AIM-7 Aerodynamics

I'm curious what the general consensus is regarding the updated Sparrow. Do people think it's now authentic, still has a way to go, or maybe even better than it should be? I'm talking specifically about aerodynamics, not sensor.

In my opinion it still seems to bleed off too much speed by overcorrecting to ever little move the target makes. I'm pretty sure the actual missile mitigates these corrections until much closer to the target in order to retain airspeed.

Thats probably more related to guidance than aerodynamics.

True that.

I think they have corrected aerodynamics. In that regard Raero seems to be greater now (at least from a naked eye not tested perception). On the other hand the guidance still cause huge corrections that doesn't seem necessary sometimes.

I don't think the planned guidance updates made it into the new OB patch - it wasn't on the changelog (even after they corrected it to put missed items in) and the missiles seem to act just as they did before the patch.

I feel that AIM-7 still has too much resistance due to its speed.

Not Official but this guy knows his stuff:

AIM-7 Family

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AIM-7M

• Now has the new APN guidance laws code implimented
  
• Now has the new AIM-7H FM, although has a much higher Cl value so will be able to pull more g at lower speeds. Will ask why
  
• Has a very shallow loft code implemented. Will start at targets greater than 6km, will terminate when target is within 5km. Angle of 0.1 radians to the horizon. I don't know how much you'll even really notice this or how much of an impact something this shallow will have on range
  

​AIM-7H - No change, did not get the new PN laws, has the same Cl value it had previously.

​

AIM-9 Family

All apart from the 9X - No Change

AIM-9X

• Counter Measure Susceptibility reduced from 0.3 to 0.2 - Seeker head view angle increased to 1.1 (I can't remember what it was before)- New APN guidance law code implemented - (Still waiting on revised FM code)
  
• ​ Changed how the thrust vectoring variable works. Used to be a binary on/off (more or less). Is now a specific additional g loading - Set to 10.
  

​AMRAAM Family

AIM-120B - Now has the new APN guidance laws code implemented

​AIM-120C - Now has the new APN guidance laws code implemented

​

R-27 Alamo Family No Change

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R-73 - Changed how the thrust vectoring variable works. Used to be a binary on/off (more or less). Is now a specific additional g loading - Set to 5.

​

R-77 - No Change

Well...whatever you ascribe it to, there is a difference between the pre-update and post-update AIM-7M missile. This is the result of a track recorded with the pre-update (the missile chasing me) and replayed post-update. Booster burn time is from launch to 04:00:25 :

OLD:

CURRENT:

Not Official but this guy knows his stuff:

https://www.reddit.com/r/hoggit/comm...ssile_changes/

Here's some general background info on the matter (same guy as in your reddit link). The APN (augmented proportional navigation) issue, which is now beeing addressed by ED with the recent updates, is discussed somewhere in there:

Well...whatever you ascribe it to, there is a difference between the pre-update and post-update AIM-7M missile. This is the result of a track recorded with the pre-update (the missile chasing me) and replayed post-update. Booster burn time is from launch to 04:00:25 :

 

OLD:

 

 

 

CURRENT:

 

So, the top speed of AIM-7 is decreased....:(

I think the top speed of real AIM-7 should be faster than AIM-7 ingame.

Based on what?

I don't have any definitive sources, but a quick Google has the 7M labelled as a Mach 4 top speed missile which would suggest it'd go up to nearly 5,000kph rather than just 2,500kph. But I'm sure someone cleverer and more informed than me will explain why that's not the case.

Mach 4 top speed, but in the launch conditions presented in this thread (~Mach 1 at 8000m/26250 ft) would it be expected that the missile would reach this mach number?

Maximum aircraft launching speed is listed by DoD documents as Mach 2.5. The max range calculation example in said document has launching conditions of Mach 2.0 at like 50,000 ft.

I suspect that it only reaches Mach 4 in optimum conditions, and at sub-optimal conditions the missile's top speed will be sub-optimal as well.

I don't have any definitive sources, but a quick Google has the 7M labelled as a Mach 4 top speed missile which would suggest it'd go up to nearly 5,000kph rather than just 2,500kph. But I'm sure someone cleverer and more informed than me will explain why that's not the case.

"Quick google searches" are not even worth bringing up in conversations like this. You have to have access to information that sometimes isn't easy to get or even understand.

http://www.alternatewars.com/SAC/AIM-7F_Sparrow_CS_-_January_1976.pdf

This pdf reading the speed should reach Mach 2.9... although it has no such specific as we needed.

The current AIM-7 FM matches very closely to known reliable data. The in game AIM-7 can exceed Mach 4 when fired in the right conditions. Nothing to see here.

How do the APN AIM120 versions compare to the old?

The current AIM-7 FM matches very closely to known reliable data. The in game AIM-7 can exceed Mach 4 when fired in the right conditions. Nothing to see here.

This is great news.

The current AIM-7 FM matches very closely to known reliable data. The in game AIM-7 can exceed Mach 4 when fired in the right conditions. Nothing to see here.

Good to know, thanks!

So, the top speed of AIM-7 is decreased....:(

But look at the acceleration, it's much less when the motor cuts out.

I really want to test these new missiles. This was a big change that DCS needed.

How do the APN AIM120 versions compare to the old?

Quite a bit better. I think there is a bug which I've asked about which undoes some of the good work, but I've found that for a 10kft alt engagement, it adds about 0.5-0.75M worth of energy to the missile. The bug I think I found is where at 8km, the missile suddenly switches to 100% PN which if I understand the code correctly, it shouldn't. This means when it hits 8km it suddenly goes from gentle 1.5g turns to 10-15g turns which dumps a ton of energy. We'll see if this is a bug or is as intended though.

