apocom Junior Member

Join Date: Oct 2015 Posts: 94

Chaff and R27(E)R



1. Chaff is not like flare

You can't simply say flare is an IR and chaff a radar decoy. Flare is an IR decoy, but chaff is not a radar decoy.

There are so many sources how chaff works, here is an example:



Basicly:

Chaff consists of many small particles that should reflect as much energy back to the radar as possible. What happens, is that the radar can no longer track the target, because the energy reflected back by the target is too small in comparision, and can't be distinguished from the chaff cloud.



Therefore the radar looses lock of the target (not implemented in DCS or bug).



2. SARH missiles are just following the radar

As long as the missile "sees" the illuminated target, it follows it.

https://web.archive.org/web/20070109...andout_f02.pdf



http://www.ausairpower.net/TE-Radar-AAMs.html



So, in order to hit a target, the missiles sensor has to lock on onto the radar beam reflected by the target. Two conditions must be fullfilled, the target must be illuminated and the sensor has to be able to see the target. So if a SARH can't see the illumination anymore, it goes ballistic.



In conclusion, chaff is not only very effective against the missile itself, but also against the hostile fighters radar.



3. SU27 IRL features

To overcome the problems with chaff the russians have at least two ways to increase the missiles hit chance."(I dont understand russian and I hope I've copied the correct parts )



a) "расчет условий пуска ракет, формирование и выдачу разовых команд в СУО-27Э2, а также подсвет атакуемой цели и передачу команд управления на пущенную ракету в РГС по линии радиокоррекции;"



So a link to the missile for controlling it



b) "выдачу угловых координат визуально видимой цели в РЛПК и в управляемые ракеты с ТГС при прицеливании с помощью кнюпеля в режиме ОПТ и от НСЦ в режиме ШЛЕМ;



So giving the radar the IRST target information. So, as long as IRST has a stable lock, the radar illuminates the target and the missile is homing it. Because IRST is immune to chaff, the whole process makes the missile more or less (proximity fuse may cause problems) immune to chaff.



Source: САМОЛЕТ СУ-27СК РУКОВОДСТВО ПО ЛЕТНОЙ ЭКСПЛУАТАЦИИ Книга 1





4. BUG



So, but what happens really often, is that my missiles are chasing chaff. This cannot happen because chaff is not a decoy, but by no means it is possible that 2 missiles are chasing 2 different chaff-decoys. My radar can only lock 1 thing.



Ok, I'm rewatching some of my tacview files because I wanted to add some screenshots, but there is so much unlogic behaviour, that I don't think a screenshot can transport all the problems.



5. Conclusion

Overall I think that chaff is implemented like flare, as a decoy, and that my passive missiles behave, like they have an active radar that locks on chaff.



EDIT: Some spelling, shouln't make such topics that late. Ok, I think here are numerous bugs or implementation problems.You can't simply say flare is an IR and chaff a radar decoy. Flare is an IR decoy, but chaff is not a radar decoy.There are so many sources how chaff works, here is an example: http://www.dtic.mil/dtic/tr/fulltext/u2/a135928.pdf Basicly:Chaff consists of many small particles that should reflect as much energy back to the radar as possible. What happens, is that the radar can no longer track the target, because the energy reflected back by the target is too small in comparision, and can't be distinguished from the chaff cloud.Therefore the radar looses lock of the target (not implemented in DCS or bug).As long as the missile "sees" the illuminated target, it follows it.So, in order to hit a target, the missiles sensor has to lock on onto the radar beam reflected by the target. Two conditions must be fullfilled, the target must be illuminated and the sensor has to be able to see the target. So if a SARH can't see the illumination anymore, it goes ballistic.In conclusion, chaff is not only very effective against the missile itself, but also against the hostile fighters radar.To overcome the problems with chaff the russians have at least two ways to increase the missiles hit chance."(I dont understand russian and I hope I've copied the correct partsa) "расчет условий пуска ракет, формирование и выдачу разовых команд в СУО-27Э2, а также подсвет атакуемой цели и передачу команд управления на пущенную ракету в РГС по линии радиокоррекции;"So a link to the missile for controlling itb) "выдачу угловых координат визуально видимой цели в РЛПК и в управляемые ракеты с ТГС при прицеливании с помощью кнюпеля в режиме ОПТ и от НСЦ в режиме ШЛЕМ;Source: САМОЛЕТ СУ-27СК РУКОВОДСТВО ПО ЛЕТНОЙ ЭКСПЛУАТАЦИИ Книга 1So, but what happens really often, is that my missiles are chasing chaff. This cannot happen because chaff is not a decoy, but by no means it is possible that 2 missiles are chasing 2 different chaff-decoys. My radar can only lock 1 thing.Ok, I'm rewatching some of my tacview files because I wanted to add some screenshots, but there is so much unlogic behaviour, that I don't think a screenshot can transport all the problems.Overall I think that chaff is implemented like flare, as a decoy, and that my passive missiles behave, like they have an active radar that locks on chaff.EDIT: Some spelling, shouln't make such topics that late. Last edited by apocom; 11-15-2015 at 12:28 AM .