AIM-7 Performance

[IASGATG]

& if the target has no chaff ?

 

Hey Weta, any thoughts on the missile falling well short on sea level up to 30kft?

[Ironhand]

& if the target has no chaff ?

FWIW, I reran a year old experiment from this thread (R-27ER Experiment & Findings) that used the AIM-7M. My contributions to that thread start at the end of March, if you want to see my methodology.

 

Anyway, the track plays virtually identically in both 1.5.8 and the current 2.5.2 (2.5.2.18307 Update 3). The difference is that 1 of the 30 missiles fired always misses in 2.5.2 from the group that had to wait a bit to be within launch parameters. The AI in 2.5.2 waits a fraction longer to launch and my supposition is that the last one waited long enough that I ended up notching his missile.

 

Anyway, here's a quick video overlaying the 1.5.8 and 2.5.2 tracks. Sorry for the coloration, I don't have time today to experiment with the video editor to do something more pleasing to the eye. Pink is 1.5.8 and blue is 2.5.2. The range is 20km. No chaff is expended.:

 

 

Don't know about you but I'm not seeing any different is AIM-7M flight from that range. This obviously doesn't address concerns about missile range. But, at this range at least, nothing about the missile's flight behavior seems to have changed.

[Ironhand]

The sparrow clearly launches with terminal guidance making stupid movements that follow enemy's micro manouvers. That leads in losing its energy in seconds.

Maybeso. But that wasn't my point and, in this test, there was no change in my direction of flight. Among the concerns voiced in this thread was a concern that something had recently changed in AIM-7M behavior. At least where energy expenditure is concerned, nothing appears to have changed.

[lunaticfringe]

Well get ready to get murdered' date=' because the F-14 never had the AIM-120, it was tested on the F-14, but it was never approved for service, and I don't think that any F-14's other than the one/s that it was tested on were ever modified to fire it...[/quote']

 

All F-14Ds began carrying the compatible firmware in 1997. Squadrons, however, were not allotted the necessary funds for the launch rails, specifically because the AIM-54C maintained a range and energy advantage over the AIM-120C. The community was faced with a choice- either they could increase the LANTIRN buy and diversify their usefulness, or buy the rails and face an uncertain future. It was really a moot decision- by the time the AIM-120C-7 was deployable and able to match the mid-range performance (of the Phoenix), circa-2003, the Tomcat was already set for retirement.

 

If the F-14 would have gone to 2010 or so as originally planned, there would have likely been a renewed push to get the necessary hardware, because the window would have been seven years rather than less than three, and Phoenix was dating out of the inventory. But it was not to be. And Navy got the better end of the deal, with a faster, longer ranged strike platform than the airplane that replaced it for the time that it remained in the inventory.

[Ironhand]

...The issue here is how the sparrow uses the energy.

 

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That's true of all DCS [edit: radar guided] missiles, isn't it? At least the ones I'm familiar with.

 

EDIT: Just ran the same scenario as above with chaff. Results were too similar to claim there was a difference (17 hits vs 18 out of 30 missiles).

 

So nothing apears to have changed in that regard either. It's the same AIM-7M it's been for awhile. So for those in those who find that they can't hit anything with this missile--the post that started this thread and others in this thread--the missile hasn't changed. If you suddenly can't hit anything with it and you're using the F/A-18 as the launch platform, then that's the place to look for the problem.

 

How the missile's tracking is modeled is yet another and separate issue.

Edited June 11, 2018 by Ironhand

[GGTharos]

It's true of all DCS missiles. Everything is terminal.

 

IMO no, the sparrow now goes into terminal guidance immediately after launch, which causes the missile to react to micro movements of the enemy at 20nm losing all energy.

[Ironhand]

Well, I have the release version and the sparrow doesnt react like a girl after launch but once it is very close.

 

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:) Then perhaps you need to do a repair on your release version... :) Seriously, I don't recall seeing DCS SARH missiles behaving in any way other way.

