Air-to-Air Missile Discussion

[GGTharos]

The missile drag profile is a curve, not a single value.

 

I've done some testing on this. The problem isn't so much the Δ v the missiles generate. It's how quickly they slow down. Using simple drag force equations and manipulating the Cd from .5 all the way up to 1.0, the missiles are still decelerating anywhere between 50% and 150% too much. We're in the process of calculating an estimated Cd, but without knowing where to input it, and out of curiosity see what the current one is. We're a bit stuck on that.

[karambiatos]

Is the ER in the game suppose to have less range than the aim-120, same goes for the R-73, which has a lot less range than the aim-9m, the R-27ET and aim-9m seem to have about the same range, or at least thats what ive noticed.

 

On top of that the aim-120 seems to be too easy to spoof, just by dumping chaff, and turning into it at the right time.

Edited May 3, 2013 by karambiatos

[GGTharos]

The R-27ER has shorter range than the AIM-120 due to its flight profile. Where the R-27ER will have a 'maximum range' of 66km at 10km altitude, the AIM-120 will exceed 70km of range - but this is with the C5 variant which uses a more powerful rocket.

 

The AIM-120B through C4 use a different, less powerful rocket motor but the range is still impressive.

 

As for the R-27ET vs. AIM-9, the R-27 should be quite a bit superior in terms of range.

[IASGATG]

No, it isn't useful to define it because there are too many factors.

 

Is it the maximum range at which you can still hit a target than only performs a last second jink?

Is it the maximum operating time of the battery? (it may be a factor at higher altitude but not at lower, perhaps?)

Is it the maximum range of the seeker, but not the rocket?

Is it the ballistic range?

Is it the range at which the missile slows to M1?

Is it the range at which the missile still has 5g capability left?

 

Exactly! That's why you have to define it. It's like any definition for anything, ever. You have to set a benchmark of assumptions and say "In order for our word to have any validity, we have to assume x, y, and z." Just because a definition takes more than five words to define, doesn't mean you shouldn't define it. Look at philosophy, words can take paragraphs or even essays to define, and that's FINE. As long as you make it know that that's YOUR definition.

 

The missile drag profile is a curve, not a single value.

I know it's a curve based on a number of variables, but we know through simple physics, as the missile gets slower, what happens to its Cd? What happens to its drag force? And the missile should do what? Exactly, it doesn't. What it does do is slow down WAY too quickly.

Edited May 3, 2013 by IASGATG

[GGTharos]

Exactly! That's why you have to define it. It's like any definition for anything, ever. You have to set a benchmark of assumptions and say "In order for our word to have any validity, we have to assume x, y, and z." Just because a definition takes more than five words to define, doesn't mean you shouldn't define it. Look at philosophy, words can take paragraphs or even essays to define, and that's FINE. As long as you make it know that that's YOUR definition.

 

No, it isn't fine. It leads to bad results. It's better to admit that we don't understand maximum range and apply the stuff that we do know. This is the result of direct experience with defining our own max range defaults and trying to force the missiles to match them ... it led to the poor performance you see now.

 

I know it's a curve based on a number of variables, but we know through simple physics, as the missile gets slower, what happens to its Cd? Oh right, that's constant. What happens to its drag force? And the missile should do what? Exactly, it doesn't. What it does do is slow down WAY too quickly.

I don't get your argument; I'll say again, the Cd is not constant in any part of the missile's flight profile that you might be interested in. A missile that's at mach 1 isn't terribly interesting.

 

You are right that they slow down too fast, but it's not a matter of just changing one value.

Edited May 3, 2013 by GGTharos

[NineLine]

Maximum Range shouldn't be defined it should be a result.

[IASGATG]

No, it isn't fine. It leads to bad results. It's better to admit that we don't understand maximum range and apply the stuff that we do know. This is the result of direct experience with defining our own max range defaults and trying to force the missiles to match them ... it led to the poor performance you see now.

 

I don't get your argument; I'll say again, the Cd is not constant in any part of the missile's flight profile that you might be interested in. A missile that's at mach 1 isn't terribly interesting.

 

You are right that they slow down too fast, but it's not a matter of just changing one value.

 

Okay. You can do it your way. We'll try it our way, see what happens. I assume you'll be open to looking over our results when we publish them, and if you cannot find any faults in the findings, it'll be incorporated. Obviously if you do find faults, we'll make changes accordingly.

[GGTharos]

It's not up to me to incorporate stuff, but if you do a good job, why not?

 

On the other hand, what's the point in duplicating work?

[IASGATG]

It's not up to me to incorporate stuff, but if you do a good job, why not?

 

On the other hand, what's the point in duplicating work?

 

I have lots of free time.

[GGTharos]

The problem is that 'Maximum range should be a result' means you have a definition. And the problem with that definition is that a) we don't know it, and it may be different for each missile and b) it may be a bunch of factors, not just one.

 

To give you an example, the AIM-7F had a maximum range of 22nm ... but a ballistic range of 57nm.

 

Wait, what? That's less than half the missile's range! Why?

 

So it turns out that it was homing-all-the way and against a 2m^2 target the seeker's maximum range was 22nm.

 

We see similar things for heat seeking missiles. One fairly obvious way to define Rmax there is the range at which the missile can lock on head-on, but the range at which the missile can just barely overtake its target when it reaches it (down to some minimum speed, because some targets like helis are so slow that the missile couldn't possibly maneuver at such speeds) OR the amount of available working time, ie. battery time. For dogfighting heat seekers, pretty much all three are sort of taken into account. You can't easily tell if there is something wrong with them because they are used at short ranges and at those ranges they more or less work, plus their head on use is rather limited ... you don't get many chances to observe problems, until you get into the 27T's and radar guided missiles.

