Chinese air to air missiles

ougoah said:

Making staged AAM is ridiculous. Not even long range AAMs use rocket stages. The cost per missile will almost double considering you got to do a hell of a lot more engineering to get everything else to perform equally well despite having multiple stages.

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Yup, too expensive, but it has been considered (KS-172, AIM-152 AAAM).

ougoah said:

Now how cheap can we make ramjets. The PLA uses many air breathing air to surface and surface to surface missiles. A long range (much longer than Meteor) ramjet/scramjet powered missile should be the sweetspot for an air breathing AAM.

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Manufacturing cost for a ramjet is not that different from a rocket - neither has any moving parts. It does make flight control development more challenging, for the reasons outlined earlier (but that stops being a financial drain once you complete testing).

Totoro said:

Firstly, i have yet to see a high speed AAM missile that's been fielded anywhere in the world, with folding fins. While it may seem like a logical thing to do, obviously there are drawbacks to that solution, otherwise everyone who has stealth jets would also use such missiles. (weight and added drag are among them) That doesn't mean such missiles can't happen in the future, and it doesn't mean China won't be the first country to field such a missile - but I personally won't use an image of a tabletop model plane to make my decision on it.

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R-33/R-37 top side fin pair, for semi-recessed carriage in x-attitude under the MiG-31. Plenty of high-speed SAMs too, including some of the fastest outright (9M82, 9M96, Standard Missile family). It's expensive and might make stable separation difficult (fins can only pop out once clear of whatever obstacle requires them to be folded in the first place) but it's an established solution.

Aerodynamic stability during separation is probably the crucial problem, rather than speed, which is why it's much more common in SAMs (TELs are to all intents and purposes stationary during launch).

Totoro said:

Secondly, not to use a staggered arrangement of missiles when 3 missiles are in a bay is wasteful and probably unlikely. There are two options, really. One, to have long missiles which take up most of the length of the bay, which would preclude staggering the position of the middle one. But for that to work and still have room for 3 missiles, the missiles themselves would have to be quite narrow.

Second option would be to have a shorter missile, not by much, and certainly still longer than an amraam, so the staggered arrangement can be accommodated. That would also mean missiles themselves could be made wider, which is pretty important for various front section subsystems. Bigger cross section usually means more capable seeker, fuze, warhead, etc. Staggered arrangement would make any folding fins and the drawbacks coming with those unnecessary.

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Another consideration is the aspect ratio of the flying surfaces. Long chord strakes make staggering just as difficult as a very long missile, because the offset required to align the fins of one missile with the fin/strake gab of its neighbour becomes prohibitively large. Try staggering R-77s, the package would be almost 1m longer than the individual missile! Of course, this is exactly the situation we see in this model (assuming the strakes aren't also folding), and fortunately the span of low aspect ratio strakes is often compact enough that staggering becomes unnecessary.

Not all missiles lend themselves to such an arrangement, and with the serpentine inlet duct encroaching on the top of the weapons bay in the forward section there might not be sufficient depth to stagger this particular design.

One thing I forgot to mention is that the official models is always suppose to show known information. So I find the fact this model shows 6 missiles in the central bay surprising.

I got my j10A model when the J10b came out. Basically there is nothing new on j10A that can be learned from a model.

I wonder if the j20 can always take 6 missiles in the central bay but they just showed 4 on displays......

I thought dual-pulse air to air missiles were basically staged? Perhaps I am wrong but.
It does add complexity and failure modes when you add staging to any rocket but it's not impossible.

gelgoog said:

I thought dual-pulse air to air missiles were basically staged? Perhaps I am wrong but.
It does add complexity and failure modes when you add staging to any rocket but it's not impossible.

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Pulsed rockets are simpler than staged rockets, you don't have seperate nozzles for each section, and each section doesn't detach after fuel is spent. There is more complexity compared to simple solid rocket motor, but not that much I think.

