How does the SD-10 missile compare to the AIM-120C?

[Exorcet]

Somebody help me out here. How are we defining "accurate" and "realistic" in this context?

 

I see how we can get a reasonable approximation of D and Cd from a photograph because we can see A.

 

https://www.grc.nasa.gov/WWW/k-12/airplane/dragco.html

 

https://www.grc.nasa.gov/WWW/k-12/airplane/drageq.html

 

Where are we getting all the other variables and parameters? e.g. thrust, burn time, weight?

 

I keep seeing phrases like "OP", "I feel", "based on the information available", "behaving like I would expect". I don't get it.

 

 

With an approximate drag value, you can work out a deceleration based on altitude (air density) and roughly compare with DCS.

 

 

If you want to go a step up the missile can be simulated. I don't know a lot about the SD-10 itself, but IASGATG's already mentioned work is available for comparison:

 

 

http://www.zaretto.com/sites/zaretto.com/files/missile-aerodynamic-data/AIM120C5-Performance-Assessment-rev2.pdf

 

 

One of the good things about is that it provides information for the missile at g loads above 1 vs range and vs time (pages 28 and 29). With this you get some rough idea about how the missile will work vs a maneuvering target. In the tracks I recorded the SD-10 hovers around 5 g a few miles before impact. It does seem to outperform the simulated AMRAAM, it can hold that 5 g for longer, but I wouldn't consider it completely unreasonable.

[Terrorban]

No, ultimately I'm comparing drag coefficients, so don't need to know anything about internal workings.

You could argue that comparing these things so directly isn't super-accurate, and I agree - but we don't need super-accurate here because the SD-10 behaves outside of the realm of physics wrt drag coefficients. In other words, it's so far out there that it cannot be correct.

 

 

Anyway Deka has responded, ED has responded, all of this will get sorted out.

 

I have no arguments against your data. It is just when you began comparing the performance with how other missiles behaved I wanted to clarify if any of that influenced your reasoning.

 

Furthermore, I know that Deka has responded to this issue but where is ED’s response? Would love to get all this sorted out so we don’t get used to one thing and then it changes quite late.

 

I’ll be honest, I still sweat salt when someone jumps in here demanding the missile be nerfed because it is overpowered without explaining much.

[GGTharos]

I have no arguments against your data. It is just when you began comparing the performance with how other missiles behaved I wanted to clarify if any of that influenced your reasoning.

 

Furthermore, I know that Deka has responded to this issue but where is ED’s response? Would love to get all this sorted out so we don’t get used to one thing and then it changes quite late.

 

I’ll be honest, I still sweat salt when someone jumps in here demanding the missile be nerfed because it is overpowered without explaining much.

 

 

I would argue that 'nerfed' is the wrong word when asking to bring it more in line with reality. It belongs to a different game type.

 

 

An SD-10 brought to a much more proper drag model would still outperform the 120 as it is in game right now.

 

 

Maybe some people asked for it to be brought in line with other missiles, which isn't unfair (as in, for it to be tuned according to how other missiles are tuned), but I'd prefer it to be more realistic and re-tune other missiles to have a more realistic drag model.

 

 

Also, please realize that previous tuning was done according to data and technique known a long time ago. Today we have more/better knowledge.

[shaHeen-1]

that much salt is enough to give anyone heart diabetes

[falcon_120]

that much salt is enough to give anyone heart diabetes

So much wrong in this post...dont even know where to start XD

 

Enviado desde mi SM-G950F mediante Tapatalk

[CommanderRabb]

Blue guys finally get a taste of what we have been going through every day in an MP server. Enjoy the experience

 

 

Not really. Most of the people who've been (apparently) kicking your butt in BVR, aren't the ones suffering. They're doing just fine and not much has changed for them. Personally I haven't found the JF-17 or the SD-10 to be much more of a threat than the usual fare either.

 

The guys reliant on the AIM-120 though, they're the ones suffering, due to the abysmal performance of their flagship weapon, which is so poor (in BVR) that I'm amazed they were able to cause you so much grief as you claim.

 

And that is why they are angry. It's not that the JF-17 is actually better (despite the widespread and ignorant gloating). It's the fact that the appearance of the SD-10 has put a spotlight on how bad the AIM-120 is, which wasn't that big of an issue prior to the appearance of a properly modeled competitor. But now you have modern fighters that are basically fighting with their hands chopped off in BVR and shouldn't be, because they're perfectly capable.

