JF-17 Block-3 -- Updates, News & Discussion

[GumNaam]

I think it has to do with launch parameters...if a jet is going to shoot a missile in hi hi(high altitude high speed) imparting the most amount of KE...then depending on how high the jet is while shooting the missile...the atmosphere may be too thin for a Ramjet engine to function as intended.
So it could be that a Ramjet may put an upper limit on the launch altitude...which in turn lowers the amount of KE to begin with.

In contrast an AAM that carries all it's fuel internally(instead of using Ramjet) like for example PL15 or AIM120...there would be no such limit...if anything a thinner atmosphere means less air resistance...and that's even more favorable.

P.S. I'm no expert...just speculating.

the need for air in ramjets is a limiting factor...

 

[CriticalThought]

I am not sure why americans & chinese didnt pursue Ramjet AAM...they perferred pulse rocket engines..there are reasons to do so

It's all about tactics that play to your advantage. The meteor has a clear advantage at low to mid altitudes. In order to realize this advantage, the enemy will try its level best to force you into a low altitude situation.

Let us review an incident from Kargil debacle when PAF Vipers were locked by Indian (Mirage 2000s? not too sure), and in a standard breaking maneuver they dove for the ground. Now this is from memory, I might have gotten some details wrong here. But, in general, this type of tactic will need to be revised because with meteor they will be walking straight into the enemy trap.

Similarly, any aircrafts trying to use NoE tactics will have to avoid the killzone of meteor. This needs an investment in longer range data links, satellite coms, and longer stand off ranges. Thankfully, satellite coms is under active development under the space command.

But your army helis will also need to train for this new threat. And that is where chinks in our armor might occur. PAF is quite well aware of these threats, but is the army aware as well? Now imagine this, on this forum if I try to raise the question about how well prepared the army is, the army boys form a coalition and get my post shot down. We can't have an open and honest discussion about it.

 

[luciferdd]

the need for air in ramjets is a limiting factor...

And when the fuel is run out,meteor's big inlet will make great air resistance that is a totally cumbersome，it will reduce the speed and motility of the missile quickly.

 

[serenity]

Actually Chinese also played with ramjet missiles developed based from PL-12 and possibly others including totally ground up designs which just never revealed. Most important weapons projects are never revealed until it is impossible to hide for example many units of H-20 in service around many bases, or revealed to show the enemy some ability so they are deterred from war. Other cat and mouse games like this. For example the microwave weapons systems used during Ladakh was shown in this year's Zhuhai. The PLA has many types and might show one that can be exported and already old or less capable if revealed the details do not matter too much.

The problem is that ramjet powered missiles are costing more and they are more complicated and heavier. They are excellent for extending range but energy management is different to rocket. For example total energy per time could be like constantly 80 for a ramjet until it runs out of fuel while rocket would be 200 and then nothing depending only on momentum.

With dual pulse, the rocket will kick and accelerate missile again as it closes onto target. Ramjet is more suited for larger cruise missile weapons where you have fewer and have more expensive equipment on. For something you want hundreds of thousands of it costs too much more and more time required.

Other downsides as mentioned is larger diameter not including the fins so fitting into stealth fighter bay means less missiles compared to dedicated missiles with folding fins.

The main reason is due to cost and production speed. But also because with pulse rockets, the performance exceeds ramjet for air to air missiles. Pulse means you go from 200 and then slow down to 50 and then 200 again as you close in. Overall it also has faster average velocity throughout the flight but ramjet has more constant speed maintained. Ramjet is superior to single pulse missiles but inferior to dual pulse. Soviet SAMs designed with Ramjet such as Kub missile system also long phased out and India's Akash copy of Kub is redesigned to get rid of ramjet engine and replace with dual pulse.

 

[CriticalThought]

Actually Chinese also played with ramjet missiles developed based from PL-12 and possibly others including totally ground up designs which just never revealed. Most important weapons projects are never revealed until it is impossible to hide for example many units of H-20 in service around many bases, or revealed to show the enemy some ability so they are deterred from war. Other cat and mouse games like this. For example the microwave weapons systems used during Ladakh was shown in this year's Zhuhai. The PLA has many types and might show one that can be exported and already old or less capable if revealed the details do not matter too much.

