Questions about AIM-120 HUD display
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Hello everyone,
I was going through the -34, and reading the AIM-120 part, I notice a few things I would like to have more informations on.
When looking at range indications on the DLZ it says that Ropt is the same thing as Raero but a shot at this range will end up with high termination criteria instead of nominal termination criteria. And the only definition for high termination criteria is that a missile with high termination criteria has more energy than a missile with nominal termination criteria. I’ve been looking in IRL F-16 MLU Part 2 manual only to find out this same definition.
My question is : Is there an other definition somewhere (something that’s not relative to an other abstract quantity) ?Second question : How do you use the DMC (digital manoeuvring cue) ? I thought the aspect of the target displayed on the HUD would be enough information to establish the probability of my missile to hit the target so I’m wondering if there is an other use to it.
I thank you in advance for your answer.
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Not sure what exactly the quantitative difference between nominal and high terminal criteria is besides the rather vague “more energy.” I do know there is some difference in symbols that depends on current maneuvering. The maximum one assumes you are pointing exactly at ideal loft and azimuth. The other ones I think are based on current aiming.
The DMC is pretty simple though. Put the DMC as close as possible to the middle of the ASEC. It tells you where to point the jet in azimuth and elevation to shoot. There’s only two pieces of information that DMC can provide other than steering and that is if X is over it you are outside R-aero and no X if inside.
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Frederf, your talking about the attack steering cue ,and not the DMC. Give it another go
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TLAs are hard to keep track of.
OK DMC is a number expressed in degrees 0-180 which represents how much turn is required by target to spoil (degrade) the shot kinematically. It only appears in the range R-PI to R-TR. We expect that DMC value just barely outside R-TR is equal to his aspect because at this range the assumption is that a turn to 0 aspect is marginal kinematically.
At farther ranges the amount of turn required by the target to degrade the shot decreases from his aspect (the maximum that will display) down to zero at R-PI. The value always assumes target turns in the unfavorable direction.
And to correct what I said before R-OPT and R-AERO both assume ideal launch azimuth and elevation. It’s R-PI that assumes current conditions. Thus we expect R-OPT and R-PI symbology to be equal positioning when we aim the airplane ideally (no post launch missile steering required) at the moment of launch.
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TLAs are hard to keep track of.
OK DMC is a number expressed in degrees 0-180 which represents how much turn is required by target to spoil (degrade) the shot kinematically. It only appears in the range R-PI to R-TR. We expect that DMC value just barely outside R-TR is equal to his aspect because at this range the assumption is that a turn to 0 aspect is marginal kinematically.
At farther ranges the amount of turn required by the target to degrade the shot decreases from his aspect (the maximum that will display) down to zero at R-PI. The value always assumes target turns in the unfavorable direction.
And to correct what I said before R-OPT and R-AERO both assume ideal launch azimuth and elevation. It’s R-PI that assumes current conditions. Thus we expect R-OPT and R-PI symbology to be equal positioning when we aim the airplane ideally (no post launch missile steering required) at the moment of launch.
Thank you for your answer. The way DMC was explained I thought of it as a pure function of the AA of the target, I understand know that it’s also a question of termination criteria.
Remain my question about what exactly is a high quality termination criteria.
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Does high termination criteria also relate to Husky, i.e. missile (radar) goes active earlier for high aspect/closure targets? Nominal likewise to Pitbull, i.e. missile relies on data-link for longer before it switches on it’s own radar?
ASC = Attack Steering Cue. Just put it in the centre of the ASEC (big circle) to ensure optimum loft for your BVR shots.
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High termination criteria is Husky, i.e. missile (radar) goes active earlier for high aspect/closure targets. Nominal is Pitbull, i.e. missile relies on data-link for longer before it switches on it’s own radar.
I have difficulties to understand you here.
In the definition given in both the BMS documentation and the irl doc, it’s only linked to the missile energy during its endgame. I don’t see why PRF of the seeker would be involved. The notion of HTC (which is also linked to Rpi in the documentation) remains pertinent even for close range shot with a target fleeing me (low closure speed, short range, the missile should not use HPRF). Furthermore, at range above Ropt the missile might go husky too so I don’t quite see the link between HPRF and HTC.
ASC = Attack Steering Queue. Just put it in the centre of the ASEC (big circle) to ensure optimum loft for your BVR shots.
I know ;), I think Frederf just mixed up DMC and ASC in its first answer.
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Does high termination criteria also relate to Husky, i.e. missile (radar) goes active earlier for high aspect/closure targets? Nominal likewise to Pitbull, i.e. missile relies on data-link for longer before it switches on it’s own radar?
No
If the target is exceeding or will exceed (at some point) the DMC value, the missile will have nominal termination criteria.
If it does not exceed the DMC value the missile will have high termination criteria.This does not guarantee you a hit,nor does is guarantee the termination criteria.
It is the prediction (at time of launch) of the energy state of the missile if the scenario remains constant.