Your Attention Please!
This article is outdated. Heatblur and ED have developed a new missile API in late 2020 so the way the WCS guides the missiles has changed.
I am waiting for them to finalize the new implementation before writing a new study about the updated guidance model and the AIM-54.
The AIM-54 “Phoenix” is a great weapon. I mean, it’s big. According to wiki, it’s a 1,000lbs, 4m long, 500,000$ missile. Nevertheless, it’s not the fire-and-forget weapon of doom sometimes described on the internet. In fact, it possess pros and cons and it’s double-tied to the proficiency of the RIO along with the strengths and weaknesses of the AWG-9 WCS.
The following study addresses three variants of the AIM-54 available to the F-14 in DCS. Tests are conducted at multiple altitudes and distances from the target, in order to better understand the differences between the Phoenix versions, how denser and thinner air affect its massive solid propellant rocket motor, how much energy it retains at different distances and how we can adjust our engagement tactics to better benefit from the AIM-54 – AWG-9 duo.
Upon launch, the AIM-54 burns all of its propellant immediately, following a trajectory dictated by the AWG-9 WCS instead of throttling its engine depending on the situation, as other missiles do (see the Meteor, for instance). Therefore understanding how it performs in different conditions is very important for the DCS F-14 crew: the theoretical range of the Phoenix is well over 100nm but it doesn’t matter if the missile flies slower than my grandmother on her wheelchair when it finally gets close to the target!
Three versions of the AIM-54 Phoenix are available in DCS:
- AIM-54A mk47: The oldest version in DCS, it mounts the Mk 47 motor.
- AIM-54A mk60: Upgrade of the AIM-54 Mk47, it uses the Mk 60 motor, improving its range and speed.
- AIM-54C mk47: The C version mounts and improved, smokeless, Mk47 motor on top of an improved digital seeker.
What may come as a surprise is the fact that the motor of the AIM-54A Mk60 is actually more powerful than the smokeless Mk47 used by the more recent AIM-54C. On the other hand, not giving away your position at launch (hence somehow defeating one of the big advantages of the TWS) is definitely important, especially in a PvP scenario.
The three versions of the AIM-54 are fired at targets located at a distance of 30nm, 40nm, 50nm, 60nm, 70nm and from an altitude of 1,000ft, 10,000ft, 20,000ft and 30,000ft.
A number of values will be collected:
- MOff-H: The Altitude when the rocket motor stops;
- MOff-S: The Speed of the AIM-54 when the rocket motor stops;
- H-Peak: The highest Altitude reached by the AIM-54;
- Act-SPD: The Speed of the AIM-54 when it turns active, and;
- Act-D: The Distance from the target when the AIM-54 goes active;
The distance is measured at the moment of launch. The targets are MiG-21s, Average skill, flying head on at 200kn, in order to reduce the intrinsic measurement error (although of course these are empirical tests).
The speed of the launching platform (our F-14B) is set to 600kts (Mach ~0.9): I assume every fighter wants to build up speed before launching a missile (→sum of velocity vectors). A speed close to Mach 0.8-0.9 is reasonable for the F-14 even for “dirty” (ergo aerodynamically disgraceful) configurations.
Targets are radar locked in PD STT.
Let’s start by taking a look at the data collected:
Note: only one measurement has been collected for each set of conditions therefore the chance of error is higher than by collecting multiple samples and interpolating the results.
A vs C and Mk47 vs Mk60: Versions comparison
The AIM-54C mk47 uses an improved and smokeless version of the motor mounted on the AIM-54A mk47. I was curious to see if there were any notable discrepancies but there are no real important differences. It seems that the AIM-54A performs slightly better than the AIM-54C at higher altitudes but the difference is very marginal.
The real difference between these two versions of the Phoenix lies in the digital seeker of the AIM-54C Mk47 on top of its improved smokeless motor. Out of experience, the seeker makes the missile much harder to defeat and the smokeless motor makes the target less aware of being under attack (especially vs Humans and if combined to the TWS).
AIM-54A Mk47 and AIM-54A Mk60 use different motors, neither of which is smokeless, and the latter is much more powerful than the former. This is evident when comparing the speed at which the missile goes active and is true at any distance. The smoke from the motors is very visible at close range but at farther distances it becomes a minor issue.
The AIM-54A Mk60 and the AIM-54C Mk47 are the most dissimilar versions of the AIM-54. Each has its own strengths, namely the more powerful motor of the former and the newer digital seeker combined with the smokeless motor for the latter. Ultimately the choice depends on the mission: the AIM-54A Mk60 has inferior seeking capability than the AIM-54C Mk47 but offers longer range. This is perfect for Interception missions or when the targets are bombers or CAS-dedicated aircraft, usually bigger and less agile than fighters. Their reduced maneuverability summed to their bigger size offsets the inferior performance of the AIM-54A’s seeker and the increased range allows the F-14 to engage them before getting too close to enemy CAP.
