Interesting stuff Garry. I think that the Tu-22 suffers from ageing problems like the Mig-31 does.However there's still life in the bird yet ofcourse.
The Mig-31 is still the best at what it does... no other aircraft on the planet can fly to a target 1,400km away at mach 2.4 and then fly 1,400km back to base at mach 2.4 with air to air missiles.
If you look in the thread about S-400 and S-500 missiles you might spot that they mention a future model of the S-500 as being an AAM for intercepting ICBM warheads in space... you are going to need a big aircraft for that, and you are going to need to have external weapons carriage... which makes any talk of stealth pointless.
Speed and range.
A replacement Tu-22 and replacement Mig-31 could potentially share some characteristics, as could the Pak-Fa IMO.
It would be nice to combine requirements with existing programmes, but a supercruising PAK DA would be more use than a PAK FA design...
My concern is that a replacement 31 could be open to attacks from an F-22 or similar.
The speed and height the Mig-31 and any replacement would operate would make the threat from F-22 fairly limited... even if there were F-22s operating anywhere near the Mig-31 or its replacement.
Yes I know it could spot an F-22 quickly. But what about 2 F-22s flying together. The Mig 31 thinks its shot the one down, only 2 find a second one creep up on it..
How exactly would an F-22 creep up on a mach 2.4 Mig-31?
My option would be a collaborative defence. Ground SAMs and radar. Air superiority Pak Fas and the legacy jets. Air radar. The usual stuff.
The new Mig-31 replacement will be for the Aerospace defence forces, which has control of thousands of ground, air, and space based radars all networked. The Mig-31 and its replacements job is interception. Any threat of F-22s will be dealt with using PAK FAs and S-400s.
My concern is... what if the non-stealth Mig-31 replacements were taken out..?
How would that happen? A coalition of NATO suddenly takes over all of Russian airspace? Unlikely. BTW F-22s don't operate in pairs... operating in pairs requires a datalink which would give away their position... F-22s operate alone. They can receive data from a network but if they contribute to that network they reveal their location and presence.
Maybe an advanced Mig-31 replacement is actually the most cost effective way.
It doesn't need expensive stealth coatings or design... that reduces design and operational costs dramatically to start with.
It can use a huge AESA and IRST and it can use new engines for the PAK FA. It doesn't need to be super manouverable... speed and range are important so it will have a high fuel fraction along with powerful but fuel efficient engines.
The new engines for the PAK FA are variable cycle so using them in such a way to allow them to operate with bypass air acting like a ramjet should allow very high flight speeds without excessive reduction in range.
x2 to Medos' post.
In the S-400 and S-500 thread it is mentioned that there will be AAM versions of the S-500 for hitting ICBMs in mid course... you will need a big aircraft for that and speed is always important for interception.