thing. Jamming is a Suppression of Enemy Air Defenses (SEAD) technique. It's not stealth.

      The AF hasn't abandoned other approaches. SEAD/DEAD is as important as ever. MALD/MALD-J are state of the art decoy/jammers. We have state of the art emitter locators on the F-22 and F-35, and strategic ELINT systems on Rivet Joint and other aircraft.

      All true VLO aircraft attempt to reduce IR signature, to a greater or lesser degree of success. Unfortunately jet engine exhaust and skin heating aren't all that easy to hide.

      The AF wanted to equip B-52s with strategic jammers, but the program was nixed due to lack of funds. They still have Compass Call aircraft, though they aren't tactical jammers like the Growler.

      So really it's just a modern, tactical/theater jammer aircraft that they're missing.

      Since we fight joint, they appear to feel the Navy has that, more-or-less, covered at the moment.

      The way the AF thinks about penetrating air defenses goes something like this,

      Avoid it if possible, (Stealth)
      Kill it if you can, (DEAD)
      Suppress it if the other options don't work. (SEAD)

      Obviously there is overlap, but it's clear the other two (Avoid and Kill) are preferable to Suppress.

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    3. "but I don't call all of them a "driver"."

      No, but you do call the net result of all their usage, "golf". They just each contribute different aspects to the overall result.

      Your "problem" is, essentially, a semantics issue. If you don't want to call the various methodologies "stealth", that's fine - call it whatever you want. It doesn't change the concept.

      SEAD/DEAD are not stealth enablers, they're survivability enablers. The next post will cover that!

      The AF dropped the EW aircraft. The MALD family is limited to F-16/B-52, at the moment, as far as I know. The F-22 had some degree of IR reduction. I don't know if the F-35 had any particular emphasis on IR reduction. It seems clear that the AF bet on stealth shaping and is now going to have a problem as technology slowly negates that. They'll have to scramble to catch up in other areas. Dropping the SparkVark without replacement was a mistake.

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    4. "The AF dropped the EW aircraft"
      yes sadly for them, the F-15E with its big conformal pods would make great use of that for jamming equipment.

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    5. "Your "problem" is, essentially, a semantics issue."

      "SEAD/DEAD are not stealth enablers, they're survivability enablers."

      I think you just made my point. Doctrinally, ECM and decoys are lumped under the SEAD umbrella, which, as you say, is a survivability-enabler. Nobody lumps ECM and decoys under the term "stealth". Sticking with accepted terminology makes discussing these topics easier.

      "The MALD family is limited to F-16/B-52, at the moment, as far as I know."

      MALD has up to a 500nm range. In light of this, tasking legacy aircraft to carry it makes perfect sense. These aircraft would sortie to deliver MALDs from standoff distances, in support of strike aircraft.

      "The AF dropped the EW aircraft."

      I do agree, raid/theater jamming is a weak spot in the USAF portfolio. Just Compass Call at the moment. However, they do have excellent ELINT aircraft (e.g. Rivet Joint).

      My hope is the Navy will bail the AF out by integrating NGJ on the F-35C, which will make it easy to port over to the F-35A.

      There is also AF pie-in-the-sky talk of jammer UAVs but who knows if anything will come of it.

      Lastly, we have to recognize that jamming effectiveness ain't what it used to be either. Modern antennas and signal processing techniques used on newer radars make simple techniques far less effective.

      Jamming effectiveness in general is less predictable and less durable. A simple software upgrade could greatly diminish the value of a specific technique. Plus, it is very threat-specific. What works on one radar might not work on another. We only find this out through painstaking and difficult intelligence work, or losing aircraft.



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  3. The Tom Clancy novel Red Storm Rising illustrates some of the alternatives you mentioned:

    1) The Soviets fired a load of Target Drones at a NATO fleet from one direction, then as soon as the AAW was concentrating on that 'threat' another group of bombers fired real missles.

    2) Both sides (I think) used jammers among fighters/bombers.

    3) NATO initiated a massive jamming mission (made of converted B52s I believe) from one direction of a Soviet airbase, while low and fast attack aircraft came from another direction.

    4) NATO placed a load of radar reflectors on rocks in a bay, essentially creating more ships for the Soviets to attack.

    Plus others I've no doubt forgotten.

    Just fiction, I know, but it shows the sort of thing that could be done.

    Lofty.

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    1. I've read that book. It offered a lot of creative ideas - the kind of things that we should be exploring but are not.

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  4. EW test ship DDG-1001, already has a reduced signature and lots of electric power. Just think of the decoys
    you can launch with ADLS x-AGS.
    Capt. Lemonade.

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    1. This idea was proposed recently in this post,

      The Third Zumwalt

      The post offers several possible uses for the Zumwalt. Check it out.

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  5. The first thing that I thought of when reading the post, "That's the game we play."

    Radar, Stealth to defeat, better radar, better stealth.
    Vidar, stealth to defeat, better vidar, better stealth.
    IR, stealth...

    Then we can combine them in novel ways. We are just beginning to understand how stealth, vidar, ew can be combined to defeat an enemy. I suspect that will go on well past our lifetimes.

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  6. You could add Emitter locating systems, they are a huge advantage, no modern ship or plane cannot go without them .

