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Citat:Defeating the Missile
Modern combat aircraft must face SAMs and AAMS in almost any scenario, whether MiG hunting or mud bashing. Significantly, Western nations rely strongly on tacair, both Close-Air Support (CAS) and deep strike playing a major role in defensive and offensive strategies. Therefore many aircraft will have to repeatedly penetrate MiG and SAM infested airspace. While ECM may be most effective, it is best used by dedicated bombers, eg. F-111, Tornado, B-1B, which have the airframe space to carry capable systems and extra crew to manage them.
Air superiority aircraft and strike fighters such as the F-16, F/A-18, Lavi or A-7 have little space for ECM, a limitation exacerbated by a single person crew; the high level of automation thus required is at the expense of ECM capability, particularly the ability to jam multiple threats simultaneously. Evasive manoeuvring then becomes essential to survival.
Ideally, the pilot of a penetrating aircraft should try to discourage a missile launch, if this is unsuccessful, he must then exploit every known weakness of the missile's system to defeat it. Unlike AAA, missiles are a visible threat which act on a timescale which does allow some response.
When dealing with SAM sites, launches are most easily prevented by remaining outside of the known envelope of the SAM, moving fast and low and exploiting terrain to frustrate tracking. Jamming can be useful but is often futile at very close range, especially against massed SAM systems.
Denying a missile launching aircraft an opportunity to shoot is more demanding and generally constitutes the defensive aspect of aerial combat, a major subject in itself. To a large degree, it will depend upon the known performance limitations of the threat aircraft, its fire control system, its missiles and the competence of its pilot. A key factor is the capability of the defending aircraft's Radar Homing and Warning (RHAW) system and the pilot's visual awareness. The threat must be denied a favourable launch aspect and always offered a maximum LOS rate to hinder acquisition of the defending aircraft by the threat's fire control system.
LTV YA-7F Corsair II prototype in flight. LTV have proposed the A-7 Plus, a stretched A-7 with an afterburning 25,0001b class fan, as the USAF's interim Close Air Support aircraft replacing the vulnerable A-10A. Modern CAS aircraft such as the Su-25 Frogfoot possess a 1:1 class combat thrust/weight ratio offering the acceleration and turn rates needed to counter battlefield SAMs.
Once a launch has occurred early and accurate warning is vital to success. While RHAW systems can accurately identify the threat and its direction, they cannot indicate rate of closure and usually will not detect heatseekers. SAM launches are usually easy to detect visually, as large dust and smoke clouds are created and boosters tend to have large and bright exhaust plumes; similarly most AAMs will generate visible plumes while accelerating.
In this context, it is worth noting that flying above an undercast over SAM infested territory is asking to get hit, as many US aircrew learned the hard way over North Vietnam. A SAM call or RHAW warning must be treated seriously and imminent impact by an unknown missile must be assumed.
The initial defensive manoeuvre should be a hard break turn while deploying flares, chaff and throttling back. This will increase the LOS rate relative to the incoming missile which can affect tracking, while also changing aspect which introduces jitter and rotates the tailpipe away from a six o'clock threat. Attaining beam aspect relative to the missile can be most effective when dealing with Doppler radar guided missiles at lower altitudes, as the resulting rapid drop in Doppler can and often does result in lock being broken. Fuse performance may also be degraded.
Turning to beam aspect should allow visual acquisition and tracking of the incoming missile, particularly if fired from six o'clock. It is important that tactical aircraft maintain high airspeed over hostile territory, preferably above vc (v, - corner speed = minimum speed at which maximum load factor (G) may be attained) to allow the application of maximum G when under attack. A good rule of thumb quoted [1 ] is that a missile must pull at least five times the G-load of its target for a successful interception, therefore an aircraft maximises its chances of survival by maintaining a high energy state.
Good thrust/weight ratio and turn rate are not lost under these circumstances, getting caught at low airspeeds has often proved to be fatal. The direction of the break turn is dependent upon the aspect from which the missile is approaching, the objective always being to attain beam aspect relative to the missile. Breaking downward can force a radar guided missile to look down into clutter, while breaking into the sun or clouds can saturate a heat seeker's detector with background infra-red.
