Russia’s fifth generation SU-57 fighter flies successfully for first time with new engine

The Russian authorities have confirmed that on 5th December 2017 Russia’s new fifth generation SU-57 fighter jet carried out its first successful flight test with its new definitive Isdeliye 30 (ie. product 30) engine.

The successful flight test was confirmed by Russian Industry Minister Denis Manturov on Tuesday 5th December 2017

A successful flight with a new engine gives an additional boost to the program of the 5th generation fighter. This is proof of the high potential of Russian aircraft building, capable of creating highly intelligent advanced systems – a unique glider, innovative digital avionics and the latest engines

The Russians have released only limited information about the Isdeliye 30 engine.  However it is known to be significantly more powerful than the AL-41F1 engine which has been powering prototype and test versions of the SU-57 up to now.

Sputnik says that the Isdeliye 30 engine has a power rating (obviously with afterburner) of 19,000 kgf as compared with 15,000 kgf for the AL-41F1.

Other sources give power ratings for the Isdeliye 30 of 108 kN (24,086 lbf) of dry thrust and 178 kN (39,680 lbf) in afterburner, as compared with 93.1 kN (21,000 lbf) of dry thrust and 147.1 kN (33,067 lbf) in afterburner for the AL-41F1.

The new engine is also said to be significantly lighter than the older AL-41F1, and to have been designed by NPO Saturn in Rybinsk, the design bureau which traditionally provides the engines which power Russia’s Sukhoi fighters.

It has always been the intention that the Isdeliye 30 would be the SU-57’s definitive engine.

All discussions of the SU-57, and all comparisons of the SU-57’s performance with those of the US’s F-22 and F-35, which are based on the SU-57 flying with the older, heavier and less powerful AL-41F1 engine used by the test aircraft are misleading and invalid, and should be ignored.

The Russians claim that with the Isdeliye 30 engine the SU-57’s flight performance surpasses that of any other fifth generation fighter planned or in service, including the F-22 and the F-35, and there is no reason to doubt this.

The SU-57 programme has recently been the subject of much confusion stemming from a previous decision of the Russian Aerospace Forces to field the SU-57 with AL-41F1 engines until the new Isdeliye 30 engine became available from about 2022 .

The idea was that between now and 2022 the Russian Aerospace Forces would introduce the SU-57 into service with the AL-41F1 engine, and would then remove the AL-41F1 engines from the SU-57s when the new Isdeliye 30 engines became available so as to replace them with Isdeliye 30s.

That plan has now been dropped, with the current plan being to deliver SU-57s to the regiments from 2020 with the new Isdeliye 30 engine already installed, procuring only a small batch of 12 SU-57s with AL-41F1 engines until then, and buying more SU-35 and SU-30 fighters in the meantime.

Inevitably this decision has led to some talk that the SU-57 programme has run into difficulties, supposedly causing the SU-57’s entry into service to be delayed until 2020.

The reality is almost the exact opposite.

The reason the previous plan to deploy SU-57s with AL-41F1 engines has been dropped, and the SU-57’s entry into service has been postponed until 2020, is that progress with the Isdeliye 30 engine has been much faster expected, making it possible to field the SU-57 with the Isdeliye 30 much earlier than was previously expected.

Given that the Isdeliye 30 engine is now expected to be available as early as 2020, it makes no sense to field the SU-57 for just two years without this engine, which is why its entry into service has been put off until then.

In the meantime the Russian Aerospace Forces will acquire more of the excellent SU-35s and SU-30s.  The point is that the SU-35 and SU-30 also use the AL-41F1 engine.  Since the engine is the single most expensive part of a fighter aircraft, it would be extremely wasteful to field SU-57s with AL-41F1 engines, and then throw away these expensive engines just a few years later when new Isdeliye 30 engines become available.

By contrast building more SU-35s and SU-30s with AL-41F1 engines makes perfect sense since not only will this provide the Russian Aerospace Forces with more of these excellent aircraft, but these aircraft can remain in service with their AL-41F1 engines until sufficient numbers of SU-57s with Isdeliye 30 engines become available to replace them, probably some time in the late 2020s.

At that point these SU-35s and SU-30s can be sold abroad.

It is precisely this sort of cost-effective and rational approach to military procurement which explains why Russian defence costs are so much lower than those of the US.

The two big remaining mysteries about the Isdeliye 30 engine are (1) it’s real name (the designation Isdeliye 30 – “product 30” – is not a name at all); and (2) why its development has proved to be so rapid.

A possible explanation for the speed of its development is that the Isdeliye 30 engine may have its roots in an engine NPO Saturn is known to have started developing in 1982 for the aborted MiG 1.44 project.

Confusingly this engine was also called the AL-41, though it is a completely different engine from the AL-41F1 engine which currently powers the SU-35 and SU-30 and the test versions of the SU-57.

The AL-41F1 engine is in fact an advanced version of the AL-31 engine developed by NPO Saturn in the 1970s for the SU-27, which first entered service in 1981.  NPO Saturn’s decision to call this engine AL-41F1, though obviously intended to hark back to the entirely different AL-41 of the 1980s, is actually somewhat misleading, since it has obscured the AL-41F1’s origins in the earlier AL-31.

The AL-41 engine that was to have powered the MiG 1.44 is claimed by some sources to have had a power rating of 39,680 lbf in afterburner, which is exactly the same as the power rating in afterburner some sources give for the Isdeliye 30.  That suggests that the two engines are related to each other, with the later engine possibly taking some of its design cues and concepts from the earlier engine.

If so, then given that considerable work was apparently done on the AL-41 engine in the 1980s – including apparently a test flight on a MiG-25 aircraft – that might explain why the Isdeliye 30‘s development has been so fast.

If the Isdeliye 30 ultimately stems from the AL-41, that might also explain why the Russians have not yet disclosed its true name.  Conceivably it too might originally have been “AL-41”.

The Isdeliye 30 engine will not however be the same engine as the AL-41 engine of the 1980s.  The period since the 1980s has witnessed huge advances in aircraft engine technology.  Even if NPO Saturn has taken the AL-41 as its starting point for the Isdeliye 30 engine, the Isdeliye 30 engine will certainly benefit from these advances and any resemblance between the Isdeliye 30 and the AL-41 of the 1980s will be superficial.

Doubtless it is these technological advances which explain why the Isdeliye 30 is said to be so much lighter than existing engines, with some reports saying that it is a third lighter than the AL-41F1.

Regardless of the design history of the Isdeliye 30, the fact that it is now on flight test after what looks like a very rapid and trouble free design process is a considerable achievement .

It is a further sign of Russia’s recovery, not just as a military but also as a technological and industrial power.