F-35's Most Sinister Capability Are Towed Decoys That Unreel From Inside Its Stealthy Skin


One of the least talked about, but most potent capabilities that can enhance the survivability of a combat aircraft these days is the ability to deploy towed decoys. Often referred to as "little buddies" by the crews that bet their lives on them, they have existed in miniature form for over two decades on aircraft like the F-16C/D, B-1B, and F/A-18E/F, as well as foreign fighter aircraft. But most wouldn't think such a system would be included in a 5th generation fighter that was designed from the ground up to evade enemy radars. This isn't the case. Although it isn't something touted by the manufacturer or its operators, the F-35 has this capability concealed beneath its curvaceous and stealthy skin.

First off, you are probably thinking that the inclusion of such a system in the F-35's design is a sign of weakness in its stealth capabilities. Maybe it could be framed in such a manner, but doing so really doesn't do the topic justice and it wouldn't be fair to the F-35 either. 

Stealth fighters, as we know them today, are not highly optimized to evade a broad range of radar types. Instead, they are optimized to give fire control radars used to actually engage targets, as well as detect them in many cases, a very tough time. The classic appendages of a fighter aircraft—nose, tail surfaces, exhaust nozzles, and even wings—do not lend themselves to broadband radio frequency low-observability, but they are conducive to maneuverability and speed. So, while aircraft like the F-35 are effective at hiding from the most threatening radar types, and especially when viewed by those sensors from certain aspects, with the frontal-hemisphere profile being most optimized, they are less adept from doing the same when it comes to radars operating at lower frequencies or when viewed from rearward angles. 

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The fusion of information from many types of sensors' dispersed over a wide area that make up an integrated air defense system also degrades a stealthy aircraft's ability to remain undetected, although it is key to remember that detection does not equal the ability to engage with weapons that rely on higher-quality and persistent telemetry. So even though a stealthy aircraft may be detected momentarily or even fairly persistently, that does not mean it can be engaged by surface-to-air or air-to-air missiles. The lack of broadband low observability, like that provided by stealthy subsonic flying-wing designs that have minimal smaller appendages and features, also puts a stealthy fighter at greater risk.  

No aircraft, not even one that is designed with broadband low-observability as the goal above all else, is totally invisible to radar and other sensors. Stealth means a reduced probability of detection and engagement, not invincibility. Careful route planning and high situational awareness of threats in an aircraft's vicinity are also essential to the survivability of stealthy aircraft, with the goal being to only provide the most unfavorable (detectable) aspects of the aircraft to a threatening enemy's sensor view for the least amount of time. 

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F-35 fires an AIM-120 AMRAAM in testing. 

So, stealth is not some monolithic concept, it has many variables and degrees, and above all else, it relies on a cocktail of measures, with a low-observable design and radar-absorbent coatings being just some ingredients in that cocktail, albeit quite important ones. Other key aspects include reduced infrared signature and the ability to tightly control an aircraft's own radio frequency emissions so as to not let the enemy know of its presence. Low probability of intercept (LPI) radars and radios allow for reduced chances of being detected while still offering key functionality. They use highly directional emissions, frequency hopping, and wavelength modulation, as well as other clandestine techniques, to allow their operations to remain undetected by the enemy's surveillance equipment. 

All these features are very important, but one of the most essential ingredients in the success of any stealthy combat aircraft is electronic warfare. 

Electronic warfare paired with low observability is really a magic potion for survivability over the modern battlefield. Whatever weaknesses a stealthy aircraft has in its shaping and coatings can potentially be offset, to a certain degree, by the ability to wreak havoc on enemy radar and communications systems via electronic attacks. In the past, aircraft like the F-117 Nighthawk had zero electronic warfare capabilities as the technology to make such a system's emissions undetectable and not self-defeating was very limited. Instead, those aircraft relied on jamming support from other aircraft, such as EF-111 Ravens and EA-6B Prowlers, operating at standoff ranges. In practice, it was very seldom that an F-117 would venture deep into denied territory without robust jamming support. In fact, the one time it did, during Operation Allied Force two decades ago, it was shot down.

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F-117 breaking away from the tanker. The aircraft would 'clean up' by retracting all its antennas and turning off anything that produces an RF emission before heading into contest territory. The F-117s were largely defenseless and blind to nearby threats and relied heavily on external jamming support. 

