IASGATG

Someone would have to put one together for you.

You're welcome. :)

http://forums.eagle.ru/showthread.php?t=131806

So, 4 pages later and nothing that disproves the paper?

I looked at the AIM-9 family and found that preliminary the curves and the thrust for the missile are pretty close to anything literature comes up with. CFD might gleam some greater accuracy on it, but if you have flight performance for an AIM-9L, the shape of the Mike is so similar that the Cd will be very minor. The motor is correct so that missile is fine. I then considered doing the Sparrow because that missile is pretty damn broken. There is quite a bit of conflicting information when it comes to the Sparrow and without CFDing it I pretty much gave up on attempting to resolve the missile in the same way that I did for the AIM-9. Then I looked at the R-27 family. First hurdle is that it's all in Russian, specifically technical Russian, so that makes life extremely difficult when you don't have a fluent Russian speaker who can translate scientific expressions from Russian to English. Next was gaining enough and accurate date on the Russian equipment. Some playing was does with the 27ER, correcting the motor (As I've found making the motor accurate is perhaps the easiest part of anything) but then trying to make it with Russian Airforce tables of flight performance it is impossible to replicate in the game or generates a Cd curve that is absolutely unrealistic. Again would have to be CFD'd and then I'd want some sort of literature to help back up the CFD's analysis. So the question becomes "Why not just CFD everything?" Well firstly the hassle of making all the 3D models is a couple of days work per missile to get a basic model that we could CFD, assuming we already know the exact specifications down to the airfoil shape of all the missiles. Secondly creating the boundary layers and solvers for the CFD for the missile, then running the weeks of computer time and then running coding a second solver for the output to turn the Cd curves into flight paths again. Basically a shit ton of ****ing work. We did the first one has a hobby, to see if it could be done, to see how close we could get and see how the Dev's would respond to it. Given the response we are not eager to put x months into repeating the process again for nothing.

It did have its own thread and suddenly it ended up here. As for a 0-0 launch, well from a CFD point of view we wont be doing that. As for the missile used, the C-5 and C-7 have the same kinematic profile so it wont make a difference; same body, same motor.

AIM-120C-5 Performance Assessment Hello wonderful DCS community. We've had this document written up for about the past nine months now and we've debating what we want to do with it. Finally we came to the conclusion that we'd just post it to the community so that way any questions people have regarding the most current (at time of writing) information regarding the missile can be easily accessed. If there is anything in this document that is incorrect, the email at the top would love to hear it so that way improvements can be made accordingly. Cheers! AIM120C5 Performance Assessment rev2.pdf

Tried it, still they stop and scatter. :(

I've given this forum a pretty good look over and I cannot find anything obvious that suggests how to make ground vehicles continue onto way points whilst under fire. Am I just being dumb?

Terrible, terrible guidance.

This Scan While Track

It's okay buddy, there is a lot of shit that goes into this crap. :) <3 Just trying to get my god damn missile into this god damn game.

I just thought it'd be nice to see how close the BC is when we start to put actual numbers in. It's pretty damn close eh?

You're welcome.

With the numbers you've provided which for the napkin maths we're doing is fine, the 120 has more BC which means it slows down at a lower rate. In a Drag Force equation, the 120 has less force being applied to it. I don't understand where you're getting lost. In the two main models that are used to govern how fast an object slows down in air, both say the 120 slows down at a lesser rate than the ER, despite the ER having more momentum behind it. To be honest, I shouldn't really bring up Fd since the main comparitor here is BC which has the 120 in the lead..

I agree, that a lower Cd on it's own doesn't mean much. However if all other variables are the same, it will have a lower drag force. But, the ER has a larger area and a larger Cd which means it'll have a larger drag force. Not only does it have a larger Cd/Fd but it has a lower BC. This means that it will slow down at a faster rate. If both missiles appear in space at Mach 4, the ER will slow down at a faster rate than the 120. I don't know the Cd of the ER either, so I don't know how much larger it's going to be than the Charlie. At some point I'll get it CFD'd. Edit: Formating, grammar.

Through some pretty extensive testing on my end, I've found that the physics engine in the game is pretty reliable and behaves more or less as it should for a simplified real life simulation. So if we start on that assumption we have two things to tackle. 1. Thrust. Pretty much all the thrust data on all the missiles is known. We know how much fuel is in every missile, what fuel is in every missile, and thus what the Isp is (a yard stick I know) to generate a thrust profile. This is more than accurate enough for a video game. 2. Drag Coefficient. Since the game engine models atmosphere pretty well, all we need is an accurate Cd curve at sea level and the game engine will do the rest, and this is what I've found. There are some flaws in the game engine's generation of Cd however. For instance a modifier needs to be added for when the engine is on. This is because it reduces drag by disrupting the vortex that forms as the shockwave travels over the body. In a nutshell, motor on = less drag. Once these kinks have been worked out you're then able to, through mostly trial and error, build a Cd curve that forces the missile to behave to how we know they should at Sea Level from real world and CFD analysis. This is what I did in the AIM-9L Variant curve back on page 3 of this thread. The only thing is lacks is the motor on/off which would more or less correct the slight discrepancy it has compare to the actual flyout performance charts. We do this for every missile that players use and you've resolve the kinematic performance.

