So what's the real performance of AIM-120C

[GGTharos]

In general, I think the AMRAAM has been severely under-estimated by everyone, but I think it's 'slower' than an R-27ER, but just a bit. I've looked at some sources, and aside from not actually known how 'Raero' and 'Rpi' are defined (in terms of missile velosity, for example), the data I get from my various sources seems to short-change the AMRAAM from what it really can do, and that's just for the A version.

[RedTiger]

In general, I think the AMRAAM has been severely under-estimated by everyone, but I think it's 'slower' than an R-27ER, but just a bit. I've looked at some sources, and aside from not actually known how 'Raero' and 'Rpi' are defined (in terms of missile velosity, for example), the data I get from my various sources seems to short-change the AMRAAM from what it really can do, and that's just for the A version.

 

What I don't understand about these discussions, in terms of short-changing the AMRAAM, is why they always seem to settle into the same rut about speed and range. The big thing that I think would draw more discussions are the electronics and ECCM capabilities. YES, I know this is all classified, but so is almost everything else that is discussed, right?

 

Just think of the electronic capability that exists today. Think about how the AMRAAM has had around 10 years of Western electronics evolution and R&D put into it. The possibilities of what that could mean are endless. I don't mean to suggest that its some 100% PK super missile, but it should be very, very, very good at what its designed to do. Like "comparing it to Aim-7s launched in Desert Storm is just plain silly", type of good. ;)

[GGTharos]

Precicely because range is something we at least have data on. We can specilate everything we like about the ECCM capability, but since we don't even know how ECM works ... although it is my understanding that the MiG-29S jammer is tied to SPO-15 for example, which might make that jammer fairly ineffective against an AMRAAM.

 

And comparing it to AIM-7's IS just plain silly ;) It has twice the Pk, that's without ignoring out-of-parameter shots.

[cool_t]

I think we have been through this befor.

 

The game is what it is, we all know about the missiles and jet performances.

 

So why bother again and again and again.

 

DCS should clear things up a bit, I have a feeling that there will be no "Over/Under" modeling.

 

The AIM-120 should have 2/3rds more of the range 2/3rds less drag on the jet (Especilay the semi-recessed ones on the belly of the F-15)

 

Thats why we should have an experiment.

 

1. Some one runs a server for a month with the F-15c that can use ETs and R-77s. This should balence the game out even more.

 

2. We analize the Data and come to a conclution about the R-77 and the ET on the F-15c.

 

3. Then we also can understand the importaince of "Good" piloting when the results come in to a final conclution.

 

4. Or we just get the missiles how they were because we will never know the "Real performance" of the AIM-120C.

[nscode]

although it is my understanding that the MiG-29S jammer is tied to SPO-15 for example, which might make that jammer fairly ineffective against an AMRAAM.

 

yes, there is a link between the jammer and the spo:

 

@ http://aerospace.boopidoo.com/philez/Su-15TM%20PICTURES%20&%20DOCS/Overscan's%20guide%20to%20Russian%20Military%20Avionics.htm

SPS-201 / Gardeniya-1FU / L203 The Mig-29 was always intended to have an internal jammer, but in the event the first production version did not have one. The 9.13 "fatback" MiG-29 was the first MiG-29 to be fitted with such a device, the Gardeniya. Gardeniya can emit high frequency noise, low frequency doppler noise or flashing interference signals around the 3cm waveband. It is effective against CW, quasi-CW and PD radar and covers an area of ±60° azimuth, ±30° elevation. Unit weighs 70-73kg. Links to existing Beryoza RHAWS via L138 communication module. Also fitted to the MiG-29K and M, where it was part of an integrated EW suite including the Pastel RHAWS. Claimed to have similar performance to that of such Western systems as the ALQ-135.

 

But we can't know what that link does. Maybe it's just for the interleaving purposes (with both the RWR and radar.. since RWR is already synced with the radar).

[SwingKid]

Mostly I agree, but on the point of range and max speed I see no real

reason why mach 4 is a problem. Consider a missile being launched from

a fighter flying mach 1.2 at 35.000 ft.