The AIM-54C Mk47’s digital seeker increases kill probability considerably against smaller and agile targets such as fighters.
The data collected offer plenty of interesting information useful for better understanding the performance of the AIM-54 missile.
AWG-9 and AIM-54 at low altitude
The reason why I haven’t collected data for launches at 50+ nm at 1,000ft is because the target simply wasn’t appearing in the AWG-9, in Pulse or PD. I didn’t expect that because usually the AWG-9 has an impressive detection range but I suppose that the unwanted returns can have an important impact here. The situation can probably be improved by adjusting the antenna but this is beyond the purpose of this article.
Moreover the results of the launches at 30nm and 40nm show how abysmal is the performance of the AIM-54 is at very low altitude (compared to high altitude) so there is little point in testing distances of 50+ nm.
The AIM-54 Trajectory
Let’s consider the AIM-54A mk47 at 10,000ft.
The Ratio value is interesting because it shows how the trajectory defined by the AWG-9 WCS is not related to the AIM-54. The missile starts its rocket motor a moment after having been launched and fires until it runs out of propellant. At shorter distances the AIM-54 is guided into the flat part of the trajectory with its engine still providing thrust, hence reaching the target at incredibly high speeds. At longer ranges (especially when launching beyond the optimal range), the AIM-54 runs out of propellant before reaching the top of the trajectory arc; therefore, it may lack the energy necessary to later chase a defending target.
It is also interesting to note the three versions of the Phoenix have more similar performance at longer ranges rather than close ranges due to the fact in the latter cases the motor is active for a longer portion of its total flight time.
“The higher the better” is common knowledge when the topic is missiles. I expected a gain in terms of performance but I am surprised by the magnitude of the effect.
The first hint of how positively the altitude effects the Phoenix is visible on the speed (SPD) reached by the AIM-54C Mk47 before its motor runs out of propellant (at 10,000ft and 20,000ft):
If the increment of speed is marginal in this scenario, the speed at which the AIM-54 turns active is dramatically higher.
Let’s consider the AIM-54C Mk47 at 30nm:
- 1,000ft: the missile goes active at 970kts, mach ~1.5.;
- 10,000ft: the missile goes active at 1230kts, approximately mach 1.8;
- 20,000ft: the missile goes active at 1590kts, approximately mach 2.3, and;
- 30,000ft: the missile goes active at 1810kts, approximately mach 2.7;
The launch altitude has a dramatic effect when the target is at longer ranges. Consider the AIM-54A Mk47:
The speed of the 30nm launch at 20,000ft and 30,000ft is increasing probably due to the fact that the AWG-9 WCS guides the Phoenix into the flat part of the trajectory before the missile’s propellant is exhausted. This allows the Phoenix to retain more speed thanks to the reduced friction of the thinner air.
The chart also shows how by increasing the launch altitude by 10,000ft the AIM-54 increases its Act-SPD for an additional 7nm-20nm. This is very important because it allows the crew to quickly evaluate and answer to the changes of a fluid AO by simply hitting the burner, gaining speed and therefore altitude; therefore, offensive range.
Launch Ranges and TID
The AWG-9 WCS is well aware of the effects that the altitude has on the engagement range and this is well reflected by the Launch Zone vector on the TID (altitude is of course not the only parameter affecting the indicator).
This is how the Launch Vector looks at different altitudes for a target locked 40nm from our Tomcat.
It is interesting to note that the effective range of the AIM-54 at high altitude and up to ~100nm is limited only by the capability of the AWG-9 to find and track contacts. In fact, the reason why I didn’t test at distances higher than 70nm is because the radar wasn’t able to detect the small MiG-21 farther than ~75nm. If the target of the mission is a bigger aircraft instead, such as an AWACS or a transport, the AIM-54 is capable of destroying such a target even if it’s flying at more than 100nm from the Tomcat.
Out of curiosity, I tested by launching an AIM-54 Mk47 from 35,000ft to a Il-76 distant ~105nm and flying at 25,000ft. It has peaked at 71,524ft and hit the target at 620kts (mach ~1.04).
Note how the Launch Zone indicator on the TID clearly suggests that I was beyond Rmax and how the DDD and the TID show different Rmax.
I fired at 105nm after climbing to 35,000ft to further improve the range of the Phoenix and destroyed the target.
The considerations about altitude and speed are a very important aspect of the engagement tactics with F-14 (not only for over-Rmax-spray-and-pray shots!). But this is a topic for another article.
A big thanks to Skipjack from Sabre Squadron for the grammar and syntax corrections!