Air-to-Air Missile Discussion

[Essah]

so how long should we expect to wait before a fix to this might appear? 3 months? more?

[GGTharos]

The more you complain about it, the more weeks I add to my missile work. :P

[pyromaniac4002]

 

So if I'm reading this correctly I should be loading my F-15 with AIM-7Ms now?

 

That pretty much says all you need to know about how much the missiles have been messed up if it's more advantageous to carry Sparrows instead of AMRAAMs. Seems to me like I would leave out the missile FM changes from the patch if it screws them up this badly.

 

I'm looking forward to the day where there's enough quality control in these patches that we don't have to cripple an aspect of the gameplay just for the sake of including some incremental improvements.

[Loki_]

Maneuvering missiles will lose speed quickly, it's just the way things are.

 

I don't think missiles should be maneuvering at constant 4g turns during their decelration phase against non-manuevering targets when they are launched with the steering dot in the center of the ase circle, do you? That is precisely what is going on right now.

 

The missile decelerates at a predictable rate and its range and pk would improve greatly if its initial heading on launch already factored that decel into the angle of intercept.

[Loki_]

So if I'm reading this correctly I should be loading my F-15 with AIM-7Ms now?

 

That pretty much says all you need to know about how much the missiles have been messed up if it's more advantageous to carry Sparrows instead of AMRAAMs. Seems to me like I would leave out the missile FM changes from the patch if it screws them up this badly.

 

I'm looking forward to the day where there's enough quality control in these patches that we don't have to cripple an aspect of the gameplay just for the sake of including some incremental improvements.

 

Did a simple test with mission editor. Launched aim120b, 120c, 7m all in rapid succession in that order. This was a simple test of range with no target for these missiles to track. Despite being fired third the aim7 passed the 120s and went an additional 3nm before plunging into the sea. I was flying as slow as possible so im certain i didnt travel more than 0.2nm total between launches 1 and 3. I agree that the aim 7 has greater legs currently - but try your own tests if you are skeptical.

 

That said most people start manuevering against launch indications so the aim7 may be worse in mp environments currently.

[GGTharos]

I don't think missiles should be maneuvering at constant 4g turns during their decelration phase against non-manuevering targets when they are launched with the steering dot in the center of the ase circle, do you? That is precisely what is going on right now.

 

Depends on the missile.

 

4:19:

 

The missile decelerates at a predictable rate and its range and pk would improve greatly if its initial heading on launch already factored that decel into the angle of intercept.

 

For some missiles yes; one way or the other, such guidance improvements are not for now. Flight dynamics are first.

[*Rage*]

Missiles are really low aspect ratio bodies, and most of the body is just a cylinder. They'll have lots of drag when trying to turn.

 

However I sort of agree. They might have a little bit too much drag when maneuvering. What complicates this is flight profile though. Right now active missiles basically suicide when lofting which is severly cutting range, at least against non maneuvering targets. PN causes a similar issue.

 

But that's not what I came here for. I have some potentially good news for MiG-29S pilots

 

EDIT UPDATED CHART

 

 

EDIT UPDATED CHART

 

The 120B seems to be the weak missile in 1.2.3. The R-77 is only slightly worse than the AIM-120C on a non maneuvering target.

 

L[T]_a/v/r = Launch [Target] altitude (ft)/velocity (knots)/range (nm)

 

V_mx is max velocity

V_im is impact velocity

 

Semi actives next. And the SRM's are doing well, though I have no hard data. AIM-9 outranges its seeker now.

 

EDIT

 

Added SARH's

 

Great chart.

 

An AIM7M should not be outranging a 27ER however...

[71st_Mastiff]

The aim9 on the F15C HUD there is no DLZ for the Aim9?

[71st_Mastiff]

All so i see that the aim7 is only 6miles?

[Teknetinium]

Could someone who made some testing tell me what is needed to be fixed at the moment? Have no time to test it all the way. My experience from some bvr tests in 1.2.3 Su-27 vs Su-27 is that red missiles do actually impose threat now compere to 1.2.2. I dont know exactly what is correct or not but this feels much better when the opponent feel threatened.

 

Something that I found strange when I was looking at aim-120 in F6 view is that the missile was wobbling in the air, ERs did not have same behavior.

Edited February 28, 2013 by Teknetinium

[GGTharos]

Right now, AIM-120B and C are way too slow, and C is dead when subsonic. and I suspect R-77 could use some correction for rocket parameters also. The R-27's are tuned to RL data but I will re-check anyway.

 

Could someone who made some testing tell me what is needed to be fixed at the moment? Have no time to test it all the way. My experience from some bvr tests in 1.2.3 Su-27 vs Su-27 is that red missiles do actually impose threat now compere to 1.2.2. I dont know exactly what is correct or not but this feels much better when the opponent feel threatened.