 

One of the problems is that in some official-sounding sources, the AMRAAM speed is given as "Mach 4 above the speed of the launching aircraft," or "Mach 4+". If we assume the mass of missile and propellant is known and the impulse is the same as HTPB (about 250 s IIRC), then even if drag is zero, the missile cannot reach Mach 4 (when fired from rest) by simple F=m*a, and the statement is provably wrong. At that point, you begin to wonder whom you can trust.

 

Another problem is the whole boost-sustain story. You would expect that with this type of flight profile optimized for longer range, the AIM-120 conserves fuel by cruising at a lower speed, so that it doesn't waste energy fighting against higher-than-necessary supersonic drag, and is thus able to fly longer and farther. But the same sources that describe the AIM-120 flying farther than the AIM-7M also invariably claim it flies faster, by far - the AIM-7M speed is only claimed to peak at Mach 3.5, versus the AIM-120's erstwhile "cruise" speed of Mach 4. The claimed ability of the AIM-120 to fly both farther and faster than the AIM-7M, by such huge margins, cannot seem to be explained by known advances in propellant technology. In fact, the AIM-120 propellant impulse seems to have been reduced with respect to AIM-7M, twice, in order to give it (a) a "smokeless" motor and (b) a slower-burning sustain thrust.

[GGTharos]

Specific impulse is higher at higher altitudes, IIRC. However, at least according to minizap,

even if you set drag to about 0.7 (because I claim this takes care of the fact that MZ uses the R-27 drag coefficients, and that missile is much draggier than a 120), and SI to 250 or so (which is the high range for a SPARROW), a launch from mach 1.2 still only takes you to mach 3.8 or so. Launching an ER under the same circumstances takes you just over mach 4. In minizap. But you've said yourself MZ isn't perfect either - and it DOES underestimate the 120's range in at least one case. So, who can you really believe? ;)

 

You also said missiles 'slow down much faster' after 30 sec or so. This implies the missile must travel faster to begin with if it is to match 'known ranges' if it's going to slow down a lot more a tthe end.

[SwingKid]

How useful is it to be talking about supersonic launch speeds for these things anyway? Who fights like that? At launch, you want to minimize your fighter's own closing speed, so to maximize F-pole or A-pole.

[GGTharos]

I heard somewhere that F-15s will happily go to mach 1.3 for their BVR launch, depending on whom they're facing.

[HubMan]

Mostly I agree, but on the point of range and max speed I see no real

reason why mach 4 is a problem. Consider a missile being launched from

a fighter flying mach 1.2 at 35.000 ft. This guy fires slightly upwards,

and under these conditions the missile has to work very hard NOT to

reach mach 4 . At these altitudes the missile would probably even

need to compensate for overspeed close to mach 5 i believe.

 

Before anything more, consider that flying up compared to

a rocket engine is probably a very small problem, that is easily

compensated by the lack of AoA drag, since the missile could fly

a 0g loft path.

 

So let's assume missile is going mach 1.2 on launch,

which is around 1200 km/h at this altitude(even less), alright

so the missile's average net accelleration required to reach mach 4

is ~10 G(assuming burn time as specified to 8 sec). Is this unreasonable?

 

Let's consider this. The amraam most likely has a high G boost stage

(at least I have some ....ehum....sources ^^ of this) and a medium

acc cruise stage. The drag up here isn't a big factor unless you go really

fast. The amraam is surely more aerodynamic than most planes (0 AoA path).

 

Bring here the SR-71, well known mach 3 aircraft. Although this mach 3

was achieved at high altitude, the plane did this with only

0.39-1.0 T/W ratio (source wiki, please correct if wrong). Obviously the

drag reached close to this ~1 G around mach 3.

(-1.5 because of less fuel)

 

If we make some CLEARLY VERY UNFAVORABLE assumptions for the

amraam, we could say it is around the same or double as draggy/w

as the sr-71. K so for the assumption let's say the amraam needs to

push 2-3 G at mach 3. Let's also say we increase drag as a

^4 function of these very supersonic speeds. This incredibly

unfavorable assumption gives a required thrust of 8 G drag at

mach 4. Very high, but clearly not big deal.

