AIM-7 Sparrow: Table of Contents
- Part I: Unsung Hero: The AIM-7 Sparrow [Part I]
- Part II: Loft Performance [Part II]
- Part III: Range, Geometry, Phoenix [Part III]
The modus operandi used to collect data for these tests is the same used for Part II: every value of each scenario is collected multiple times, and the average is displayed in the charts.
When the range is discussed, collecting every value, from 5nm to 30nm, for each loft combination, would result is an incredibly time-consuming effort. Therefore, I used the standard employment mode, the no-loft (ACM cover up), and a 30° induced loft for the AIM-7P, and standard and 30° loft for the AIM-7F.
Different Geometry
The scenario used sees the habitual combination of parameters, but compares a “hot” geometry (TA = ATA ≈ 0°), with an almost collision with (TA = ATA ≈ 23°-25°) and an even greater offset (TA = ATA ≈ 37°-40°).
For simplicity’s sake, I labelled them Hot, Flank and Beam, albeit the geometry does not satisfy the definition of such terms.
The altitude is 25,000ft and the speed of the F-14 is slightly higher than the target, M.9 vs M.8.
Similarly to Part II, the results are represented by charts organised in columns. The left column is about Speed at F-pole, the Right column is about the distance.
Note that the ASE was not centred in these tests, as the objective was evaluating a “static” geometry. During a mission, take advantage of the lead collision and the ASE, they are both useful tool to improve the PK of any missile.
AIM-7P: Different Geometry vs Range
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OBSERVATIONS
Starting from the Speed at F-Pole, at the shortest range, nothing really changes. Some speed is lost due to the high-angle manoeuvre, but the No Loft employment is still the most performing, as the rocket motor is still burning at impact. This leads to the question of whether the reduced LTE of the NL option is affecting the results, since the missile is launched earlier and the rocket motor burns for longer than in the standard launch scenario.
As the range increases to 10 nm, the higher-ATA scenario (Beam) starts to fall behind, but the difference is marginal, and the missile is only about 250 kts slower at impact compared to the Hot scenario. The in-between scenario (Flank) sits in the middle.
The situation suddenly changes at 15 nm. At this range, the No Loft options fall behind, no matter the aspect, and the induced loft become more and more meaningful. Interestingly, the 30° loft for the Beam scenario fares quite well, comparable to the standard employment of the Flank setup. Nevertheless, the loss in terms of performance is drastic, and the trend continues.
At 20 nm and beyond, only the Hot scenario and the Flank scenarios, when both lofted, may be still considered threats to a non-aware, non-manoeuvring target. At 30 nm, only the Hot 30° loft remains.
The speed comparison chart shows, as the angles increase, how the additional loft angle at short range decrease its negative impact, something we noticed already in Part II.
The distance comparison chart shows something interesting: both 30° and no-loft perform slightly better than the default option until 20 nm (15nm in one case). In a sense, we can say that, distance-wise, it is better for the missile to go straight for the target or invest heavily in altitude, rather than do something in-between.
Takeaway points
- 7P: poor shot parameters can be improved by increasing the loft angle. Calling the “T”, or approximating with Lead Collision, also help, if the geometry can be changed.
On the bright side, subpar geometry does not affect as much as expected up to 15 nm, even 20 nm in some cases.
Remember that the distance at F-pole is generally greater as the angles increase as VC is lower.
AIM-7F: Different Geometry vs Range
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OBSERVATIONS
Besides the extreme tests, the performance of the two missiles is however quite comparable.
Takeaway points
- 7F: Similar behaviour to the AIM-7P, but the fall energy-wise is greater as the distance and the angles increase.
High and Fast
A scenario not covered in Part II is the “high and fast” F-14: the Tomcat flies at 35,000 ft at Mach 1.2, the target is co-alt and flies at M0.8.
This test has two purposes:
- Assess the performance in good/optimal conditions*;
- Compare the results with the AIM-54.
The results can be useful to choose the best missile for the job, or to know the AIM-7 behaves in case a follow-up shot is necessary (as it happened in one of my recent videos, I had two hostiles but only one AIM-54). Without the heavy and draggy AIM-54, the Tomcat has little issues reaching the altitude and speed used in the test.
Moreover, in mid-cold war scenarios (until mid-to-late ’80s), the AIM-7 was the weapon of choice vs fighters.
For example, in a 3h / 4h mission, proper fuel management is essential, the top-up at the tanker must be planned and coordinated with other assets, there are restrictions in place and ROE, sometimes VID is required as civilian aircraft may be in the area or the scenario is not open conflict. Therefore, shots are usually not taken at 40,000+ ft and M1.3+ as often happens in casual / arcade servers, since there you can just respawn or zoom back to base without caring too much about the bigger picture.
High and Fast – Results
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OBSERVATIONS
As seen already, the No Loft option works better or worse than the Standard depending on the range, with 15 nm behind a sort of cut-off. In slower tests, the threshold was closer to 10 nm.
Another point noticed in Part II is the “additional” loft angle: it seems that the sweet spot is, in Hot scenarios, the loft angle equal to the range. After that, the gain decreases and, in some cases, it becomes minimal.
Distance-wise, the raw chart does not help to assess the gains, but the absolute and relative comparisons are much more interesting. In particular, not only greater loft allows the missile to impact earlier (probably because the Sparrow travels earlier through thinner atmosphere, although we are already quite high enough in this scenario), but the gain is much more impactful as the target is farther.
