I know CxK is not analog to drag coefficient. However estimating drag coefficient allow players to evaluate how much excessive drag that phoenix has.
People have already made tools that show this is the case. The top speed by altitude is erroneous, yet the motor performance is fairly close to reality. The top speed by altitude is too low currently… Ergo the drag is too high.
Speaking of drag, I’m trying to figure out a way to compare the NASA sim (reminder its not perfect, its using a basic, likely ballistic, trajectory, and only publicly known info, which they themselves specify isn’t accurate and only served as preliminary analysis for feasibility of using the AIM-54 in the ALSM role).
The issues I’m running into are:
- The loft profile and the fact it needs to be fired with guidance and not in a purely ballistic trajectory in-game makes the missile act differently than the NASA sim likely did
- Setting up the shot is awkward, particularly the high angle (30 and 45 deg) shots at M1.2, 45kft.
I did do some quick testing trying those shots, with some odd/interesting results. iirc, the peak mach numbers achieved by the missile all overperformed the NASA sim (likely from the loft), with the 0 deg shot outperforming the NASA sim the most, likely due to the 15 deg loft. The mach number at impact post-motor-burnout of the 0 deg launch also overperformed the NASA sim, but iirc for the 30 deg and 45 deg launches both underperformed the NASA sim, with the 45 deg shot underperforming the most (iirc impact was around 65-70 seconds from launch but impact velocity was close to Mach 2 instead of above Mach 3 like shown in the sim).
If I were to guess why all shots overperformed in top speed compared to the NASA sim in top speed, it would the loft itself for the 0 deg angle shot, and the straightening/diving of the AIM-54 during motor burn for the 30 and 45 deg launches (as it guided towards the target). As for why 2/3 shots underperformed in sustained mach numbers, that could be related to the trajectory of the ALSM sim leaving the missile in lower drag air for longer, or it could be due to excessive in-game drag.
I’ll correct this post and possibly add the screenshots later if I remember/care enough to do the work later, but thought it to be interesting and an idea for someone who cares more about this than I do and can actually do custom testing.
Once again, the NASA sim are not accurate representations due to only using publicly available info and an unknown flight profile. I just thought it was an interesting thing to try to recreate in-game best I could to try out the new sensor view and to see how NASA’s sim stacked up against gaijins.
9000m m1.2 vs m1.2 75km launch
The phoenix’s loft code has been changed here, and now its loft route is similar to aim120a.
Changed phoenix performs very well in BVR situations, and its speed drop rate during gliding is similar to the aim120a.The Phoenix hits the target 5 seconds earlier, and its terminal speed is 0.56 Mach faster.
Phoenix drag is currently low enough in the game (maybe even too low), but the lower flight path affects missile performance.
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Out of curiosity, have you tried other loft codes, such as the Derby which lofts more aggressively? Or have you though of trying to use not only the AIM-120’s loft code, but also its time to gain code? I’m curious to know how the 54C would perform if it got the full guidanceAutopilot code from the AIM-120 or Derby, not just the loft code.
54C vs 120A guidance code:
Not sure if you seen Jaek’s video, but Derby’s loft code makes it arrive later and also has it overshooting targets, often missing it completely at longer ranges.
Hopefully will be different in June
The AIM-54 may not interact the same way with the Derby’s loft code simply due to its longer burn and higher drag. It should by all accounts work better with more aggressive loft than just about any missile in-game afaik (up to a point obviously).
There’s a reason why irl the missile has in some cases climbed as high as 103,500ft…
Also, as a sidenote, unless gszabi hasnt updated the datamine, or im misunderstanding @dark_claw 's post, the loft code provided to the 54C in his test is in some ways more aggressive than the derby loft code:
i keep hearing this missile got buffed. is it worthwhile taking it in sim now?
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This isn’t true, the drag is too high. We know this rather simply because the missile can’t even achieve proper maximum speeds based on altitude in-game.