 

Something that I found strange when I was looking at aim-120 in F6 view is that the missile was wobbling in the air, ERs did not have same behavior.

[RIPTIDE]

Great chart.

 

An AIM7M should not be outranging a 27ER however...

Depends on how you look at it though. AIM-7M has a nice end game speed... but R-27ER gets to places faster at the start and middle.

 

https://dl.dropbox.com/u/600721/MissileTAC123.rar

[blkspade]

Something else I've noticed that in 1.2.2 you could crash DCS world by firing an missile straight up and watching it in missile view after it reached beyond 260,-300k feet. I ususally did this with the aim-7 and after trying it in 1.2.3 the missile barely breached 180k', and thus no crash. The launch was only from mach 1, will have to try and get faster and test some more.

[GGTharos]

The R-27ER has a much higher fuel fraction than the AIM-7 has (that I know of, I only know of very old Mk-58 motor configuation, new configuration could have the 7 being a lot scarier ... but I doubt it) so it should stand to reason that the 27ER will go the distance.

 

However, aerodynamics like to complicate things, so if drag is not equal ...

 

Depends on how you look at it though. AIM-7M has a nice end game speed... but R-27ER gets to places faster at the start and middle.

 

https://dl.dropbox.com/u/600721/MissileTAC123.rar

[volk]

MRM all need tuning, though I believe the AIM-7 is doing relatively well ... possibly under-performing in speed a bit still, but we will see...

The R-27's are tuned to RL data but I will re-check anyway.

Динамика AIM-7 и Р-27 в 1.2.3 не сответствуют реальным данным. 68 кг топлива в Р-27Р и 60-61 кг в AIM-7F/M (столько имеют модификации двигателя Hercules MK58 в AIM-7F и модификации MK58-6 и MK58-7) - Р-27 должна лететь дальше.

Это из-за принятых в игре коэффициентов Cx и Cy сейчас AIM-7 летит дальше - у нее меньше сопротивление, и почему-то при этом лучше маневренность, и это должно быть исправлено. Кстати кто-нибудь знает, сколько топлива в AIM-120, чтобы например сравнить энергетику AIM-7 и AIM-120? У меня есть некоторые данные по топливу в 120, может, у кого-то есть еще?

Кстати дымное топливо в AIM-7 более энергоемкое, чем малодымное в AIM-120 - не удивляйтесь, что AIM-7 летит дальше, чем AMRAAM.

[GGTharos]

Fuel amounts are correct, in case of AIM-7 at least it is correct for the old rocket. With this rocket, max aero range is claimed at 50nm+. The thrust profile for the AIM-7 rocket is also exactly as what is in the declassified document for AIM-7F.

 

I don't know about drag coefficients, but AIM-7 has smaller diameter so it could be immediately suspected of being less draggy. As for maneuverability, both are ~25g missiles.

 

Fuel for AIM-120A/B should be about 108lb, for C5 it can be as high at 140lb, but this is all educated guesses from knowing old motor weights.

 

One of the AIM-120 design goals was 'higher average speed than AIM-7'.

 

Also, low-smoke fuel having less energy now appears to be old news, and this fuel can now be very energetic.

Edited February 28, 2013 by GGTharos

[volk]

Fuel amounts are correct, in case of AIM-7 at least it is correct for the old rocket.

Что значит "старая ракета" - это какая модель? Есть какие-то точные данные для "более новых" модификаций? И например модификация MK58-6 и -7 - старые или новые?

I don't know about drag coefficients

если в игре, то Eagle Dynamics\DCS World\Config\Weapons\missiles_data, если в реальной жизни - то навряд ли кто-то знает кроме тех, кто продувал их в аэродинамических трубах :)

but AIM-7 has smaller diameter so it could be immediately suspected of being less draggy.

Да, но в то же время у AIM-7 больше размах крыльев и рулей, у Р-27Р есть дестабилизаторы (больше сопртивления), у Р-27Р больше масса после выгорания топлива - а более тяжелый объект сохраняет энергию дольше (как пули и артиллерийские снаряды). В любом случае сейчас AIM-7 на пассивном участке траектории тормозится ГОРАЗДО МЕДЛЕННЕЕ, чем Р-27Р - это странно.

As for maneuverability, both are ~25g missiles.

Да, но у AIM-7 больше коэффициенты подъемной силы - смотри missiles_data.lua.

Fuel for AIM-120A/B should be about 108lb, for C5 it can be as high at 140lb, but this is all educated guesses from knowing old motor weights.