The F-35, on the other hand, is designed with its own highly-integrated, highly-advanced AN/ASQ-239 electronic warfare system. It takes advantages of its active electronically scanned array (AESA) radar and the antennas that are buried along the edges of its wings and control surfaces and beneath its skin. This capability allows the F-35 to 'self-escort' to the target area and back, taking on enemy emitters electronically that it may have trouble staying far enough away from to evade detection entirely. This same electronic warfare suite and the jet's high degree of sensor fusion offers F-35 pilots the ability make rapid decisions regarding their survivability on the fly. They can decide to destroy threatening emitters that may pop-up in their way, and new weapons are being developed to do this quickly and over relatively long ranges, or to avoid the threat entirely if possible, or to try to blind and confuse it via electronic attacks, allowing the F-35 to sneak by unscathed. 

This electronic warfare capability gives the jet an enhanced degree of survivability and helps offset reliance on its low-observable design alone, which does have its weaknesses. Beyond being optimized to defeat higher-frequency fire control radars, like those that operate on and around the X band, the rear of the F-35 has been a bit controversial as its perceived radar cross-section is larger than some would like, possibly leaving it vulnerable to detection and even engagement from rear aspects. Quite honestly, I haven't seen this really disputed, but as we discussed above, weaknesses in an aircraft's low-observable design don't mean it is totally vulnerable. While the F-35 may have shortcomings in terms of detectability to certain radars and from certain aspects, it seems Lockheed and their partners have come up with novel ways to help fill in the gaps. 

One of the Joint Strike Fighter's tricks that has remained largely in the shadows is the inclusion of an internal towed decoy system—one that has "little buddies" that are wicked smart to boot. We know for a fact that the F-35 is capable of deploying a specially-built version of advanced electronic warfare-enabled towed decoy known as the ALE-70. 

The ALE-50 and electronic warfare-enabled ALE-55 are currently in service with the USAF and U.S. Navy. The first generation-variant of the ALE-50 towed decoy was unreeled out behind an aircraft and basically gave threatening air defense systems a much larger and more enticing target to attack than the host aircraft itself. As a result, the missile would home in on the decoy and blow it off its wire instead of destroying jet itself. During various operations, including the invasion of Iraq in 2003, the system worked incredibly well and clearly saved many lives and aircraft. Maybe the best look at the system in action was in Dan Hampton's memoir Viper Pilot, which I highly suggest you read.

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Since then, little buddies have morphed from decoy target to advanced electronic warfare-enabled extensions of the plane's own self-protection suite. The ALE-55 that is reeled out from the center of the Super Hornet's belly is capable of jamming enemy emitters in an effort to keeping them from locking onto the aircraft, or directly executing electronic attacks on an emitter that has already locked on, or goading a missile into attacking it instead of the aircraft if an attack is already underway.

BAE Systems (main image), Wikicommons (inset)

Sometimes these modes of operation are aptly referred to suppress, deflect, and seduce. This is done via a range of guileful electronic warfare programs the decoy can employ in concert with the jet's self-defense suite. An aircraft-mounted control unit sends the specific signals to the decoy over a fiber-optic line. Once at the decoy, those signals are translated into radio frequency emissions. The ALE-50's electronic systems were self-contained in the expendable decoy itself, making them far less capable. 

The towed fiber-optic decoy arrangement makes for a highly capable, fully tailorable, and rapidly adjustable response to a whole range of threats. For instance, the decoy can first try to generally jam a radar that is in search mode, then it can try to attack it directly to break its lock once it locks on. Then, if a missile locks on in flight, the decoy can instantly turn into a juicy target, or even targets, misdirecting the missile away from the aircraft.

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Concept art of a Hornet with ALE-50 in tow. 

Clearly, these "little buddies" are vicious, but beloved helpers to have along on a mission. Aircraft with 'doghouses' built-in to deploy these types of decoys usually carry between four and eight of depending on the design. Other aircraft, like the F-16, have the doghouses built into their weapons pylons. 

MKFI/wikicommons

ALE-50 housing on a Block 50 F-16. 

A version of the ALQ-184 electronic warfare pod also has towed decoys built in, offering a broader spectrum of tactics for protecting the aircraft it is attached to. 

Raytheon

ALQ-184 equipped with towed decoys. 

On the F-35, its ALE-70s seem to be deployed via a trapdoor that pops open on the right underside of its fuselage, aft of the weapons bay and infrared countermeasures doors. Supposedly, at least four ALE-70s can be carried at a time in the drop-down enclosure. 

