J-10 Thread III (Closed to posting)

[shen]

we have the same understanding of off-boresight. my point is that since the current WVR missile for J-10 is PL-8 which doesn't have wide off-boresight capability, widespread deployment of HMS is not a priority.

An HMS/HMD would not pass the first selection criteria if its weight would limit the pilot's ability to pull max Gs in flight.

That is why you see those fancy HMD on Z10s but not on fighters - even though those HMD are generations ahead of the basic HMS currently used on J11s and J10s, their weight means pilots cannot pull 9G+ with them, so they do not even qualify for consideration for fighters.

You also seem to be a little confused on what off-boresight capacity means, off-boresight means away from where the nose is pointing. In addition, it refers to the missile's seeker field of view rather than some limitation on the missile's turning ability. That quote 30 degrees off boresight is therefore a reference to how wide the field of view the PL8 seeker has.

This is significant because until relatively recently with the introduction of lock-on after launch (LOAL) capability, you can only launch a missile after it has acquired a lock. Traditionally even IR missiles are cued via radar, so the radar's field of view limits how far off boresight you can get a lock.

With earlier HMS, you can use the HMS to cue the missile, which freed you from the limitations of the radar's field of view, allowing for greater off-boresight capability, but that was still limited by the missile's own seeker field of view. The missile cannot lock on to what it cannot see. Which is why the off-boresight capability of the missiles themselves were seen as an important indicator for a long time.

With modern HMS enabled LOAL missiles, the off-boresight capacity of the missile does not really have a great deal of correlation to how far off boresight the missile can be fired any more. Theoretically, if the pilot can see the target and keep it in his sights for the few seconds, you can launch agains that target. Off-boresight capabilities of missiles are still important, because they determine how well a missile can maintain a lock during violent manoeuvring. But that's not really what we are talking about here.

So, no matter how well your turning ability, it has nothing to do with your off-boresight capability. Those are two completely separate things.

Using HMS and high off-boresight launches does carry a cost, more like a cost and a benefit rolled into one.

The cost is to the range and kill probability (KP) of the missile. A dogifghting missile only has a range of a few dozen miles in most cases, and their rocket engines typically only burn for 30 seconds or less. These missiles are also designed to burn their fuel ASAP to accelerate to their max speed ASAP.

Rocket engines don't have throttles, so the missile will be burning its engine just as hard whether it is flying straight forwards or doing a 180. If you have your missile do too violent a turn at the start of its flight, you are wasting a lot of its fuel and speed and energy, so it may not have the range and/or speed needed to catch its target.

The advantage is that if your missile is doing much of the hard work, your plane doesn't have to. HMS and off-boresight capacity, if used right, can drastically reduce the number of Gs the plane and pilot had to pull to get a shot off. The less violent the turn the plane has to make, the less energy and airspeed it looses, so the pilot will have more options to go chase another target and/or avoiding becoming a target himself. To a lessor degree, the fewer Gs the pilot has to pull, the less fatigued he should get, but since pilots are trained to pull heavy Gs regularly, their endurance should not really be a big issue in a dogfight. Thus, on balance, off-boresight is a very big plus for the pilot and plane, less so for the missile and its KP, but the benefits to the former two overwhelming compensates for the latter.

 

[thunderchief]

we have the same understanding of off-boresight. my point is that since the current WVR missile for J-10 is PL-8 which doesn't have wide off-boresight capability, widespread deployment of HMS is not a priority.

If PL-8 really does have 30 degrees off-bore-sight angle , that is not to impressive . For example , even old R-73 has about 40 degrees off-bore-sight angle , and new R-73M has about 60.

 

[shen]

PL-8 is based on the Israeli Python-3, which was a very good missile for its time. Likely with larger engagement envelop than the smaller American contemporary AIm-9L/M. But it is getting old. Python-4 was the first Israeli missile designed with wide off bore sight capability in mind. The upcoming PL-10 (the one testing on J-20) should be better.

 

[plawolf]

If PL-8 really does have 30 degrees off-bore-sight angle , that is not to impressive . For example , even old R-73 has about 40 degrees off-bore-sight angle , and new R-73M has about 60.

That 30 degrees figure is based on the Israeli Python 3, which the earlier PL8s were a licence version of. However, over the decades the missile has been in service with the PLAAF, it would have been upgraded many times.

We are still using the 30 degrees figure because we simply do not have reliable information of what the off-boresight capabilities of late model PL8s are, but I very much doubt it is still 30 degrees.

I remember seeing a quoted off-boresight capability of 90 degree for the PL9, yet the PLAAF still favour the PL8, so that might give you some indication of what a late model PL8 might be capable of.

 

[thunderchief]

I remember seeing a quoted off-boresight capability of 90 degree for the PL9, yet the PLAAF still favour the PL8, so that might give you some indication of what a late model PL8 might be capable of.

You could estimate off-boresight capability of the missile if you have close-up picture with position of the seeker . For example , this missile at the picture could not have more then 45-50 degrees for obvious reasons

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[plawolf]

You could estimate off-boresight capability of the missile if you have close-up picture with position of the seeker . For example , this missile at the picture could not have more then 45-50 degrees for obvious reasons

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That's because that is a picture of an early PL8 with the clear window.

Upgraded PL8s use the milky Magnesium Flouride nose window with a much greater field of view.

 

[Jeff Head]

You know...I like the J-10. It's like the stable, very nimble, effective fighter/attack bird of the PLAN that can and will be built probably in large numbers

This is a general comparispon and not wholly accurate, but it reminds me a lot of the F-16 in US service in terms of its basic fit, function and capabilities.

In fact (again, in very general terms) I like to compare the basic fit of Chinese to US fighters like so:

J-10 = F-16
J-11 = F-15
J-15 = F-18
JH-7 = F-15E
J-16 = F-15E
J-20 = F-22
J-31 = F-35

Again, not perfect fits, but something like that. You can fit Russian birds right into that matrix too.

 

[SteelBird]

You know...I like the J-10. It's like the stable, very nimble, effective fighter/attack bird of the PLAN that can and will be built probably in large numbers

This is a general comparispon and not wholly accurate, but it reminds me a lot of the F-16 in US service in terms of its basic fit, function and capabilities.

In fact (again, in very general terms) I like to compare the basic fit of Chinese to US fighters like so:

J-10 = F-16
J-11 = F-15
J-15 = F-18
JH-7 = F-15E
J-16 = F-15E
J-20 = F-22
J-31 = F-35

Again, not perfect fits, but something like that. You can fit Russian birds right into that matrix too.

Just a warm remind that many of the Chinese fighters on the list are not operational yet.

 

[Jeff Head]

Just a warm remind that many of the Chinese fighters on the list are not operational yet.

Thanks. I know. I'm just talking about how and where they stack up to one another in terms of function.

 

[Deino]

Red numbers .... Maybe our new PLANAF unit ???

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Deino