Aircraft such as the Rafale, the Eurofighter Typhoon, the Saab/BAe Gripen and the Lockheed Martin/Boeing F-22 Raptor are well ahead of the previous generation of fighters, both in terms of performance and as weapons-carrying and deploying systems.
This improvement has come from advances in the technology of control systems and structural materials which have allowed aircraft designers to exploit more fully unstable configurations, such as the Rafale's canard/delta, while substantially reducing the aircraft's basic structural weight. Advances in engine technology have also played an important, although less obvious, part.
At the same time, the capability of the avionics contained within fighters and missiles has changed out of all recognition from aircraft weapon systems of only 20 years ago. Earlier computer systems used on aircraft had a total memory of just 8Kbytes, which was not enough to compute the weapon-aiming calculations and drive the moving map at the same time.
Given such advances, it is reasonable to ask why the constant, and expensive, search for yet more aircraft performance has continued - why has Dassault Aviation striven to make the Rafale as light and as powerful as it has?
The answer lies partly in physics and partly in tactics. The physics starts at the beginning of an air-to-air engagement. Modern radar and infrared missile systems can detect and engage other aircraft many kilometres ahead. Although missile performance varies greatly between systems, it is generally true that the more energy the aircraft launching a missile has at the moment of release, the further the missile will fly and the more effective it will be.
Of course, there is more to the air-to-air engagement problem than that simple statement. The launching pilot will seek to maximise the "no escape zone", the envelope within which the enemy fighter cannot escape simply by employing manoeuvring tactics.
Electronic systems also play a significant role in both attack and defence. However, the need to launch missiles at the highest practical airspeed possible has driven fighter designers to improve acceleration, climb rate and supersonic performance.
Why, then, do fighters also need good handling and a high turn rate, both instantaneous and sustained? Firstly, the enemy aircraft may take the unsporting action of shooting back. The maximum range of a missile depends not only on the energy at launch, but also on the closure rate between the aircraft.
The maximum range of a missile against a receding target is less than against a closing one. So the fighter pilot will endeavour to launch the missiles and, at some point - depending upon the weapon system's characteristics - turn away from the enemy as quickly and with as little energy loss as possible, hoping to negate the return fire.
The second reason for requiring good manoeuvrability is that of close-in combat. Air battles of modern times continue to reinforce the message that, despite being equipped with the most capable systems, it is still not always easy to know whether the aircraft to be engaged is friendly, hostile or neutral.
If there is any doubt, the only option is to go and look. If the other aircraft turns out to be hostile, a close-in fight will start, from which it is difficult to escape without one of the aircraft being shot down. So if you go in close, you had better be there to win. Agile, manoeuvrable aircraft and weapons systems are definitely preferable in such a situation.
Source: Flight International