Lockheed Martin

The towed decoy deployment door is located just aft of the dual flip-open infrared countermeasures dispenser door. 

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This rare image appears to show the towed decoy door open. 

Budget documents not only confirm the ALE-70's existence, but also the fact that it is accommodated internally on the F-35. A line item within the USAF's 2017 budget states:

"The ALE-70 Towed Decoy is a countermeasures dispenser system designed to fit into the F-35 Joint Strike Fighter (JSF) aircraft. The ALE-70 provides aircraft self-protection against radar guided missiles."

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ALE-70 is also listed in the Navy's budget from the same year, along with the aircraft's other countermeasures. It is worth noting that various flares and infrared countermeasures, as well as the ALE-70s, are the aircraft's only listed expendable countermeasures. Chaff, which is used to blind and confuse enemy radar, is not included in the F-35's countermeasures suite. This makes some sense as low-observability, the aircraft's highly advanced and deeply integrated electronic warfare system, and the ALE-70 offers enhanced survivability against radar and radar-guided threats. Still, it is interesting that chaff was indeed omitted. 

The budget document reads:

"F-35 COUNTERMEASURES: Includes all unique countermeasures that provide self-protection for the Joint Strike Fighter (JSF) aircraft, specifically ALE-70, MJU-68, MJU-69 and CCU-168. In addition to F-35unique countermeasures, MJU-61 and MJU-64 are also used for F-35 self-protection."

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We also have an updated unit cost for the ALE-70 from the Pentagon's 2020 budget request, which comes in at $56,375. Not cheap, but hardly expensive compared to the loss of a $100M F-35 and its pilot.

Considering the F-35's already potent electronic warfare capabilities, you can just imagine how the advanced electronic-warfare capable towed decoy could be used by the jet in combat. If a radar system threatens the aircraft and it cannot be avoided via a course change or attacked directly, reeling out an ALE-70 would probably give the F-35 the best chances of survival, especially if a missile launch was already detected. The decoys could also help when it comes to mitigating the aircraft's rear radar cross-section. As it flees from a target area, unwinding an ALE-70 would definitely give enemy radar operators a much harder task of successfully targeting the aircraft, let alone bringing it down.

Also, when operating in a non-stealthy configuration with external stores, the advanced towed decoys will give the F-35 a means to better defend itself against pop-up threats, such as road-mobile surface-to-air missile systems or even enemy fighters. 

And above all else, towed decoys will be incredibly important when operating in the Wild Weasel role—the mission of taking on enemy air defenses directly—something the F-35 is supposed to be incredibly adept at already. 

An astute Wild Weasel F-35 driver could work with his or her wingmen to act as both the hunter and the prey. ALE-70s could be reeled out to turn one stealthy F-35 into the most enticing target imaginable for enemy air defenders. Meanwhile, another F-35, operating in full stealth mode, would be waiting to geolocate the enemy's radar emissions once they take the bait. At which time that F-35 would proceed to pummel the threatening emitter or air defense system to death. 

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USAF F-16CJ Wild Weasel pilots were among the first to put the little buddy to work, they know full well how capable it is and how it could be used in concert with a stealthy airframe to really ruin an enemy radar operator's day. This will allow F-35s to more easily clear a path for other assets, including older and more vulnerable 4th generation fighters and non-stealthy bombers, many of which also have their own towed decoys to watch their backs. 

Tyler Rogoway/Author

The B-1B was one of the first aircraft to get towed decoys. Notice the doghouses on either side of the tail.

Similar tactics can be used in the air-to-air arena, with the ALE-70 acting to sucker-in enemy fighters or to make phantom formations of aircraft appear on their radar scopes. Then, once they have committed to an engagement, the F-35 reels-in its decoy and disappears and the enemy fighters find themselves outflanked by other F-35s with missiles locked on and inbound. 

So, you can see just how awesome a feature this is to have built into a stealthy airframe. It offers maximum tactical flexibility, will keep the enemy guessing, and will even make them outright vulnerable without them ever knowing they had been had before it is too late. Above all else, it gives the F-35 another layer of protection that will keep it survivable even if its stealthy shape and radar-absorbent coatings become less effective on the battlefield in the decades to come.

Little buddies—now quietly paling around with the stealthy F-35 Joint Strike Fighter. 

Contact the author: Tyler@thedrive.com