 

So once again, making the EXTREMELY unfavorable (from

the amraams point of view) simplification that the amraam

ALWAYS suffers this super-drag during boost and cruise phase.

So what happens? ..... well.....we needed 10 G net accelleration.

with 8G drag that means 18 G mean accelleration. And we are

not even considering that the missile also becomes lighter and

lighter(fuel) and goes through less and less dense air(climbing!)

 

Is 18 G accelleration unlikely for a missile?

I would say no. Even under these almost stupidly

unfavorable assumptions for the amraam, 18 G of thrust

for an a2a missile is not strange. In fact lockon models 33 G constant

and Falcon(OF 4.5) models around 25 G for boost and ~15 for cruise phase of the amraam.

 

So we see that mach 4 is very simple to reach for a small piece like

the amraam. This is how i reason anyway. 4 is just a number, like 3,2 or 1.

The only reason for not reaching mach 4 should be the missile wanting to

save fuel, thus instead increasing burn time. (Structural integrity is not

an issue here, this is a high G a2a missile ^^)

 

Also one other point I find very frustrating about this thread overall

is why everyone find it unlikely that an american made missile could never

reach mach 4 while the russian ones flying mach 4.5 arent a problem.

 

Heck, I'm neither russian or american myself, Im swedish, but R-27 are

performing above official specifications from manufacturers and amraam

is clearly below.

 

I believe GG has some simulation data showing a ballistics test Rmax hit at

60 nm of reasonable amraam data, however here the missile BATTERY

(for maneuvering and course stabilization) becomes a bigger issue. The missile

was still supersonic on impact.

 

That missile was launched from angels 60 and lofted to angels 100.

 

Also I can provide lockon data showing that the amraam (and other missiles)

are as aerodynamic 0 AoA as a flying cow(same terminal velocity)

 

Another point...that is 30nm Aim120A.....we (should) have aim120C-5

maybe this model provides longer range, maybe not.

 

Also there are some f-15 accounts of pilots saying "At less than

60 nm we will already have a missile flying at them"

Hi Yoda :)

 

I agree with you : I don't see too many problems for a real AMRAAM launched at mach 1.4 at 30 000ft to reach mach 4. What I was willing to say is that you have to get quite high and fast to be able to do that : firing an AMRAAM at mach 0.8, 10 000ft will not give the same result. But unfortunatly, going supersonic in Lockon before firing your missile is not modelized. It's as if all the shots are considered taken at the same subsonic speed (remember the way the NEZ is computed ? ;)) As a result, top speed is not what educated guesses could suggest, but overall range seems just under under what it should be.

 

About the 30nm range, I was thinking about AIM-120A/B, not an AIM-120C-5 that should have a far longer reach :)

 

Concerning the 0 AoA, lofting the missile optimally by pointing the nose of your plane at the exact required angle is a good way to have the optimal AoA to start with, but the way the autopilot is optimized is making all the difference, because lofting is also a very good way to reduce the lift the the missile wings must produce, and less lift means... less induced drag. That's the hardest part to modelize, as the software algorithms must be now quite sophisticated and totally top secret :)

 

Another issue is friction and the temperature the missile will have to sustain : it is probably possible to make an A/A missile go mach 6, but I wonder about the kind of materials to use for the tip / leading edges and mostly how to dissipate the heat, as heat is producing thermal noise, always a bad thing for a radar receiver :)

 

Finally, I still wonder is the propellant is not conceived in such a way that it gives longer burn and less peak thrust at high altitude :) Like something burning slower, colder, producing less energy at there is less drag on a longer period :) That's just and idea I got and I may be completely wrong, but I wanted to share :)

 

Thanks for your long post by the way, always good to swap ideas :)

 

Cheers :)

 

 

Hub.

[RedTiger]

How useful is it to be talking about supersonic launch speeds for these things anyway? Who fights like that? At launch, you want to minimize your fighter's own closing speed, so to maximize F-pole or A-pole.

