fixed internally Aim9B/GAR-8 should not uncage like it currently does

[Harlikwin]

The Gar8/aim-9B is bugged with regard to its uncage-lock/pre-firing behavior.

Currently, you put the gun piper on the target until you get “tone” (~4 deg IFOV). Which automatically “locks” the target, and “uncages” the seeker head, and you can freely maneuver within the seeker gimbal limits (~25 deg).

While this behavior or variations thereof may be found on later models of the aim-9 its not correct for the 9B since its seeker only uncages (locks) the target after being fired. Correct behavior would look like maneuver till you get tone on target. Then fire, and the firing process takes ~1 sec from depressing trigger to missile leaving the rail. The seeker gyro is uncaged with the firing command, never before. If the target maneuvers out of the 4 degree seeker FOV during this time you loose lock.

Early versions of the sidewinder used a mechanical cage mechanism as described below. Later 9B versions used a magnetic cage mechanism which still mostly operated in similar fashion.

Pg 71

Pg 115 sidewinder

Magnetic caging and firing sequence, and 9B firing sequence from OP 2309 (3rd) page 2-2AIM-9B (https://archive.org/details/OP23093rdAIM9B) Declassed pre-1980.

As stated above, only AFTER firing does the gyro uncage. 

And finally the first sidewinder to have uncage capability was the aim9E as mentioned in the Project CHECO report from Vietnam (pg10-11). https://apps.dtic.mil/sti/citations/ADA486826
 

[2alpha-down0]

This is also supported by the documentation provided for this bug that was fixed a few months ago.

 

[Harlikwin]

52 minutes ago, 2alpha-down0 said:

This is also supported by the documentation provided for this bug that was fixed a few months ago.

 

Yeah thanks for that. Also good thread for the other issues as well.

 

[PinkCube]

Thank you for posting about this problem. It has been nearly one year since you highlighted this issue and nothing has been done. I believe this is also an issue with other ED modules that carry the 9B such as the F5.

With the introduction of the Mirage F1 and its new and more realistic launch characteristics with the 9B, this problem became even more so highlighted with other modules. It is my belief that this is partly what also lead to RAZBAM removing the auto-uncage of the R-3S (historically a very similar missile) on the mig-19 and changing other launch sequences such as the time it takes to leave the rail.

I am bumping this topic simply because although here; on the forum, it doesn't "seem" much of an issue and I hope it gets more attention. Among the cold war multiplayer player base, it's very common that "little" issues like this tend to elevate our disdain for the game and gives us the feeling that these modules have been abandoned.

Edited August 19, 2023 by PinkCube

[Flappie]

This was reported internally a while ago following @Harlikwin 's post. I'll ask for the Reported tag and bump the internal report.

[[MVP] Mugga]

Thank you @Flappie

[Flappie]

On 8/22/2022 at 5:39 PM, 2alpha-down0 said:

This is also supported by the documentation provided for this bug that was fixed a few months ago.

 

Where does this image come from?

The other document states the gyro is uncaged right after missile release ( OP 2309 (3rd) page 2-2AIM-9B ), which contradicts the "Gyro optics uncage" happening at 0.8 seconds before missile launch.

Quote

At firing, the caging coil and motor drive coils are disconnected; the gyro is then free to precess to its limits in any direction necessary to track the target.

I'm asking because if the gyro uncaged at -0.8, that would mean the pilot is able to uncage without releasing the missile.

Edited April 26 by Flappie

[Harlikwin]

On 4/26/2024 at 10:15 AM, Flappie said:

Where does this image come from?

The other document states the gyro is uncaged right after missile release ( OP 2309 (3rd) page 2-2AIM-9B ), which contradicts the "Gyro optics uncage" happening at 0.8 seconds before missile launch.

I'm asking because if the gyro uncaged at -0.8, that would mean the pilot is able to uncage without releasing the missile.

 

No it doesn't. Look at the firing sequence  once the gas generator is lit (literally step1) the missile is committed. Yes it can mess up and you can get a hung store etc, but once the gas gen is lit either the missile continues down the sequence and fires or if there is an error it dies on the rail. The gas generator only runs once since its pyrotechnic (fancy black powder if you want to think of it like that). So no, there is no "uncage" in practice. You don't "ulight" a burning pyrotechnic charge which is what the gas generator is.  Gas generator runs the fin actuators and the turbo alternator which provides power to the seeker once it leaves the jet. 

