Superweapon or a super letdown? You decide.
In Len Deighton’s book Fighter, he describes the tactics used by the outnumbered English fighter pilots defending against German Luftwaffe bombers in the Battle of Britain:
The professional fighter pilot gained height as quickly as he was permitted, and treasured possession of that benefit. He hoped always to spot the enemy before they spotted him and hurried to the sun side of them to keep himself invisible. He needed superior speed, so he positioned himself for a diving attack, and he would choose a victim at the very rear of the enemy formation so that he did not have to fly through their gunfire. He would hope to kill on that first dive. If he failed, the dedicated professional would flee rather than face an alerted enemy.
Deighton’s point was that the best British pilots used hit-and-run tactics emphasizing surprise and speed in order to minimize losses, rather than dogfighting at length with enemies after those advantages were spent. These tactics permitted small numbers of British fighters to tackle the aerial armadas of the German Luftwaffe.
Obviously, technology has changed dramatically since 1940. While contemporary fighters can now go more than five times as fast as the Spitfires and Messerschmitt fighters of the Battle of Britain, two new technologies promise to make hit-and-run tactics more effective: stealth technology and long-range air-to-air missiles.
Stealth and Its Limits:
While virtually any plane can be equipped to fire long-range missiles, stealth airframes are built using radar-absorbent materials and engineered precisely to minimize reflection of radar waves. This constrains their load-carrying abilities, as external weapons or drop tanks could increase their visibility on radar. The United States fields two stealth fighters, the F-22 Raptor and the F-35 Lightning II.
Stealth planes are properly described as “Low Observable” aircraft. They are not actually undetectable, but are very hard to spot on radar. Let’s review the limits on stealth technology, and how fighter doctrine may evolve around them.
Stealth aircraft are optimized to be difficult to observe on the precise X-Band radars used on modern fighters: while some radars have better resolutions than others, most will only be able to track a stealth fighter at shorter distances. An F-22 is claimed to have the radar cross section of 0.0001 square meters in certain aspect—the same as that of a marble.
Low-bandwidth radars are more effective at detecting stealth aircraft. These are typically used by ground installations and ships, but also found on specialized aerial platforms such as the E-2D. However, they come with a major limitation: they can reveal only the general location of a stealth fighter and are too imprecise to be used to target missiles—though they can indicate to an X-Band radar where to look.
Infra-Red Search-and Track (IRST) systems offer another means of detecting stealth aircraft, but their range is generally limited. The latest IRST system on the SU-35 has extended the range up to 50 kilometers, whereas its radar has detection range of up to 200 kilometers. Just like low-band radar, IRST doesn’t give a precise track and can’t be used to lock on weapons. Stealth fighters include features designed to minimize heat signature, but they are far from completely effective.
Of course, a stealth fighter can be seen within visual range, and is vulnerable to heat-seeking missiles.
To recap: stealth technology is more effective at a distance. Although there are a number of methods to detect stealth fighters at long range, they generally don’t permit weapons to lock on to them.
In return, nothing prevents the stealth aircraft from firing at its opponents.
Enter the beyond-visual-range (BVR) missile.
Long Range Air-to-Air Missiles
Around the late 1990s, a new generation of long-range radar-guided air-to-air missiles entered service, notably the AIM-120 AMRAAM and the Russian R-77. These could hit targets over 50 kilometers away. (The earlier AIM-54 Phoenix boasted even longer range but was very expensive). In subsequent decades, the range has continued to increase to well over 100 kilometers, and new types such as the European MBDA Meteor and the Chinese PL-15 continue to push the envelope of speed and range.
The current AIM-120D has a theoretical maximum range of 160 kilometers; although in practice firing range will likely be much shorter for reasons soon discussed.
As long-range missiles are radar-guided, stealth fighters are not particularly vulnerable to them. The same cannot be said for non-stealth aircraft. An F-15 or Su-35 may attempt to avoid missiles with evasive maneuvers and counter measures—but doing so will disrupt whatever they are doing, and an opponent is likely to fire more than one missile.
One factor that is difficult to calculate is how likely long-range missiles are to hit. Extrapolating from past usage of radar-guided missiles is problematic, both because missile technology has advanced considerably since its inception (early radar-guided Sparrow missiles had a less than 10 percent kill probability in the Vietnam War), and the conflicts in which radar-guided missiles have been more successful (Arab-Israeli conflicts, the Gulf War) involved poorly trained opponents lacking effective countermeasures.
It’s safe to say that long-range missiles will have lower hit rates than short-range missiles like the AIM-9 Sidewinder and the Russian R-73—modern versions of which have chalked up a roughly seventy percent probability of kill.
Attrition and High Value Targets
Third- or fourth-generation fighters seeking to engage stealth aircraft in combat must close within short range so that their targeting systems are effective, all while dodging volleys of deadly missiles. As the stealth fighters themselves are difficult to track, they can disengage to avoid entering the short-range envelope in relative security.
It’s a difficult advantage to overcome.
But referring back to the Battle of Britain can reveal a limitation of this strategy. The British hit-and-run attacks succeeded in inflicting deadly attrition on German bombers over time until they were forced to call off the air offensive. But they rarely prevented the German formations from hitting their targets. The German simply had too many aircraft.
At first, this was a problem: the Germans relentlessly pounded British airfields, degrading the Royal Air Force’s ability to fight in the air. But then the Germans switched to bombing civilian targets in London. While this inflicted many civilian casualties, the raids did not degrade the RAF’s ability to fight back. The British fighters could sustain their advantageous rate of attrition versus the German Luftwaffe until the latter was forced to tap out.
So what happens if the other side attacks with superior numbers a target that must be defended?
An F-22 has a combat radius of some five hundred miles on internal fuel. The F-35 can fly 875 miles when loaded for air-to-air combat. Now consider the thousands of kilometers lying between U.S. bases in the Pacific and Europe and various potential conflict zones. To operate over those distances, stealth fighters would require aerial refueling from tanker aircraft. If fighting a well-equipped opponent, carrier-based aircraft would also likely be distant from the warzone, as carriers are at risk if they approach too close to ground-based anti-shipping missile batteries and aircraft.
American fighters would also likely be supported by AWACS airborne radar and command and control platforms, notably the E-2 Hawkeye and E-3 Sentry. The tankers and the AWACS aircraft are basically lumbering airliner-sized planes crammed full of fuel and electronic equipment respectively.
Let’s consider what would happen when American fighters encounter a much larger force of fighters based on the coast. The American fighters could fire their long-range AIM-120D missiles from more than one hundred kilometers away—four from each F-35 and six on the F-22. Soaring at Mach 4—twice the maximum speed of the aircraft that launched it—an AIM-120 can traverse eighty kilometers in one minute.
The radar-warning receivers on their targets would light up as they detect the incoming attack. The further away the target, the more time it has to evade the missile. Therefore, BVR missiles may be fired at well below their maximum range to ensure a higher probability of a kill, particularly when engaging maneuverable fighter aircraft.
Most opposing aircraft would not be able to shoot back at the stealth planes, though they might have a general idea of their position if they are supported by low-band radar or good infrared sensors. They could close on the American fighters, hoping to enter the envelope in which their sensors are effective.
What if the U.S. fighters close to short range after expending their long-range armaments, rather than prudently disengaging? If both sides are closing upon each other at maximum speed at high altitude, the distance between them would diminish at a rate of 60-80 kilometers a minute. Even if the AIM-120s were fired at maximum range, the opposing aircraft could close that distance in one or two minutes.
In short-range engagements, surprise, pilot training and flight performance will determine the victor.