boogieman wrote:I think the goal is as much about the guidance/seeker stack as kinematics. An AESA seeker with complementary/backup IIR ought to do nicely.
You'd think so, but I'm doubting it's IR.
First, more range is not better than say an average 1,500 knots higher fly-out speed than AIM-120D, to shorten the time and prevent the target moving too far (thus prevent forcing the missile to loose too much energy leading it, at long-range).
Second, even if bled at long range, a much faster missile has a lot more energy to bleed, and can also fly higher to lose less energy in gradual turns against jinks. Plus a really fast heavier missile can come down almost vertically and much faster than the AIM-120D could, with a lot more energy stored. Especially if it dropped the engine and fuel section just before terminal phase.
Third, to be worth pushing much past the radius of the AIM-120D the replacement missile will need to coast at a hypersonic speed and close to hypersonic at terminal range, with little loss of velocity in the descent.
Fourth, this makes for a very heat-soaked nose cone material (glowing hot) and an IR emissivity/transmissivity window in the nose material may still impair IR sensitivity.
Fifth, the initial target tracking can not be IR, it would have to be a very capable fighter radar.
The plan is to go on 4th gens first after the F-22A. So how many combat-loaded 4th gens can get the altitude and speed to hit past 200 km? Or could lock and guide a missile that far against lower RCS, and against a long-range counter-launch? Few, to none.
So I'm doubting that the range advantage is as important as the speed advantage, for 4th gens. And IR will be even more affected at lower altitude, of a high parasitic-drag 4th-gen launcher.
So I'm thinking this is more about a faster initial radar-guided self-defense for shorter or else same range as AIM-120D's range limits, with a very fast missile at even shorter loft ranges, especially when using an IRST-cued shot, and datalink guidance, for a 4th verses 5th defense.
Obviously I'm missing important considerations here, but overall this seems to be more about kinematic performance and the datalink, than a possible IR sensor for terminal redundancy. I'm wondering if a high sensitivity short-range LIDAR terminal guidance sensor against a transonic J20 with a hypersonic missile would not make more sense than IR? Both are affected by WX, but hard to see how IR can work well with such a fast missile. And I can't see why an AMRAAM-ER couldn't be adapted to this also.
Or has it been?
But then again, if the premise is A2A missiles are expensive, and money is tight, so new missiles will be cut. Then the same logic applies to producing AIM-120Ds in numbers. So I doubt anyone will be cutting A2A missiles with J20s in growing numbers.