Heads-Up Display Modes 35 - Metaboli

118 Air Combat Basics
Homing
The most effective type of guidance against evasive targets is homing, when the
missile guidance system gets information about the target and produces control
commands on its own. Thus, the control post does not guide the SAM.
For active homing, the SAM illuminates the target and receives the signals
reflected off the target. In the case of semi-active homing, the source of
illumination (tracking radar) is located at the control post, and the SAM receives
signals reflected from the target. Passive homing systems use heat or light
emitted by the target to estimate the parameters of the target’s motion.
In general, homing systems operate in the following way: while the SAM rests on
the launcher, its seeker is locked onto the selected target, and the parameters of
the target’s motion are being measured. After launch the SAM seeker tracks the
target, estimates the tracking error, and produces control commands
independently from the ground.
Combined Guidance
As the name implies, some missiles combine guidance methods to improve
performance. The Kub (Cube) SAM system (SA-6A Gainful) is an example of a
system with combined guidance. This system employs radio-command guidance
on the initial part of the missile trajectory and homing when closing in on the
target. This provides high accuracy at long range.
SAM Engagement Envelope
Like air-to-air missiles, SAMs have specific engagement envelopes. Firing at
targets within the heart of the envelope increases the likelihood of a hit. Just like
air-to-air missiles, the envelope varies based on the target’s range, altitude, and
aspect. In the engagement diagram shown, the area defined by the numbers 1, 2,
3, 4, and 5 represent the missile’s effective area. Note that this envelope shifts if
the target is moving toward the launcher, in the area defined as a, b, c, d, e. In this
case, the missile must be fired at longer range since the target will fly part of the
way into the missile. If the missile is fired too late (once the target has crossed
the a, b, c line), it passes out of the envelope before the missile arrives.
Typical SAM engagement envelope