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  7. Stealth may be less effective all the time, but don't ignore that US 90s-early 2000s stealth was damn near invulnerable (one F-117 aside). B-2s can strike with impunity over the most heavily defended airspaces. Sure more LR surveillance radars and IRST are changing that, but the advantages of stealth haven't gone away.

    Stealth is improving all the time too. Better coatings, Engines shape and materials that have lower thermal signatures, better shaping. Not to mention if you change your attack profile and use different shape/size aircraft you make it harder too.
    In the long term stealth will likely not be a static advantage - it will have to be combined with other aspects such as PCA, SEAD/DEAD, jamming, and eventually self-defense weapons like lasers. But the fact that everyone else who can afford it is actively trying to develop stealth should be a good clue that stealth will continue to be at a premium for the next 20-30 years.

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  8. The one other problem with USAF/USN being so enamored with LO is that not only they have focused all the money solely on LO to the determent of EO/IRST, ECM,decoys,etc that USA is falling behind compared to other countries R&D and deployment....they seem to be oblivious to the fact that there really isn't any reason why Russia or China can't develop and deploy LO soon on their own fighters or ships....and I've looked around, I don't see any evidence that USAF/USN is working in the "white world" at least to fight one day with a peer LO force...what happens when everybody has LO jets or ships? Has anyone heard of war games or Red Flag where the OP-FOR has a LO fighter too? Has anybody heard of what happens next? What happens if China develops a whole new series of decoys that USAF isn't prepared to defeat? Isn't that similar to achieving a form of LO? Are we looking at all the avenues to achieve LO? Russian, Chinese and even Euros have very good IRST on their fighters, we deleted it on the F22 to save money....what happens if one of them makes a technological break-thru and USA is left behind? USAF especially spent a ton of money on their LO god, better not turn out to be an empty promise....

    It seems to me that US DoD is still living in a world where US is the dominant and unique player with LO....very dangerous mindset.

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  9. One good measure to reduce ships IR signature is to place engines exhausts underwater. It is widely used by German Naval shipyards.

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    1. I'm not intimately familiar with German naval ship design. What are some specific ships that have subsurface exhaust and how is it working out?

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    2. I found this Navy Recognition article about the new, german-built, Algerian Meko 200 frigates. They lack a funnel because all exhausts are below the waterline, this reducing the IR signature. This concept is also working in some Bundesmarine ships.

      http://www.navyrecognition.com/index.php/news/defence-news/2016/february-2016-navy-naval-forces-defense-industry-technology-maritime-security-global-news/3624-first-of-two-german-built-meko-a-200-an-frigate-commissioned-with-algerian-navy.html

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    3. As best I can tell from a quick search, the MEKO 200 appears to exhaust out the stern, above the waterline rather than underwater. The exhaust gas/line appears to have seawater injected into it for cooling (IR signature reduction).

      Am I missing something? Is there an actual underwater exhaust?

      Regardless, it's still interesting.

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    4. Several years ago, I spent a couple of days in the Baltic, navigating in a German Navy 130-class corvette, which had the said IR signature reduction device.

      I don´t know how much IR signature was actually reduced, but what I do know is that, on daylight, you just needed to look for the white steam cloud on the horizon to know where our ship was!

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    5. Andres, that's absolutely fascinating. It would seem to somewhat defeat the purpose? Thanks for sharing.

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  10. Most of the "stealth" techniques you mentioned are rather soft kill than true "stealth" (= avoiding or delaying detection). So I agree on this with "Anonymous April 3, 2018 at 8:09 AM".
    ------------
    Low observability against IIR is almost impossible to achieve for an above-water ship unless it washes itself with seawater a lot.

    The Peltier effect might help to break a lock by IIR sensors that are not prepared to deal with Peltier effect camo, but multispectral smoke as projected by MASS is vastly easier to implement and it's cheap. You just need to deal with the missile before it succeeds on a repeat attack run.

    https://www.youtube.com/watch?v=LDk5cA8JUIQ
    https://en.wikipedia.org/wiki/Thermoelectric_effect#Peltier_effect

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    1. Stealth is the ability to avoid detection. Anything that enables that ability is a stealth attribute. Hence, the post discussion.

      However, the semantics is utterly unimportant. Call it whatever you wish. It doesn't change the concept.

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    2. BAE's Adaptiv technology is intriguing. I'm unaware of any real world user. Do you know of any?

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    3. It's fairly new. I suppose there's a high probability that it's in experimental use in UK or US, maybe some black special forces helicopter program. The feasibility and cost/benefit ratio looks the most convincing for attack and CSAR helicopter applications, as it can almost certainly break if not prevent the lock-on of far IR-guided missiles.

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  11. I suspect that the main attribute of stealth is that it seems to make one's decoys look that much more attractive.
    As previously noted - all part of a developing process.

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  12. I can see the Army using obscurants on individual vehicles, but I'm not so sure about the Navy and Air Force. The exhausts on a destroyer size ship are pretty big. I would think they would only work best at low speeds and with low prevailing winds that would disperse the obscurants. On an aircraft going 500 miles an hour, I don't see how that works at all.

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    1. Smokescreens have been commonly used in naval warfare.

      No one is calling for smokescreens for aircraft!

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    2. Anon, see this (especially the parts about Pandarra fog and MASS):

      http://defense-and-freedom.blogspot.de/2018/02/modern-warships-iii-aaw.html

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