Tuesday, March 12, 2024

Missile and drone guidance systems: the old is new again?


I was interested to read that a new Russian battlefield drone appears to be guided by unspooling several miles of optical fiber cable behind it as it flies.

Russian forces in Ukraine appear to now be using so-called first-person view kamikaze drones controlled via a physical fiber optic line rather than a wireless data link. This configuration offers a control method that is immune to radiofrequency electronic warfare, but that also imposes certain limitations on how the system can be employed.

. . .

This is not a new concept, broadly, either. Wire-guided anti-tank missiles have been in service around the world for decades now and many current-generation designs, such as some of Israel's Spike family, use fiber optic cables. The ubiquitous American-made TOW missile has that feature directly in its name: Tube-launched, Optically-tracked, Wire-guided.

It's also worth noting that many torpedoes also use a similar spooling wire command-link concept.

. . .

Another major advantage to a wired FPV drone is that it would not radiate any energy, nor would the user some distance away, that could be detected. These electronic emissions are key ways drones are detected in the first place and they can also prove deadly for the operator if electronic surveillance systems can triangulate their position. There is no such vulnerability with a wire-guided FPV drone.

There's more at the link.

It's interesting to view this "new" technology through the lens of the history of military technology.  The first anti-tank missiles, such as the French SS.10 (also used by the USA) and ENTAC, the Soviet Snapper, Swatter and Sagger, and some others, were guided by means of instructions sent to the missile in flight over wires it unrolled behind it.  Steering was usually by some kind of joystick, something like those seen on computer game controllers.  On battlefields where many such weapons had been used, such as those of the Yom Kippur War in 1973, observers sometimes found such guidance wires "festooning the landscape", to quote one report.  The system worked, but due to the slow speed of the missiles and their limited range, the operators had to keep their eyes on the weapon to control it.  That meant their position might be identified by the launch plume of the missile, allowing enemy tanks to target it, trying to take out the missile operators before they could steer the missile into the tank.

The US TOW missile of the late 1960's was designed to simplify this system by taking out the need for continuous operator guidance.  Instead of manipulating a joystick, the operator kept his sight focused on the target.  A computer in the launch unit translated the movements of the target into instructions to the missile, which was still guided by wires it unspooled behind it.  Later models allowed the missile tube to be some distance from the control unit, protecting the operator from enemy interference, but still requiring him to keep his sights on the target.

The wire unspooled from the missile was necessarily very light and thin, and could be torn or broken by obstacles on the battlefield.  Accordingly, efforts were made to develop missiles that did not need wires.  For example, Israel developed the MAPATS missile in the 1980's, which was basically a copy of the TOW missile with a laser guidance unit replacing the wire.  The operator simply shone a laser beam onto the target, and the missile slaved itself to the beam and remained aligned with it until it struck.  South Africa copied that concept with its ZT3 version of MAPATS.  Two disadvantages remained:  the operator had to keep the laser beam on the target, meaning he could not duck down behind cover, and the laser beam could be detected by the target, which could then maneuver behind cover to get away from it or fire at the source of the beam.  That's why almost all front-line armored vehicles today have laser sensors, to tell the crew when a laser is being shone at them and from where it's coming.

The latest anti-tank missiles have incorporated the targeting and guidance system into the missile, which is now entirely independent of the operator once it's been launched.  The US Javelin missile is an example of this, as is the Russian Kornet-EM.  The operator merely shows the target to the missile using its built-in sensors, then launches it.  He can take cover or move to a new position while the missile navigates itself to its destination.

Meanwhile, the first battlefield unmanned aerial vehicles (UAV's, or "drones") began in much the same way.  Early models were guided by means of a joystick sending radio commands to the drone.  This system worked, but was prone to interception or jamming.  Many drones today still use it, meaning they can be countered by stronger signals sent by an enemy to "take over" the drone, or jamming instructions from its operator.  Satellite guidance is a lot more difficult to jam, but it's also a lot more expensive to install, so smaller battlefield drones mostly don't use it.  Other models are autonomous, in that they're programmed with a preset course and then sent to fly that circuit, returning to a preprogrammed point with video or other sensor information about their targets.  Since there's no continuous operator guidance, there are no signals to jam, so the drone is much harder to stop.  On the other hand, an autonomous drone can't be directed to new targets as they're detected, or commanded to strike one of them if necessary.

By going back to the early concept of wire guidance (in this case, optical fiber cable rather than plain copper wire), a drone is once again invulnerable to jamming or other electronic countermeasures.  Fiber optic cable is much thinner and lighter than copper wire, meaning more of it can be carried aboard the drone without too much of a weight penalty;  and it can carry a lot more information than wire, meaning the drone can use its own sensors to send data back to the operator, who can then redirect the UAV as required.