 

Once the AIM-120 is fixed. The JF-17 and you will likely be in for a humbling.

Edited December 10, 2019 by CommanderRabb

[ShadowFrost]

Not really. Most of the people who've been (apparently) kicking your butt in BVR, aren't the ones suffering. They're doing just fine and not much has changed for them. Personally I haven't found the JF-17 or the SD-10 to be much more of a threat than the usual fare either.

 

The guys reliant on the AIM-120 though, they're the ones suffering, due to the abysmal performance of their flagship weapon, which is so poor (in BVR) that I'm amazed they were able to cause you so much grief as you claim.

 

And that is why they are angry. It's not that the JF-17 is actually better (despite the widespread and ignorant gloating). It's the fact that the appearance of the SD-10 has put a spotlight on how bad the AIM-120 is, which wasn't that big of an issue prior to the appearance of a properly modeled competitor. But now you have modern fighters that are basically fighting with their hands chopped off in BVR and shouldn't be, because they're perfectly capable.

 

Once the AIM-120 is fixed. The JF-17 and you will likely be in for a humbling.

 

I wouldn't be so sure, the SD-10 is widely regarded to fit inbetween the 120B-C and the gap between B and C isn't very large. Once the missiles undergo their overhaul and are more or less equal. The missiles wont be too much of a concern, more the platform. The JF-17 lacks in outright speed against F-16/F-15 so it will have to rely on better tactics to keep up once that day comes.

[Oceandar]

Blue guys finally get a taste of what we have been going through every day in an MP server. Enjoy the experience

Lmao dont be surprised if in the next update the missile gets more drag thus more "realistic range". I found Tharos arguments quite legit and reasonable.

I have almost all modern fighter modules so I'm both on Bluefor and Redfor. I enjoy all of them.

[Oceandar]

......The JF-17 lacks in outright speed against F-16/F-15 so it will have to rely on better tactics to keep up once that day comes.

Thats quite true. Eagle and Viper would happily eat JF-17 alive with their energy if JF-17 dares head to head BVR.

[Terrorban]

Let this thread die please. At this point there is nothing left to discuss and now these fanboys are jumping in looking for arguements. Can we lock this thread now?

[Annelid]

Hope the jf-17 gets to release branch before they nerf it. Want to try sd-10 myself.

Edited December 10, 2019 by Annelid

[LJQCN101]

As for the shape of the graph itself - the SD-10 in-game has the same drag coefficients for subsonic and high supersonic mach numbers. But pretty much every missile out there has a higher supersonic drag than subsonic, at least up to the mach numbers we're concerned about

 

We beg to differ here. From the CFD data we obtained, the Cx0 of SD10 should be lower than subsonic values above M2.25.

[Kumabit]

I don't get it. Why you guys are so sure that the AIM-120 is modeled wrong currently in DCS. We don't know which version of the AIM-120C is modeled in DCS, and since the F-15 is in FC3 competing with the old-school SU27, I don't think the version of the AIM-120 should be higher than AIM-120C-4. Thus, I don't know why you guys are soooooo sure that the AIM-120C is modeled wrong.

[falcon_120]

I don't get it. Why you guys are so sure that the AIM-120 is modeled wrong currently in DCS. We don't know which version of the AIM-120C is modeled in DCS, and since the F-15 is in FC3 competing with the old-school SU27, I don't think the version of the AIM-120 should be higher than AIM-120C-4. Thus, I don't know why you guys are soooooo sure that the AIM-120C is modeled wrong.

Well we only have guesses tbh, but i can give you a few to consider:

 

-All old missiles from fc3 time, not only the aim120, are too draggy which means that over 20mn shots even at high altitude high speed are a non sense against a half brained opponet. For these scenarios and conditions the overall feeling is that r27er and aim120c should be really deadly from 25/30nm, intead of 12/15 nm as of now.

-At the same time, those missiles that have been revisited by ED to new standard have improved their range considerably, take the new aim7 as a good example. This missile right now outrange an aim120c.

-There are navigation problems like wrong or non existent loft logic, which is a key thing at long range.

-The manufacturer/engineers of the SD10 place this missile somehow between an aim120b and C regarding performance.