У меня есть данные - 113 фунтов для WPU-16/B (AIM-120C-5) и 102,6 фунта для WPU-6/B (AIM-120A и вероятно AIM-120B)

http://forums.eagle.ru/showpost.php?p=1687933&postcount=1917

One of the AIM-120 design goals was 'higher average speed than AIM-7'.

При том, что топлива на 14 кг меньше, а топливо - менее энергоемкое? Странно.

Also, low-smoke fuel having less energy now appears to be old news, and this fuel can now be very energetic.

Есть какие-то подтверждения? У меня есть это:

 

 

[GGTharos]

Что значит "старая ракета" - это какая модель? Есть какие-то точные данные для "более новых" модификаций? И например модификация MK58-6 и -7 - старые или новые?

 

The model was not specified. It was for AIM-7F, which received the Mk-58 originally. It could be mod-anything. AIM-7M will be newer.

 

если в игре, то Eagle Dynamics\DCS World\Config\Weapons\missiles_data, если в реальной жизни - то навряд ли кто-то знает кроме тех, кто продувал их в аэродинамических трубах :)

Exactly, this is what I mean. I am afraid to even discuss them :)

 

Да, но в то же время у AIM-7 больше размах крыльев и рулей, у Р-27Р есть дестабилизаторы (больше сопртивления), у Р-27Р больше масса после выгорания топлива - а более тяжелый объект сохраняет энергию дольше (как пули и артиллерийские снаряды). В любом случае сейчас AIM-7 на пассивном участке траектории тормозится ГОРАЗДО МЕДЛЕННЕЕ, чем Р-27Р - это странно.

I agree that there may still be problems.

 

Да, но у AIM-7 больше коэффициенты подъемной силы - смотри missiles_data.lua.

Ok, for this I cannot argue - I just don't know enough at the moment to say it's right or its wrong.

 

У меня есть данные - 113 фунтов для WPU-16/B (AIM-120C-5) и 102,6 фунта для WPU-6/B (AIM-120A и вероятно AIM-120B)

http://forums.eagle.ru/showpost.php?p=1687933&postcount=1917

При том, что топлива на 14 кг меньше, а топливо - менее энергоемкое? Странно.

I did see your post. Which document is this from? This data is supposedly classified. The problem is that I had to work from some academic data - some knowledge about AMRAAM performance (For newer 120 like C5, it has to hit M4 or almost M4 from a 20000' or 25000' launch while lofting, and hit a 30nm target).

 

Unfortunately getting accurate info for AIM-120 is very difficult, I can only work from some public hints and what little official information is out there.

 

The only way I can make this happen is if it has a very high fuel fraction, like R-27ER. This is possible if they are using very expensive/advanced, but still possible technology today to give them a 0.85 rocket motor fuel fraction.

 

To do it with 113lbs requires either fuel that is too energetic for me to believe in, or physics that I do not know about (but they are not necessarily fantasy either). For example, speed of exhaust gas may play a very big role in how much thrust there is.

 

Есть какие-то подтверждения? У меня есть это:

Yes, but realize that this may be out of date. In fact, it appears to be out of date for AIM-7F already, or at minimum, it is necessary to assume that military rockets seem to have higher impulse. Or it is possible that some of the aerodynamics are not correct or perhaps rocket nozzle can make the exchaust reach higher speed and make it appear like the fuel is more energetic. (Think about jet fuel. Burn it in a tank, it goes nowhere. Burn it in a jet engine, it goes at mach 2. Same energy).
Edited February 28, 2013 by GGTharos

[BRooDJeRo]

This is starting to be a very interesting post, almost for 007 eyes only. :D

 

CNN: Al Shabaab developes suitable countermeasures on information gathered from a die-hard edu-sim bulletin board to avoid fightercraft attacks.

Edited February 28, 2013 by BRooDJeRo

[Mandrake5]

This is starting to be a very interesting post, almost for 007 eyes only. :D

 

Care to translate?

[volk]

Which document is this from?

Which document is this from?

http://forums.eagle.ru/showpost.php?p=1620348&postcount=908 ( https://files.myopera.com/SpbGoro/LO_2_Patches/38141871-Hazard-Classification-of-United-States-Military-Explosives-and-Munitions-USA-2009.zip )

 

Прикол :):

 

[GGTharos]

Very good :)

 

So, I had to dig deeper to solve the puzzle, and it turns out that fuel mass * Isp is not enough to determine thrust.

 

You also need to know the parameters of the rocket nozzle. Depending on the shape of the rocket nozzle, and the velocity of the gas, you can achieve a lot more thrust than you would guess by using mass * Isp (you can already see this with AIM-7 rocket. The rocket parameters in the lua file are from the real rocket thrust profile).

