PAK DP prospective long-range interceptor

The MiG-31 didn't use Klimov engines. It used engines based on the D-30 engine core. The core was designed by Aviadvigatel from Perm but the D-30F6 engine itself was made at Rybinsk i.e. at Saturn. The guy who designed the AL-41 at Saturn used to work in the D-30F6 engine team. So its not like MiG are wedded to Klimov or something like that.

The MiG 1.44 also used Saturn engines.

All very true, but what I am saying is that it is not guaranteed that the engine will be Saturn based, because other companies make engines and an engine for a mach 4.2 interceptor has different flight requirements to an engine used on the Su-57 or any other type already in service.

Will be interesting if they decide to make a drone with this new engine... the high speed flight comes from either a ramjet or a scramjet so the jet engine used for takeoff and landing doesn't need to be anything special because if it spends most of its time at very high speed the conventional jet engine will only be used for takeoffs and landings. Most of the cruising flight will be ramjet or scramjet.

The engine core is the high pressure section and the gas generator. If they modified a civilian airliner engine (D-30) into the MiG-31's main engine (D-30F6) by changing the low pressure section, and adding an afterburner, they can certainly do the same thing with the Al-51 engine core.

They could also develop a new engine type specifically for very high speed aircraft that could be used for new interceptors, but also applied to other aircraft like an upgrade for the Tu-160 further down the track that might allow supercruising or other useful features.

The idea the PAK DP is supposed to fly at Mach 4 or 5 is a mistake by journalists. I remember the original press releases with actual comments by politicians in the security council supervising the program. The PAK DP is meant to have similar performance envelope to the MiG-31 but will be able to fire hypersonic weapons. It isn't the aircraft that is hypersonic but the weapons.

Mach 4.2 is not hypersonic, and the current speed of the MiG-31 is Mach 2.8, and if you multiply the speed of the MiG-31 by 1.5 then you get mach 4.2.

Coincidence?

A 50% improvement in flight speed might be a goal... it is certainly a very strange speed in terms of known propulsion options... with ramjets being up to mach 5 or so and scramjets able to operate at much faster speeds it is a strange number to just come up with.

That makes sense to me. It will not only be pointless to develop a Mach 4+ PAK DP but extremely expensive as well. As I've said before - it will be much easier/cheaper to develop hypersonic missiles instead.

With ramjet propulsion it shouldn't actually have to be very expensive at all, though it is going to be a big aircraft and carry lots of fuel.

If they don't want it to go faster then the new engines they are developing for the Tu-160M could be fitted to the Tu-22M3M with several modifications it could carry an enormous nose mounted radar and its belly could be covered in semi recessed launch positions for a range of different long range air to air missiles and also anti radiation missiles if you want to use it for a SEAD role. The payload capacity means it can carry more bombs than you could probably fit on the aircraft, and some new technology wing designs to replace the swing wing with something more modern... there is enormous potential for growth... start by removing two crewmen and adding fuel or weapon bay internal capacity... Maybe even a dorsally mounted ramjet engine at the base of the vertical tail so at top speed the air intakes for the two engines close completely and it s ramjet or scramjet powered in flight...

So it can be either a plane that take the existing concept into 5 gen or instead something completely new with quasi hypersonic performances but at the expense of a much longer developmental phase.

They are talking about stealth too, which seems a bit redundant to me... perhaps it might be a photonic radar debut platform... remember the MiG-31 was the first fighter/interceptor to carry an electronically scanned radar, so maybe the MiG-41 might be the first aircraft to deploy a new technology radar again.

The Mach 4.2 might be a 1.5 times increase in flight speed over the MiG-31 (which could certainly be achieved with new engines), or perhaps 5,200km/h which is mach 4.2 at 20 degrees C at sea level... note that mach 2.83 is 3,500km/h and 1.5 times that speed is 5,250km/h, which is as close to mach 4.2 as worth worrying about.

It will certainly be quite a feat for the Soviets Russians and it would in all likelihood be possible to produce a Mac4+ interceptor. I guess we will have to wait and see, but I think 200 Mach 3 Mig-41's would be far more useful as defenders of the Motherland than 20 Mach 4 Mig-41's.

I don't think a mach 4 MiG-41 would be ten times the price of a Mach 3 MiG-41. The Russians have lots of experience with ramjet propelled missiles and some experience with scramjet propelled missiles now too so I think using the correct propulsion type achieving such speeds is really only limited by their capacity to design the right shapes and develop and produce the right materials to allow it to happen and I honestly think their design and materials technology is ready for Mach 4 planes.

