TWS and semi-active guidance

[Exorcet]

Yes, unfortunately I tend to lead with an ER in a BVR scenario. I just wish I could fire the ER and let the computer track the target while I switch to a mode that will let me queue up an ET or 73 on a different target while we close in. I suppose the Su-27 has the advantage in this regard because an ET can be fired from a fair distance. But the F-18 has the same issue. I would be silly not to fire a sparrow first, yet there is no provision for queuing a sidewinder on another approaching target, supposing the seeker head is within range to acquire it. I'm just not sure why this is a limitation. Considering IR missiles are autonomous, I can't imagine it would be that much more work for the plane's computer.

It's probably technically possible for a plane to guide a SARH while tracking another target for IR, but then you also have to ask about the doctrine of the force using the aircraft. Under what situation would they find this capability valuable?

 

 

Soviet doctrine involved mixing SARH and IR missiles launched at the same target. Their aircraft were also heavily controlled by GCI and directed to specific targets. US doctrine doesn't use IR missiles in BVR, and at this point SARH has been replaced, AMRAAM allows for you to fire on one target and then forget about the missile (if the target is close enough) and attack another with a different weapon.

[GGTharos]

Thanks for clarification.

I was wondering how it would work, it would require TWS with trackfile and STT at the same time with conventional array. But I believed what I've read since many F-15 monographs repeated this - looks like - fake.

 

 

There WAS a proposed capability and it's even documented as a 'future capability', it just never happened.

 

 

All tracks are erased when going STT IIRC.

[bies]

There WAS a proposed capability and it's even documented as a 'future capability', it just never happened.

 

 

All tracks are erased when going STT IIRC.

 

To be 100% sure - you have an information straight from the horse's mouth?

cheers

[GGTharos]

I have an APG-63 review document that states some future stuff (from way back then) that didn't happen.

 

 

The STT thing is AFAIK from -34.

[Notso]

I suppose I should rephrase part of my question. I understand why SARH missiles cannot be guided by TWS. What I don't understand is why the AIM-120 or any ARH missile can be guided if it is effectively identical to a SARH missile until the seeker goes active.

 

Because -120s are NOT effectively identical to SARH missiles before the seeker goes active. They operate on completely different concepts of guidance.

[Poopskadoop]

The Fire Control System would have to do two things at once still, calculate DLZ and tracking information for two different points in space. I mean I don’t know about F-18 but the sidewinder doesn’t have to slaved right? Doesn’t that mean that if you have to fire on two targets with a sparrow first, couldn’t you fire the sparrow switch to AIM-9 keep it caged and point your nose on the bandit you want to fire on and fire while the FCR still maintains STT and semi active illumination. Would that work in F-18?

 

I guess with Su-27 you could try that this Phi0 mode, but I don’t know if it’ll maintain STT guidance for R-27.

 

I get why you think there’s obvious utility to it, but to me it seems like a pretty limited use case. These weapons have so many limitations already, if you have Fox 1 you are really have to focus on one at time. But if you can make it work go for it

I might be wrong, but IIRC, if you switch weapons away from the sparrow, it will lose guidance. I'll have to double check.

 

As for the FCS system, doesn't the IR missile do most of the work and calculations? The plane only tells the seeker where to look, and the seeker head reports back whether or not it has acquired a thermal signature. When it has, the plane simply says "yes, launch at whatever that is." Once it's off the rails, the plane's computer doesn't have to do anything. Take, for example, the Su-25. It has no radar and I'm pretty sure its FCS has no provisions to track aerial targets (I'm not counting using the vikhr against air), but it can still launch an R-60 or R-73 in longitudinal mode using the seeker head.

 

Again, it's quite likely I may be over simplifying things, but one thing I'm certain about is that I can find great utility for this ability. Consider a merge scenario where you have launched on a target with a sparrow which then begins to evade in another direction. Meanwhile, another bogey is closing on your wingman or some other target, maybe even a strike aircraft trying to fly past you to reach a ground target you are trying to protect. They will be within range for a sidewinder, but I can't stop guiding my sparrow to send one their way. I've found myself wishing for this ability many times in various engagements. If it's not realistic, then it's not, but I would be curious to know why that's the case. Seems more like a software rather than hardware problem.