 

Heh, good question, I've often wondered that myself. The fact that launching "high and fast" is the opposite of what you would think you would do to reduce closure and cause look-down problems for the opposing missile or aircraft radar. Going Mach 1+ at 35,000 feet and then slamming on the brakes and cranking doesn't sound unreasonable. Slamming on the brakes, cranking, and then diving down below the bandit (like LOMAC) sounds like you're giving up a rather large advantage, and spending lots of effort going from one extreme to the other. When does the force of gravity on a missile climbing up out-weigh the drag created by going through denser air at lower altitude in a dive?

 

Do F-15 pilots actually do this? Given this altitude and range advantage and the fact that they can launch with a target bugged in TWS, do they ever just press the attack? I've read tons of stuff on how to do BVR in LOMAC and Falcon 4, but I've read very little on how the real guys do it.

[HubMan]

How useful is it to be talking about supersonic launch speeds for these things anyway? Who fights like that? At launch, you want to minimize your fighter's own closing speed, so to maximize F-pole or A-pole.

Hi SwingKid, :)

 

At launch, you want to fire your missile largely above the mach, because, going through the mach costs it's fair amount of energy : a missile is just a sleeker aircraft with short endurance and no way to land by itself :D

The advantage is more than just giving a good initial velocity to the missile : it's saving him all the energy he would have spent otherwise to go through the transonic / mach 1.1 region :)

 

About maximizing the A-Pole, F-Pole, you can always crank and slow down after launch.

 

But and if you are cranking at really high speed fast (provided if you have a good gimball limit / large maximum angle to point your radar antenna) you will have a bit bonus, even though the A/F-Pole will be shorter than if you slow down : the E-Pole of the weapons fired at you will be definitl y smaller too, because you will make the missiles your opponent may have fired correct their course on a -longer- way.

 

Of course, the minimum A/F-Pole is is better larger than the Fox 2 range of your target :D

 

 

I heard somewhere that F-15s will happily go to mach 1.3 for their BVR launch, depending on whom they're facing.

+10000 :)

 

Hub.

[RvEYoda]

Hi Yoda :)

 

I agree with you : I don't see too many problems for a real AMRAAM launched at mach 1.4 at 30 000ft to reach mach 4. What I was willing to say is that you have to get quite high and fast to be able to do that : firing an AMRAAM at mach 0.8, 10 000ft will not give the same result. But unfortunatly, going supersonic in Lockon before firing your missile is not modelized. It's as if all the shots are considered taken at the same subsonic speed (remember the way the NEZ is computed ? ;)) As a result, top speed is not what educated guesses could suggest, but overall range seems just under under what it should be.

 

About the 30nm range, I was thinking about AIM-120A/B, not an AIM-120C-5 that should have a far longer reach :)

 

Concerning the 0 AoA, lofting the missile optimally by pointing the nose of your plane at the exact required angle is a good way to have the optimal AoA to start with, but the way the autopilot is optimized is making all the difference, because lofting is also a very good way to reduce the lift the the missile wings must produce, and less lift means... less induced drag. That's the hardest part to modelize, as the software algorithms must be now quite sophisticated and totally top secret :)

 

Another issue is friction and the temperature the missile will have to sustain : it is probably possible to make an A/A missile go mach 6, but I wonder about the kind of materials to use for the tip / leading edges and mostly how to dissipate the heat, as heat is producing thermal noise, always a bad thing for a radar receiver :)

 

Finally, I still wonder is the propellant is not conceived in such a way that it gives longer burn and less peak thrust at high altitude :) Like something burning slower, colder, producing less energy at there is less drag on a longer period :) That's just and idea I got and I may be completely wrong, but I wanted to share :)

 

Thanks for your long post by the way, always good to swap ideas :)

 

Cheers :)

 

 

Hub.

 

Agreed on all points :).

[HubMan]

Actualy no, fox 2 is not as good as the real thing, be it the sidewinder or AIM-9, for different reasons.

 

For the R-73, no TVC modeled. It overshoots targets when at the extreme off boresight angles.