I'm curious what the general consensus is regarding the updated Sparrow. Do people think it's now authentic, still has a way to go, or maybe even better than it should be? I'm talking specifically about aerodynamics, not sensor.

 

 

In my opinion it still seems to bleed off too much speed by overcorrecting to ever little move the target makes. I'm pretty sure the actual missile mitigates these corrections until much closer to the target in order to retain airspeed.

The general consensus is that as long as you're firing them within the recommended range limits, especially Rne, the most authentic missile behavior is the one that gets you the most kills :)

Realistically, no-one here really has a clue how the real missiles behave, and I seriously doubt even the folks at ED really know as much about them as there is to know. As far as firing actual missiles at live-human-piloted adversaries goes, I doubt there are many real-life fighter pilots that have much experience with that! Yes, it happens, and no, it doesn't happen all the time every day--and even if it was, the details would be unavailable to anyone but other fighter pilots, and missile manufacturers.

That leaves official manufacturer's documentation to give ED most of the general parameters they need to model the missiles as realistically as possible. Oh yeah, little problem here--it's all classified.

So, it's down to educated guesses based on general info like missile size, shape and weight, rocket engine burn time and thrust profile, guidance system expectations, and guesses about seeker behavior--all based on general knowledge about how it "could" be done, and of course a lot of anecdotes. Guided missiles of any variety are complex, very expensive devices and the gory details of how the radar, seeker, flight control system and guidance algorithms all work and behave in actual use are classified. That means, the kind folks who've given the world these technological marvels might be willing to tell you a few things about how they actually behave in real life--but first, they'd ask you for permission to kill you after telling you. :D

What we get is a rather insightful, artist's representation of how these missiles perform. It might be insightful, but it's still based on educated guesses--some more educated than others, and all guesses nonetheless.

If you want a really good, realistic representation of how air-to-air weapons really behave in a consumer sim designed primarily for entertainment, you'll just have to go Gunzo, and that's all there is to it :)

Peace and happy warfare

AD

The general consensus is that as long as you're firing them within the recommended range limits, especially Rne, the most authentic missile behavior is the one that gets you the most kills :)

 

 

Realistically, no-one here really has a clue how the real missiles behave, and I seriously doubt even the folks at ED really know as much about them as there is to know. As far as firing actual missiles at live-human-piloted adversaries goes, I doubt there are many real-life fighter pilots that have much experience with that! Yes, it happens, and no, it doesn't happen all the time every day--and even if it was, the details would be unavailable to anyone but other fighter pilots, and missile manufacturers.

 

 

That leaves official manufacturer's documentation to give ED most of the general parameters they need to model the missiles as realistically as possible. Oh yeah, little problem here--it's all classified.

 

 

So, it's down to educated guesses based on general info like missile size, shape and weight, rocket engine burn time and thrust profile, guidance system expectations, and guesses about seeker behavior--all based on general knowledge about how it "could" be done, and of course a lot of anecdotes. Guided missiles of any variety are complex, very expensive devices and the gory details of how the radar, seeker, flight control system and guidance algorithms all work and behave in actual use are classified. That means, the kind folks who've given the world these technological marvels might be willing to tell you a few things about how they actually behave in real life--but first, they'd ask you for permission to kill you after telling you. :D

 

What we get is a rather insightful, artist's representation of how these missiles perform. It might be insightful, but it's still based on educated guesses--some more educated than others, and all guesses nonetheless.

 

If you want a really good, realistic representation of how air-to-air weapons really behave in a consumer sim designed primarily for entertainment, you'll just have to go Gunzo, and that's all there is to it :)

 

 

Peace and happy warfare

AD

I don't feel that you're doing justice to how accurately modeled missiles can be. There will always be an element of assumptions made even when you have models in a wind tunnel. This doesn't mean you cannot generate a reliable predictive model for how something should behave.

The stuff that is classified, which cannot be independently and accurately assumed, is stuff that doesn't really matter since DCS doesn't/can't really simulate it.

If you look at the AIM-9M modeled in DCS. There are publicly available documents that list it's Cd, Cl, Cm, Xcp, Thrust, Structural Limits, etc etc. This gives you all the information you will ever need to make an accurate and realistic simulation of how it performs.

Likewise, having spoken to people at ED, I know they have reliable data for the Sparrow as well. Similar techniques that can be applied to any missile, given the time and money. None of this is breaking any secrets acts or IP law. It's just physics. Saying that they are taking artistic licence with it is like saying that the cockpit isn't realistic and they are just taking artistic licence with that too.

The current AIM-7 FM matches very closely to known reliable data. The in game AIM-7 can exceed Mach 4 when fired in the right conditions. Nothing to see here.

I tested AIM-7M at M2.1 60000ft (target is same speed and altitude) but according to tacview AIM-7 stack around M3.9 and never exceed M4.

In what conditions can AIM-7 exceed M4?

I tested AIM-7M at M2.1 60000ft (target is same speed and altitude) but according to tacview AIM-7 stack around M3.9 and never exceed M4.

In what conditions can AIM-7 exceed M4?

You are right. In testing at 40kft at Mach 2 it hit high M3 so I assumed it'd break M4. Nevertheless, the Cd curves match wind tunnel data and the fly out performance is very close to known DLZ and range criteria so I'm confident in its modeling.