[GGTharos]

Without looking at what you're looking I can't tell why you think you're seeing something different from what is there :)

 

DCS AAM guidance has always been terminal all way. Even if say, lift parameters are changed in such a way that the missile cannot kill its speed, it's still terminal all the way.

 

The entire idea behind guidance updates is to hopefully create a more complex guidance box - including the ability to alter particular parameters of the guidance (for example, sparrow alters the navigation constant, among other things). Bonus points for being able to actually select from multiple algorithms, and extra bonus for being able to run separate algorithms based on nav channel (vertical vs horizontal for example).

 

Well, I have the release version and the sparrow doesnt react like a girl after launch but once it is very close.

 

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[TLTeo]

That's true of all DCS [edit: radar guided] missiles, isn't it? At least the ones I'm familiar with.

 

EDIT: Just ran the same scenario as above with chaff. Results were too similar to claim there was a difference (17 hits vs 18 out of 30 missiles).

 

So nothing apears to have changed in that regard either. It's the same AIM-7M it's been for awhile. So for those in those who find that they can't hit anything with this missile--the post that started this thread and others in this thread--the missile hasn't changed. If you suddenly can't hit anything with it and you're using the F/A-18 as the launch platform, then that's the place to look for the problem.

 

How the missile's tracking is modeled is yet another and separate issue.

 

 

Honestly this seems fairly straightforward when you put it this way - given the differences in performance of the two planes, the Eagle will systematically launch its Sparrows with (a lot) more energy than the Hornet which a) allows them to do more stupid stuff and still connect and/or b) makes them to approach the target faster, thus reducing the amount of time they are exposed to chaff.

[JorgeIII]

Excellent post with hard data. There is no doubt now with real unclassified data vs inside DCS testing. Should be more than enough to make at least this missile range closer to real life.

 

I dont know if ED has to increase engine power / burning time or decrease drag but we now have a real life document to compare the final result they will bring to us.

 

 

 

 

 

Okay lets make this test as clear and simple as possible.

 

AIM-7F/M, at 30kft, at M1.2, vs 30kft M1.2, has an RAero of approximately 30nmi. For this to be considered successful RAero intercept, the missile needs to hit the target within 70seconds, and with a Mach number of approximately 1.2 to have the energy necessary to make an intercept turn.

 

 

Here we see the setup, slightly under 30nmi, with the launcher slightly under M1.2 (1.15).

 

 

On impact, the missile made the intercept within the 70 second timer (61 seconds), but was too slow (Mach 0.79)

 

 

Rewinding the track, we see that at the intercept velocity of M1.2, the target is still 5.8nmi from the target.

 

Overall this means that the FM is not representing the RAero performance.

[*Rage*]

Arent these the same issues we've always had with SARH missiles?

 

Another factor is the F18 radar. To put it mildly its a bit special in its current state:) Still its EA so plenty more to come.

[GGTharos]

This isn't a SARH missile issue. This is an all missile issue. As time goes on, some times we get more data on the flight dynamics. But this comes along rarely.

[MiG21bisFishbedL]

If the F-14 can't carry AIM-120B at least if not the C, I'm not buying it. There's no reason to spend that much to be that handicapped against murderous Flankers in multiplayer servers.

 

 

Isn't that kind of the point of a simulation? To deal with handicaps and limitations that we'd realistically encounter? Also, try dodging AIM-54s. They're a lot harder to jink than R-77s.

[OnlyforDCS]

I've been reading variations of the subject of this thread for years now on these forums. I wouldn't hold my breath on things changing anytime soon, or at all.

 

Let's hope Im completely wrong about this, but you know what they say about hope right? ;)

[OnlyforDCS]

Yeah I just said I'm gonna pass so no gettin murdered.

 

I can't be bothered to look for the post, but Heatblur commented on the problematics of missile kinematics in DCS and how they are handling it with regards to the AIM54.

 

It boils down to G limits. They are artificially lowering the G limit on the AIM54 so that it retains some of its legendary reach. It will definitely not be as potent as its real-life counterpart but it was the only way they could get partly past the "terminal guidance off the rail" issues that all missiles share in DCS.

