Naval warfare has been defined by transitions, all triggered by major advances in technology. Steam power, radar, aircraft... all have led to drastic changes.
Today, we are on the verge of another such transition.
The defining technologies of current naval warfare are the guided missile, the submarine and the jet plane.
The modern guided missile delivers a warhead accurately to the target, without risking a pilot and without requiring external guidance. The latest developments have focused on extending range, reducing time spent within the zone of defensive fire from the target, and evading that fire with techniques such as sea-skimming or high-speed evasive maneuvers.
Aircraft evolved from directly attacking ships with bombs and guns to becoming missile launch platforms. A missile designed to have the speed to penetrate an enemy ships's defenses does not generally have very good range. This means an aircraft, submarine or another ship is required to approach the target, and close the final distance with the missile itself.
As anti-air defenses became more effective, aircraft and the missiles they carried were forced to evolve.
The premier defenses for a ship today are the anti-aircraft missile and the CIWS gun.
|The RIM-174 ERAM, a Mach 3.5 air target interceptor|
Anti-aircraft missiles allow warships to take down helicopters and jets within range, and force them to drop their anti-ship missiles from as far as 400km away. With a service ceiling of 34000m, it precludes any sort of high-altitude attack alternative.
The result is that anti-ship missiles have a minimum range to be useful when mounted on aircraft. As a secondary consequence, they have a minimum size that makes it difficult to mount a huge number of them on a single airframe, making overwhelming defenses through saturation more difficult. This is further compounded by the fact that the target ship may be covered by its own aircraft, and the attacking craft must remain agile enough to evade them.
|The now famous Phalanx CIWS, shooting up to 5000 rounds a minute|
The last line of defense is the Close-In Weapons Systems such as Oerlikon or Goalkeeper. They rely on interlinked gun systems shooting a hail of bullets into the predicted path of incoming missiles. They can be backed up by anti-missile missiles such as the Aster missile family, which intercept threats at hypersonic velocities.
Together, they relegated the subsonic cruise missile to the past. Today, anti-ship missiles are required to sea-skim to evade radar for as long as possible, then 'pop-up' and accelerate to supersonic speeds in the final stretch. This is in direct contradiction with their extensive range requirements.
The results these technologies have had on naval warfare over the past 40 years have been varied.
Countries such as the United States have concentrated their power into Aircraft Carrier strike groups, able to launch missile-equipped aircraft anywhere in the world. In turn, they are protected by an entire cortège of ships dedicated to anti-aircraft, anti-missile and anti-submarine roles. To improve their attack performance, stealth technologies are being developed to give aircraft an undetected-launch capability or alternatively, shoot from closer ranges with faster missiles.
Others such as Russia have instead developed an entire suite of warships with the capability to launch dozens of missiles at once, from hundreds of kilometers away, to perform a coordinated strike that would overwhelm any carrier group's defenses.
Smaller nations such as the UK or France have given up on the expensive carrier group strategy, and instead focus on more flexible helicopter carriers and stealthy submarines that can bypass the majority of a target's defenses.
What's coming next?
A leap in missile performance, and the tentative failure of stealth technologies, will define naval warfare for the next few decades.
One technology being integrated into anti-ship capabilities is stealth, either through stealthy missiles or stealthy jet bombers.
The LRASM project promises stealthy missiles that work together to find their target even when satellite guidance is unavailable and to cooperatively evade anti-missile defenses.
|Screen capture from Lockheed's simulated attack on Russian destroyers.|
Other nations are not gambling on stealth, instead focusing on making anti-ship missiles much, much faster. An example of this is the BrahMos-II, a joint development by India and Russia. When the attacking missile is faster than the bullets sent to shoot it down, and crosses the final 10km in less than 5 seconds, it has a real chance of evading defensive fire.
A great fear of today's navies is the ballistic anti-ship missile - tactical ballistic missiles accurate enough to hit warships are sea. Being much larger than the regular supersonic cruise missile, they can perform hundred-gee maneuvers at Mach 10+ plus, coming from thousands of kilometers away and attacking from a vector most current anti-missile defenses are not equipped to handle. China apparently has this capability with the DF-26.
The ships themselves are evolving into stealthy missile platforms, with anemic guns and a small onboard flight deck for a helicopter.
|The Zumwalt-class destroyer, ironically resembling an ironclad, one of the earliest warships.|
In a world of rapidly evolving missile capabilities, it becomes more important to deliver massive, rapid missile strikes that overwhelm defenses, than it is to counter the rapidly diminishing role of aircraft. If tactical ballistic missiles become a widespread threat, then the requirement for aircraft to act as intermediaries will be abolished entirely, paving the way for aircraft carriers to be replaced by Missile DD groups and attack submarines.
This is further compounded by the fact that semi-stealth aircraft such as the F-35 Lightning II were unable to deliver on the promised performance, much less so when trying to handle the requirements for naval variants or effectively defend itself against agile 'old-school' interceptors such as the SU-35 Flanker.
What are the game-changing technologies?
The first is lasers.
There is every reason to expect that in the relatively 'clean' environment of an open sea, and with megawatts of electrical power directly available from a warship's nuclear reactor, that laser technology will become of great importance in naval warfare.
The main advantage to lasers is the increase in effectiveness in defending against missiles.