-Although you are right that the F15C we have in FC3 should use something like a Aim120C3/C4 the hornet and viper we have now are circa 2007, so they should use the C5-C7 which have a sustantially better range.

 

 

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Edited December 11, 2019 by falcon_120

[WOPR]

We beg to differ here. From the CFD data we obtained, the Cx0 of SD10 should be lower than subsonic values above M2.25.

 

 

Which means the AIM-120 drag coefficients are just wrong or there's an error in your CFD model (I am not stating an opinion on either possibility). However, I applaud this level of effort and attention to detail. Hopefully DI and HB will help ED continue to improve DCS fidelity and quality.

[L0op8ack]

Which means the AIM-120 drag coefficients are just wrong or there's an error in your CFD model (I am not stating an opinion on either possibility). However, I applaud this level of effort and attention to detail. Hopefully DI and HB will help ED continue to improve DCS fidelity and quality.

 

 

1. Cx vs M curve, AA missiles have characteristic similar curves;

2. do adjustment to be between B and C, move the curve up or down to match the design;

3. energe management, loft should work much better.

Edited December 11, 2019 by L0op8ack

[TLTeo]

I don't get it. Why you guys are so sure that the AIM-120 is modeled wrong currently in DCS. We don't know which version of the AIM-120C is modeled in DCS, and since the F-15 is in FC3 competing with the old-school SU27, I don't think the version of the AIM-120 should be higher than AIM-120C-4. Thus, I don't know why you guys are soooooo sure that the AIM-120C is modeled wrong.

 

Because CFD clearly shows that the AIM-120 indeed is not modelled correctly: http://www.zaretto.com/sites/zaretto.com/files/missile-aerodynamic-data/AIM120C5-Performance-Assessment-rev2.pdf

 

"After conducting the aerodynamic study of the capability of the AIM-120C-5 AMRAAM shape, important physical phenomena were successfully reproduced according to the declassified references, and no discrepancies were found in the results. Therefore, these simulations are as accurate as he supporting mathematical and physical models are, and that also means the only way to get more accurate than this is to measure it with physical experimentation. A comparison of the calculated performance of the AMRAAM to the performance of in-game employment of the AMRAAM shows that the missile is not properly modelled in Digital Comba Simulator. Similarly, other missiles exhibit performance characteristics that are not representative of their real performance. In some cases, this causes missiles to underperform; in other cases, missiles such as the AMRAAM will over-perform their real flight characteristics. In addition to the flight characteristics of the missile, the tracking capability of the missile was not studied. The performance of radar and external or internal tracking hardware onboard the AMRAAM was not studied in this assessment"

 

They even showed how to adjust the .lua files to make the missile perform more realistically, and those adjustments are in agreement with the CFD calculations they ran (section 8 ). In other words, a short term fix for the AMRAAM is actually fairly straightforward.

 

edit: interestingly, the changes they recommend put the AMRAAM somewhere between what it is currently in DCS, and what the SD-10 is like. As GGTharos, pointed out,

The CFD curve for AMRAAM in DCS looks like this:

0.023

0.048

0.40

0.027

2.3

1.5

 

Your numbers look like this:

0.012

0.042

0.012

0.003

1.20

1.50

while the CFD paper recommends the following:

0.016

0.045

0.02

0.016

1.2

1.5

so that kind of implies that a) the current AMRAAM is too draggy, which we knew already and b) Deka's SD-10 is still less draggy than the improved AMRAAM the CFD group recommended, which does lead some weight to GGTharos' arguments.

 

But then again, who am I to know, I do work with some fluid dynamics but my field of expertise is pretty far from aerodynamics so this is basically dark magic to me :P

Edited December 11, 2019 by TLTeo

[GGTharos]

We beg to differ here. From the CFD data we obtained, the Cx0 of SD10 should be lower than subsonic values above M2.25.

 

 

Ok, I understand, but as far as I've seen you need a different missile body shape to achieve this. Take the V-2 rocket, you can see its drag graph here:

 

 

https://space.stackexchange.com/questions/22907/modelling-spacexs-lift-and-drag-versus-angle-of-attack-and-mach-number

 

 

I can find more relevant research closer to the correct missile body, but I would dare say that the V-2 shape is actually MORE aerodynamic than most missiles. Note the Cd0 does not drop to be the same as subsonic drag until about M5.

