Giving a single "maximum range" value for an IR missile is even less meaningful than it is for a radar guided missile. Two parameters must be considered to find the maximum effective range of the missile assuming the target is within the missile seeker's field-of-view, and the lesser of the two is what determines the maximum effective range: missile kinematic range and seeker lock-on range.
If you picture a God's-eye view looking straight down at the target, typical IR seeker performance would place a heart-shaped zone around the target where the seeker can lock-on to the target when the seeker is within that zone and has the target in its field-of-view. Lock-on range from the frontal aspect might be only a few miles, while from dead astern might be 20 miles. This can vary significantly with altitude and weather conditions affecting visibility in the seeker detection spectrum. Note that with older seekers this is relatively independent of target speed, but very dependent on target throttle setting (particularly afterburner). Furthermore, a sudden maneuver could change the target aspect such that what was previously tail-on and within seeker range is now abeam or even head-on and outside of seeker range. Of course, recent seeker advances have greatly improved seeker performance, particularly against the target's forward hemisphere aspect.
On the same God's-eye view, missile kinematic range would place an eliptical zone around the target extending primarily ahead of the target where the missile has the kinetic energy to physically arrive at the target when launched toward the target from within this zone. Kinematic range from dead ahead might be 20 miles while from the stern aspect might be only a few miles. This can vary significantly with altitude and weather conditions affecting atmospheric density and hence drag on the missile. Note that this is very dependent on target speed and somewhat dependent on launch aircraft speed. Initial launch aircraft aspect to the target could impose some penalty if it requires significant initial missile course-correction. Furthermore, a sudden maneuver could change the target aspect such that what was previously head-on and within kinematic range is now abeam or even tail-on and subsequently outside of kinematic range.
Therefore the maximum effective range of an IR missile is the intersection, or overlap, of these two zones. It tends to look something like a tomato. For AIM-9M/AA-11 class weapons, it ranges roughly from several miles head-on to quite a few miles from the target's 10- and 2-o'clock aspect, and back around to several miles from dead astern. In no case is it more than 10 miles. Barring some significantly improved seeker lock-on ranges, the only way at this time an IR missile could have a maximum effective range much greater than that would require some means of being able to launch the weapon without an initial lock-on to the target and then acquire a LOAL (Lock-On After Launch) once it comes within seeker lock-on range. At that point the missile maximum effective range would be dominated or completely determined by the kinematic range zone.
Displacedjim
|