 

AIM-9 range and speed is basicaly halved in this game. It drops short ridiculously fast, if your target is not goin STRAIGHT at you it will miss 95% of times.

IRL frontal aspect shots are the ones that miss the most. You get a major discrepancy right here.

Hi Pilotasso :)

 

I agree the Thrust control of the R-73 is almost useless, but on the other hand it gives a decent chance in a CAC if you are merging a MiG-29 with a F-15 :)

 

I would say, that low PK with the Fox 2, to the exception of the R-27ET which is largely outperforming, is the best way to end up going in for guns :D And I wouldn't be surprised if it would be voluntary from ED : guns kills are the sweetest :)

 

Cheers :)

 

 

Hub.

 

 

PS : besides AIM-9M were biting very, very easily on russian flares during the first Gulf War :)

[GGTharos]

Okay, think about this, and just this:

 

Why are all the interceptors being build to get *higher* and *faster* than the other guy, and get there sooner than the other guy too?

 

Heh, good question, I've often wondered that myself. The fact that launching "high and fast" is the opposite of what you would think you would do to reduce closure and cause look-down problems for the opposing missile or aircraft radar.

Do F-15 pilots actually do this? Given this altitude and range advantage and the fact that they can launch with a target bugged in TWS, do they ever just press the attack? I've read tons of stuff on how to do BVR in LOMAC and Falcon 4, but I've read very little on how the real guys do it.

[RedTiger]

Okay, think about this, and just this:

 

Why are all the interceptors being build to get *higher* and *faster* than the other guy, and get there sooner than the other guy too?

 

To get into missile firing parameters ASAP...before the other guy can? I'm ok with that. Its the part afterwards that I wonder about. A first hand account of what exactly pilots are doing after they fire that missile is something I've never seen. They tend to gloss over that and talk more about whats going on around them rather than what specific manuevers they're doing. I'm specifically interested to see if they really dump speed and crank and dive below the bandit, seeing as how right before, and I mean right before pickle, they're attempting to do the exact opposite of this.

[GGTharos]

I think I can tell you why we don't get to see this information:

 

1) It's part of BVR tactics, and as such classified

2) It may well be situational. When you're facing MiG-29A's armed with R-27's, your 120's will reach them before they can even do something significant. Why even bother turning away, and degrading your SA. But if you run into say a flanker with R-77's, things might be a BIT different.

 

A specific maneuver is something they brief before the mission - 'this is how we will deal with this type of opponent, we'll launch at this range, we'll crank in this direction (or keep nose on)' etc etc. This is probably why such stuff isn't discussed. Probably.

 

To get into missile firing parameters ASAP...before the other guy can? I'm ok with that. Its the part afterwards that I wonder about. A first hand account of what exactly pilots are doing after they fire that missile is something I've never seen. They tend to gloss over that and talk more about whats going on around them rather than what specific manuevers they're doing. I'm specifically interested to see if they really dump speed and crank and dive below the bandit, seeing as how right before, and I mean right before pickle, they're attempting to do the exact opposite of this.

[SwingKid]

At launch, you want to fire your missile largely above the mach, because, going through the mach costs it's fair amount of energy

 

Do you mean to say that there is less drag at Mach 2, than there is at Mach 1?

 

I think you'll find that's incorrect - it's the drag coefficient that spikes at Mach 1, not the total drag. The energy saving is only if you stay below Mach 1. Which the missile doesn't do.

[Pilotasso]

PS : besides AIM-9M were biting very, very easily on russian flares during the first Gulf War :)

 

They all do IRL and ingame as I would expect. The sidewingder is a flare eater. But in GW I the hot desert was a very good noise factor. Targets are not always aware that a missile is coming though.

[HubMan]

Hi SwingKid :)

 

Do you mean to say that there is less drag at Mach 2, than there is at Mach 1?

No :) As you know, you are usually supposed to get more drag when the speed increases :smilewink: But you will probably get more drag at mach 1 than at mach 1.3 :) (wave drag / shock-induced boundary-layer separation )

 

I think you'll find that's incorrect - it's the drag coefficient that spikes at Mach 1, not the total drag. The energy saving is only if you stay below Mach 1. Which the missile doesn't do.

