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    Il-106/PAK VTA Heavy transport

    kvs
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    Post  kvs on Fri Aug 07, 2020 3:37 pm

    It would be nice to see actual estimates of the gain from the body lift. It looks to me like it is overhyped.

    Rodion_Romanovic
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    Post  Rodion_Romanovic on Fri Aug 07, 2020 4:39 pm

    kvs wrote:It would be nice to see actual estimates of the gain from the body lift.  It looks to me like it is overhyped.  


    By the way an oval fuselage shape was also proposed for the Medium Range widebody airliner frigate ecojet, which development has been frozen due to the lack of a modern engine in this thrust range...

    Il-106/PAK VTA Heavy transport  - Page 5 Frigate_ecojet_1


    LMSF wrote:By the development schedule and due to the need to replace the D-18T I think it is fairly reasonable to think it could be a further development of the NK-32-2 with increased bypass ratio. The original engine has already the right size and with the proper materials and modern technologies it should be quite OK by now, even if stage count or general design is not 100% modern. It would serve as a first step towards the production of newer, clean sheet designs.
    Well a large bypass turbofan engine based on the NK32 will need for sure a new large fan, and consequently a bigger LP turbine (with a higher number of stages, also because the fan LP shaft speed will be lower).
    Probably it will require also some changes in the IP compressor.

    Some changes in materials (the nickel based superalloys used in the HP turbine of modern engines grant a considerable improvement in operating temperatures, compared with the nickel superalloys used in engines that entered service in the 1980s...), cooling and minor redesign of HP compressor and  HP Turbine could be also needed, but ideally for those improvements they can piggyback on the improvement planned for NK32-02.


    If the same engine need also to be used for civilian applications, a new combustor more respecting of new emission rules will also be needed.


    I do not know if there is cooperation between Perm (Aviadvigatel) and Samara (Kutznetov), but it would be ideal if they could reuse some of the design solutions, technologies and lessons learned from PD14 and PD35.

    In addition, the development of dedicated nacelle and pylon also take their time, but it is not the highest technical challenge for this engine...
    kvs
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    Post  kvs on Fri Aug 07, 2020 5:32 pm

    I knew, it is a way to get more passengers inside and to maybe gain some percentage in fuel savings which is important for the
    civilian airlines. But the oval body section is really not that different from a circular one. A lifting body needs more surface to
    volume to be effective. So a flying wing or delta-wing is more effective. But delta wings are only used for high speed aircraft.

    LMFS
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    Post  LMFS on Fri Aug 07, 2020 6:26 pm

    kvs wrote:I knew, it is a way to get more passengers inside and to maybe gain some percentage in fuel savings which is important for the
    civilian airlines.   But the oval body section is really not that different from a circular one.    A lifting body needs more surface to
    volume to be effective.    So a flying wing or delta-wing is more effective. But delta wings are only used for high speed aircraft.

    It works very well under high angles of attack and apparently gets better L/D than conventional layouts at operational speeds and altitudes. The main problem is to create a non-cylindrical pressurized fuselage that is not substantially heavier, but apparently Myasishchev had managed to develop the technological processes needed. I didn't knew the history of this idea, but it is very interesting, quite old in fact. It would be great if Russia could put it to good use finally.

    There are some details here:

    https://bmpd.livejournal.com/2773002.html

    @Rodion_Romanovic:

    yes surely the LP part of the engine needs redesign, but if the gas generator can be taken from the NK-32-02 they would save a lot of work, I think it could be a smart move. I would expect of course engine control, ignition system, materials in general to be updated for better reliability and thermal efficiency. For instance TIT changed from 1665 to 1745K between AL-31F and 41F1S, in RD33 family was 1680 to 1720K in the new MK, I would expect something similar may happen with the NK-32 just due to technological upgrades (1630k TIT now if my data are correct). They said the range would improve ca. 7% so that means the engine is more efficient now, that increase is in line with what we see from other soviet engines that have been updated recently.
    GarryB
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    Post  GarryB on Sat Aug 08, 2020 7:35 am

    The article linked mentions that there is no engine in that class yet.. as if forgetting the engine of the Pak-Da (unless they do not want to use it for some reasons.... e.g. not to compromise the technology used in a strategic bomber... but that would be strange, since the D30 engine used on the tu134 airliner and on original il76 was modified to make the d30f6 engine for the mig31 interceptor.... (but in that case the development went on the other direction...e.g. from civilian engine to military engine)

    Actually a few years ago I remember making the same comment regarding the Il-76 D-30 engine (which is also used on the A-42 Albatross amphibious aircraft) and the D-30 for the MiG-31, but Vlad mentioned they are not the same engine... they just have a similar designation... I remember checking and of course he was right.

    Note the D-30 is also a 122mm towed artillery piece too.

    The D-30KP is the engines used for the Il-76 and other civilian types and is a high bypass turbofan engine for subsonic aircraft, while the D-30F6 is an afterburning bypass turbojet designed for supersonic aircraft like the MiG-31 and was also used with the experimental S-37 aircraft too.

    I seem to remember a British expert mentioning they were the same, which I repeated here without really thinking about it for myself...

