Target aspect switch

[TLTeo]

So TLDR is the least bad way of trying to shoot down a Mach 3/4 high altitude cruise missile with a Phoenix would be to lock it in PSTT and therefore fire at relatively close-ish range?

[BreaKKer]

2 minutes ago, TLTeo said:

So TLDR is the least bad way of trying to shoot down a Mach 3/4 high altitude cruise missile with a Phoenix would be to lock it in PSTT and therefore fire at relatively close-ish range?

As of now, it seems to be. Crank the pulse gain, and pulse video up, and just wait for that thing at angels 74 to pop up on radar, then make sure the ADL is roughly leading the cruise missile, or else the Phoenix will never see it

[Harlikwin]

7 minutes ago, Naquaii said:

 

Only PD, Pulse mode does not use the filters at all.

 

Yeah thats what I figured, thanks. 

1 minute ago, BreaKKer said:

As of now, it seems to be. Crank the pulse gain, and pulse video up, and just wait for that thing at angels 74 to pop up on radar, then make sure the ADL is roughly leading the cruise missile, or else the Phoenix will never see it

 

Again, this doesn't really seem unrealistic.

 

[MBot]

26 minutes ago, TLTeo said:

So TLDR is the least bad way of trying to shoot down a Mach 3/4 high altitude cruise missile with a Phoenix would be to lock it in PSTT and therefore fire at relatively close-ish range?

 

A successful PSTT shot is basically impossible. In my experience, in DCS you need to be as fast and high as possible and launch shortly after maximum PD detection range (60ish NM) in order for the Phoenix to be able to climb and intercept the target nearly head on. Remember that even if launched high, the missile still has to climb around 40'000 ft.

 

It seems that AS-4 interceptions are over, and apparently the Tomcat was never capable to do so. Such a shame, as I really enjoyed them

 

 

[Biggus]

17 hours ago, FWind said:

2900 closing in PD form F-4K，not form F-4X.http://aviationarchives.blogspot.com/2016/01/royal-navy-f-4k-phantom-ii-report.html?m=1

 

Look at the date.

 

The AWG-10 still hadn't reached proper production by May '66 when the first J hit the fleet.  The tactical manual I referenced was produced in 1972.  I'll go and dig through the F-4J/S NATOPS book later and see if there's more information there, but I'd suspect that the FG.1 report might not have been completely accurate.

[FWind]

3 hours ago, Biggus said:

Look at the date.

 

The AWG-10 still hadn't reached proper production by May '66 when the first J hit the fleet.  The tactical manual I referenced was produced in 1972.  I'll go and dig through the F-4J/S NATOPS book later and see if there's more information there, but I'd suspect that the FG.1 report might not have been completely accurate.

2900 is closing rate, not target speed. 

[Biggus]

I'm not sure I am ready to agree yet, switchology notwithstanding.

 

My interpretation of the passage I posted is that in a scenario where an F-4 has been vectored to a frontal intercept, a target traveling above 1800kn is going to be impossible to find in PD.  Given the scenario, this means Vc of greater than 1800kn but quite a bit less than 2900kn.  Maybe I'm misunderstanding something.

[Katj]

I find it a bit weird that the range is centered around 0. I.e. +/- 1800 knots. E.g. -600 to +3000 would make a whole lot of more sense unless this is a side effect of the implementation.

I don't understand why they'd even bother to implement the aspect switch for the PD modes. 600 knots of opening is plenty, anyone escaping with more speed than that isn't going to be a factor in the immediate future. Conversely, a target with 2000 knots closure is really something of a problem you need to deal with.

[Golo]

10 minutes ago, Katj said:

a target with 2000 knots closure is really something of a problem you need to deal with

Yes, and yet as I understand it, it is now invisible to the AWG-9 due to now implemented PD 1800 kts Vc limit. I belive this is misrepresentation of AWG-9 capabilities. Logically it does not make sense to me for high speed interceptor to be "crippled" in such manner and there is a hint in manual of DDD being able to show Vc of 4000 kts with a use of Vc switch, which would make hell of a lot more sense for F-14/AWG-9.     

[Katj]

Yes, and yet as I understand it, it is now invisible to the AWG-9 due to now implemented PD 1800 kts Vc limit. I belive this is misrepresentation of AWG-9 capabilities. Logically it does not make sense to me for high speed interceptor to be "crippled" in such manner and there is a hint in manual of DDD being able to show Vc of 4000 kts with a use of Vc switch, which would make hell of a lot more sense for F-14/AWG-9.     

I'm not familiar with the internal workings of the awg-9, but in my mind it could conceivably make sense from a technical viewpoint. I am somewhat skeptical though. There should be a fairly simple technical explanation as to why the interval would be centered around 0. Someone on these forums should know.

Operationally it is obviously less than ideal.