What I was trying to say, is that firing a missile over the mach, gives you a nice energy bonus, because going through the mach is quite energy consuming for everything that flies.

I shouldn't have mislead you and use in a wrong manner the word "drag" but talk about energy. My bad :)

 

Anyway, the transonic regime is not an 'efficient' one and until you clear mach 1.2, you are in a very specific area where you need more energy to accelerate than in low supersonic.

To my opinion, it's definitly harder to modelize missile cinematic if the weapon is fired at subsonic speed because you need to take in account the transonic part of the flight, which modelization is an extremely tricky one :)

 

And if as you said, flying below mach 1 is less energy consuming than over mach 1, provided you fly high enough and use the good steering algorithm, I'm sure that, going from mach 0.8 to mach 2.8 will cost more energy to a missile than going from mach 1.4 to mach 3.4 :)

 

Cheers :)

 

 

Hub.

 

PS : Congratulations for Minizap, quite an achievement :) And I mean it :yes:

[Merc]

I don't usually get into these kind of arguments, but here's a good source :

 

http://www.ausairpower.net/APA-JSF-Analysis.html

 

This review is independent of USA and Russia.

It also gives a comparison of Western to Warsaw A2A weapons.

 

Now, how can this data be analysed, I'll leave that up to you.

 

I made my own mind about the game : I think the Aim-120C is less energy effective than it should, but obviously more maddogable than it should. The worse drawback of LockOn's western weapons being lack of variety. What works against an Aim-120C will work against another. With the russian payloads you get almost a dozen different missiles with different kinetics for the enemy to deal with.

 

However with a Aim-120C you do get the valuable fire and forget warhead.

 

Baseline :

Know your flaws, know your strengths.

 

Enjoy the choice!

[GGTharos]

Actually, it's a pretty horrible source. Carlo Kopp has an anti-JSF agenda, and for some reason likes to list Russian missiles as having twice the range (or more!) than what they are actually capable of - unless you dropped them from orbit.

 

His projections on IRSTs and passive weapons are also rather optimistic. Really optimistic. To the point of lies, damned lies, etc.

 

I don't usually get into these kind of arguments, but here's a good source :

 

http://www.ausairpower.net/APA-JSF-Analysis.html

 

This review is independent of USA and Russia.

It also gives a comparison of Western to Warsaw A2A weapons.

 

Now, how can this data be analysed, I'll leave that up to you.

 

I made my own mind about the Aim-120C being -slightly- less effective in the game than it should, the worse drawback of LockOn's western weapons being lack of variety. What works against an Aim-120C will work against another. With the russian payloads you got 7 different missiles with different kinetics to deal with. Start shooting Aim-7s and you might get good results.

 

However you do get the valuable fire and forget warhead.

 

Baseline :

Know your flaws, know your strengths.

 

Enjoy the choice!

[Merc]

Change good to interesting then :)

 

About the anti-JSF, he's also pro F-22 and if I remember often compares the F-22 to the F-15.

[GGTharos]

Yeah - he provides some -interesting- analysis, though it is all obviously slanted to -his- goal, and you probably shouldn't trust him a whole lot for numbers. :)

 

YOUR analysis on the LOMAC situation however was more interesting I'd say :)

[Mugatu]

That's not quite true, his agenda is to get the best a/c for australia and on unclass data the JSF looks like it struggles, but that's another story.

 

It looks like the new goverment has decided the JSF + AESA+ Aim-120s + AWAC is very capable combo.

 

ps his numbers are backable by unclassified sources, doesn't just pluck em out of the air. Now those sources may be dodgy :)

 

 

Actually, it's a pretty horrible source. Carlo Kopp has an anti-JSF agenda, and for some reason likes to list Russian missiles as having twice the range (or more!) than what they are actually capable of - unless you dropped them from orbit.

 

His projections on IRSTs and passive weapons are also rather optimistic. Really optimistic. To the point of lies, damned lies, etc.