【转】AMRAAM Pilot Guide

lkyfly0531

The goal when you shoot an AIM-120 is to be able to preserve range while maintaining the highest probability of kill. To do so, you will have to use all the tools at your disposal and a bit of sound logic! When talking about tools, I’m referring to the AMRAAM Dynamic Launch Zone (DLZ) and the Head-Up Display (HUD) symbology modeled in BMS which is simulating current F-16 software.

1. A Bit of Theory

Before going into details about the avionics itself and the tactics to be employed I’ll give you first some theory about the AMRAAM and active missiles in general.

--The AMRAAM is an active missile which is considered to be “fire and forget”. That’s not exactly true. The AIM-120 has its own radar but this one is much smaller than the one of the launching aircraft. So the range at which the missile will be able to detect and lock a target will be smaller than the radar detection range of the aircraft. However, the missile can be launched from further away than its detection range. In this case, the launching aircraft will have to send information to the AMRAAM via datalink (or support the missile) about the target position, aspect angle and speed until its own radar is able to detect it by itself (missile becoming finally active). Once the missile is active, you will be able to break track of the target (which is called a 'snip') however that’s not mandatory! Why continue to support the missile if it’s active? Accuracy when having 2 radars is always better than one!

--The AIM-120 has 2 active states: HPRF (High Pulse Repetition Frequency) and MPRF (Medium Pulse Repetition Frequency). I won’t go into details about these right here (it is described below) but only know that HPRF will be used from further away than MPRF and is less accurate concerning the information about the target location. Anyway, you can snip the target as soon as the missile is HPRF active or choose to continue until MPRF active. This choice will depend on the tactical situation and will be discussed later on.

--When launching an AIM-120, this missile can end up with 2 different termination criteria. What’s a termination criteria? It describes the kinetic energy and the maneuverability potential the missile has to successfully intercept the target and destroy/damage it. It can have High Termination Criteria or Nominal Termination Criteria. The latter means the missile will have less energy and maneuverability thus less probability to hit the target.

--Sometimes, you will have to loft the missile to increase its effectiveness. Lofting will be done via a small pitch up maneuver of generally 30 to 40° just like when you want to throw a stone the furthest away.

2. Hud Symbology: The Dynamic Launch Zone (DLZ)

What does it look like and what’s the use of all these numbers and symbols?



RAERO (Range Aerodynamic): Represents the max kinematic range of the missile thus the longest range shot having a chance to hit the target. This is assuming the target won't maneuver, the pilot performs optimal loft/steering and will result in Nominal Termination Criteria.

ROPT (Range Optimal): Basically the same as RAERO but with High Termination Criteria this time.

RPI (Range Probability of Intercept): Same as ROPT but without having to loft or make azimuth change. We still assume the target is non-maneuvering.

RTR (Range Turn and Run): Represents the max range shot assuming the target turns away from you aircraft to tail aspect at launch.

RMIN (Range Minimum): Self-explanatory!

A-POLE: Range from your aircraft to the target when the missile will go active (HPRF).

M-POLE: Same as A-POLE but MPRF active.

F-POLE: Range from your aircraft to the target when the missile will impact the target.

DMC (Digital Maneuvering Cue): Represents the heading change the target has to make to degrade the AMRAAM from high termination criteria to nominal. This value will never exceed the AA (Aspect Angle) and the RTR cue will grow up to this value.

For example:



Let’s see all the possibilities we can encounter in flight.

----When the target is beyond 125% of RAERO (unexpanded DLZ)



----When the target is within 125% of RAERO (expanded DLZ : Raero grows up to the former tick mark)



----When the target is within ROPT



----When the target is within high termination criteria of the AMRAAM (RPI)



----When the target is within the no-escape zone of the AMRAAM (RTR)



Once you’ve launched a missile, the M-pole or F-pole of the missile in-flight (depending if the missile is already MPRF active or not) as well as the Time to HPRF active or Time to MPRF active or Time to Impact will appear below the DLZ. This is a dynamic countdown that will be updated if the target or your aircraft maneuvers. Consider a shot taken at Ropt then you fly straight ahead to the (maneuvering) target.



3. HUD Symbology: ASEC/ASC

Allowable Steering Error Circle (ASEC) – The ASEC is a variable diameter circle displayed on the HUD and MFD when an AIM-120 is the selected weapon, sighting option is Slave, and a bugged target exists. The weapon status must be RDY or SIM (Master ARM in ARM or SIM) in order for the ASEC/ASC and DLZ to appear. If there is no bugged target, the AIM-120 Boresight reticle will be displayed. The ASEC is an aid for positioning the attack steering cue in order to take the best shot possible based on the steering. At target ranges from outside Raero to Ropt, the ASEC is its smallest size, 11mr radius. At Ropt, the ASEC begins to grow in size until target range reaches Rpi where it reaches its maximum size (the ASEC represents 45 degrees of allowable steering error at Rpi). From Rpi to midpoint Rtr, the ASEC remains its largest size, at which point it begins to shrink again until it reaches minimum size at Rmin. The ASEC flashes when the target range is within the maneuver zone. The ASEC’s variable radius varies from 11mr to 56mr with a slaved target. For a bore shot, the radius is static at 131mr (262mr diameter). The ASEC on the MFD is identical in function.

