Putin discusses big Russian engine for civil aircraft

The meeting on 23rd September 2017 between President Putin and two of his key economic officials, Economics Minister Oreshkin and Industry Minister Manturov, provided an interesting insight into Russian civil and military aerospace projects.

Here is the exchange between Putin and Manturov as reported by the Kremlin’s website

Vladimir Putin: I have two specific questions regarding the Il-114 regional aircraft and the 35-tonne increase in aircraft engine capacity. How are these projects proceeding, are there any difficulties and what has to be done to support these projects?

Denis Manturov: Mr President, as for the projects that you ordered us to implement last year: these include a new version of Il-96–400, the Il-114, the PD-35 engine, the TB7-117 engine for the Il-114 aircraft that will also be used for the cargo version of the Il-112, and for the Mi-38 helicopter. These projects are proceeding on schedule. We have the funding allocated for 2018, and are now working with the Ministry of Finance to seek funding for 2019–2020. This has yet to be resolved. But as regards 2018, the required funding has been provided in full.

Vladimir Putin: As for 2019–2020 funding, these programmes are important and needed, and everyone expects them to be implemented. Let us arrange it this way: we have funded the spending from Rosneftegaz through 2018, while the expenses for 2019–2020 have to be paid for from the budget. I will arrange for this with the Ministry of Finance.

Denis Manturov: Thank you very much. We will definitely build these aircraft and, most importantly, the engine.

All of these projects are well known save for the big PD-35 aircraft project, which as the exchange between Putin and Manturov makes clear, is however the priority project attracting the most funding.

The fact that Russia was working on a big 30 to 35 tonne aircraft engine to replace the Ukrainian D-18 engine of the Soviet era has been known about since 2015.  It was discussed, in vague and elliptical language, during a meeting in the Kremlin on 3rd August 2015 between Russian President Putin and Dmitry Rogozin, the Russian Deputy Minister in overall charge of Russia’s defence industries.  This is what Rogozin said to Putin during that meeting

Following your instruction, we carried out unprecedented work to restore production in Samara of NK-32 engines for our Tu-160 strategic bomber.

Having analysed the situation and spoken with the designers, we came up with an interesting solution. We think we should look at the issue not as a single priority goal tied to the development of particular models of aircraft, because it takes longer (from three to five years) to develop an engine than to develop a plane. We believe we need to look ahead and create a reserve for the future.

Our solution is based on the work underway at Perm Motors, where we want to develop a gas-generator based engine that would allow us to expand our engine range for aircraft with a take-off thrust of 9 to 16 tonnes.

This would enable us to eventually replace the engines on the new Sukhoi Superjet, develop a replacement for the Ukrainian engines our Mi-26 helicopters are using, and provide engines for the future Russian-Chinese heavy helicopter and a larger version of the MS-21 for 210 passengers.

We can achieve the same goal by enlarging the NK-32 engine’s gas generator. In other words, we can do what we are already doing now for engines for our strategic bombers, adapting them for military transport aircraft and for the Russian-Chinese heavy long-haul wide-bodied aircraft. I have already told our Chinese colleagues that we can do this work independently of any third parties, and they reacted positively to this.

(bold italics added)

Rogozin’s words, though vague, clearly referred to the PD-30, a Kuznetsov design based on the military NK-32 engine which powers Russia’s TU-160 and TU-22M3 supersonic bombers.  Here is how that engine was described in an article dated 4th May 2012

The PD30 is portrayed as a low-risk project through extensive use of off-the-shelf components and technologies proven on other projects. However, it features many innovations: a high-power (50,000 hp, 99 percent efficiency) reduction gearbox between fan and turbine, wide-chord hollow (honeycomb) fan blades, very-low-emission combustor, mono-crystal blades, blisks in the HP compressor and booster, chevron nozzle, all-composite nacelle, intake and thrust reverser, and Fadec.

When fitted to the An-124-300, the PD30 would develop 29.5 metric tons (65,000 pounds) of thrust for takeoff and 5.7 to 6.2 metric tons (12,560- to 13,670 pounds) when cruising at 11,000 meters (36,000 feet). Low specific fuel consumption (SFC) of 0.535-0.548 lb/lb/hr is achieved through a high bypass ratio (between 7.65 and 8.7), while gas temperatures are kept at 1,433K at maximum continuous power.

By comparison, the D18T series 5 delivers 27.85 metric tons (61,400 pounds) thrust at takeoff and 6.28 metric tons (13,840 pounds) in cruise, with an SFC of 0.541 lb/lb/hr. At 5,140 kg (11,330 pounds), the PD30 weighs 560 kg (1,235 pounds) less than the D18T. Kuznetsov says that the PD30 has a similar performance to the Rolls-Royce Trent series, while running at lower temperatures for higher margins and lower emission levels.

The centerpiece of the PD30 project is the use of a “modified baseline gas generator” from the improved NK32 turbofan that powers the Tupolev Tu-160 strategic bomber. Production of the NK32 was restarted recently, with some 40 engines already manufactured. The fleet leader has logged more than 3,500 flight hours. The modified gas generator is undergoing bench testing, and has so far amassed 1,000 hours. Kuznetsov says its industrial turbine NK36ST that is derived from NK32 has logged 25,000 hours without removal, while running continuously at 1,520K.