[Exorcet]

Consider a merge scenario where you have launched on a target with a sparrow which then begins to evade in another direction. Meanwhile, another bogey is closing on your wingman or some other target, maybe even a strike aircraft trying to fly past you to reach a ground target you are trying to protect. They will be within range for a sidewinder, but I can't stop guiding my sparrow to send one their way. I've found myself wishing for this ability many times in various engagements. If it's not realistic, then it's not, but I would be curious to know why that's the case. Seems more like a software rather than hardware problem.

At that point it could be considered a failure on your part. You should have taken out the closing target already if it was going to be a problem. Aircraft typically work in groups, you don't need one to do everything. If that's how they're used, then this multiguidance capability isn't going to be incorporated into them.

[Poopskadoop]

It's probably technically possible for a plane to guide a SARH while tracking another target for IR, but then you also have to ask about the doctrine of the force using the aircraft. Under what situation would they find this capability valuable?

 

 

Soviet doctrine involved mixing SARH and IR missiles launched at the same target. Their aircraft were also heavily controlled by GCI and directed to specific targets. US doctrine doesn't use IR missiles in BVR, and at this point SARH has been replaced, AMRAAM allows for you to fire on one target and then forget about the missile (if the target is close enough) and attack another with a different weapon.

It would allow simultaneous BVR and WVR engagement using different seeker types. One of your targets may be far away and require a SARH missile, but suddenly you notice a bogey you missed or that your wingman failed to destroy appear WVR. Things don't always go according to plan in aerial combat, especially if everyone starts going in different directions at high speeds. This would be a useful fall back that lets you defend yourself or someone else without having to give up your radar target.

[GGTharos]

It would allow simultaneous BVR and WVR engagement using different seeker types.

 

 

You haven't got the brainpower for this, and frankly, what on earth is going on that you have to fight BVR and ACM simultaneously in a real world scenario?

 

 

 

One of your targets may be far away and require a SARH missile, but suddenly you notice a bogey you missed

You're suddenly dead. The end.

 

 

 

Things don't always go according to plan in aerial combat, especially if everyone starts going in different directions at high speeds.

You have no idea how much more coordinated IRL is than the virtual air warfare circus we see in games.

 

 

 

This would be a useful fall back that lets you defend yourself or someone else without having to give up your radar target.

Nope. It is mostly useless at this point. You've already been ambushed, and you're making some sort of pie in the sky claim that you can blend ACM and BVR against two targets simultaneously. We've already established that they're not flying fat dumb and happy because they're already managed to sneak an un-targetted shooter in. You're dead and your tricks don't matter.

 

 

Once exception here might an F-35 that could manage a revenge shot...but you're still dead.

[Poopskadoop]

At that point it could be considered a failure on your part. You should have taken out the closing target already if it was going to be a problem. Aircraft typically work in groups, you don't need one to do everything. If that's how they're used, then this multiguidance capability isn't going to be incorporated into them.

Perhaps, but let's just say shit happens :doh:. I'm sure that it can happen to anyone. Maybe one bogey hid their approach using ground features. Maybe your wingman screwed up. Maybe your sparrows, as they tend to, decide they just don't feel like doing their job anymore. Maybe your target decides to take the scenic route to avoid your sparrow while his own wingman closes in. Having a fall back can't be considered useless. What's the saying? "No plan survives contact with the enemy."

[GGTharos]

Your fallback is tactics, not magical weapon modes :)

[Poopskadoop]

You haven't got the brainpower for this, and frankly, what on earth is going on that you have to fight BVR and ACM simultaneously in a real world scenario?

Who, me personally or people in general? As for what scenario, I listed a few in my posts above.

 

 

You're suddenly dead. The end.

Maybe. Probably even. But maybe not. If your enemy has also made a mistake, you'll be able to take advantage of it quickly. That's why I'm saying it's a contingency.