Attack Steering Cue (ASC) – The ASC (8 mr diameter circle in the HUD, 10 pixel radius circle on the MFD) provides several types of steering: horizontal aircraft steering, a blend of aircraft and missile steering, optimal missile steering (with horizontal and vertical missile steering), or Rmin steering (shortest LOS to the target). The type of steering provided is a function of range to the target. Horizontal aircraft steering is provided against targets beyond 1.2 X Raero (where Raero is the maximum kinematic range of the missile) and is based on the limits of the ASEC and a 45 degress LOS to target limit. Blended aircraft and missile steering is provided for target ranges between 1.2 Raero and Raero. Inside Raero, the steering provides optimal horizontal and vertical missile steering. Once inside mid-point Rtr (half-way in the maneuver zone), the ASC provides Rmin steering. The pilot follows the ASC cue by rolling until the cue is on the HUD centerline above the center position of the ASEC and then pulls the aircraft (if commanded) to put the ASC in the center of the ASEC. When the target range is greater than Raero, a limit cross (X) is displayed inside the ASC to indicate that an AIM-120 shot does not exist even if the pilot performed a loft maneuver. The limit cross will also be displayed when the required lead angle exceeds 60 degrees, even if the target is nominally in range. Neither the ASEC nor ASC are displayed on the HUD in DGFT mode.

The following diagram sums ASC/ASEC relationship to the DLZ and the type of steering provided.



4. HPRF vs MPRF, A/F-pole cues & Missile Datalink

This version of BMS features a major revision of the AMRAAM DLZ A/F-pole cues and associated range and timing readouts. HUD, HMS and FCR displays now all include updated A/F pole cues. In addition, the AMRAAM loft cue was moved (look above Raero caret) to make room for the new Digital Manuevering Cue (DMC) (shown above the target closure value by the range indicator >). 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 (aircraft) 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 (it 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 pilot can now select the RCS size on the AMRAAM's SMS page. Options are small, medium, large or unknown. Note: you can select SMALL in the SMS page but doing so doesn't make a lot of sense in Falcon 4 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.

HUD A/F pole cues are provided for pre-launch and post-launch. Post-launch cues are relative to winning Missile-Of-Interest (MOI) for the current bugged target. Changing the bug in TTS or TWS will provide A/F pole cues for the MOI for each if missiles are in flight to both. Time remaining cues are provided for the MOI for the current bugged target. This can show "A" (time to HPRF), "M" (time to MPRF), "T" (time to intercept) or "L" (time to termination; basically missile time of flight remaining). Note that this timer is more persistent than before. It’s dynamic for bugged target and a winning MOI. For a winning missile where you lost track or snipped, the count becomes a simple stop watch. One note of caution: it’s not a bug that the timer doesn't count down in linear fashion for a bugged target with an active DL missile. The time to intercept is calculated dynamically and takes target maneuver into account so it’s perfectly reasonable for that count to increase even in some cases.

Missile datalink has been fixed to allow you to support up to six missiles in flight. AMRAAMs may be fired on up to two targets (TTS) or up to six targets (TWS). You can get A/F pole and time remaining data for all six missiles if you have six in flight and provided that their intended targets are still present on the FCR as track files.

There is also a bug fix for bogus clearing of target when you flip between override modes or SMS changes from one missile type to another while you have a bugged target – now the lock is maintained. There is also a fix for datalink – previously last slammer was never provided with any datalink guidance making it significantly worse in performance compared to a missile fired with more of the same (slammer) type left on the rail.

5. Tactics - Some Basics

This section is not intended to go into a full BVR employment discussion, but at least provide you with some very basics on how to tactically apply the tools you learned above. Let’s see what you can do to maximize the probability of kill while staying alive! Let’s play it safe by learning first how to survive the threat. For this purpose we’ll take as example a Mig-29A playing the threat equipped with AA-10A missiles. Let's assume the maximum kinematic range of this missile while launched around 25,000 ft and subsonic is around 18 NM against a head-on fighter. Less aspect angle will subsequently decrease the first launch opportunity (FLO). To survive this missile launch, the simplest solution is simply to avoid this max kinematic range by turning away from the MiG.

Does it mean that you have to turn @ 18 nm from the MiG? No! The kinematic range takes into account that the fighter will continue straight ahead until missile impact. So the distance the missile will have to fly will be less than 18 nm. Actually, if you turn away from the MiG at or beyond 13 NM, the missile will never catch you and will fall behind you. This distance at which you have to turn cold (13 NM in this example) is called MAR - Minimum Abort Range.



The way you have to abort is simple: you obviously want to avoid being hit by the missile so put your nose down and try to keep the maximum speed you can while turning away from the threat as fast as you can. A split-S maneuver can also work, but there could be consequences for trading too much altitude for airspeed (for example you may not want to do this if there is a MANPAD threat at lower altitudes). Anyway, watch your G’s and don’t over-g your aircraft! G’s should be around 5 to 6. This will give you a good turn rate while preserving some speed.

Still alive? OK then we continue! From the theory we learned, we know that the maximum probability of kill of the AMRAAM happens when it’s launched as close as possible from RTR (or even within RTR) and when the missile is MPRF active. The goal will then be to have an AMRAAM in flight MPRF active before 13 NM as we will abort at that range if we are spiked or shot at. How do we do that? We will look to the Pre-launch M-pole displayed on the left of the DLZ when inside Ropt and shoot not later than 13M! When approaching 13 NM from the MiG, the Time to MPRF Active should read M00 meaning the missile is MPRF active. So you can snip the target (break radar lock) and perform the abort.

Happy Chucking!

Ragnarok

这不是官网上的那篇文章嘛。写得比手册里好一点。[113]

lkyfly0844

太长，太累了，顶一下再慢慢看

lkyfly0531

Ragnarok 发表于 2011-10-7 00:26

                               
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这不是官网上的那篇文章嘛。写得比手册里好一点。

你人捏～～