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Speaking from experience, the AIM-54 has this nasty bug in sim where if you hit someone with it, they get sent back to hangar (from the shame of dying to such a bad missile or their anger to dying to something so “OP”, depends on the victims skill level)
I’d never really consider it “good” in sim, simply due to TWS bugs (particularly bad in sim last I checked), coupled with the fact that unless you do a lot of launches followed by RTB’s, you run the chance of getting ambushed by an enemy and either having to ditch the AIM-54 or fire it with minimal effect compared to something like an AIM-7M/R-27ER. It could be usable if it got some more QoL fixes such as getting its full maneuverability and more notably for sim, the low smoke motor (as most of the combat is at lower alts due to everyone trying to abuse multipath 24/7.
Its very good at clearing aerial objectives easily in sim though, but the fin AoA buff has nothing to do with that
To note, I still run it in sim, simply cuz its more fun to use imo, and its gameplay is unique. I do like doing weird stuff in sim though, like running hard ground strike missions vs convoys and stuff, so others experiences may vary.
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loftElevation : missile loft flight elevation angle
loftAngleToAccelMult : missile pull-up using overload
The remaining two lines affect the trajectory. The smaller the loftTargetElevation and the larger the loftTargetOmegamax, the later the missile enters the dive and the larger the dive angle.
The derby loft code value is too high. The missile hits the target almost vertically when firing from long distance, which is very detrimental to the missile’s stable tracking of the target.At the same time, an excessively high trajectory will also cause the flight distance to be too long, and the missile’s hit time will be very late.
AIM-120A 178mm , end mass 101kg , sectional density 4.05 g/mm2
AIM-54C 380mm , end mass 293kg , sectional density 2.58 g/mm2
The sectional density of aim54c is much lower. and the aim120 also has a cleaner body and smaller wings. It is difficult to understand that the speed drop rates of the two missiles are similar.I am more willing to believe that there are some problems with the missile’s drag line and power setting.
Thrust and burn time is accurate, drag currently is too high as top speed is not met. It is extremely plain to see and understand this, if it does not meet your expectations perhaps there was an error in your process.
Time to target given can be more easily achieved with a faster missile without such a high loft, with an even higher impact speed.
Omega is usually used to denote angular velocity, I guess loftTargetOmegaMax means, when delta angle to target per second goes beyond the specified value then go into terminal phase. This is likely used in case target is flying too fast.
At 0.25 degrees per second and 20km to target, target has to fly ~87m/s perpendicular to the missile for it to go into terminal phase due to speed difference. If this is correct, then assuming target is flying at 340m/s, a 14.8 degree offset will yield ~87m/s perpendicular to the missile.
At 14.8 degrees, that translates to a max loft altitude of 5.28km, this will explain why Phoenix never wants to fly above ~6000m since it thinks target is too fast and it will miss the target if it climbs too high, thus it never performs the 35 degrees aggressive lofting when shooting down. Also angle to accel mult is low, it is not pulling into a climb fast enough. Perhaps loftAngleToAccelMult = 3 may help.
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It was more out of curiousity to see how it might affect a missile with more energy.
I’d also be curious to see what might happen if you increase the loft angle to something like 45 deg, seeing as according to the NASA sim, that left the missile with a slightly lower peak Mach number, but over 100 seconds of Mach 3.0+ flight, or what might happen if you add the energy management code from the AMRAAM’s guidance autopilot I mentioned earlier alongside your adjusted loft code:
seeing as the AIM-54’s are likely to still be wasting energy during their trajectories currently as they’re cleared to use 100% of max G load immediately once control surfaces are unlocked in-game.
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45000ft 1.2M 45°
The AIM-54C here had all guidance codes removed and was fired as a rocket for testing. Phoenix can fly to Mach 4.12, which is higher than NASA’s test. Due to the influence of the rocket’s center of gravity, the missile will gradually turn downwards during flight. It is not clear whether this dynamics is accurately simulated in the game. Therefore, the longer the flight time, the greater the gap between the rocket flight trajectory and the real missile.
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Thanks for testing it!
The erroneous NASA figures based on public data, the top speed is much higher as we’ve discovered since.
The aim54C can go over mach4?
If i launch a aim54C at 340m/s how fast it goes?