So how it should work for the 9B specifically.

You have tone (and you guys should model the seeker null too) (ref Mirage F1 that does it right)

You push and hold down the firing button.

Electrical impulse ignites the gas generator, which gets the pyrotechnics burning. 

9B uncages the gyro to track the target for the 1sec or so before launch. 

It takes time for the gas gen to generate enough pressure to run the turbo alternator/fins (at .4sec) 

Then once the turbo alternator is producing enough voltage the firing relay closes taking the missile OFF the jet electrical and onto the turboalternator. (Also the firing button has to be depressed for this to happen, otherwise you get a hung store with the gas generator fizzling on your wing for 21 seconds) And the motor lights. 

Then Mr Missile goes on his happy way.

The seeker uncages immediately because its difficult to keep a good track with the missile, and after it uncages you don't have to cuz mr missile will do it for you (in theory). You should also loose tone once it does this because it will be in the seeker null.

Later sidewinder versions worked a bit differently ofc and you could uncage/recage the 9E for example (At the risk of damaging the seeker, not like you guys would model that tho). And then the later navy winders with SEAM compatibility starting with the 9G

 

Edited April 27 by Harlikwin

[Flappie]

Thanks @Harlikwin.

I realize what you describe (once the scrub ignites the "powder", the missile WILL depart, unless it is faulty) does not happen in DCS.

What happens: the AIM-9B missile departs exactly 0.8 s after the button was pressed. Yet, if you release the button before this delay, the missile won't depart: the launch can be aborted. And the missile can be fired later on, as if the gas generator had not been ignited.

I now have another question: did the F-5E missile launch button had a safety delay or was the launch initiated as soon as the button was pressed? I couldn't find the answer in the real aircraft manual.

What I read in the manual is this:

Quote

Assuming all of foregoing flight conditions are met, the pilot will fire the missile, keeping the firing button depressed until the missile leaves the aircraft.
On missile firing, the following sequence of events occurs:

Initial impulse fires the squib of the servo grain only. As the servo grain burns, gas pressure is built up and it distributed through a manifold to the turbogenerator and to the servo pistons within the drive cylinders.

When the turboalternator is rotating with sufficient velocity to generate enough power to operate the missile on internal supply, a relay in the launcher power supply is closed, and 28 volts of aircraft power is supplied through the relay to the two firing pins of the launcher. The time to effect this is 0.8 second, maximum.

If the sequence is interrupted before the relay is closed, the servo grain will continue burning, but motor firing will not occur and the missile will not leave the launcher. Continued burning of the servo grain on the aircraft does not cause any safety in-flight hazard.

If the sequence described is uninterrupted, the firing power is delivered simultaneously to the firing squib of the rocket motor and to the thermal battery of the influence fuze. The missile will then leave the launcher.

Does it mean there was a safety delay, which would explain why the pilot had to press then hold the button?

Or does it mean that the pilot would screw up the launch sequence -and thus screw up the missile- if he let go of the button before T0?

Edited April 27 by Flappie

[Harlikwin]

3 hours ago, Flappie said:

Thanks @Harlikwin.

I realize what you describe (once the scrub ignites the "powder", the missile WILL depart, unless it is faulty) does not happen in DCS.

What happens: the AIM-9B missile departs exactly 0.8 s after the button was pressed. Yet, if you release the button before this delay, the missile won't depart: the launch can be aborted. And the missile can be fired later on, as if the gas generator had not been ignited.

I now have another question: did the F-5E missile launch button had a safety delay or was the launch initiated as soon as the button was pressed? I couldn't find the answer in the real aircraft manual.

What I read in the manual is this:

Does it mean there was a safety delay, which would explain why the pilot had to press then hold the button?

Or does it mean that the pilot would screw up the launch sequence -and thus screw up the missile- if he let go of the button before T0?

 

#1 Thats  not what happens IRL. IDK in DCS, if you can try to re-fire it in DCS thats wrong too. Once the gas generator is initiated thats it, its a one  time event. You can't stop the the gas generator from burning. 

#2 AFAIK thats what happens if you don't hold the button down long enough missile stays on the rail but its basically dead, while the gas generator burns for the full 21 seconds (or whatever time it is). (bonus sparky smokey missile effect if you want to be accurate)

As for your earlier question, yeah it looks like in OP 2309 (1966) (navy) it does in fact say the gyro uncages at launch. I "think" that chart posted above is from the F-8 crusader manual. It might be a later or earlier manual or maybe a navy F4 manual. And a later version of the 9B. 

