GarryB wrote:An interceptor needs to get to its intercept point as quickly as it can... the difference between Mach 2.84 and Mach 1.8 super cruise might be the difference between shooting down 10 B-1Bs, or having to take on 10 B-1Bs plus the 220 cruise missiles they just launched...
Who is talking about reducing speed of the plane?
These are charactristics of the D-30F-6 engine:
Maximal thrust (H=0, M=0, t=15°C) 9500 kp (93,16 kN)
Full afterburner thrust (H=0, M=0) 15500 kp (152 kN)
Specific fuel consupmtion on maximal thrust 0,72 kg.kp-1.h-1
Specific fuel consumption with full afterburner 1,9 kg.kp-1.h-1
Maximal turbine inlet temperature 1387 °C
Air flow 150 kg.s-1
Pressure ratio on low pressure compressor 3
Pressure ratio on high pressure compressor 7,05
Overall pressure ratio 21,15
Bypass ratio 0,57
Inlet diameter 1020 mm
Length 7040 mm
Dry mass 2416 kg
Maximal operation speed M=2,83
This is a huge engine with levels of thrust smaller products already reach (F119 indeed, AL-41F1 is close). It is even larger than the F135, which is not a supercruising engine and still produces ca. 128 kN mil. thrust and ca. 191 kN with AB. I don't think it is too risky to say that lower bypass or two stage VCE with today's technology could reach levels of thrust close to 150 kN in military settings. In fact the izd. 20 was tested on the MiG-25, supposedly 176 kN max thrust, I didn't manage to find dry thrust, but in any case it was an already designed supercruising engine
with the right size, if you know what I mean...
Operation in afterburner has advantages at high altitudes because in mil settings the power of the turbine is being extracted at the same level while the thrust itself decreases with increasing altitude so in the end there is little left for propulsion. That creates an additional difficulty to reach AB thrust in mil settings, but even if it was not possible to cruise a 2.8 M but 2.3 or 2.5, it would be already a huge advantage in fuel consumption.
Look at the TSFC in dry vs. wet modes above, there is a 2.6 factor between them which would be translated almost directly into range. So you cannot fly 2.35 M to 700 km but to what, >1000 miles? And therefore allows to attack carriers even before they release long range missiles like AGM-158 JASSM-ER, or to substantially extend the range of Kinzhal attack missions too... it is a massive improvement, one that would put NATO again on their back foot, threatening their assets theatre-wide.
BTW another possible optimization of the MiG-31 could be to unify the K and BM versions, so it is not necessary to divert airframes from air defence to attack roles and vice-versa. Work on airframe + re-engining would make it possible, since the K got its radar removed and fuel increased due to the needs o the new mission, so a more powerful engine with lower fuel consumption is a big deal. They were not exaggerating when they said the modernization potential of the plane was far from exhausted...
For an interceptor the best propulsion would be a combined bypass turbofan with a ramjet or scramjet...
The YF-120 was modified in such way, since it was a VCE this was already implicitly possible in the original design. They said it could reach 4.1 M... which is shockingly similar to the speed announced for PAK-DP (4.2 M) and, to me, it makes clear what solutions the Russians are considering. Since izd. 20 was already done and probably izd. 30 is its continuation, an ABVCE based on it is only a logical following step...
The YF120 was also proposed as the basis for a more exotic engine, the Turbine-Based Combined Cycle (TBCC) engine that was to be used in demonstrator aircraft like the X-43B and future hypersonic aircraft. Specifically, the YF120 was to be the basis for the Revolutionary Turbine Accelerator (RTA-1). The variable cycle technology used in the YF120 would be extended to not only turn the engine into a turbojet but also into a ramjet. In that mode all airflow would bypass the core and be diverted into the afterburner-like "hyperburner" where it would be combusted like a ramjet. This proposed engine was to accelerate from 0 to Mach 4.1 (at 56,000 ft) in eight minutes.
But you know they will...
Sure, since Maidan was Putin's fault, the dementia of US politicians must be his fault too!!
I would say they are repeating what they did with the Blackjack... the difference is that while they only had 16 odd Blackjacks available so they had to restart production, with the MiG-31 what they were short of was the hot sections of the engines... which are the bits that wear out. Building new hot section bits should allow existing engines to be brought back to service and use meaning all those MiGs in storage can be used if needed... together with upgrades and overhauls to existing models they should be able to spend extra time getting the MiG-41 to where it needs to be... the US is funding hypersonic weapons... so clearly a good focus for the MiG-41 is to deal with such threats and also potentially launch weapons and satellites out of the atmosphere...
Exactly. New capabilities are needed no doubt, a very long range / very high speed performance on PAK-DP would benefit from a very big airframe capable of providing high performance weapons with additional launch energy, which is critical for operations against very high speed threats or in near space. That is not necessary for other roles the MiG-31 is covering now. The repair of the D-30F6 was already solved, and as said before, one of the main problems they found and that significantly delayed their capability to overhaul and airframes was de deviations from spec that they find in the planes. This forces them to rework the pieces before installing them, which is a very time consuming and very ineffective effort. With 3D printing they can tackle that problem much better.
They could be the inner layer... the inner ring defence, with the faster likely longer ranged MiG-41 being an outer layer of defence.
That is a good idea, and one that is also reminiscent of the PAK-DA / Tu-160 case, with different performances that actually allow to think about parallel operation in complementary roles...