 

You have no idea how much more coordinated IRL is than the virtual air warfare circus we see in games.

Sure, but I've read about more than one engagement where one side or the other got caught off guard. Even in reality, I highly doubt everything always goes according to plan. And to have at least some back up is better than nothing, even if you know your chances are slim. There's always a chance your counter-measures will work, especially against dissimilar opponents.

 

Nope. It is mostly useless at this point. You've already been ambushed, and you're making some sort of pie in the sky claim that you can blend ACM and BVR against two targets simultaneously. We've already established that they're not flying fat dumb and happy because they're already managed to sneak an un-targetted shooter in. You're dead and your tricks don't matter.

Wouldn't that highly depend on who and what you're going up against? It could be some MiG equipped with R-60s. Maybe they managed to evade detection by some dumb luck but they've also lost SA. At least I would still have some kind of chance to kill my original target and the new target both. Sparrow ranges can quickly turn to sidewinder ranges before the original (or second) sparrow has time to hit its target. I'm not talking about Super hornets outfitted with AIM-120Ds and all the detection support in the world. I'm talking about our F-18C outfitted with sparrows.

[Poopskadoop]

Your fallback is tactics, not magical weapon modes :)

Would't hurt though, would it?

[Exorcet]

Having a fall back can't be considered useless. What's the saying? "No plan survives contact with the enemy."

Yes, but to field aircraft in the first place, they need to be designed and built to a budget in a finite time frame. You could probably list an infinite number of features that would benefit a pilot in some niche situation, but there is no way the manufacturer could add them all.

 

 

In that case, you plan for the most likely situations, and you build a doctrine to force situations to be ones that are to your advantage. In the real world, any kind of SARH multi tracking went out the window with AMRAAM. That was the answer to SARH inflexibility, at least for the NATO. If you're flying in DCS (or the real world) before the AMRAAM era, then you'd fall back on tactics.

 

 

If we want to get into why the capability that you're suggesting wasn't one of the things militaries tried to acquire, I think that's because it's less useful than it sounds. I agree with GG here that finding and destroying the enemy before they're a problem is the better plan. WVR isn't a place a fighter wants to be, especially without the advantage, there is less chance of escape there.

[Poopskadoop]

Yes, but to field aircraft in the first place, they need to be designed and built to a budget in a finite time frame. You could probably list an infinite number of features that would benefit a pilot in some niche situation, but there is no way the manufacturer could add them all.

 

 

In that case, you plan for the most likely situations, and you build a doctrine to force situations to be ones that are to your advantage. In the real world, any kind of SARH multi tracking went out the window with AMRAAM. That was the answer to SARH inflexibility, at least for the NATO. If you're flying in DCS (or the real world) before the AMRAAM era, then you'd fall back on tactics.

 

 

If we want to get into why the capability that you're suggesting wasn't one of the things militaries tried to acquire, I think that's because it's less useful than it sounds. I agree with GG here that finding and destroying the enemy before they're a problem is the better plan. WVR isn't a place a fighter wants to be, especially without the advantage, there is less chance of escape there.

Fine, I agree in principle. I only wonder, purely from a technical standpoint, how difficult of a thing it really would have been to add. If it's a matter of a few lines of code, I don't see why it would hurt. If it's a lot more than that, then I agree.

[GGTharos]

Who, me personally or people in general? As for what scenario, I listed a few in my posts above.

 

 

People in general.

 

 

Maybe. Probably even. But maybe not. If your enemy has also made a mistake, you'll be able to take advantage of it quickly. That's why I'm saying it's a contingency.

 

 

You break lock on the SARH to take care of this guy. The guy with the SARH on him should already be defensive.

 

 

Sure, but I've read about more than one engagement where one side or the other got caught off guard. Even in reality, I highly doubt everything always goes according to plan. And to have at least some back up is better than nothing, even if you know your chances are slim. There's always a chance your counter-measures will work, especially against dissimilar opponents.