Takeaway points
- 7P: as expected, the faster and higher the F-14 flies, the better is the performance of the missile.
Generally speaking, the performance and the behaviour of the missile follow the pattern discussed in Part II of this study, but with a great positive offset.
High and Fast – 10nm comparison
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OBSERVATIONS
It is interesting to observe how the speed comparison chart shows how the gains from the loft are lower when the Tomcat is high and fast. The energy advantage might make the Sparrow less receptive to the bonuses of the greater loft angle at this range.
High and Fast – 25nm comparison
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OBSERVATIONS
Interestingly, the gains in absolute and relative terms close when the F-14 is flying over Mach 1, making the employment in the upper part of the transonic range more relevant in terms of potential proportional gain, which is then positively offset by the increase in altitude.
Similarly to the observations made in Part II, the distance at F-pole is hard to assess, due to the different VCs. The only point worth highlighting is how the high and fast shot arrived well before the others, breaking the pattern that saw faster Tomcats have a lower distance at F-Pole. This means that additional energy and altitude paid much greater dividends, in terms of separation, than flying faster at the same altitude (ref M1.1 and M.9 at 25,000 ft).
In other words, the AIM-7 really benefit a lot by flying higher and faster, a trend common to the AIM-54.
AIM-54 vs AIM-7
The last part of this study compares the AIM-54 Phoenix and the AIM-7 Sparrow directly.
The first test occurs at 25,000 ft, the second at 35,000 ft. These are the same scenarios used in the previous quick look at the new AIM-54.
AIM-54 vs AIM-7: 25,000ft, M0.9
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OBSERVATIONS
The Sparrow at 5 nm looks impressive, but it is explainable by the fact that the AIM-54 is well known for its poor acceleration. As the first speed chart shows, the Mk47 reaches its top speed at ~10 nm, and the rocket motor keeps burning even at 15 nm. The Mk60 behaves differently, as it provides a greater but shorter burst.
Distance-wise, as expected, as the range passes the 20 nm mark, the Sparrow starts to lose speed and performance, whilst the AIM-54 begins to finally earns its name.
AIM-54 vs AIM-7: 35,000ft, M1.2
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OBSERVATIONS
The tests show otherwise, and the AIM-7P is closer than expected to the performance of the AIM-54, even at 30 nm. The AIM-54 clearly wins when the rocket motor is still pushing the missile to its top speed and this occurs, incidentally, as the Sparrow starts to lose energy.
Interestingly, the distance at impact favourites the AIM-7, albeit marginally.
AIM-54 vs AIM-7: Comparison
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OBSERVATIONS
This is important as, generally speaking, a Tomcat would use the Sparrow only after running out of AIM-54 (with the usual exception of pre mid-80s restrictions). Thus, the F-14 should be light and more efficient drag-wise, and it can easily climb to 35,000ft and reach M1.2, if not better.
This profile gives a fantastic boost to a missile that is generally overlooked.
Takeaway points
- 7P and 7F: as expected, the AIM-7 can’t fill the gaps in the performance envelope by the AIM-54 (those areas are where the AIM-120 shines), but the 7P especially is a surprisingly good substitute at short range, if pushed and employed correctly.
Understanding what the Sparrow can do, is key to the proper employment of the F-14 Tomcat, especially in mid-Cold War scenarios.
Conclusions
This study has shown how the AIM-7 is a much more complex and intricate missile than thought by many, whose performance is heavily dependent on the ability and knowledge of the crew.
As we have seen, in fact, the standard employment method is usually one of the least performing, and manipulating the missile is something the crew is encouraged to do. For example, although subpar geometry does not affect as much as expected up to 15 nm, even 20 nm in some cases, changing when and how much additional loft is introduced can increase the probability of hitting the target. Accelerating and climbing also help to drastically improve the energy of the missile.
However, different speed, altitude, and geometry shift the performance envelope, and the crew must know how to offset, or take advantage of this peculiar behaviour.
The quick comparison with the AIM-54 leaves plenty of room for a much more in-depth discussion.
For instance, the WCS commands the Phoenix active off the rail in certain scenarios (10nm Hot / 6nm Cold). This concept is applicable, to an extent, even as the range increases to ~15nm/20nm, since the RIO can manipulate the target size, increasing the A-Pole and allowing the Tomcat to manoeuvre earlier, or can use the PH ACT switch. To add further complexity, the AIM-54C now behaves more closely to an AIM-120, and PSTT is always a solid, yet underrated, employment method.
All these variables provide options to the crew, as an active AIM-54 “frees” the F-14, but sometimes sustaining an AIM-7 until timeout may be preferable. Therefore, there is always more than one viable solution given a certain situation.
The other side of the coin is that options means complexity, and consequently make knowledge and experience more important.
Hopefully, this study has provided a bit more light into the behaviour and the performance of the AIM-7 Sparrow, sufficient enough to add this missile to your pool of options when it comes to engaging a target.
Part III concludes this overview of the AIM-7.
I can invest more time studying and preparing a more comprehensive model of the performance of the missile. It is a time-consuming effort, though, so I will do it only if there is enough interest.
You can find the Iranian skin used in cover here: DCS User Files
FlyAndWire 