If beam aspect is attained before the missile closes, it may not be advantageous to continue the turn and the best alternative can be an out-of-plane turn which maintains beam aspect and a high LOS rate while also maximising the rate at which the aircraft's aspect relative to the missile changes. If the threat is an AAM launched at substantial range and acquired visually at an early stage, a useful tactic may be to unload and dive away from the missile at full throttle to outrun it or outlast its engine. Visual contact should be maintained to allow a break turn if the missile can keep up.
Early visual acquisition in aerial combat is most useful as the launch vehicle, smoke plume/contrails can identify the weapon, while the launch aspect alone may betray its capabilities. Visual tracking should be used to identify the plane of attack which can be exploited with an in-plane break turn to maximise the LOS rate.
The missile's trajectory may also serve to identify it. A CLOS or beam rider will appear to superimpose itself upon the LOS to the launch platform/site, whereas a proportional nav weapon will tend to stabilise its position relative to the distant horizon. If an AAM is launched from the forward quarter at close range, time may not be available to attain beam aspect and other measures must be taken. Breaking toward the AAM may require a large correction which the guidance cannot carry out at the high closure rate. If the missile does correct, rapid reversal of the turn may cause overshoot or exceed the seeker's tracking rate limit as it attempts to follow the LOS. A light dogfight missile may not be outmanoeuvred by this tactic.
While SAMs and AAMs represent a serious threat to combat aircraft, they can be defeated by appropriate countermeasures and manoeuvring. This perception is reflected in the USAF's current CAS/Battlefield Air Interdiction (CAS/BAI) programme which is aimed at replacing the A-10 CAS aircraft with a more agile successor. This situation is the result of the Russian's deployment of systems such as the SA-8, SA-9, SA-11 and SA-13 all of which carry radar sets on each launcher. The increase in the number of emitters to be jammed reduces the effectiveness of airborne ECM and results in a need for higher agility to avoid tracking and to outmanoeuvre launched weapons. While the A-10A is accurate, robust and has a relatively low heat signature, it is also very large, has a poor thrust/weight ratio and is rather slow with a combat speed around 350kt. While the US Army is delighted with the aircraft, TAC are unhappy about its survivability in an environment saturated with radar guided SAMs and shootdown AAMs and thus want a replacement [Editor's Note 2005: this is the beginning of the development effort which led to the JSF program a decade later].
Interestingly, it indicates a away from the Shturmovik philosophy of CAS toward the Typhoon philosophy, ie. use an aircraft which is agile enough to fend for itself in hostile airspace. The leading contenders in the CAS/BAI programme (at the time of writing) were the A-16 and a modified A-7D, the latter preferred for its lower cost. The A-7 Plus aircraft would be rebuilt from existing airframes. The 15,000 lb thrust TF41A-1 fan would be supplanted by either an F-110 or F-100-220 25,000 lb class afterburning fan and a 48" fuselage stretch carried out to accommodate the new engine. The wing would receive trailing edge flap augmenters, lift dumping spoilers and, significantly, leading edge strakes to improve turn rate.
Flir night vision equipment and terrain following radar would be carried, with some additional fuel against the earlier A-7D. The new engine will allow mildly supersonic speed but should vastly improve acceleration and sustained turn rate by virtue of nearly 1:1 combat thrust/weight ratio, much improved over the A-7D at about 0.6:1. The aircraft's high subsonic penetration speed, improved manoeuvr ability and demonstrated good low level handling should provide a quantum leap in survivability against the lumbering A-10. The other contender, the A-16 which is essentially a reduced capability F-16C offers even better manoeuvre performance but at a greater cost.
Guided missiles are a threat which can be countered, but success demands awareness both in planning and execution.
REFERENCES:
Shaw R.L., 'Fighter Combat, Tactics and Manoeuvring', Naval Institute Press, 1985.
Nordeen L.O., 'Air Warfare in the Missile Age', A&AP, 1985.
Editor's Note 2005: the advent of 4th Generation AAMs and 'double digit' SAMs has effectively eroded much of what could be achieved by using manoeuvre techniques. Nevertheless they remain effective against many legacy weapons and MANPADS, providing the aircraft has the required performance capabilities - kinematics do still matter.
http://www.ausairpower.net/TE-Evading-Missiles.html
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