It might have been changed at some point as there are a few revisions of the 9B (as noted in OP2309  but it  only goes to 66), the earliest of them actually had a mechanical cage system that would would only uncage on firing. That was later changed to an electromagnetic system. 

So if you want to be "correct" for the F86 and a GAR-8 and make players lives sad, yeah uncage it only on departing the rail. Or add a second version that uncages immediately (probably what was used for most of the VN war, and on your late model F5E) It also couldn't uncage on the 5E (yes I know what the manual says but it seems to be a copy pasta from a 9E/J/P description which all could uncage).  Given that the 9E entered service in like 68 and was mostly rebuilt/improved 9B GCS it makes little sense that the AF would have further improved the 9B between 66 and 68. 

Edited April 28 by Harlikwin

[Flappie]

28 minutes ago, Harlikwin said:

Once the gas generator is initiated thats it, its a one  time event. You can't stop the the gas generator from burning.

That's what I understand too when reading available doc.

28 minutes ago, Harlikwin said:

#2 AFAIK thats what happens if you don't hold the button down long enough missile stays on the rail but its basically dead, while the gas generator burns for the full 21 seconds (or whatever time it is).

We need a good source for this, because it would be a big change. If I'm not mistaken, dead missiles on the rail don't exist (yet) in DCS.

28 minutes ago, Harlikwin said:

As for your earlier question, yeah it looks like in OP 2309 (1966) (navy) it does in fact say the gyro uncages at launch. I "think" that chart posted above is from the F-8 crusader manual. It might be a later or earlier manual or maybe a navy F4 manual.

I'll see if I can find it.

It sounds logical that the gyro would uncage immediately though, for better chances to hit a target that is about to get out of the detection cone.

EDIT: Yes, I've read about the initial uncaging system. And I don't want to make players lives sad. Dilemma... I'd say having the more recent uncaging system and a fix for the issue described in OP would be a good step forward.

Edited April 28 by Flappie

[Harlikwin]

45 minutes ago, Flappie said:

That's what I understand too when reading available doc.

We need a good source for this, because it would be a big change. If I'm not mistaken, dead missiles on the rail don't exist (yet) in DCS.

I'll see if I can find it.

It sounds logical that the gyro would uncage immediately though, for better chances to hit a target that is about to get out of the detection cone.

EDIT: Yes, I've read about the initial uncaging system. And I don't want to make players lives sad. Dilemma... I'd say having the more recent uncaging system and a fix for the issue described in OP would be a good step forward.

 

#1 Its in OP 2309, 2-1, 2nd part of the below. It  will apply to pretty much all sidewinders, since they all use gas generators (well, later ones use a gas gen AND a battery but I'm pretty sure the firing seq is similar enough in that regard). Should also be the same for soviet R3S, R13M and Chinese sidewinder copies, Pl2/5 etc. 
#2 yeah its fine if it did it, but if you wanted a gar8 as a separate thing from the 9B that would be an easy way to differentiate it and give the F86 both.
null

Edited April 28 by Harlikwin

[Flappie]

Yes, I've read this part a few times already and I wonder whether the 28 volts are conditioned by the maintained press on the Weapon release button or not.

When they write "if the sequence is interrupted", I read it as a vague "if anything goes wrong". They don't explicitly write "if the pilot does not hold the button long enough".

They clearly state that the pilot must hold the button until missile release, yes. Is that a simple precaution or an absolute condition for the launch sequence to not fail? That's what I find unclear.

[Harlikwin]

10 hours ago, Flappie said:

Yes, I've read this part a few times already and I wonder whether the 28 volts are conditioned by the maintained press on the Weapon release button or not.

When they write "if the sequence is interrupted", I read it as a vague "if anything goes wrong". They don't explicitly write "if the pilot does not hold the button long enough".

They clearly state that the pilot must hold the button until missile release, yes. Is that a simple precaution or an absolute condition for the launch sequence to not fail? That's what I find unclear.

I'm going of really old memory here, but I think the button needs to stay depressed or the relay wont flip when its ready. I forget where I saw that circuit diagram tho, it was a long time ago.

Honestly I care way more about getting the lock/uncage behavior right than getting this 100%. 