Before jet engines flying at supersonic speeds was ridiculous, and then when the first jet engines were developed they were unreliable and not very fuel efficient, but over time they matured and got massively more powerful and became relatively fuel efficient to the point where they were a viable alternative on subsonic planes with high bypass designs, but also the only game in town when it came to supersonic flight (other that the dangerous and fuel inefficient rocket options).

New types of jet engine open up lower speed with turboprops and even pulsejets for drones and cruise missiles, through to supersonic speeds for turbojets and turbofans up to about mach 2.8 and then they start to become less effective and tend to damage themselves... a bit like the rubber tire on your car being driven on a salt lake race track at 200 miles per hour... it will rip itself apart.

But a ramjet does not have blades or shafts, just airflow and fuel burning in that airflow, and a scramjet is even better because that airflow can be supersonic so you don't need to slow the airflow down to burn the fuel.

The SR-71 could fly at up to mach 3.4 because its jet engines operated in a ramjet mode the blades in the jet engines were idling and not providing any thrust at all, it was bypass air in the turbofan design that operated as a ramjet that propelled the aircraft and maintained that speed.

There was nothing otherwise amazing about those engines... no super technology, no special materials from UFOs. Just two turbofans that operated as ramjets at higher flight speeds.

Keep in mind, that the speed of a carrier strongly corresponds to the speed of the missile.
The high release profile does magic to the operational range of the missile.

A mach 4 aircraft would probably be able to operate at 30-35km altitude, which for a solid fuelled missile like the Kinzhal would probably add quite a distance to its flight range without any other modification... the rocket is based on the Iskander so the first minutes of rocket fuel burn is to get the 4 ton missile off the ground and climbing and accelerating to flight speed. The flight range can be increased three fold by carrying it to perhaps 18km and mach 2.5 because launching from that speed and that altitude all that energy from the rocket motor goes into further increasing the altitude and flight speed, meaning it can climb to even thinner air and accelerate to much higher flight speeds which at the higher altitudes it can maintain for longer... meaning it can reach much further.

It is essentially what they do to ICBMs... most of which are three stage rockets... in the case of the Iskander using the MiG-31K as the first stage extends the effective range of the missile from 500km to 2,000km.

Being launched from higher and faster means it can go further... of course some air breathing attack missiles or glide bomb kits might not work at that speed, but they developed custom designed bombs for the MiG-25RB and the MiG-31RB so they could handle flying at mach 2.5 for long periods without spontaneously exploding... they developed special tail fuses so they could be safely carried and dropped at that speed.

Note there is no high speed version of the AA-8 AAM so when MiG-31s carried them they could not fly at top speed or they would ruin them.

Where do you get that from? I could be wrong but that sounds to me like typical Western propaganda.

I agree we should be skeptical... ignorant western "experts" made up all sorts of shit when they didn't know or didn't understand.

However it was found that the R-27 missile was not designed to withstand the kinetic heat of the high Mach number typical of the Mig-25.

The excuse given, I seem to remember for the R-60 was that while in flight it reached supersonic speeds, it did not do so for 13 minutes at a time like it would on a MiG-31 flying 750km out to a threat and then being launched at that threat. The book was about the MiG-31 and didn't mention the MiG-25, but I would assume the same problems would apply.

I can't remember where I read this fact/myth, it could have been talking about R-60s specifically in regard to MiG-31s or the R-40TD. Pretty sure it was in a book specifically about the MiG-31 but there are a lot of those.

I will have a look and see if I can find it.

My understanding was that the big missiles like the R-40 and R-33 and now R-37 were intended for heavy targets so big warheads would be needed, but that the R-27 with its improved accuracy could also deal with heavy targets by actually hitting the targets instead of exploding near them.

Equally the heavy missile has smart fuses that directed the blast and fragments in the direction of the target as detected on detonation.

Like a claymore mine.

My understanding of carrying R-60s and R-73s was after the heavy missiles had been fired for use against any cruise missiles that the targets had launched before being hit, where the aircraft chases down the cruise missile threats and hits them with these two types... both of which would be very effective in the role.

The R-60 seemed sensible to me because it was a self defence missile for use by not particularly manouverable aircraft defending themselves from other threats, but then the high offboresight capability of the R-73 actually was even better from a platform that is not going to be pulling high g turns with enemy aircraft.

They kept the R-40TDs in service because there was no IR model of the R-33 and having a big IR AAM was useful for chasing down receding targets as radar homing is not so effective against retreating targets, while a receeding target, especially one that is legging it with full AB, is a good target for IR guided weapons.