Concept drawing of a Northrop Grumman-designed 'sixth-generation' fighter jet.Northrop Grumman.
According to Northrop engineers, it is tailless,
stealthy, and packs a laser cannon. It conspicuously resembles a
scaled-down version of Northrop’s most notable feat of aerospace
engineering, the B-2 stealth bomber.
Planners want greater weapons capacity, greater stealth, and higher survivability—jets.
Key to achieving that self-sufficiency: directed-energy weapons, more colloquially known as lasers. The idea: The jets could use a rechargeable solid-state
laser to shoot down enemy missiles or aircraft that come within a
certain range, essentially creating a no-fly zone around each aircraft.
The major challenge, Northrop acknowledges, isn’t so
much in airframe design but in conquering the constraints of fundamental
High-powered lasers are famously inefficient,
converting only about a third of the energy they expend into
target-incinerating laser beam power. So for every megawatt of energy
from a laser weapon, twice that is wasted as heat. For a stealth jet
trying to hide from sophisticated radar and infrared sensors, venting
huge amounts of heat is roughly equivalent to firing off signal flares.
1. According to Fortune, a laser is only 1/3
efficient. To achieve a one megawatt laser output, you need three
megawatts of power input!
2. To focus a megawatt laser (like the Boeing ABL), need two sets of
huge optics. Need a tracking laser and a second firing laser. An
additional problem is the constant fluctuation of air density. This
makes it difficult to keep a beam focused on a target. This means wasted
3. A laser weapon would require a big aircraft. This is bad for stealth.
A large airplane means a larger RCS.
4. In the thin upper atmosphere, the Boeing ABL could only achieve a 50
to 100 mile range. In the mid-atmosphere, probably looking at 50
miles maximum. Modern BVR missiles have greater range than 50 miles.
This means a BVR missile has longer range than a laser.
5. No practical defense (aside from electronic countermeasure) can be
placed on an aircraft to stop a kinetic kill by a missile. On the other
hand, lots of defenses can be employed to defeat a laser.
Countermeasures against a laser include spinning, mirror-like finish,
heat tiles, ablative armor, etc.
As the Fortune article mentions, a laser weapon creates a new heat problem of infrared detection.
In conclusion, I don't think a laser weapon is practical. The downsides
far outweigh the benefit. Sure, a solid-state laser is reloadable.
However, there are too many problems and I still think a salvo of BVR
missiles is more effective. Martian2