[Smyth]

12 hours ago, Flappie said:

Yes, I've read this part a few times already and I wonder whether the 28 volts are conditioned by the maintained press on the Weapon release button or not.

When they write "if the sequence is interrupted", I read it as a vague "if anything goes wrong". They don't explicitly write "if the pilot does not hold the button long enough".

They clearly state that the pilot must hold the button until missile release, yes. Is that a simple precaution or an absolute condition for the launch sequence to not fail? That's what I find unclear.

The one place I've seen where this is specifically called out is the Danish Draken manual. I'm not sure if I should post screenshots since other parts of the manual are post-1980, but it's easy enough to find online (check page 4-93). It says that if pilot does not hold down the button, firing sequence is interrupted, with consequences listed above.

Of course it's not clear if this changes on different aircraft with potentially different launcher wiring.

21 hours ago, Harlikwin said:

#1 Its in OP 2309, 2-1, 2nd part of the below. It  will apply to pretty much all sidewinders, since they all use gas generators (well, later ones use a gas gen AND a battery but I'm pretty sure the firing seq is similar enough in that regard).

Later Aim-9D manual (OP 3353) says specifically that the pilot does not need to hold down the firing button. Again, it's not clear if this is a missile difference or a launcher difference.

22 hours ago, Flappie said:

We need a good source for this, because it would be a big change. If I'm not mistaken, dead missiles on the rail don't exist (yet) in DCS.

2 hours ago, Harlikwin said:

Honestly I care way more about getting the lock/uncage behavior right than getting this 100%. 

Also agree, I would focus on correcting the uncaging (self-track) behavior which is unambiguous and correct on other DCS modules. F-86 does not even have a manual uncage button anywhere, let alone a SEAM computer, and even SEAM does not behave like what is currently on the F-86 in-game. Automatic self-track is a feature of 1970s dogfight missiles (R550 and R60?), which is not correct for any original sidewinder.

[Harlikwin]

@Flappie

 

IDK if ED really wants to do it but if would be cool to at least break down the 9B/Gar8 on the f86 into an early/late model (call the Original Gar-8, call the later the 9B)

 

Main differences: 

Gar8: 20deg gimbal limit, uncages on missile departing the jet

9B: 30deg gimbal limit, uncages immediately after gas gen is ignited.

There is also a photocell change in there, but frankly I Don't think it would mater for DCS. 

 

[Smyth]

5 hours ago, Harlikwin said:

IDK if ED really wants to do it but if would be cool to at least break down the 9B/Gar8 on the f86 into an early/late model (call the Original Gar-8, call the later the 9B)

Are you sure about that? GAR-8 seems to be a pre-'62 synonym for Sidewinder 1A (Aim-9B). The 1960 USAF Statistical Digest lists 12,386 "GAR-8" procured to date, plus 1,350 for MAP. That's many more than the <300 'Mod0' Sidewinder 1 (Aim-9A) seekers built. If any pre-production Sidewinder 1 were given to the USAF, they never got their own designation.

I just want to see a high-fidelity generic Aim-9B. If other cool early missiles get added that's great, but let's keep things simple to start.

Edited Wednesday at 06:48 AM by Smyth
tl;dr

[Dragon1-1]

I want to add one more thing: the electronics in those early jets were not complex. If there's a 0.8s delay, that's because a bunch of things start to happen when the firing circuit closed. If it's opened during that time (button released), before they can finish, then they're no longer able to, and the missile dies on the rail. There's no complex safety logic or anything because it's all based on a handful of relays, and the firing switch is just that, it physically closes the firing circuit.

[Harlikwin]

13 hours ago, Smyth said:

Are you sure about that? GAR-8 seems to be a pre-'62 synonym for Sidewinder 1A (Aim-9B). The 1960 USAF Statistical Digest lists 12,386 "GAR-8" procured to date, plus 1,350 for MAP. That's many more than the <300 'Mod0' Sidewinder 1 (Aim-9A) seekers built. If any pre-production Sidewinder 1 were given to the USAF, they never got their own designation.

I just want to see a high-fidelity generic Aim-9B. If other cool early missiles get added that's great, but let's keep things simple to start.

 

 

Mk1 mod0 GCS was what was used on the Gar-8. In Navy speak, mk1 = First thing, mod0 = modification 0. 

And yes Gar-8 is what the AF called the navy missile. If yoou check I forget which one of the 3 2309's it mentions the 1A=9B thing.