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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(1)http://www.wood.army.mil/chmdsd/images/pdfs/Winter%202011/Chapman-Reichert.pdf

Tomcat Eyes

Observers are looking with excitement and anticipation at the development and eventual inclusion of an Infrared Search and Track (IRST) sensor into the F/A-18E/F Super Hornet.  This will be a significant advance for the Hornet and broaden the aircraft’s capabilities.

The Boeing/Lockheed Block II IRST, under development in an $89M contract, will be housed in the nose section of an external centerline fuel tank.  Development is scheduled to be completed in 2020. (1)

"IRST is yet another addition to the Super Hornet Block II arsenal, and it will truly change the nature of the air-to-air fight," said Capt. Donald "BD" Gaddis, U.S. Navy F/A-18E/F and EA-18G program manager, PMA-265.” (2)

This revolutionary, first of a kind capability will …huh? … what?  …  Hold on a minute.  Someone is interrupting me.  What?  It what?  Back then? 

Uh, I’ve just been informed that this state of the art IR sensor may not be quite as revolutionary as I thought, having been lead to believe, by the Navy, that nothing like this has been achieved before.  Apparently, I’m told, the F-14 Tomcat had this sensor capability, and more, decades ago.  Okay, let’s take a look back and see what the ancient, outdated, hopelessly outclassed Tomcat had in the way of sensors.

The Tomcat’s non-radar sensors were mounted in distinctive chinpods under the nose. 

ALQ-100 E/F/G/H-Band Track-Breaker – The early F-14A had the ALQ-100 mounted under the nose.  While not a sensor, the electronic countermeasure device was a prominent chin-mount and I mention it for clarity.

ALR-23 IR Seeker - The early F-14A had an IR seeker in a chinpod mount.  The seeker could be slaved to the radar or used independently and was gimbal mounted and could be steered.  I’ve been unable to find much additional information about the sensor’s capabilities or how it was used tactically.

AXX-1 Television Camera System (TCS) – The Northrop TCS was an optical sensor consisting of a telescopic television imager and cockpit display and provided telescopic images of targets far beyond unaided visual range.  Identification ranges are stated to be 10 miles for small fighters and out to 85 miles for large bombers and cargo planes. (4)   The TCS had a 30 degree conical field of view and could be slewed at a rate of 30 degrees/second and was gyroscopically stabilized in pitch/yaw at up to 150 degrees/second.  Thus, the TCS was unaffected by the aircraft’s maneuvering within the field of view.  The TCS also had a tracking-lock capability to enable the target to be continuously followed.  Automatic scan-lock was another built in feature which allowed automatic target detection during continuous scanning.  The Tomcat’s AWG-9/71 radar could be slaved to the TCS or vice versa.  The TCS was first fitted to the late model F-14A.  Additional information is available in a summary report (5).

TCS System

AAS-42 IRST – A more advanced IR sensor, the AAS-42 appeared on the F-14D in 1990.  The sensor provided search and track capability as well as IR imagery.  From Deagel website,

“Operating in six discrete modes, the AN/AAS-42 provides the aircraft mission computer track file data on all targets while simultaneously providing infrared imagery to the cockpit display.” (3)

F-14D’s often utilized a potent side by side, dual combination of IRST and TCS which may have had detection ranges as much as 110+ miles, thereby greatly enhancing air-to-air targeting and useful missile launch ranges. (6)

 

AAS-42 IRST and TCS

While the Navy is loudly and proudly proclaiming the coming use of IRST on the F-18 Hornet, we see that the reality is that effective IR and optical sensors existed on the F-14 Tomcat long ago.  Why the Navy abandoned these sensors when the Hornet was developed is baffling.  Today, as we look at the F-35 and all its problems and costs, we view the Hornet fondly and think of it as a good, if not great, aircraft.  The reality is that the Hornet was a very compromised and, as regards combat effectiveness and range, a very ineffective aircraft.  The addition of IRST is a welcome development but, good grief, we had that and better in the F-14 many decades ago.  Even with the IRST, the Hornet will still lack the F-14’s highly effective TCS.

The eyes of the Tomcat were highly effective combat enhancers that the Navy is only now, and only partially, matching with the Hornet’s cobbled together IRST/fuel tank conglomeration. 

As the Soviet pilots of the era knew well, the eyes of the Tomcat were always on them.  We need to remember the capabilities we had decades ago and begin designing actual combat aircraft again that can at least match what we once had.  What passes for a combat aircraft today is a sad reflection of what once was.

Note:  I’m well aware that other aircraft in the ‘60’s and ‘70’s also had similar sensors – no need to list them in a comment.  Again, it just shows how far we’ve drifted away from actual combat aircraft design.

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(1)Defense Systems website, “Navy integrates new F-18 infrared sensor”, Katherine Owens, 20-Jun-2017,

https://defensesystems.com/articles/2017/06/20/navy-irst.aspx

(2)Boeing website,

http://boeing.mediaroom.com/2007-07-02-Boeing-Selects-Supplier-for-Super-Hornet-Block-II-Infrared-Search-and-Track-Capability

(3)http://www.deagel.com/Sensor-Systems/F-14D-IRST_a002575001.aspx

(4)Air Power Australia website, “Electro Optical Systems”, Carlo Kopp, Mar 1984,

http://www.ausairpower.net/TE-EO-Systems.html

(5)Forecast International,

https://www.forecastinternational.com/archive/disp_old_pdf.cfm?ARC_ID=462

(6)http://theboresight.blogspot.com/2009/07/airborne-infrared-and-supersonic.html

IRST

The Navy is developing an Infrared Search And Track (IRST) sensor as a means of producing passive, infrared target location and tracking with accuracy sufficient for weapon guidance.  This would be useful for combat while remaining “stealthy” and not broadcasting with one’s own radar and for operating in an electromagnetically challenged environment where normal radar operation is degraded.  The system is initially intended for the F-18 Hornet.

DOT&E has reported its assessment of the IRST in the 2015 Annual Report.

“The system tested in OA 1 [ed., Operational Assessment 1, conducted in 2014] could not detect and track targets well enough to support weapons employment in an environment that reflects realistic fighter employment and tactics.”

Disturbingly, the unit’s basic design criteria is questionable, according to DOT&E.

“The Key Performance Parameter (KPP) and the derived contract specification for detection and tracking describe only a narrow subset of the operational environments where the Navy will employ IRST. Meeting the KPP (with a narrow reading of the KPP requirement) does not ensure a useful combat capability.”

Who came up with the initial spec????

IRST Mounted in Nose of Fuel Tank

Despite this, the Navy granted approval to enter into Low Rate Initial Production (LRIP).  This is a growing trend in the Navy, to accept products that fail to meet specs or fail to demonstrate useful combat capabilities.  Why are we building and buying a product that is not yet useful?

IRST Fuel Tank Mount

All of that aside, an IRST ought to offer a much needed capability for very little impact on aircraft performance (the IRST is mounted in the nose of the centerline fuel tank so fuel/range will be slightly reduced).  This is just one more incremental improvement that will help keep the Hornet viable.  I just wish the Navy would complete development before entering into production.  This is concurrency, again, which will require the initial IRST’s to be remanufactured, eventually.

Update:  This is why the DOT&E is so important and why there is tension between the Navy and DOT&E.  The Navy is entering into LRIP even though DOT&E testing shows the IRST to be of very questionable combat value.  If DOT&E didn't exist, we'd never know about the problems until combat revealed them and the Navy would have already committed to full scale production of a marginally useful system.  Why the Navy insists on putting badly flawed and substandard systems into full production is beyond me.