 

Not exactly a fix, more like a band-aid, but better than nothing.

[PeaceSells]

I can't be bothered to look for the post, but Heatblur commented on the problematics of missile kinematics in DCS and how they are handling it with regards to the AIM54.

 

It boils down to G limits. They are artificially lowering the G limit on the AIM54 so that it retains some of its legendary reach. It will definitely not be as potent as its real-life counterpart but it was the only way they could get partly past the "terminal guidance off the rail" issues that all missiles share in DCS.

 

Not exactly a fix, more like a band-aid, but better than nothing.

 

So they are making the high fidelity module and they can't adjust the missile's guidance algorithm itself? I wonder about the level of 'fidelity' that will come out of this.

[Tango777]

As of the update yesterday:

 

When I select the Sparrow, I can have any enemy aircraft 10 nm in front of me, positioned in the middle of my hud, and the radar in the F-18 will not detect the enemy aircraft. BUT when I select the gun or the Sidewinder, the radar begins to work properly.

 

So I narrowed the radar's horizontal movement to 40 degrees, at 10 nm range, middle of my hud, and with the Sparrow selected the radar is blank.

 

However when I leave the radar range at the "default" 40 nm range, the radar picks up every piece of metal in the sky. So I move the TDC to an echo that is about 20 nm directly in front of me on the radar, and I literally mean the target on the radar is at my 12 o'clock. I select that echo (target), then look up in my hud and the aircraft on the hud is to my 10 o'clock.

 

How is this possible?

 

Before yesterday's update I could easily lock onto an airborne target.

[antagonist]

I can't be bothered to look for the post, but Heatblur commented on the problematics of missile kinematics in DCS and how they are handling it with regards to the AIM54.

 

It boils down to G limits. They are artificially lowering the G limit on the AIM54 so that it retains some of its legendary reach. It will definitely not be as potent as its real-life counterpart but it was the only way they could get partly past the "terminal guidance off the rail" issues that all missiles share in DCS.

 

Not exactly a fix, more like a band-aid, but better than nothing.

 

I'm actually surprised DCS doesn't support an initial inertial targeting phase for its missiles.

[Chizh]

DCS missiles have inertial phase and have radio correction.

[GGTharos]

No, it isn't. Everything is true.

 

Also, sparrows shouldn't have interial or radio-correction until 7P. 'Terminal guidance' has a very specific meaning which has nothing to do with having/not having the other two.

 

So all of what has been said here is wrong? I see now why the sparrow got so many complaints in this thread. It is actually only doing the terminal guidance off the rail.

[ouPhrontis]

Is there consistency then with ordinance, such that an AIM-9L (or whichever) for one module is the same for the others, like a global armoury if you will?

[GGTharos]

Indeed there is.

 

Is there consistency then with ordinance, such that an AIM-9L (or whichever) for one module is the same for the others, like a global armoury if you will?

[*Rage*]

Is there?

 

Didn't Razbam make their own missiles? Aren't Heatblur making their own? Both are different to EDs implementations. I'm not arguing for one side or another. Just the lack of consistency as it appears to me.

[nighthawk2174]

Is there?

 

Didn't Razbam make their own missiles? Aren't Heatblur making their own? Both are different to EDs implementations. I'm not arguing for one side or another. Just the lack of consistency as it appears to me.

 

Heatblur are making a custom cfd model for their Phoenix but beyond that I don't think so

[IASGATG]

Is there?

 

Didn't Razbam make their own missiles? Aren't Heatblur making their own? Both are different to EDs implementations. I'm not arguing for one side or another. Just the lack of consistency as it appears to me.

 

In the code you can set physical missile characteristics, like weight, thrust, burn time, drag curves etc. What you can't change is the guidance laws the missile follows.

 

This means that third parties can make missiles that fly in a straight line quite closely to how they should, but they cannot stop the missiles from bleeding energy from constant little turns.

 

The bigger problem for the AIM-7 is that at low levels, it has about half the straight line range it should. This is a relatively quick and easy fix, where as the guidance requires a code overhaul.