Here is an interesting document that my answer why PL-15E has a max range of 145KM as opposed to PL-15's speculated range of around 180KM. The table lists the maximum range of AAM depending on the duration of time that elapses between the two pulses of a dual-pulse rocket motor. Under the head-on condition, the maximum range occurs when there is a 30 second gap between firing. If the gap between firing is 0s, the head-on maximum range is -- SURPRISE -- 145KM. What do you call a dual-pulse rocket motor with no pause between firing? A plain old single-pulse rocket motor.

This pretty much confirmed my suspicion that PL-15E does not feature dual-pulse rocket motor.

siegecrossbow said:

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Here is an interesting document that my answer why PL-15E has a max range of 145KM as opposed to PL-15's speculated range of around 180KM. The table lists the maximum range of AAM depending on the duration of time that elapses between the two pulses of a dual-pulse rocket motor. Under the head-on condition, the maximum range occurs when there is a 30 second gap between firing. If the gap between firing is 0s, the head-on maximum range is -- SURPRISE -- 145KM. What do you call a dual-pulse rocket motor with no pause between firing? A plain old single-pulse rocket motor.

This pretty much confirmed my suspicion that PL-15E does not feature dual-pulse rocket motor.

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Wow nice find. This stuff isn't classified at all?

So the essential max difference for applying dual pulse on the PL-15 specifically seems to be roughly 35km extra range with same probability of intercept. This 35km extra range for basically controlling second boost timing is assumed to be at optimal factors under which second boost is to be performed i.e. the max extension having dual pulse over non dual pulse is a MAX of 35km extra or roughly 25% more effective range to achieve same P(K)... obviously I mean what else is it measuring against.

I assumed it would be a little less effective range but more probability of kill within that stretch where the missile is losing KE at the extremes of range. 25% range boost might translate from higher P(K) at extremes of undetermined (unspecified) range.

ougoah said:

Wow nice find. This stuff isn't classified at all?

So the essential max difference for applying dual pulse on the PL-15 specifically seems to be roughly 35km extra range with same probability of intercept. This 35km extra range for basically controlling second boost timing is assumed to be at optimal factors under which second boost is to be performed i.e. the max extension having dual pulse over non dual pulse is a MAX of 35km extra or roughly 25% more effective range to achieve same P(K)... obviously I mean what else is it measuring against.

I assumed it would be a little less effective range but more probability of kill within that stretch where the missile is losing KE at the extremes of range. 25% range boost might translate from higher P(K) at extremes of undetermined (unspecified) range.

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The original article was purely academic and didn't mention the missile type, why would it be classified?

What I found interesting is that the optimal pulse duration differs depending on the head-on/tail-on condition. For head-on condition, a 30 second gap can achieve the best result of 187KM. Tail-on, however, you need to wait 50 seconds between pulses to achieve 30KM range.

siegecrossbow said:

The original article was purely academic and didn't mention the missile type, why would it be classified?

What I found interesting is that the optimal pulse duration differs depending on the head-on/tail-on condition. For head-on condition, a 30 second gap can achieve the best result of 187KM. Tail-on, however, you need to wait 50 seconds between pulses to achieve 30KM range.

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Yep but that would just be simple physics. With enough details even here we could probably work out how the missile range changes as target flight profile changes and chart those curves.

Basically what is properly interesting is how the missile can compute and optimise all this with sensor data. But even this is easy work for any competent engineer in those fields. No doubt PL-15 optimises when it performs second boost and probably integrates flight profile with second boost i.e. pitching up or not and by how much.

ougoah said:

Yep but that would just be simple physics. With enough details even here we could probably work out how the missile range changes as target flight profile changes and chart those curves.

Basically what is properly interesting is how the missile can compute and optimise all this with sensor data. But even this is easy work for any competent engineer in those fields. No doubt PL-15 optimises when it performs second boost and probably integrates flight profile with second boost i.e. pitching up or not and by how much.

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My guess would be that the missile alters the pulse duration based on data feed back from the fire control radar.