The problem is that ramjet powered missiles are costing more and they are more complicated and heavier. They are excellent for extending range but energy management is different to rocket. For example total energy per time could be like constantly 80 for a ramjet until it runs out of fuel while rocket would be 200 and then nothing depending only on momentum.

With dual pulse, the rocket will kick and accelerate missile again as it closes onto target. Ramjet is more suited for larger cruise missile weapons where you have fewer and have more expensive equipment on. For something you want hundreds of thousands of it costs too much more and more time required.

Other downsides as mentioned is larger diameter not including the fins so fitting into stealth fighter bay means less missiles compared to dedicated missiles with folding fins.

The main reason is due to cost and production speed. But also because with pulse rockets, the performance exceeds ramjet for air to air missiles. Pulse means you go from 200 and then slow down to 50 and then 200 again as you close in. Overall it also has faster average velocity throughout the flight but ramjet has more constant speed maintained. Ramjet is superior to single pulse missiles but inferior to dual pulse. Soviet SAMs designed with Ramjet such as Kub missile system also long phased out and India's Akash copy of Kub is redesigned to get rid of ramjet engine and replace with dual pulse.

That low speed phase mid flight reduces the NEZ (No Escape Zone) for dual pulse. There are always pros and cons.

 

[GumNaam]

And when the fuel is run out,meteor's big inlet will make great air resistance that is a totally cumbersome，it will reduce the speed and motility of the missile quickly.

agreed. there's a reason why ramjet air to air missiles never caught on. they are good for air to surface rules though, since gravity and low altitude flight works in its favor but for air to air or surface to air roles, it leaves a lot to be desired. explains why even other european missiles makers never bothered to come out with their own ramjet versions.

 

[serenity]

That low speed phase mid flight reduces the NEZ (No Escape Zone) for dual pulse. There are always pros and cons.

Actually when the total energy is accounted the net effect is not like you said. It's highly complex to determine real NEZ. The second boost can boost missile up to mach 4 again which is much higher than ramjet speeds. There is no NEZ advantage for ramjet but it depends on many things. Certainly not just because ramjet.

 

[CriticalThought]

Actually when the total energy is accounted the net effect is not like you said. It's highly complex to determine real NEZ. The second boost can boost missile up to mach 4 again which is much higher than ramjet speeds. There is no NEZ advantage for ramjet but it depends on many things. Certainly not just because ramjet.

NEZ is determined by how fast a missile can move for how long. During the glide phase of dual pulse missiles, it is constrained by the lift/drag/thrust/weight relationship, with thrust being zero. The ramjet is in its element after the boost phase - that is what it was designed for. PLAAF's answer is the PL-XX - as far as I can parse the available info, it seeks to do away with the glide phase by increasing missile size and putting more fuel and oxidizer. Possibly AIM 260 might try that as well. Now if China can invent a variable pulse motor that can continuously vary fuel burn throughout missile flight, that would be a game changer.

 

[serenity]

NEZ is determined by how fast a missile can move for how long. During the glide phase of dual pulse missiles, it is constrained by the lift/drag/thrust/weight relationship, with thrust being zero. The ramjet is in its element after the boost phase - that is what it was designed for. PLAAF's answer is the PL-XX - as far as I can parse the available info, it seeks to do away with the glide phase by increasing missile size and putting more fuel and oxidizer. Possibly AIM 260 might try that as well. Now if China can invent a variable pulse motor that can continuously vary fuel burn throughout missile flight, that would be a game changer.

NEZ is a function of missile speed and remaining energy and the distance to target. This changes throughout the course of flight.

Show me mathematically how ramjet is always better than rocket for greater NEZ.

Ramjet sustains a speed better. The pulsed rocket method allows slow down to around mach 2 or even lower before second boost kicks again. It is highly complex but the way we can determine it is based on how much potential energy is in the rocket powered missile. Overall NEZ is mostly the potential energy but has impact of factors such as lift, thrust to weight, drag, and external factors such as new interception point changes but this last factor we assume as same conditions for both assessment.

So I said before it is impossible to say which has better NEZ. Ramjet doesn't automatically equal better NEZ because sustained mach 3 flight let's say during a period of time when rocket missile is only mach 2, does not give ramjet missile more NEZ since the rocket one will soon be boosted again to mach 4.

 

[Dazzler]

The appearance of swashplate, improved version of this radar suggests two things.