I feel as though this thread needs to be split into three very different topics. 1. Kinematics which imo is the most important as it's one of the easiest things to fix and EVERYTHING else stems off of getting it right. 2. Navigation and to some extent maybe counter measure susceptibility. Much much harder to do anything with as that's all game code stuff due to being in the backend you don't really have much to say beyond "It'd sure be nice if my missile doesn't pull 30g as soon as it comes off the rail for no reason" 3. AI. Well... Don't have much else to say on that really.

The 120 has a better BC even if they have the same Cd. The 120 has a lower Cd than than ER. The ER will slow down faster. I'm interested to know where kirky got the surface area data from. I don't dispute it, merely curious. Edit: I get it, just using the diameter of the missile, okay. Fair enough.

Please stop saying inertia when you mean momentum.

I don't know if I'm being dumb and this has been discussed but I just thought I'd check. I pledged: MATRIX Tier 1. Everything at the $10 level, plus a digital copy of all flyable aircraft in the initial release, plus ONE extra (with the exception of the DCS World FW.190D-9). The one extra I chose was the P-51D. The question I have is when does that get activated on my account. Does that make sense?

A lot of information around modern missiles is classified, yes. But, more than enough is unclassified (But perhaps not public) that can be used to generated a very close approximation of it's kinematic behaviour. This is more than enough for a video game. You are right, you wont be able to accurately model how a missile behaves in real life in a game. Nobody is trying to. You physically cannot run CFD in real time like this, and even if you could, it's still not as accurate as real life. The variables that are required to build a flight model are in the game, the accuracy of them and the reliability of them is entirely down to the physics engine of the game that we are beholdent to. However, if you know that the motor has x Newtons of thrust for x number of seconds, you can put that into the game engine. And if you know that it decelerates from Mach 3 to Mach 2.5 in x seconds at 5 different altitudes, and you build a Cd curve that matches this, you can start to build a drag profile. You do this for the full spectrum from M4+ to M0.8 and you match the curves up. You don't need Raytheon's classified data on the ECCM algorithms to do this. Nobody is trying to do this. Nobody is even suggesting to do this. You haven't provided me any sources from anything you've said. You haven't even said where you got your sources from. It still sounds like you're making them up. Everything I've gotten was from either ditc.mil or from ATK or Raytheon or US Navy Dept of Research, etc. Tell me exactly how much information you want to know before you believe that the missile behaves correctly? You're asking for the burden of proof, I'm asking you what is required to make you believe? I don't even know what this paragraph means, I'll assume language barrier. Yes, the shape of the 120 hasn't changed much. So? Please rephrase. I don't have to assume your knowledge is superior. If you know what you say you know, then you know there is more than enough public and unclassified information out there to generate a reliable missile model for a video game. I am saying you're wrong because you're saying "My mate in the pub said" whilst doing nothing to verify your point. For example. I can easily say that "I am RAF and I know exactly what the 120 can do and having flown with Indian Air Force I know exactly what the R-27 family can do and I know for a fact the 120 out performs it in all arenas, you just have to trust me!" See how retarded that sounds? I think that in a frictionless vacuum the only thing that affects it's top speed is the force applied to it yes. In this instance the force is thrust of a solid rocket motor.

Order of priority is kinematics, guidance, counter measure susceptibility and finally AI. There is no point altering the AI until you have the game behaving how it should.

Sorry, sarcasm is coming back out because of the dumb. If you have a classified document from 1970 that is now deemed unclassified and viewable by the public doesn't suddenly make all the information in it made up. What it makes it is valid and correct information that has since become no longer a threat of national security because of more advanced replacements. Hence why you can get all the spec on AIM-9's all the way up to the L but now further. Why you can get specs on all the AIM-7's all the way up to the F but not further. Moreover, physics doesn't give a **** if you're classified or not. Laws of nature don't change because sometimes they're used under secrecy and sometimes they aren't. If you obtain correct missile data and it says a missile behaves in a specific way under specific circumstances and you then build a curve that makes the missile mirror that, you have generated an accurate simulation of real world performance. Just because the numbers you're using in the back engine might not be right. The Cd curves, the A curves, the rho curves might all be off. The way the engine interpolates them might be off. Ultimately, if you have a set of curves that say how the missile flies in the real world, and your sim missiles fly the same, what's the problem? I'd imagine they're assumed as well, except for maybe the R27 family. And yes, it is worse. Else the Russians wouldn't replace it. In the computing world, 20 years is a long ****ing time. I'm just gonna assume you're either kidding or incredibly ignorant. This is where you're again, hilariously wrong. You just dropped the assumption that most of us don't know what we're talking about. Granted, most of the people (You included) have no idea what you're talking about. You are pulling numbers out your arse without providing any sources what so ever. Since we know what the thrust output of the R-27ER is from Russian Air Force sources, and we know (Close enough) what the thrust output of the AIM-120C is from US sources, we can see who is able to go faster under what circumstances. The delta V on the ER is not more than twice that of the C. Therefore even under frictionless vacuum circumstances, the ER will not go twice as fast as the Charlie. You're just incredibly wrong or you have information I haven't seen. If you have got new information regarding the specific thrust output/fuel grain/motor specs, I'd love to see them. And then the conversation about missiles ends and so does my interest Edit: A word.

Cd at super sonic can be lower that sub sonic, however, not with the shapes and speeds we're talking about. Moreover, since surface area wont change, since density wont change, Fd will change as Cd changes. Yes V is squared but.. ... You get what I'm saying right? The conversation is mute.. I feel we're talking in circles for no reason. All the points to do with the graphs are still just as valid. Can we seriously delete these last two pages because they serve no purpose at all.