[eatthis]

On 6/21/2021 at 1:52 PM, AH_Solid_Snake said:

 

 

I think there are a few misconceptions baked into some of this discussion, and while I'm by no means the final SME on the F-14, nor a math wizard I can offer the following points.

 

The F-14 is indeed designed to go high, and fast, and to kill other things that are also doing the same, but not necessarily all at the same time.

 

Geometry to manage closure is a huge part of running intercepts whether its a peace time stern conversion or a wartime weapons free, theres a reason when you see video of the F-14 doing TWS tests, or Phoenix tests in general that the wings are either full forward or in an intermediate (but still mostly forward) position - so long as you're high and pointed the right way the Phoenix will make up a lot of the range such that adding a few extra knots or breaking the mach prior to launch against a large number of targets just means you're going to end up ruining your TWS solution by the time you're getting to the 4th (or even 6th!) launch. Remember that your TWS scan volume is either wide or tall, again not both at the same time. Excess closure for this kind of shot means you're going to force some of the targets outside your allowable volume before going active simply by pushing that cone closer to them.

 

For single shots against the MiG-25/31 example these intercepts are incredibly geometry intense since you usually can't expect to be conveniently lined up right in front of them with a big rate of closure, and in this scenario we're going to be burning the Phoenix motor in order to catch them at all. F-15s with AIM-7 have even narrower margins for this type of intercept.

 

In these kinds of cases you're going to be going STT for a single shot, because against a target moving that fast a TWS scan is just not reliable enough to guide your weapon with much of a chance of hitting them.

 

TWS is more like guidelines than guidance for your missile. The best it can do is give your missile a box (usually referred to as cell) that the target is within, for the F-14, from memory these are 5 degrees wide and 5nm long...thats a lot of CEP for your Phoenix when both it and the target are doing mach 2+ in the terminal phase.

 

Secondly even with its big motor then depending on...that word again...the geometry of the intercept you are burning a lot of the missiles energy just maintaining a Pn lead pursuit course, if you were already on CAP the enemy is unlikely to just go CBDR right at your 12 oclock allowing for the perfect straight line course. And if you were scrambled to meet the threat your missile is also doing significant uphill work to meet them from a lower starting altitude.

 

In these cases you've got to manage 2 things with your geometry as usual. Range and angle off. Tracking 90 degrees or 180 degrees against a M2+ bandit will make even a Phoenix struggle, making your WEZ much smaller than the 100nm on paper.

 

Tracking nose on from below requires you to get as much height as you feasibly can before the enemy gets so close that your missile (and radar guidance) would have to do an immelman turn to maintain tracking, so you'll get whatever height you can, then get as fast as possible, then zoom climb so that at the optimum moment you are high / fast enough to catch them, followed by leveling off again before you stall out and again lose the STT guidance for the weapon.

 

All this was suffice to say that theres a hell of a lot of geometry involved and thank god there are RIOs for that

is there a rough guide to optimum zoom climb profiles for the tomcat (a and b)?

[Katj]

is there a rough guide to optimum zoom climb profiles for the tomcat (a and b)?

It goes something like:
1. Slam it in full blower,
2. Accelerate to mach .9
3. Climb at mach .9. (Adjust attitude as necessary to stay at mach .9)
4. When you pass 22 kft, unload (you should read 0 g on your accelerometer)
5. When you pass mach 1.2, pick it up again

Transsonic drag is still a bit wonky in our dcs f-14 so you will have to experiment a bit to find something that works for you.

But this is also a guide on how to lose your radar contacts due to having closure rates in excess of 1800 knots!

[eatthis]

4 hours ago, Katj said:

It goes something like:
1. Slam it in full blower,
2. Accelerate to mach .9
3. Climb at mach .9. (Adjust attitude as necessary to stay at mach .9)
4. When you pass 22 kft, unload (you should read 0 g on your accelerometer)
5. When you pass mach 1.2, pick it up again

Transsonic drag is still a bit wonky in our dcs f-14 so you will have to experiment a bit to find something that works for you.

But this is also a guide on how to lose your radar contacts due to having closure rates in excess of 1800 knots!

Thafs perfect, thanks. So 1st climb to 22k fett at m0.9, then lvl out to m1.2, pull again and maintain m1.2 in the 2nd climb?

Edited September 23, 2021 by eatthis

[draconus]

27 minutes ago, eatthis said:

Thafs perfect, thanks. So 1st climb to 22k fett at m0.9, then lvl out to m1.2, pull again and maintain m1.2 in the 2nd climb?

It's certainly optimum climb profile but I wouldn't call it zoom climb.

[Katj]

Thafs perfect, thanks. So 1st climb to 22k fett at m0.9, then lvl out to m1.2, pull again and maintain m1.2 in the 2nd climb?

Were getting off topic but anyway:

You don't exactly level off at 22 kft, you unload, which means you will follow something of a ballistic trajectory. You'll most likely end up at mach 1.2 at some other altitude than 22 kft.