- PAF opted for swashplate version with which this version was competing

- The specs/ rated power were enhanced to match swashplate klj-7A AESA.

Klj-7A nominal output is just under 11kva, and fighter size detection range is over 200km.

 

[CriticalThought]

NEZ is a function of missile speed and remaining energy and the distance to target. This changes throughout the course of flight.

Show me mathematically how ramjet is always better than rocket for greater NEZ.

Ramjet sustains a speed better. The pulsed rocket method allows slow down to around mach 2 or even lower before second boost kicks again. It is highly complex but the way we can determine it is based on how much potential energy is in the rocket powered missile. Overall NEZ is mostly the potential energy but has impact of factors such as lift, thrust to weight, drag, and external factors such as new interception point changes but this last factor we assume as same conditions for both assessment.

So I said before it is impossible to say which has better NEZ. Ramjet doesn't automatically equal better NEZ because sustained mach 3 flight let's say during a period of time when rocket missile is only mach 2, does not give ramjet missile more NEZ since the rocket one will soon be boosted again to mach 4.

I actually provided everything you needed to understand this, but you have got this messed up in your mind. No Escape Zone is the range from which target cannot escape with close to 100% probability, even if the target utilizes escape maneuvers. This happens because the missile is much more faster, and much more maneuverable. But, the missile is also an aircraft and subject to the lift/drag/thrust/weight relationship. Every time the missile is not producing thrust, drag is slowing it down and weight is drawing it down.

Given this, the standard escape maneuver against dual-pulse is to retain altitude superiority. The missile needs a terminal altitude gain to reach the target. In order to do this with near 100% probability, it must be near the target, otherwise it will have lost too much altitude. This reduces the No Escape Zone. The target can make this even worse for the missile by initially lowering altitude, making the missile follow suit and then quickly increasing altitude. The missile needs to be very close to the target so the target has no room for playing around with altitude. The No Escape Zone has been reduced. Also, without thrust, the missile cannot make any high G maneuvers.

The ramjet by definition works in the high supersonic/near hypersonic regime and achieves a thrust by managing the supersonic flow for combustion. Its boost phase is meant to push it into supersonic speed from where the ramjet engine ensures thrust. The ramjet engine cannot achieve supersonic speed on its own, rather, it is designed to retain supersonic speed. Thus, by definition, it will retain a high speed throughout flight path, which will provide it with enough lift and will overcome drag, thus the standard maneuver of retaining altitude is ineffective (within the altitude range where air density make ramjet feasible). This automatically increases its No Escape Zone. If the aircraft lowers its altitude, the missile can use gravity to retain speed and reduce fuel burn. If the aircraft increases altitude the missile will burn slightly more fuel. But there will be a range within which no amount of maneuvering will knock the missile off the tail. Because the missile has the luxury of continuously burning fuel, it will retain its energy superiority for a longer range. This increases the NEZ.

If you want something more concrete than this, you should go and write your own simulation, where you simulate the missile's control algorithm and the aircraft's maneuvers.

 

[RAMPAGE]

The appearance of swashplate, improved version of this radar suggests two things.

- PAF opted for swashplate version with which this version was competing

- The specs/ rated power were enhanced to match swashplate klj-7A AESA.

Klj-7A nominal output is just under 11kva, and fighter size detection range is over 200km.


View attachment 781819

Looks tiny.

 

[Dazzler]

Looks tiny.

I think its just the TR array, not the complete radar.

 

[Ali_Baba]

The appearance of swashplate, improved version of this radar suggests two things.

- PAF opted for swashplate version with which this version was competing

- The specs/ rated power were enhanced to match swashplate klj-7A AESA.

Klj-7A nominal output is just under 11kva, and fighter size detection range is over 200km.


View attachment 781819

Interesting and i think you could be right about PAF wanting a swashplate variant. There is the question of what whether Block 1/2s can be upgraded to the same standard as Block 3 to support the same radar as the Block 3? I suspect not judging by some of the builds and cooling requirements for the KLJ7A.

The LKF-601E may still have a future in the PAF for upgrades to Block 1 and Block 2s ( well all Bloc 1's are now Block 2's ) with an AESA radar depending on the upgrade path for the earlier blocks. Still all to play for, for the LKF-601E.

 

[Dazzler]