Chinese AAM


Bltizo

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True, but I think the underlying assumes are key here. You are assuming both to be powered in the terminal phase, while I am considering scenarios where the ramjet is still powered but the rocket has run out of propellant.

Modern counter AAM tactics is usually a game a attrition and range, where fighters try to bleed incoming missiles of all their propellant and energy before the missile can get close enough to engage, rather than super-manoeuvrability last minute extreme G jinx’s. As such, I value longer range over raw turning ability. Because even with the ramjet’s inferior terminal agility, it’s probably still far more than what fighters could hope to reliably shake off if it gets within range.

Dual pulse or multi-pulse motors.

PL-15 is known to be dual pulse, I suspect this new missile would be at least the same.


That said I imagine it's not a clear cut decision, and ramjet vs dual/multi pulse motor has been debated ad nauseum as well over the years. Benefits of ramjet (sustained energy) but its disadvantage of parasitic drag and size are known.
 

silentlurker

Junior Member
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Your instantaneous impulse, especially at higher angular changes, is much lower for a ramjet missile than a rocket. That matters a lot for the terminal phase.
??? Impulse is the integral of force over time, how can aything have instantaneous impulse?
 

Bltizo

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But the question is, is it a true new missile or - and at least IMO those in that model looks so - a variant of the PL-15 with folding wings?

It looks like there are more differences than just folding fins.

Red: rear fin geometry (folding?)
Yellow: two different protrusions (forward and behind mid fins) not on PL-15. (?datalink or guidance related addition?)
Green: different mid fin geometry and placement.
plx 1.jpgplx 2.jpg
 

plawolf

Brigadier
IMO you are reading too much into a plastic model, the yellow bits could just be casting connectors or flow channels used for casting. Like those little plastic bits in model plane sheets which keep all the parts connected to the sheet so none of them fall off.
Nope, model making is a surprisingly precise undertaking. Flash and mould lines are nothing like that pronounced. You can see actual mould lines on the missiles running the length of them.
 

PiSigma

"the engineer"
IMO you are reading too much into a plastic model, the yellow bits could just be casting connectors or flow channels used for casting. Like those little plastic bits in model plane sheets which keep all the parts connected to the sheet so none of them fall off.
Actually the official AVIC models are very good and precise compared to the real thing. I have official models for J-10A and JF17 when my uncle still worked. The models are actually not plastic, they are metal, every detail is scrutinized by the original team.
 

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latenlazy

Brigadier
??? Impulse is the integral of force over time, how can aything have instantaneous impulse?
It just refers to your impulse within a specific range of time over the whole impulse graph of an object in motion. Instantaneous force would probably have been more precise but since we’re not talking about a single moment of force impulse came more naturally to me.
 

Tirdent

Junior Member
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You guys seem to be conflating several considerations here regarding missile range and maneuverability.

Specific impulse is a measure of propulsive efficiency - simply put, the higher the more range you get out of a propulsion system, all else (weight, flight profile etc.) equal. Ramjets do well here compared to rockets because they do not need to carry along the oxidizer for their fuel, which is a big weight saving (though not a volume advantage, because of the empty air intake ducts). This can be used to carry more propellant, increasing burn time - ramjets which can be throttled improve this even further and that does mean better end game maneuverability.

Once the propellant has been used up, every turn bleeds energy that can no longer be recovered - this is where dual pulse (not strictly impulse) rockets come in. These have basically 2 independent rocket motors in series, the second of which can be ignited long after the first burns out. Think of it as a poor man's two-stage missile that does not jettison the first stage, this enables even a non-airbreathing missile to also perform its end game intercept under power.

Nonetheless, there are potential drawbacks to ramjet propulsion in terms of maneuverability. These are both, directly or indirectly, related to the presence of air intakes. On the one hand, they may encounter difficulties at high angles of attack and/or side slip, on the other they might require a bank-to-turn control scheme (Meteor is a bank-to-turn missile, SA-6 isn't). That is to say, the missile rolls into the desired direction of turn before actually turning, like an aircraft, which causes a small delay (worse *instantaneous* turn). Though the subsequent turn rate (*sustained*) of a properly designed bank-to-turn missile might actually be better.

So, ramjet = better range, pretty much unequivocally. Maneuverability-wise, it could go either way.
 
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Atomicfrog

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It looks like there are more differences than just folding fins.

Red: rear fin geometry (folding?)
Yellow: two different protrusions (forward and behind mid fins) not on PL-15. (?datalink or guidance related addition?)
Green: different mid fin geometry and placement.
View attachment 66791
It look like lattice fins on the back, well, looking at them, the missiles look like R-77 missile...
 

Bltizo

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Yeah I immediately thought of the r-77 missile the moment I saw it.... got no idea why it took so long for everyone to figure it out lol

The proportions of the midbody fins is quite different to that of R-77 which are wider, longer and with front and rear edges being much more perpendicular to the missile body, as are their relative size to the aircraft.

The rear fins also do not look like what one would expect the potato masher rear fins of R-77 to look like even if folded, in terms of individual geometry.

The angular bulges of the missile body (the yellow circles in the image highlighted) also are not present on R-77 either.

r-77.jpg



There's also the issue that if we do accept this is a proper and official AVIC commissioned model and with attention paid to details, the idea that they would have accidentally let the model accommodate R-77s be odd, bordering on outrageous.


There are basically two explanations:
1. Either the missiles themselves are not representative of anything specific and are just random stand ins that do not depict a future in development missile or real world missile in any form...
or,
2. The missiles are representative of the specific new BVRAAM that has been rumoured for the last couple years as being under development, a missile that was specifically to allow J-20 to carry six of ventrally.

Option 1 would basically have to assume that the official AVIC commissioned models are not of any particular credibility in terms of their details.
Option 2 would basically have to assume the opposite.


However in neither option IMO is there any reason to think that the missiles in the model are depicting R-77s, the differences are just too large.
 

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