 

Unfortunately that part of rocket physics is beyond my knowledge, but I believe it solves a puzzle so that we can get on with the work.

 

Basically, knowing mass of fuel is not longer good enough, you need more information - specifically, to model the rocket engine, you need to know thrust profile. Fuel mass is only important to determine mass of the missile after the fuel is used.

[volk]

Very good :)

 

So, I had to dig deeper to solve the puzzle, and it turns out that fuel mass * Isp is not enough to determine thrust.

 

You also need to know the parameters of the rocket nozzle. Depending on the shape of the rocket nozzle, and the velocity of the gas, you can achieve a lot more thrust than you would guess by using mass * Isp (you can already see this with AIM-7 rocket. The rocket parameters in the lua file are from the real rocket thrust profile).

 

Unfortunately that part of rocket physics is beyond my knowledge, but I believe it solves a puzzle so that we can get on with the work.

 

Basically, knowing mass of fuel is not longer good enough, you need more information - specifically, to model the rocket engine, you need to know thrust profile. Fuel mass is only important to determine mass of the missile after the fuel is used.

Это все слова, общие слова. Все вышесказанное - про форму сопла, скорость истечения газов и пр. - может быть применено в равной степени ко всем ракетам - разумеется если только нет ТОЧНЫХ ДАННЫХ (а не общих слов), что к ракете 1 это может быть применено, а к ракете 2 - не может быть.

Поэтому например при сравнении энергетики AIM-7 и AIM-120 есть ТОЛЬКО 2 факта:

1) масса топлива (больше у AIM-7);

2) энергоемкость топлива - опять же у AIM-7 больше. Все остальное - из области догадок, по крайней мере, не подтверждено ТОЧНЫМИ ЦИФРОВЫМИ ДАННЫМИ.

The rocket parameters in the lua file are from the real rocket thrust profile

По тяге - в значительной степени да (не всегда точные, но очень близкие), а вот коэффициенты сопротивления и подъемной силы - БОЛЬШОЙ ВОПРОС. Вот и Чиж подтвердил это в русской части форума:

http://forums.eagle.ru/showpost.php?p=1688079&postcount=1920

Также есть вопросы по предельным перегрузкам некоторых ракет.

[GGTharos]

Это все слова, общие слова. Все вышесказанное - про форму сопла, скорость истечения газов и пр. - может быть применено в равной степени ко всем ракетам - разумеется если только нет ТОЧНЫХ ДАННЫХ (а не общих слов), что к ракете 1 это может быть применено, а к ракете 2 - не может быть.

Поэтому например при сравнении энергетики AIM-7 и AIM-120 есть ТОЛЬКО 2 факта:

1) масса топлива (больше у AIM-7);

2) энергоемкость топлива - опять же у AIM-7 больше. Все остальное - из области догадок, по крайней мере, не подтверждено ТОЧНЫМИ ЦИФРОВЫМИ ДАННЫМИ.

 

We will not get accurate figures for the design of latest rockets. My point is that AIM-7 rocket already demonstrates more thrust than we suspect it should have based on academic knowledge. From this we can assume the same for all rockets.

It doesn't matter if we do not know details, the point is that it is possible, and that we can create thrust profiles for rockets that are higher than we believed they should be.

 

So you are correct, rocket nozzle etc. can be applied 'equally' to all rockets in some respect, except where accurate data is available. But comparing AIM-7 and AIM-120 motor may also not be very good. AIM-120 motor is in theory more advanced. Low smoke motor technology has also been advancing.

 

По тяге - в значительной степени да (не всегда точные, но очень близкие), а вот коэффициенты сопротивления и подъемной силы - БОЛЬШОЙ ВОПРОС. Вот и Чиж подтвердил это в русской части форума:

http://forums.eagle.ru/showpost.php?p=1688079&postcount=1920

Также есть вопросы по предельным перегрузкам некоторых ракет.

Yes this is fine, I don't know what to do about lift coefficients and drag. I know AIM-120C was given a 'zero lift' coefficient when speed is less than mach 1, but this is wrong :)

Probably, lift coefficient could be a little higher at subsonic speeds than at supersonic speeds.

 

I don't understand the questions about overload. For PN guidance, what matters is the PN constant, K.

 

The missile needs K*target_overload (target g for english speakers) to intercept the target. It appears than in DCSW, K=3.

 

It is possible to also use K=5, but this is not used much in RL because it is too sensitive to noise (not ecm, but small changes in target trajectory)

[volk]

I don't understand the questions about overload.

I mean not overload, but max G-load (probably, bad machine translation) for missiles - for example, 24g for R-27 or 40 for actives. And for some other missiles.