As we mentioned in the TAN-SAM-1C dev blog, we’d like to talk about photocontrast mode! This means today we’ll be talking in detail about some of the upcoming improvements to IR missile functionality in War Thunder and what this means for IR missile gameplay.
The technical background of IR seekers
Infrared homing heads are widely used on air-to-air missiles and ground based anti-aircraft missiles. They combine the benefits of using effective missile guidance trajectories, are also cheap and do not irradiate the target with any radiation. On the surface, making the heat source of your enemy the main target for a missile has some key advantages. On the flipside however, it does have some downsides that can be found within the main principle of how a target’s thermal radiation is captured, as the target must emit infrared waves for this to work. The higher the intensity of the radiation, the better. The range at which target lock on and tracking actually works greatly depends on this. In addition to this, a missile going for a heat source can be easily deceived by false sources of infrared radiation, such as flares.
Slower aircraft that have piston and turboprop engines emit a small amount of heat and the radiation from a jet engine is almost invisible from the frontal aspect in many cases. An infrared homing seeker head can detect a target like this at fairly modest distances. The same IR seeker of a MANPADS can capture a small helicopter from a distance of only 2-3 kilometers at most. However at this distance, you’re prone to being shot at quite easily, even by unguided aircraft rockets. Anti-aircraft missiles with an infrared seeker in those particular conditions can often hit a target as it exits from its attack run. However in this case, it relies on someone being there to launch them at this very moment.
The use of photocontrast mode
These shortcomings with the use of IR seekers as part of military air defense were especially relevant in the 1960s, when the development of IR seekers did not yet make it possible to confidently isolate a useful thermal signal from a target in the forward hemisphere. This is when the idea of using the visible wavelength range for target tracking came about. The Strela-1 was one of the first air defense systems to use a photocontrast homing head for targeting. This made it possible to capture and engage targets on opposing courses and ensure the protection of troops even before the target launched an attack. A photocontrast channel also has its own drawbacks to consider. The target can only be engaged during the day and in clear weather conditions, and the background behind the target must be uniform.
The use of combined dual and triple-band homing heads helps to smoothen out the shortcomings and makes a missile defense system function in all-weather and in day and night conditions. In difficult weather conditions, against low-flying targets and at night, guidance in infrared mode is used, and when launching from a long distance and against weakly emitting targets, photocontrast mode is used. It is also recommended to use photocontrast mode against targets on a collision course when they use countermeasures, to which the photocontrast channel is less sensitive compared to the infrared one. A dual-band seeker of this kind is equipped on the 9M37M missile system of the Strela-10M2, which is already present within the game. The use of an IR channel made this missile all-weather compatible, whilst the photocontrast channel provides the ability to capture a target and fire at it from long ranges, even exceeding the maximum flight range of the missile.
Photocontrast mode in War Thunder
Within War Thunder, the photocontrast channel will be present on missiles that are a successor to the Strela-1 system. Namely the 9M37M missiles of the Strela-10M2 SAM, as well as on the Japanese Type 93 SAM. With the release of the “Kings of Battle” major update, the Type 81C SAM will also benefit from this improvement. In game, you’ll have the ability to switch between three modes: photocontrast, infrared and automatic, which is enabled by default. In automatic mode, the seeker will perform a lock on in the most appropriate mode. However, you must take into account that after launch, it will not be possible to switch between modes. If the target was locked on in photocontrast mode, but evaded by going lower to the ground, then target tracking will fail and the missile will miss its mark.
You can look forward to these improvements and many others in the upcoming major update “Kings of Battle”! Until then, enjoy your matches and see you soon!