Russia’s renowned Mikoyan Bureau – which alongside the Sukhoi Bureau has been since the 1950s Russia’s main centre of fighter aircraft design – has confirmed that since 2013 it has been working on a replacement for its heavy long range MiG-31 interceptor under a programme titled PAK-DP (“perspective aviation complex of long-range interceptor”).
Since the 1960s the Mikoyan Bureau has been producing two distinct and very different lines of fighter aircraft.
One is a line of austere and relatively cheap “light” aircraft – typically fighters – intended to complement the more advanced and expensive “heavy” aircraft produced by the Sukhoi Bureau. These are the “MiG fighters” most people associate with the MiG name, and which played such a huge role in regional conflicts during the Cold War.
Examples of such “light” MiG aircraft are the famous MiG-21, MiG-23 and MiG-29 fighters. The latest in this series is the new MiG-35.
The other line is by contrast a line of very large, very powerful and very sophisticated ultra high performance interceptors, of which so far there have been just two: the MiG-25, which entered service in 1970, and the MiG-31, which entered service in 1981. The proposed PAK-DP heavy interceptor will be an aircraft in this series.
Here it is important to say something about the role of these interceptors, which is completely different from that of any other series of fighter aircraft which have been designed and built anywhere else since the end of the Second World War.
The MiG-25, MiG-31 and the new PAK-DP fighter are not front line fighters or air superiority fighters intended to engage other fighters in air combat. Their mission is to provide air defence over Russia’s vast territory, especially in the great empty spaces of Russia’s Arctic north.
This is an immense area where climatic conditions are harsh and military bases are few, requiring very large and powerful aircraft with very advanced radar systems able to operate over great distances at very high speeds, so that they can intercept and destroy aerial targets such as cruise missiles and bombers before they penetrate deeply into the populated areas of Russia’s interior.
This specification determines the nature of these aircraft, though it should be said that they can also be very different from each other as they evolve to counter different threats.
For example, though the MiG-25 and the MiG-31 look similar because they share the same basic size and layout, they are actually completely different aircraft, designed for quite different missions.
The MiG-25 is a very high speed aircraft able to fly at very high altitudes at three times the speed of sound (Mach 3), making it the fastest combat aircraft ever to have entered service
Its mission is to intercept fast flying bombers and reconnaissance aircraft operating at high altitudes.
The MiG-31 by contrast has a slower though still high maximum speed but has a longer range and – unlike the MiG-25 – is capable of flying at supersonic speeds at lower altitudes.
Its primary task is to intercept and destroy cruise missiles.
Since cruise missiles tend to fly in groups, the MiG-31 has a gigantic and extremely powerful radar – the first airborne passive electronically scanned phased array (“PESA”) radar ever mounted on a combat aircraft – which is able to observe and track multiple airborne targets (ie. cruise missiles) simultaneously, and direct the MiG-31’s very advanced R-33 air to air missiles to destroy them.
It is not clear what the PAK-DP’s precise role is going to be, and the Russians have not produced much information about it.
However reports say that it will be able to fly at four times the speed of sound (Mach 4) – making it much faster than even the MiG-25 – and that it will be able to reach and operate in space, becoming in effect a spaceplane.
Concepts that combine aircraft and spacecraft in one aerospacecraft have existed since the 1960s. However if the reports are true the PAK-DP is the first serious attempt to achieve that sort of capability in a combat aerospacecraft.
Development of hypersonic missiles (ie. of missiles capable of reaching speeds of around Mach 5) using air breathing engines such as ramjets has recently been making dramatic progress, with Russia at the forefront of such development,for example with its new Zircon hypersonic anti-ship missile.
It is not surprising that this technology is now being used to build interceptor aircraft, which if not quite hypersonic will still be faster than any other manned combat aircraft to have entered service up to now.
Unmodified air breathing engines such as ramjets however obviously cannot operate in space. However various types of engines have been proposed for aerospacecraft, with one possibility being a rocket-based combined cycle engine.
The Mikoyan Bureau has experience testing spaceplanes with the MiG-105 Spiral tests of the 1970s and the BOR-5 tests of the 1980s. Assuming the Mikoyan Bureau has retained the data from these tests – as is all but certain – then no doubt it is putting it to use to develop the PAK-DP.
There remains a great deal of uncertainty about this aircraft. Though an air speed of Mach 4 and a spaceplane capability is certainly achievable with today’s technology, it is not clear what the purpose would be, or what sort of combat equipment such an aircraft would carry.
Perhaps claims that the aircraft will be capable of operating in space are exaggerated, and what is really meant is that the aircraft – like the MiG-25 – will operate at very high altitudes.
Before ending this discussion of this aircraft, a few further points can be made;
(1) there have been some suggestions that this is not a real project but is purely a Mikoyan Bureau design study. However the fact that the programme has an official designation – PAK-DP – shows that this is wrong, and that this is definitely a programme which is backed by the Ministry of Defence, and which is intended in time to produce a real aircraft;
(2) though the aircraft will have extreme performance, it is not a sixth generation aircraft follow on to the fifth generation SU-57. Rather it is a specialised interceptor of the MiG-25/MiG-31 series, which like all these aircraft does not truly fit in to the generation concept which is now being applied to fighter aircraft;
(3) an aircraft able to fly four times the speed of sound and possibly able to operate in space obviously cannot be stealthy. None of the MiG-25/MiG-31 series of heavy interceptors are stealthy. Since they are defence interceptors intended to operate almost entirely over Russian territory the need for them to be be stealthy to elude ground based air defences obviously does not exist;
(4) as an interceptor the aircraft is not primarily designed for the role of combatting other fighter aircraft. The aircraft which has been designed for that role is the SU-57. Like the MiG-25 and MiG-31 the PAK-DP is neither stealthy nor manoeuvrable, as the SU-57 is. Of course the highly advanced weapons system the PAK-DP will carry will make it capable of engaging other fighters in air combat if the need arises, as both the MiG-25 and the MiG-31 at various times have done. However that is not its primary role;
(5) though the PAK-DP is the follow-on to the MiG-31 in the series of heavy MiG interceptors which began in the 1970s with the MiG-25, the Mikoyan Bureau insists that it is not a modification of the MiG-31 but is a wholly new aircraft. That is obviously true. If this aircraft really is capable of reaching Mach 4 and operating in space then it cannot be a development of the MiG-31, which is not able to do either of these things;
(6) the “MiG-41” designation the media has given this aircraft is for the moment purely speculative. It is unlikely that the Ministry of Defence has given the aircraft a formal name yet.
This is obviously a top secret programme which has not yet reached the prototype stage. However the fact that the Russians are now openly talking about it suggests that a prototype may be about to be built.
Possibly with the SU-57’s tests about to end, and with the SU-57 soon to enter service, more funds are now being released for this programme, which may from this point start to accelerate.
If and when a prototype of this aircraft does appear, then it will finally become possible to move from speculation about this aircraft to hard fact.
In the meantime all that can be said with confidence is that this is a real programme, and that the performance specifications of the aircraft it is intended to produce are extremely ambitious by any standard.