At this point the next step really depends on what you want to do. But it's often a good idea to start a climb but let the speed increase towards mach 1.3-1.6.

[eatthis]

2 hours ago, Katj said:

Were getting off topic but anyway:

You don't exactly level off at 22 kft, you unload, which means you will follow something of a ballistic trajectory. You'll most likely end up at mach 1.2 at some other altitude than 22 kft.

At this point the next step really depends on what you want to do. But it's often a good idea to start a climb but let the speed increase towards mach 1.3-1.6.

thanks

[Naquaii]

Ok, so confession time.

 

We had the AWG-9 doppler filters mixed up in how they work.

Basically the filter limits are correct but they should be applied after compensating for ownspeed.

 

This will make the whole +1800 knot range available for observed target closure rate only, without having to also add ownship rate in there.

That should make the IRL test shots possible in DCS as well.

 

Depending on testing this might make the next patch.

 

Sry guys! At least we caught it!

[BreaKKer]

Humanity is restored, thanks Naquaii

[captain_dalan]

Awesome news, this one really baked my noodle! 

[Xtorris]

[DSplayer]

9 hours ago, Naquaii said:

Ok, so confession time.

 

We had the AWG-9 doppler filters mixed up in how they work.

Basically the filter limits are correct but they should be applied after compensating for ownspeed.

 

This will make the whole +1800 knot range available for observed target closure rate only, without having to also add ownship rate in there.

That should make the IRL test shots possible in DCS as well.

 

Depending on testing this might make the next patch.

 

Sry guys! At least we caught it!

So compensating for own speed means that if a 14 and a target are both closing at 500 knots hot, this means that 500 kts will be the observed target closure rate right? Also, does this effect the notch/MLC filter as well?

[Prez]

10 hours ago, Naquaii said:

Ok, so confession time.

 

We had the AWG-9 doppler filters mixed up in how they work.

Basically the filter limits are correct but they should be applied after compensating for ownspeed.

 

This will make the whole +1800 knot range available for observed target closure rate only, without having to also add ownship rate in there.

That should make the IRL test shots possible in DCS as well.

 

Depending on testing this might make the next patch.

 

Sry guys! At least we caught it!

If the DDD is supposed to automatically subtract your own ground speed and just display the target's ground speed then would the display no long be closure? It would just be the literal ground speed of the target, would it not? The TID will already display the target's component of GS if you ask for it while still displaying absolute closure. So would that mean the closure displayed on the right of the TID when hooking a TWS contact or when in STT is no longer absolute, but just the target's ground speed? Lastly, I don't think this was the issue to begin with. It honestly would not have mattered so much if the DDD scale switch worked. AFAIK, that switch opposite to the Aspect Switch doesn't work. To me, this just seems like a work around for a different issue. 

[draconus]

Whoa, guys, what changes is just doppler filter calc, so we can actually see targets flying up to 1800kts GS - not closure speed - on the radar. Nothing on the TID or DDD will change nor the notching will be affected.

[Naquaii]

4 minutes ago, draconus said:

Whoa, guys, what changes is just doppler filter calc, so we can actually see targets flying up to 1800kts GS - not closure speed - on the radar. Nothing on the TID or DDD will change nor the notching will be affected.

 

2 hours ago, Prez said:

If the DDD is supposed to automatically subtract your own ground speed and just display the target's ground speed then would the display no long be closure? It would just be the literal ground speed of the target, would it not? The TID will already display the target's component of GS if you ask for it while still displaying absolute closure. So would that mean the closure displayed on the right of the TID when hooking a TWS contact or when in STT is no longer absolute, but just the target's ground speed? Lastly, I don't think this was the issue to begin with. It honestly would not have mattered so much if the DDD scale switch worked. AFAIK, that switch opposite to the Aspect Switch doesn't work. To me, this just seems like a work around for a different issue. 

 

As draconus says, nothing else will change. If you read target rate vs MLC it will be observed target closure rate but it always was. All the displays will be the same, this was a misunderstanding that only affected the filters.

 

The Vc switch is not a DDD scale switch, it purely controls the Vc bug on the DDD when in the STT modes. The only thing controlling scale on the DDD is the target aspect switch and then it just moves the location of the MLC around so the total scale on the DDD from top to bottom will always be 2400 knots.

[Katj]

Ok, so confession time.
 
We had the AWG-9 doppler filters mixed up in how they work.
Basically the filter limits are correct but they should be applied after compensating for ownspeed.
 
This will make the whole +1800 knot range available for observed target closure rate only, without having to also add ownship rate in there.
That should make the IRL test shots possible in DCS as well.
 
Depending on testing this might make the next patch.
 
Sry guys! At least we caught it!

Kudos for looking into this again to get to the bortom of it.

I bet there were some confusing wording in the documents with regards to own speed.

The AWG-9 knows the closure by knowing what it isn't...