AIM-120 Help
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Agave,
negative on this one. With this selection, you can only influence how your FCR calculates the theor. value for H/MPRF. Since there is no backlink from the missile (not in this version) there is no way the F16 can know that the Slammer went active. It does calculate this point based on a formula and its current reads on the radar and the (known) flightpath of the missile.
This mean, with a larger RCS it is INDICATED that the slammer woke up earlier, and vice versa -> you cannot influence that time point same as you cannot influence anything on a slammer once it is off the rail.
stingray
Without a datalink, your comment doesnt make much sense.
You are saying that a large RCS target will influence when the slammer turns its radar on, and that this is independent of the setting on the FCR, and dependent only on the RCS of the target.
The slammer doesnt know the RCS of the target. It doesnt know until it turns its radar on, at which point its at HPRF range. Therefore, the actual RCS of the target cannot influence the wake time of the missile unless it knows the RCS when it leaves the rail, or unless it is sent to the missile by a datalink after launch - which you reckon doesnt happen, otherwise the FCR would know that the slammer went active.
Agave_Blue’s understanding of the functionality of the target size selection is consistent with what Ive read somewhere. Problem is, I cant recall where… and if he (and by extension myself also) is wrong, Id be rather interested to know that.
1.7.3.6.2.24 Target size for the AIM-120A is controlled via OSB 17 on the AIM-120 weapon page (Figure 1-71). Depressing the OSB will rotary through the four selections (SMALL, MEDIUM, LARGE, and UNKN). Target size is the only geometry parameter an AIM-120A can accept, assuming that target decoupled physical size and radar cross section are always correlated. UNKN is selected if power is cycled on the ground. Physical target size and radar cross section for the AIM-120B/C missile are controlled via OSB 18 and 8 respectively on the AIM-120B/C weapon page. The AIM-120B/C missiles can accept both physical size and radar cross section information. The missile receives fuzing information based on the options selected. These options will remain through power cycles in the air. UNKN is selected if power is cycled on the ground.
EDIT: Well that was amusing, the information I was looking for was in the BMS manual. Kinda funny after the recent complaints about it not being comprehensive enough…!
@BMS:
The radar model for AMRAAMs now includes HPRF (Husky) mode for favorable target geometries. The missile will activate the seeker well before the normal MPRF (Pitbull) range and attempt to track. HPRF is better at tracking high aspect targets with high closing range rate. Datalink guidance will continue up to MPRF unless the pilot commands a snip (drops the radar track) before that time. During HPRF with host DL guidance, the missile will use the best tracking solution available (either seeker or host DL guidance). HPRF and MPRF activation are now entirely based on range to target (used to be time-to-run based). Ranges coded are rough guesses for the AIM-120B. Other (active radar) missiles will need specific dat file edits (the AA-12 has been done already). The variables are:
AspectSelectorSize – HPRF requires target aspect to be within this many degrees of 180.
HuskyMinClosure – HPRF will not activate unless range rate is higher than this threshold
HighAspectBomberHusky – Select LARGE target (AIM120 SMS page) to use this as HPRF range gate
HighAspectFighterHusky – Select MED or UNKN target (AIM120 SMS page) to use this as HPRF range gate
BomberPitbull – Select LARGE target (AIM120 SMS page) to use this as MPRF range gate
FighterPitbull – Select MED or UNKN target (AIM120 SMS page) to use this as MPRF range gateNote: you can select SMALL in the SMS page. Doing so doesn’t make a lot of sense in Falcon4 since this is apparently intended for targeting small RCS targets although it might be useful against helicopters. If you do choose small, MPRF ranges are reduced by around a third compared to MED.
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Without a datalink, your comment doesnt make much sense.
You are saying that a large RCS target will influence when the slammer turns its radar on, and that this is independent of the setting on the FCR, and dependent only on the RCS of the target.
The slammer doesnt know the RCS of the target. It doesnt know until it turns its radar on, at which point its at HPRF range. Therefore, the actual RCS of the target cannot influence the wake time of the missile unless it knows the RCS when it leaves the rail, or unless it is sent to the missile by a datalink after launch - which you reckon doesnt happen, otherwise the FCR would know that the slammer went active.
Agave_Blue’s understanding of the functionality of the target size selection is consistent with what Ive read somewhere. Problem is, I cant recall where… and if he (and by extension myself also) is wrong, Id be rather interested to know that.
EDIT: Well that was amusing, the information I was looking for was in the BMS manual. Kinda funny after the recent complaints about it not being comprehensive enough…!
I looked in the documentation and didn’t see these 4 variables. Do:
- HighAspectBomberHusky
- HighAspectFighterHusky
- BomberPitbull
- FighterPitbull
not exist anymore in the .dat files?
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Well, the documentation has been replaced now that 4.33 is out. I had thought that in 4.32, the variables for the AIM-120 were hardcoded, and that other missiles needed specific lines added to the .dat files.