The last time I mentioned the R-27ER, I showed how this missile could be manually lofted whilst inverted and pulling positive Gs. It was capable of reaching speeds in excess of Mach 6 and, kinematics-wise, be a potential threat even beyond 100 nm. The only reason why these properties could not be exploited was the relatively short battery life. This peculiarity prompted me to raise several questions. For instance, why such a marvellous, hypersonic, missile has such a limited battery, de facto handicapping itself?
Fast-forward a few weeks, the answer came indirectly in a whole new missile, introduced in patch 2.9.50.15010.
The changelog describes how every aspect of the R-27 missile has been reviewed, updated and overhauled if necessary.
Introduced advanced model for R-27 missile family. Missiles got new CFD-based flight model, authentic control system that includes wing actuator model, altitude band-switching autopilot, Kalman-type guidance filters (different for IR and RF versions) which also drive seeker gimbal mechanics, INS and datalink system with realistic inaccuracies (for RF missile only), and RF or IR seeker. New semiactive RF seeker provides ‘multitarget’ tracking feature. This means that RF signals from several distinct targets will interfere and form one bigger apparent target once they simultaneously fall into the missile tracking gate. This apparent target may lead the missile between real targets in a target group, or to dispensed chaff. It also may steal missile velocity tracking gate and break guidance. R-27 proximity fuze now has a conical antennas pattern and variable explosion command delay to adjust for target size and closure rate. And, in addition, missiles got number of limitations caused by control systems design. For example RF missile can not be launched with roll angle exceeding 120 degrees because of gimbaled INS roll limit.
The changes to this missile are fantastic, so let’s see how the R-27R and R-27ER fare against their previous incarnations.
The most common variant used in DCS is definitely the R-27ER. This is an oddity. Note that I am still searching for reliable sources, but the ER was introduced at the very end of the Cold War, and it was neither popular nor exported at any level comparable to what we see in the game. In fact, the export of such variants started only at a later time, from the mid-1990s and several nations never ordered them.
Impact Speed vs Range
The first set of parameters are impact speed versus range. This methodology is less applicable to a sortie, given the number of parameters that can affect the outcome. The launching platform released at M1 at altitudes of 5,000, 15,000, 25,000, and 35,000ft. Note that I have slightly changed the data-collection process to increase the precision of the saved values. I used to round to the closest mile, now the results are saved in steps of half a mile.
Starting with the R-27ER and comparing the missile to the 2023 dataset, it seems that the R-27ER is fundamentally unchanged, with a slight gain at lower altitudes. For this reason, I will not go too much into the details, as I covered them in the past already.
However, to quickly recap, the closest western alternatives used in the early 1990s, ergo the AIM-7F, M, and later the P, are all outclassed by the powerful rocket motor of the R-27ER. The AIM-120B is not a threat to the R-27ER, but the AIM-120C-5 is slightly closer, as far as kinematics are concerned.
The AIM-54 is a whole different missile system, and it is not worth comparing it now. As a side consideration, November marks 5 years since the announcement of the new missile API, necessary to finally better represent the peculiar characteristics of the Phoenix.
Manual loft
As mentioned earlier, I always wondered why a missile kinematically capable of reaching targets 200 km away was limited by its battery life. This patch answered the question, annulling any effect of manually lofting the R-27.
Whenever the pilot tries to release the new R-27 whilst pitching up, the missile soon corrects its trajectory.
As this example shows, having a positive attitude, besides helping to deal with the stress of the modern life, still provides a marginal bonus. However, it can be argued that the effect derives more from the additional altitude the aircraft reaches at launch, rather than manual loft per sé.
The most important aspect of pitching up, even slightly, is that the nose is not pitching down. “You don’t say?!” you might be thinking, but the truth is that for the longest time, negative pitch greatly affected the performance of missiles in DCS. Despite the prompt trajectory correction, negative pitch still has a minor effect on the new R-27 family.
So, although a marked pitch-up attitude at launch is not necessary, maintaining even just a few degree up is always useful, if coherent with the scenario.
LAR Observations
Since manual loft as we knew it is gone, the R-27 cannot be pushed behind the LAR any more. This was previously possible as the missile tended to cruise at a higher altitude following an arcuate trajectory, before diving onto the target. The Su-27’s avionics were not programmed to account for that, leading to players gaining a slightly longer maximum range. A few tests with the new R-27 revealed how the indication is now more accurate, since the missile cannot reach higher altitude any more.
Testing the New Seeker
The developers and engineers at Eagle Dynamics put significant effort into creating a whole new missile seeker technology for the R-27. Ergo, the minimum I could do is putting together some tests to discover some new features. Since I do not have a tool set dedicated to this purpose, I had to make up something, and I am sure I am missing many facets of the new missile.
