AIM-54 Probability of Kill – II – Low Altitude

The first part of the series of articles introduced the testing criteria. Instead of focusing on a single scenario, this article analyzes multiple tests at the same time: the common denominator in this case is Low Altitude. Each test, in fact, as been conducted at 1,000ft at a variable distance of 15nm, 20nm and 25nm.

As usual, some raw data. The results of the tests at 15nm have been analysed already but I report them here for sake of clarity.
As we have seen in the previous article, some aircraft manage to defend particularly well in some conditions by applying always the same successful manoeuvre. This is the reason why I tested every altitude and speed against three different aircraft: Su-27, MiG-29s and F/A-18C.

rio12-AIM-54-PK-low-altitude-su27
AIM-54 Su-27 at low altitude

rio12-AIM-54-PK-low-altitude-mig29s
AIM-54 MiG-29s at low altitude

rio12-AIM-54-PK-low-altitude-fa18
AIM-54 F/A-18 at low altitude

15nm

The results at 15nm have been analysed already in the previous article.

20nm

Something new appears in this test: a number of AIM-54 missed the target because they run out of energy. As we know from the AIM-54 Performance study, the altitude is pivotal in order to increase the range of a missile because at lower altitude the air is thicker, hence the friction is higher and it spends much more energy flying through it. This factor, added to the changes in the missile trajectory caused by the manoeuvres of the target, can bleed off the energy of the Phoenix energy very fast.

The Su-27 deserves a brief in-depth analysis. These are Tacview screenshots of Su-27 defending in the NOTCHING scenario:

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In one case the Su-27 defeated the AIM-54 by manoeuvring and dispensing countermeasures, in the other the Su-27 turned sequentially, causing the AIM-54 to readjust its trajectory multiple times and resulting in the missile bleeding off its energy.

By reviewing the Tacview, the odd defensive manoeuvre of the Su-27 appears clear: it turns towards the F-14, then notches and finally moves back. This has the effect of shortening the distance between the AIM-54 and the target itself and therefore is eventually counterproductive from the point of view of the defensive aircraft. Other aircraft, such as the MiG-29S, don’t fly as often towards the F-14 but rather away from it, and this is clearly proved by the melancholic 0% hit rate in this scenario.

25nm

The increased range has an even more dramatic effect on the performance of the AIM-54 at low altitude. The aspect of the target has a clear effect, more pronounced than at 20nm.
The rocket motor of the AIM-54A Mk60 allows the missile to maintain acceptable results if the target is coming towards the F-14, scoring a hit rate of 70%. If the target is moving away than the percentage falls to 41.7%.
The AIM-54C Mk47, having a less powerful rocket motor, suffers even more at the increase of the range: if target is Hot, the hit rate is 48.3%. If it is flanking, the hit rate is a non-existent 3.3%.
Such results are even more clear when displayed by means of Tacview:

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The following is an image of a test of an AIM-54A Mk60 versus a F/A-18C in the Flanking scenario:
rio12-AIM-54-PK-hit-A-25nm-1000-flank-fa18
HIT: F/A-18: 25nm, 1000ft vs AIM-54A Mk60. Flanking scenario.

A quick comparison of the images proves even further the fact that the more powerful rocket motor of the AIM-54A Mk60 clearly makes the difference.

Low Altitude Data Summary

By calculating the average values, we have a more clear representation of the performance pattern of the AIM-54A Mk60 and the AIM-54A Mk47.

rio12-aim-54-pk-low-altitude-summary-1

Analysis of the Results

To better understand the results, I reorganized the data in a more readable table.
I have also calculated the Relative values for the Hit rate.

rio12-AIM-54-PK-low-altitude-summary-2

I then plotted such results into charts.

Hit vs Miss

The simplest chart, a direct comparison of Hit and Miss rates of the two missiles.
rio12-AIM-54-PK-low-altitude-hit-vs-miss
The chart shows how the AIM-54A Mk60 starts in a position of slight disadvantage compared to the AIM-54A Mk47 then becomes more reliable as the range increases (Note: the disadvantage is ignorable and ascribable to the systematic error due to the low number of samples).
At a range of approximately 18nm the two missiles perform in a similar way.
The AIM-54C at 22nm-23nm sees its hit rate becoming lower than the miss rate. This marks the moment when the probability of having the missile defeated is higher than the probability of hitting.

Miss: Energy vs Radar

This chart takes into consideration the causes of the defeated Phoenixes.
rio12-AIM-54-PK-low-altitude-miss-enr-vs-rdr
The chart shows how the main reason for the incredible increase in the ratio of defeated AIM-54C Mk47 is the rocket motor. The AIM-54A Mk60 in fact has fairly stable results although I guess that results collected at 30nm and 35nm would show patterns similar to the AIM-54C between 20nm and 25nm.
The fact that the AIM-54C Radar miss rate decreases at 25nm is probably due to the fact that energy runs out of energy so fast that doesn’t even have the chance of being defeated.

Relative Hit rate: HOT vs FLANKING

This chart shows the hit rate of each missile relative to the total number of hit rates, rather than the total number of launches.
The HOT aspect is composed by the Hot and Hot Dive tests. The FLANKING is composed by the FLNK and NTCH.
rio12-AIM-54-PK-low-altitude-relative-hit-rate
This chart shows how impressive the hit rate difference between the two scenarios becomes as the range increases. Past the ~18nm, the AIM-54C Mk47 becomes immediately unreliable unless the target is coming head-on towards the F-14.
The AIM-54A Mk60 instead is fairly constant, has we have seen already.

Normalized Hit rate: HOT vs FLANKING

The following chart shows the Hit rate of each scenario relative to the number of samples of the scenario itself:
rio12-AIM-54-PK-low-altitude-norm-hit-rate
The interpolated Hit rate value of the AIM-54C Mk47 for Hot targets is ~60% at 23nm and increases faster as the target gets closer. This is a valuable information because it proves such missile to be a valid weapon; although the combined hit rate at such range is abysmal.

Conclusions

Simply put: Energy is the most important factor at low altitude. The AIM-54A Mk60 maintains a fairly constant PK even past 20nm-23nm and scores better results than the AIM-54C Mk-47 as soon as the rocket motor of the latter shows its limits. At a range of 15nm, in fact, both missiles have comparable hit rates, between 20nm and 25nm the gap widens exponentially.

The AIM-54C Mk47 is not a total lost cause at ranges higher than 15nm: the aspect of the target dictates whereas the missile can be successful or not. The values collected in this test can help the RIO in his job but let’s not forget that the Range is not the only factor the RIO can control. The launch Altitude have an important effect as well, therefore the RIO must be very careful and evaluate the situation accurately and plan the most effective approach and geometry, in order to maximise the chances of defeating the target.


As usual, feel free to share feedback, suggestions and ideas about new articles!

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