The future anti-ship missile, in its hypersonic high-g maneuvering variant, is necessarily thin-skinned. This means that lasers will be able pierce them and ignite solid propellant, spill liquid fuels or cut the airframe into an unsustainable shape. At such velocities, even minor imperfections can crush the missile.
Lasers have a practical zero flight time, meaning they hit the target as soon as it is detected. Unlike a CIWS gun mount that has to predict the missiles trajectory for slower bullets to intersect and intercept it, a laser defense requires no prediction, only tracking.
"We expect that in the future, a missile will not be able to simply outmaneuver a
a highly accurate, high-energy laser beam traveling at the speed of light," Chief of Naval Research Rear Adm. Matthew Klunder said.
Tracking a missile is also easier, since unlike a 5.7 ton CIWS gun mount that has to be skewed to point ahead of the missile, a laser only needs its comparatively lightweight optics to be rotated.
A CIWS gun system has to be installed for each possible attack vector, while a single laser generator can feed a beam to multiple optical mounts.
With the correct optics and wavelength, a laser can instantly start shooting at a target at the edge of a 20km horizon, while bullets will never reach that far, therefore vastly increasing the defensive perimeter.
Lasers can also extend to denying the defensive perimeter to aircraft. Aircraft are unlikely to be able to retaliate with a destructive beam in return unless there is a major breakthrough in energy production and density.
The second is railguns.
Railguns are not a mature technology, but like lasers, are a near future technology that will enter the battlefield and profoundly change naval warfare.
|Over-the-horizon range is expected to be over 300km|
Railguns deliver projectiles at extreme velocities to extreme ranges. The basic projectile is a metallic slug with radio-controlled fins, allowing it to be 'guided' in a sense over the course of its flight.
At short ranges, it is extremely effective. It can reach the horizon in a matter of seconds, which means it can take down even supersonic aircraft as a very effective AA gun, or throw a cloud of shrapnel in front of an incoming cruise missile before it starts its final sprint.
At medium ranges, it can replace missiles in the anti-ship role, since the small, solid projectiles cannot be easily shot down with lasers or intercepted with missiles.
At longer ranges, it can serve as artillery. With a rocket motor attached, it can reach an enemy ship from ranges rivaling dedicated anti-ship missiles, and act as ballistic warheads on re-entry (the rocket engine would ignite at the edge of the atmosphere, where air would not impede an increase in velocity from Mach 5 to Mach 10+). Alternatively, it can use the rocket engine to produce thrust-lift and to overcome the drag losses that result from travelling through lower altitudes and with high-g maneuvers. This would allow it to become a hypersonic kinetic-kill projectile that cannot be shot down by lasers.
|Rocket-assisted XM1113 artillery shells.|
How will naval warfare evolve?
Railguns will extend the warship's reach to ranges only expected of cruise missiles. However, the addition of laser defenses means that while an anti-ship missile can have even longer range or flight time, it will be shot down in the final stages of its trajectory.
Aircraft will be relegated to smaller and smaller roles - specialized stealth bombers with poor flight performance, or high-performance interceptors. Neither needs to be carried out to sea, so the aircraft carrier as a dominant force will disappear.
Missile destroyers, that would have already replaced them in smaller navies entirely, would quickly be outclassed by railgun-equipped and laser-defended warships. Both can defend themselves from each others' missiles, but the railgun rounds, especially of the sea-skimming, rocket-boosted variant, can penetrate laser defenses much more easily.
Other changes will be made. Advances in automation will reduce crew sizes drastically. Improvements in computer performance and sensor sensitivity means that radar technologies will remain ahead of stealth for the near future.
However, many of the modern technologies remain.
For non-boosted railguns, the only way to increase range is to increase muzzle velocity. An upper limit in energy requirements and airspeed survivable by the projectile will quickly be reached. This is especially aggravating since the majority of a projectile's kinetic energy is lost in the dense lower atmosphere if pushed to velocities much above Mach 7. Rocket-boosted projectile can increase range without requiring higher muzzle velocities, but weigh more.
This means that conventional missiles are required for long-range (500km+) engagements.
Ballistic missiles, naturally shielded against re-entry heating with ablative materials, are likely to survive laser defenses. This means systems such as the Aegis Ballistic Missile Defense System will still be in use.
The Battleship of the Future
|Incredible concept art from UCL Ship Designs|
Like the Zumwalt resembling its ancestor, the significance of the railgun will return naval warfare to a state slightly reminiscent of battleship supremacy.
In WWII, battleship guns could shoot beyond the horizon, and were armored against similar sized projectiles. The ships were built around their armament.
The future battleship also has guns that dominate the sea, and is built around providing the guns the necessary electricity and protection from aerial threats.
In the image above, the 'advanced hullform' is an extension of the bulbous bow concept. The lasers are mounted on top of the masts to extend the laser's horizon. It also has the benefit of shooting down on seas-skimming missiles, and therefore being able to shoot the thinner-skinned sides (and a larger target profile). Automation reduces the crew required, and increases mission endurance.
UAVs and rotorcraft do not need a large flight deck, but can vastly increase mission capability and provide anti-submarine warfare capability.
Here is another concept image of a laser and railgun equipped warship, but with a more conventional hull:
|Based on the Type 45 destroyer.|