► Test I: The Wall
The first test places the R-27ER into a challenging situation: a “wall” of closely flying targets. As the changelog described, the new seeker may struggle in such a scenario. Missiles are definitely not my realm of expertise, so I can only imagine that the reason might be related to the inability of the seekers to define a single target, overwhelmed by the returns from the pack. If this is not the case, please let me know in the comments!
Back to the test, as the R-27s approach the wall, they start behaving erratically, losing all their energy and never connecting.
► Test II: The Turn
The second test proposes a target that, as the missiles are being launched, pulls a tight turn whilst chaffing. The target bleeds off most of its energy in the manoeuvre, and eventually resumes the original path.
Six R-27ERs are launched by a Su-27. Some before the turn, others after. The last R-27ER went crazy.
I have absolutely no idea what happened here.
- The first missile tracked, but then got spoofed by chaff, probably intimidated by the posture of the F-14 Tomcat.
- The second never tracked, it flew straight, minding its business.
- The third one was so close! Then it remembered he had an appointment and left.
- The fourth one passed right in front of the Tomcat as to salute the crew, before turning hard towards the ground. It reminded me of the Costa Concordia.
- The fifth R-27ER followed a clean intercept, then, when it mattered the most, it blew it.
Fun fact: we can see some missiles flying backwards towards the target, after completing a full 180° turn.
To better understand these results, I tested the same scenario with the AIM-120C-5. From my understanding, the AMRAAM should be fairly advanced in terms of modelling. I applied the same modus operandi.
I launched a salvo of nine AIM-120C-5 and, for a second, a felt like a proper bluefor player in a casual server. These missiles went again all over the place, all besides two, which connected and hit the target.
I also tried a salvo of four AIM-54C Mk47 and all connected, probably because they all arrived when the target completed the turn and was hot again. See? This demonstrates that the adagio “Slowly but surely, it goes well and goes far.” is correct!
After I thought I was done with this scenario, I decided to test the good old Sparrow in his latest incarnation: the AIM-7P. The Tomcat never lost track of the target but the missiles, oh my. They all got defeated by the manoeuvring target and never recovered. This flat behaviour is pretty much what we are used to, so the improvements to drunkard level are possibly a positive step?
Jokes aside, I don’t know what I just watched. Perhaps the manoeuvre plus chaff and other missiles around created a situation similar to the one discussed in the previous example. Or perhaps the chaff now persists longer, thus creating a broad cloud due to the Tomcat’s manoeuvre? If you have good answers, please let me know.
► Test III: Chaff & Notching
Speaking with real crews, a point often raised against missile simulation in DCS is how Semi-Active Radar-Homing missiles are easily notched. On the contrary, these missiles should be extremely hard to notch. To verify whether the new R-27 improved the status quo, I created a mission and added an Ace AI as a target. As we know, if the standard DCS AI cheats, the Ace AI is at divine omniscience levels of SA.
To conduct this test, I downgraded DCS to the previous patch and checked the R-27. All missiles are launched from a distance of circa 12 nautical miles.
The first pair of old R-27Rs were easily defeated by the target as it dived, chaffed and notched. Neither R-27 even attempted to reacquire the defending target. Nothing different from the usual.
I then re-updated DCS, and followed up with a pair of AIM-7M Sparrows. I forgot to save the previous mission, and I did not realise that I used a different target, but little changed as guidance is what we wanted to see. Again, the two missiles chased a chaff-shaped squirrel and were defeated.
Finally, I tested the new R-27. As you can see by the path they traced, the missiles appeared more dynamic, in a sense, and recaptured the returns from the Su-27 illuminating the target multiple times. Although this behaviour may vary, I repeated the scenario three times and in no cases the missile just went dumb. More or less, they appeared to have a better resilience. It does not mean that they cannot be defeated, of course, but they showed a greater tendency to reacquire the target. I am happy about seeing this new behaviour albeit, as mentioned, the results must be taken with a grain of salt as a handful of tests is nowhere near enough to show a pattern.
Conclusions
I am eagerly waiting to see other missiles updated in the future. Eventually, the dream is to see the “stealth-missile-launch” factor so preponderant in DCS gone for good, via a combination of less “all-seeing” radars, realistic radar warning receivers, missiles, and useful Ground and Airborne Intercept Controllers.
For example, and as I mentioned in other discussions, I inquired about the usage of Single-Target Track and Track-While-Scan along the AIM-120 with former crews. Long story short, they confirmed that TWS is often a poor mode in such a scenario, although High-Datarate TWS appeared more effective. The radar mode commonly used until recently was STT, to give the missile the best chances to hit. They assumed the target was aware of their presence, so there was little point in hindering the odds of success of their attack.
Many players are starting to experience all this only now, thanks to the excellent SPO-15. The new Radar Warning Receiver tech is finally making people realise how difficult building situational awareness is, and why aircraft rarely operate as independent singletons as they so frequently do in DCS. The next piece of the mosaic is the missile simulation, and this new R-27 appears to be a very promising first step.
FlyAndWire 