If this proves successful on the Ukraine battlefields, I won't be surprised to see anti-tank missiles using the same technology deployed before long.  Since they won't need a laser beam for guidance, laser sensors on tanks will be rendered useless, giving no warning of the missile being fired or of its imminent arrival.  (Of course, there's always the possibility that there'll be a fusion between drones and anti-tank missiles.  Instead of having two separate systems, drones might carry explosive charges with them as a matter of course, turning them from sensor platforms into weapons at a moment's notice and rendering a missile unnecessary.)  Looks like a lot more battlefields might be festooned with wires in the not too distant future.

Given the still relatively slow speeds of drones, and the problem that anything moving too fast won't be able to deploy wires or cables behind it, I wonder if earlier ultra-high-speed missile programs such as the Vought HVM, the MGM-166 LOSAT, and the Compact Kinetic Energy Missile (CKEM), might not be re-evaluated?  Here's a brief overview of those programs.

None of the ultra-high-speed missiles entered production, but a lot of effort went into developing them, and that knowledge base is still out there.  If they could be engineered to carry their own sensors, not needing external guidance, their high speed might make them a real threat to an enemy expecting only much slower optical-fiber-guided drones and missiles.  In fact, what if the latest-generation fiber-equipped drones could act as remote sensors, staying a safe distance from enemy defenses while feeding targeting information to the high-speed missile launch unit using their unjammable fiber optic cable?  Just a thought . . .



Dan said...

Be interesting to see how this new wrinkle in the deadly game of drone warfare is countered.

June J said...

In an entirely different battlespace, US submarines have long deployed torpedoes with wire guidance.

lynn said...

Yup, drone systems are very subject to jamming. Not good when they are on the next continent.

My former USMC son liked the TOW missile for its firepower but not the two mile ??? long tether. That meant that the squad could not fire and run.

Well Seasoned Fool said...

The Germans developed the technology in WWII - glide bombs.

McChuck said...

TOW missiles were retrofitted with video cameras and fiber optic cables in 1985 or 86. But it was done by two American NCOs, not one of the giant defense contractors. The Army refused to adopt the system, even though mandated and funded by Congress, because it was developed in-house, and no general could retire into a million dollar contract on it.

Ukraine is the new World War One,in some ways. A return to trench warfare, because defensive weapons are too powerful. We are seeing drones, like the biplanes before them, evolve from spotters to bombers, and now the first interceptors are being tested.

Rocketguy said...

Hah! I worked on LOSAT and CKEM early in my career. They were very impressive…and operated on the hairy edge of failure. I always thought the idea of sitting in a HUMVEE a few feet under a launch box was kinda sketchy.

Will said...

I saw a program on a version of the TOW system that McChuck mentions. Then again, it might just be a slightly confused memory of it by him.

What I saw was a box that fit in the rear of a jeep, with about 20 vertical launch missiles that trailed a fibre optic cable when launched. Have the jeep loiter a couple miles away, over the hill, out of sight of the targets. Launch vertically, arc over toward the battle, and visually hunt for a tank or similar, put the crosshairs on the spot you want to hit, and steer it with a joystick. Intended to hit from near vertical, where the armor would be the thinnest. Accurate enough to hit the driver's head if the hatch is open. Origin was two or three low level officers, and it didn't get into production, due to the ridiculously cheap system costs.

Turns out, only hugely expensive boondoggles ever get the nod for attempted production, as there has to be lots of money to throw around to get any real attention from The Mil Industrial System. A cheap weapon system can't be accepted, because it might eliminate the chance of a really expensive one.

McChuck said...

@Will - The version with a dozen vertical launchers came about 10 years later, after the Congressional inquiry and funding. Every time the system exceeded the standards, the overseers moved the goalposts so they were increasingly impossible. The last standard I heard of, about 20 years ago, called for the system to simultaneously launch 20 missiles, have them loiter in circles for up to 20 minutes, then be individually guided towards a target, lock on, and finish hitting the target automagically, without further operator assistance.

The modern version is the attachment of cheap laser seeker heads to Zuni rockets, increasing their hit percentage to over 90%. Project cancelled because it was too cheap and effective, and because it was invented in-house, so there would be no huge windfall for some General's retirement. Fun fact - Ukraine is now producing them, because they're not completely stupid.

This is why we can't have nice things.

Hamsterman said...

They were developing FOG-M (Fiber Optic Guided Munitions) in the 80s but it died off with the end of the Cold War. The idea was for a dedicated missile carrier to park behind a hill, launch them vertically, and guide them into Soviet armor.

Geoff said...

Wiser head than mine has speculated, the control system from the FGM-148 Javelin which is "fire and forget" should be quickly adopted to the remaining inventory of BGM071 TOW missiles.
Who has been around since the recoilless rifles were hot stuff.