 

 

Your backup is your CMs, tactics and wingman. I'm not even sure why you're assuming your sneaky bandit is entering your WEZ at all.

 

 

Wouldn't that highly depend on who and what you're going up against? It could be some MiG equipped with R-60s.

 

 

Nope...that's what ACEVAL was all about. Once you get into ACM, as long as everyone is hauling all-aspect missiles, it's a crap-shoot...technology rapidly loses its lustre. You're need the aircraft to auto-designate and fire on multiple targets, and we're not in a macross missile massacre situation yet IRL. :)

 

 

 

Maybe they managed to evade detection by some dumb luck but they've also lost SA.

 

 

That's irrelevant to you. They either re-gained SA and they're attacking you with advantage or they keep being SA-free and they're not a threat.

 

 

 

At least I would still have some kind of chance to kill my original target and the new target both.

 

 

You wouldn't, because there's no reason for these bandits to be presenting you with any sort of geometry where you do NOT have to choose one or the other.

 

 

 

Sparrow ranges can quickly turn to sidewinder ranges before the original (or second) sparrow has time to hit its target. I'm not talking about Super hornets outfitted with AIM-120Ds and all the detection support in the world. I'm talking about our F-18C outfitted with sparrows.

 

 

Yes, they tend to choose a single target per aircraft available and prosecute that target :)

[GGTharos]

Fine, I agree in principle. I only wonder, purely from a technical standpoint, how difficult of a thing it really would have been to add. If it's a matter of a few lines of code, I don't see why it would hurt. If it's a lot more than that, then I agree.

 

 

Because you can be adding a few lines of code for something that's actually useful. Regardless of you being able to imagine why this is or isn't, realize that lots of things have been done and they've likely discussed and tried more ideas than you have. :)

[Poopskadoop]

While we're at it, if we're discussing tactics, does anyone know of good a resource for what real pilots would do in the kind of scenarios I brought up. Or WVR in general?

 

My inclination would be to abandon the sparrow target immediately and try to dispatch the closer targets with sidewinders as fast as I possibly can. Start popping flares, of course. But where to fly, I wonder? Would it be wise or unwise to hit the deck? Or maybe, depending on which direction everyone is going, to pull away from the engagement if you have an energy advantage until you can bring it back around to reestablish a shot from distance?

[Poopskadoop]

Because you can be adding a few lines of code for something that's actually useful. Regardless of you being able to imagine why this is or isn't, realize that lots of things have been done and they've likely discussed and tried more ideas than you have. :)

Oh, I don't doubt that for a second. I'm only asking the question so I can better understand how and why things are done the way they are. My posts don't show it, but I've around here a while, and I always respect your input. :thumbup: Edited March 19, 2020 by Poopskadoop

[GGTharos]

While we're at it, if we're discussing tactics, does anyone know of good a resource for what real pilots would do in the kind of scenarios I brought up. Or WVR in general?

 

My inclination would be to abandon the sparrow target immediately and try to dispatch the closer targets with sidewinders as fast as I possibly can. Start popping flares, of course. But where to fly, I wonder? Would it be wise or unwise to hit the deck? Or maybe, depending on which direction everyone is going, to pull away from the engagement if you have an energy advantage until you can bring it back around to reestablish a shot from distance?

 

 

 

 

Things like Shaw's book and CNATRA's for USAF's manuals, but you will always have to supplement them ... they're not playbooks.

[Harker]

Actually, I ran a little test. I fired a Sparrow at a target and as it was guiding, I switched to Sidewinders. The radar maintained the target in STT with MPRF (correct behavior), but the Sparrow still guided to the target. I think the latter is incorrect, since the AIM-7 requires the radar to operate in PDI in order to track to the target.

 

Thoughts? Should the Sparrow still be able to guide if the radar exits PDI mode?

[KlarSnow]

PDI (pulse doppler interleaved) just means its alternating between MPRF and HPRF during search bars, once you are STT it will then use either MPRF or HPRF as required to maintain the target track, unless you tell it to use one or the other, it can guide a sparrow in either HPRF or MPRF no problem. From an employment perspective on anything that can shoot a sparrow STT is STT, and will support the sparrow to the target regardless of what PRF the radar is in.