(bold italics added)

The fact that the proposed PD-30 is reported to use a “modified baseline gas generator” derived from the NK-32 makes it fairly clear that this was the engine Rogozin was referring to.

The PD-35 – the engine discussed by Putin and Manturov in the Kremlin – is a wholly different design, unrelated to the NK-32, which at 35 tonnes thrust is significantly more powerful than the 30 tonnes thrust PD-30, or indeed the 27 tonnes thrust of the earlier Ukrainian D-18, which the new Russian big engine is intended to replace.

Some details of the PD-35 were given in an article dated 1st December 2015, which disclosed that the engine is being developed by the Perm based Aviagdivatel enterprise and that it draws on the technology of the civil PD-14 (the engine which powers Russia’s new MC-21 narrow body airliner) rather than of the NK-32.

It is, however, the 35-ton PD-35 that will become the baseline model for the new enlarge family of powerplants, says Igor Maximov, the PD family chief designer at the development and prouction plant Aviadvigatel. For that new powerplant, the core of the PD-14 will received an additional stage at the discharge of the high-pressure compressor. As a result, the total number of stages at the PD-35 compressor and turbine will be 9+2, and the high-pressure compressor intake diameter will be 815 mm, as compared to the PD-14’s 582 mm. The engine’s fan diameter will reportedly be 3,100 mm; the engine will be over 8 m long, and will weigh around 8 tons.

At least two more powerplants will be developed from the PD-35: the 28-ton PD-28 and the 24-ton PD-24. The larger two of the engine family will be offered for next-generation two- and four-engine widebodies, whereas the smallest one will be mounted on short-haul widebody airliners and a heavy military transport, says Aviadvigatel’s presentation.

One feasible application for the smallest of the powerplants would be the widebody airliner under joint development by Russia’s United Aircraft Corporation and China’s COMAC. The 280-seat aircraft, codenamed C929, is scheduled to make its maiden flight in 2021 and enter service in 2025.

This same article from December 2015 however speaks of the PD-30 engine programme still continuing

Belousov notes that a similar powerplant program is being looked into at Samara-based Kuznetsov Company (also part of UEC), which is considering developing engines with up to 35 t thrust from the NK-32 turbojet engine currently powering Tupolev Tu-160 strategic bombers. According to Belousov, both companies are looking at the classic layout and the geared-turbofan possibility.

In their discussion on 23rd September 2017 Putin and Manturov made no mention of the PD-30.  Possibly following comparisons between the two engines a decision was made to discontinue the PD-30 so as to focus on the more advanced and more powerful PD-35.

Alternatively, since unlike the PD-30 (which has a five year start) development of the PD-35 is apparently still in its early design stages, with the engine not expected to enter production for at least a further six years, it may be that development of both engines is underway concurrently, with the less sophisticated and more conservative PD-30 intended for use as an interim engine until the more advanced and more powerful PD-35 becomes available in quantity after the mid 2020s.

The article about the PD-35 shows that not just one engine but a whole family of engines are being developed to complement the family of smaller engines being developed on the basis of the PD-14.  Apparently there will be three related engines: the base line 35 tonnes thrust PD-35 engine, and two smaller engines, the PD-28 and PD-24, of 28 and 24 tonnes thrust respectively.

The PD-24 is apparently intended for a “heavy military transport” (almost certainly this is the revived Ilyushin-106 project) as well as for various civil aircraft projects.

The bigger PD-28 is apparently also intended for various civil aircraft projects, but may also possibly be intended for use by a future replacement of the AN-124 heavy transport.

Here I will express my view that contrary to what is said in the article I think it unlikely that the Russians are planning any four engine civil widebodies beyond the IL-96-400, and that all future Russian civil aircraft projects including those being developed in collaboration with China – apart conceivably for a superheavy airliner (see below) – will be two engine designs.

There is no information of the use of the PD-35 in any planned aircraft, though the high priority given to the PD-35 engine project by Putin and Manturov shows that plans for such an aircraft undoubtedly exist.

Possibly it is intended for a big two engine long range intercontinental civil airliner along the lines of the Airbus A350 to replace the IL-96-400, which must be treated as a stop-gap until more modern aircraft become available.

Though I am not sure whether Russia needs a long range superheavy four engine civil aircraft in the class of Airbus A380, China might do so, and if so the PD-35 would also provide an engine sufficiently powerful for it.  It may even be demand from China for such an engine that is ultimately the driving force for the PD-35 project.

The PD-35 engine could also conceivably be used to power a superheavy transport to replace the AN-225, the sole example of which is now operated by Ukraine.

Unlike superheavy civil aircraft such as the Airbus A380, Russia arguably does need such a superheavy transport aircraft.  The AN-225 after all was designed by the Antonov bureau in the 1970s when Ukraine was part of the USSR to meet (Soviet) Russian needs.

Four PD-35 engines would provide sufficient power for such an aircraft, whilst providing a simpler and more elegant design solution than the complicated six engine arrangement used by the AN-225.