IMHO you need to re-visit that CFD because something isn't being interpreted correctly here. The missile nose cone, the relative poor boat-tail and mass of fins aren't likely to allow you that sort of coefficient graph shape.

 

 

Edit: I take my tweet back (LOL). This can certainly be possible, I just found the AIM-9 radar guided variant does it. However, it also has a much, much higher drag coefficient overall so my suggestion below stands:

 

 

 

 

Also, correct me if I'm wrong here, because I've done a lot of digging but I could easily get some things wrong:

 

 

The SD-10/PL-12 are not the same missile, but, at the same time they are both derivatives of the AIM-7E. As in, AIM-7E -> Aspide -> PL-12.

 

 

So my immediate instinct to get the missiles 'back to reality' is to put that AMRAAM drag curve on there and put the AIM-7F rocket motor into it.

 

 

I'm not claiming either is completely correct, the rocket configuration may have changed, and the missile itself is probably a little draggier than the 120 for bunch of reasons.

 

 

However, your drag is definitely too low (easily proven from test shots taken in-game compared with IRL data points provided, AFAIK, by you), and the rocket motor as you've defined doesn't seem quite right, namely:

 

 

You've got 70kg of fuel (sparrow has less, and it's a heavier missile) with a 6sec boost and 4 sec sustain stage. I would go with 4 sec boost and 10 sec sustain - lower the sustain power a bit, that's if you don't simply use the AIM-7F/M rocket motor definition.

 

 

Yes, the missile will be slower and will slow down faster ... and it will be more correct. Tune from there to hit your RL data-points. Best data-points involve time-to-distance, directly or indirectly computed.

Edited December 11, 2019 by GGTharos

[Terrorban]

This arguement is gonna go on loop for a while since same things are being repeated to each other. I will always believe Deka team on this since, ED has so many inaccurate modeled weapons that none of these internet engineers managed to get fixed.

[sylkhan]

2. do adjustment to be between B and C, move the curve up or down to match the design;

 

Thanks L0op8ack for the report, i hope you don't have to much lower performance of SD10 to please/calm some people.

In real life SD10 is better than most of aim-120C versions.

What version of C in DCS ?

 

 

Recently, I have seen this on the russian forum about SD10

У китайских ракет сильно занижено сопротивление.- "Chinese missiles have a very low resistance."

 

It's worrying, because PL12 is a recent missile, and the resistance to countermesure need to be on par, with aim120C.

 

There is absoletely no reason for the SD10 to have a lower resistance.

Can you give us some infos about this.

Edited December 11, 2019 by sylkhan

[L0op8ack]

Thanks L0op8ack for the report, i hope you don't have to much lower performance of SD10 to please/calm some people.

In real life SD10 is better than most of aim-120C versions.

What version of C in DCS ?

 

 

Recently, I have seen this on the russian forum about SD10

 

 

It's worrying, because PL12 is a recent missile, and the resistance to countermesure need to be on par, with aim120C.

 

There is absoletely no reason for the SD10 to have a lower resistance.

Can you give us some infos about this.

 

 

12 shot 12 hit in national test, that's what I can tell.

PL-12/SD-10 did outrange the spec in some real scenarios shoots.

[GGTharos]

A lot of missiles outrange the spec, the spec is conservative. But they're not going to out-range it by 100%.

Right now SD-10 can easily hit a target at 70nm in the 70km scenario, if I recall that one correctly: M1.2, 30000' same parameters for target, head on, non-maneuvering. And even at 70nm is has a lot of excess speed - so this is very, very significant over-performance.

 

Would you like some tracks of this type of shot?

[L0op8ack]

We have our scientists and super computer resources to CFD our model, thank you very much.

The missiles will not be crippled as expected.

[sylkhan]

We have our scientists and super computer resources to CFD our model, thank you very much.

The missiles will not be crippled as expected.

:thumbup:

[GGTharos]

Then I'll pose this question:

 

According to a data-point related by one of the PL-12/SD-10s designers, M1.2 at 30000', co-altitude co-speed, head on and non-maneuvering range is ~70km.

 

Why, then, does your missile reach a target 70nm away in this scenario, and can actually reach further (70nm is the earliest we can launch due to radar limitations).