 

When you select sidewinder the default setting for the radar should default to MPRF, since it should be bringing up a short range search by default, Im sure you can change that to whatever you want and hit "set" on the radar display.

Edited March 19, 2020 by KlarSnow

[Santi871]

PDI (pulse doppler interleaved) just means its alternating between MPRF and HPRF during search bars, once you are STT it will then use either MPRF or HPRF as required to maintain the target track, unless you tell it to use one or the other, it can guide a sparrow in either HPRF or MPRF no problem. From an employment perspective on anything that can shoot a sparrow STT is STT, and will support the sparrow to the target regardless of what PRF the radar is in.

 

PDI means Pulse Doppler Illumination in the Hornet, interleaved is INTL. Harker is correct in that tracking in PDI PRF should need to be retained during the Sparrow's entire flight or else it will be trashed. So that is a bug.

[grafspee]

My question partly relates to discussions in a previous thread I made on the "ode to Mongo" mission for the F-18C. I want to understand more about the TWS function of aircraft in general, and I'm sure there are some smart folks here that can answer my questions.

 

So, how does the AWG-9 radar of the tomcat simultaneously guide multiple AIM-54s and the APG-73 of the hornet guide multiple AMRAAMs but neither the tomcat nor the hornet can guide AIM-7 Sparrows simultaneously against targets? Both the AIM-54 and AIM-120 are effectively semi-active missiles until they are within range to engage their active seekers, is that not correct? My understanding is that semi-active missiles cannot be guided in TWS mode unless the radar is a PESA and literally splits the beams, such as on the MiG-31. So how does that work? Does the computer give the missiles "rough" guidance until the seeker heads go active? Is it just the fact that the software is not integrated to work with the AIM-7?

 

Further, why does ECM negate track while scan from a technical standpoint? Is there no provision for TWS to guide against multiple scrambled returns until the missile can engage some kind of Home-on-jam or otherwise get close enough to burn through the ECM?

 

Also, when did they introduce TWS mode 2 for the MiG-29S!? I had no friggin' idea it could engage multiple targets with the R-77 until I was messing around with the options yesterday. And would the J-11A, which can launch the R-77, really not have this functionality as well, given the similarity of the radars?

 

Finally, why does no aircraft in dcs (and I assume the real counter-parts) have the capability to guide a missile in STT while setting up a shot from an IR seeker? The AIM-9, R-73, and R-27ET do not require the radar to fire on a target, so why do aircraft not have such a simple functionality?

 

Many thanks for anyone who can answer my slew of (possibly) silly questions.:thumbup:

 

AIM-7 is semi active this mean that missile do not have own emiter. Radar contain simply wave emiter and wave receiver. Aim-7 is equipped only with receiver so radar wave must come from other source like main radar from plane. Aim-7 require continuous radar reflection of the target to be able to guide towards target.If lost or disrupted missile stops tracking target.

aim120 r77 aim54 are active missiles, this mean that they are equipped with fully functional radar capable of emitting and receiving radar waves. But power of inboard radar are limited so missile often is not able to track far targets by its own,In first stage those missiles are radio guided using launch platform radar and computer, inboard plane's radar and computer is capable of tracking multiple targets and is capable of sending trajectory corrections for each missile for best intercept, then when active missile is close enough inboard radar and tracking system is being activated and missile guide it self to a target.

At least this is how i understand this.

[Notso]

Fine, I agree in principle. I only wonder, purely from a technical standpoint, how difficult of a thing it really would have been to add. If it's a matter of a few lines of code, I don't see why it would hurt. If it's a lot more than that, then I agree.

 

It wasn't added because that's not how the real aircraft that are being modeled here in DCS actually work. The whole point of DCS is to simulate the real aircraft in the time period they are modeled for. Writing a "few lines of code" for something that doesn't exist defeats the point.