 

Maximum Range shouldn't be defined it should be a result.

Edited May 3, 2013 by GGTharos

[GGTharos]

By all means, enjoy :)

 

I have lots of free time.

[IASGATG]

You could say the the AIM-120C has light years of maximum distance if shot from the ISS into space.

 

If you don't want to create a sensible definition, that's fine.

If you want to say the maximum range is the ballistic range, that's fine.

If you want to say it's the range at which it can still pull x g, that's fine.

If you want to say it's the range at which it is still travelling at x speed, that's fine.

If you want to say it's the range at which it loses the ability to keep track of a non-moving target, that's fine.

If you want to say it's the range at which it can hit a maneuvering target pulling x g's, that's fine.

If you want to say it's the range at which it can hit a target that only begins to evade at range x at g load y, that's fine.

If you want to set the base altitude benchmark at x height, that's fine.

If you want to set the base IAS benchmark at x speed, that's fine.

If you want to add any more possible variables to this, that's fine.

If you want to use a combination of these variables and pick the lowest number, that's fine.

If you want to use a combination of these variables and pick the highest number, explaining why, that's fine.

 

At least we then know what you mean.

[NineLine]

Well I still stand at it is a result, I didnt say I had the variables to get that result ;)

 

The problem is that 'Maximum range should be a result' means you have a definition. And the problem with that definition is that a) we don't know it, and it may be different for each missile and b) it may be a bunch of factors, not just one.

 

To give you an example, the AIM-7F had a maximum range of 22nm ... but a ballistic range of 57nm.

 

Wait, what? That's less than half the missile's range! Why?

 

So it turns out that it was homing-all-the way and against a 2m^2 target the seeker's maximum range was 22nm.

 

We see similar things for heat seeking missiles. One fairly obvious way to define Rmax there is the range at which the missile can lock on head-on, but the range at which the missile can just barely overtake its target when it reaches it (down to some minimum speed, because some targets like helis are so slow that the missile couldn't possibly maneuver at such speeds) OR the amount of available working time, ie. battery time. For dogfighting heat seekers, pretty much all three are sort of taken into account. You can't easily tell if there is something wrong with them because they are used at short ranges and at those ranges they more or less work, plus their head on use is rather limited ... you don't get many chances to observe problems, until you get into the 27T's and radar guided missiles.

[karambiatos]

Where. Is. The. Code. Please.

you wont see the code, maybe in 20 years if eagle dynamics closes theyll be nice enough to show us the code, until then you wont see it.

[Angel101]

Where. Is. The. Code. Please.

 

I could not resist...

 

 

 

 

[Exorcet]

1.2.3

 

 

 

 

Quick 1.2.4 comparison

missile - Vmax - Vfinal

 

120B - 2050 - 480 (fail)

120C - 2250 - 838

A-7M - 1680 - 565

27ER - 2580 - 955

 

The Sparrow did get hit pretty hard, I would have thought it was the closest to correct in 1.2.3. Yet it still out did the 120B in this test. R-27ER gets a slight boost, seems to be a good missile in this patch.

[Nate--IRL--]

Where. Is. The. Code. Please.

 

I know perhaps I am jumping into the deep end here, but......

 

What do you expect to see?

 

Perhaps you can provide your equations for missile fight to compare first ?

 

Would that be too much to ask? I am more than willing to challenge the dev team with solid evidence.

 

Give us evidence to fix what you think is wrong. Verifiable evidence ONLY.

 

Nate

Edited May 4, 2013 by Nate--IRL--

[IASGATG]

I know perhaps I am jumping into the deep end here, but......

 

What do you expect to see?

 

Perhaps you can provide your equations for missile fight to compare first ?

 

Would that be too much to ask? I am more than willing to challenge the dev team with solid evidence.

 

Give us evidence to fix what you think is wrong. Verifiable evidence ONLY.

 

Nate

 

Drag Force equation.

 

Well aware that the drag co-efficient changes depending on x,y,z. Having looked through the code, the best I can see is the Cx_K0-3 and the Cx_pil. What these do exactly would be most appreciated.

 

Burn time of missiles.

 

They are burning too long/staging is funky. Resulting in incorrect acceleration of missiles.

 

These two things together are pretty much the big things we're looking at currently. Having a missile decelerated from M3 to M2 at an estimated 20-30s, and having it do it in 6 means that there is an error somewhere. Either in us, or you.

 

If it's us, that's fine, we'd just like to figure out your end. Google translate of Russian isn't that helpful and our Russian is took busy reporting to the KGB.

 

There are several others as well of course. At this point we're just compiling as much data as we can get. Any data that you can give us that you know is accurate would of course be appreciated as it'd save us time. We understand the hassle of data mining, that's fine, I'll happily go through a 400pg pdf to find the 1 line of stuff I'm after. :)

Edited May 4, 2013 by IASGATG

[GGTharos]

Who is 'us'?

[IASGATG]

Who is 'us'?

Some friends and I. Why? Want names for the KGB list? ;)

[GGTharos]

No, I was just wondering if you were using the royal We :D

[ralfidude]

Who is 'us'?

 

[Grimes]

I think I'd trust this guy more:

[theChris]

is it safe to say at a 65km shot the r-27er would reach the target first compared to the aim-120c5? Because of lofting. Note: this is a non maneuvering target

[ralfidude]

Well this is how they are doing it;

 

 

 

And this is how we see that you guys do it;

 

 

 

 

Then again, I haven't just yet taken fluid mechanics so I can't help them with the equations, but so far what they have found out through pure simple physics and mathematics, and a little information fact finding is rather astonishing compared to what is presented in the game thus far. So we are hoping that once they get their numbers sorted out right and get the missiles to behave as they should, you will consider it based on what's presented.

Edited May 4, 2013 by ralfidude