    PAK VTA will be equipped with four turbojet engines with a thrust of 20-25 thousand kgf. They will give the aircraft the ability to fly at altitudes up to 12 km and a cruising speed of 850 km / h. However, there was no information about the design of such an engine (PD-23?), It has yet to be created. The promising PD-35, which is now being developed, is indicated as a candidate in the documentation.

    I doubt very much they will be turbojets.. vastly more likely they will be high bypass turbofans... for efficient long range subsonic flight.

    (And finally, even if they use the Pak-da engine and keep the same fan size also on the pak-vta/ il-106, they will need a different nacelle and pylon....)

    With a flying wing design the engines on the PAK DA will be internal...

    some of the older info I read about a replacement engine for the An-124 based on a NK32 core mentioned that due to trying to adapt the engine to the Nacelles and pylon of the D18T, the preliminary data showed it having limited bypass ratio and worse consumption than the D18T, so not having real benefits of a better engine core and higher temperatures, but probably it was still about something done in cooperation with Motor Sich, so the ukrainian firm was not really working on the best interests of Russia

    Or maybe the article was written by someone from Motor Sich and was a bit bitter about it all...

    It is interesting because the cylindrical shape is best from a structural point of view, but it seems they get a lot of lift from that oval shape

    Agreed, but with Submarine design the strongest shape is a sphere, so inside the deepest diving subs are sphere shaped inner hulls linked together with a cigar shaped outer hull... so circle for pressure and cigar for hydrodynamics...

    I suspect a similar solution for an aircraft where cylinder for strength and aerodynamics is being replaced with essentially a super thick wing form for strength but also volume as well as aerodynamics...

    It would be nice to see actual estimates of the gain from the body lift. It looks to me like it is overhyped.

    It is actually significant on the MiG-29/35 and the Su-27/35 family with the engine nozzles adding to the effect.

    If you take a big plastic back like a shopping bag that has been flattened and is empty and try to fully inflate it by blowing with your mouth with the bag pressed around your lips you can't fill it in one blow because your lungs don't contain enough gas to fill the bag. If you hold the bag further from your face and blow into it however air around your face gets caught in the airflow you create and a lot more gas goes into the bag and it fills up much more efficiently.

    I would say the design with the engines above the tail maximise that effect the most with the added bonus of giving better rough field performance with the risk of dirt and dust entering the engines greatly reduced because of their position on the aircraft.

    Would not be 100% effective of course and would make the engines a pain in the ass to service unless there is a walkway there... in which case it might be easier than servicing underwing engine pods on the ground.

    Rodion_Romanovic
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    Post  Rodion_Romanovic on Sat Aug 08, 2020 11:03 am

    GarryB wrote:
    The article linked mentions that there is no engine in that class yet.. as if forgetting the engine of the Pak-Da (unless they do not want to use it for some reasons.... e.g. not to compromise the technology used in a strategic bomber... but that would be strange, since the D30 engine used on the tu134 airliner and on original il76 was modified to make the d30f6 engine for the mig31 interceptor.... (but in that case the development went on the other direction...e.g. from civilian engine to military engine)

    Actually a few years ago I remember making the same comment regarding the Il-76 D-30 engine (which is also used on the A-42 Albatross amphibious aircraft) and the D-30 for the MiG-31, but Vlad mentioned they are not the same engine... they just have a similar designation... I remember checking and of course he was right.

    Note the D-30 is also a 122mm towed artillery piece too.

    The D-30KP is the engines used for the Il-76 and other civilian types and is a high bypass turbofan engine for subsonic aircraft, while the D-30F6 is an afterburning bypass turbojet designed for supersonic aircraft like the MiG-31 and was also used with the experimental S-37 aircraft too.

    I seem to remember a British expert mentioning th
    ey were the same, which I repeated here without really thinking about it for myself...
    I thought they are not the same, but they come from a common development (keeping the core basic design), and that was the reason of the common designation[/quote]


    GarryB wrote:
    (And finally, even if they use the Pak-da engine and keep the same fan size also on the pak-vta/ il-106, they will need a different nacelle and pylon....)

    With a flying wing design the engines on the PAK DA will be internal...
    yeah, I meant that should they decide to reuse the Pak-Da engine for the il-106 even if they could keep most of the engine, they would need a new nacelle, new mounts for installation under the wing for it, and possibly to reinforce some of the core components (if the mounts that connect the engine to the pylon are attached to those)...

    By the way, an interesting fact is that the nacelle make a considerable part of a powerplant cost (the powerplant Us the engine plus the nacelle plus some additional equipment) and (at least for civilian engines for passengers aircrafts) the nacelles are not certified together with the engine (engines are certified under EASA CS-E in Europe and under FAR-33 in US) but together with the aircraft (CS-25 or FAR-25) and often they are developed and build by a different supplier (e.g. often Safran make the nacelles for both GE and RR engines mounted on Boeing aircrafts
    Rodion_Romanovic
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    Post  Rodion_Romanovic on Thu Aug 27, 2020 12:21 pm

    https://iz.ru/1043474/anton-lavrov-roman-kretcul/gruzovik-vysokogo-poleta-rossiia-gotovit-zamenu-124-i-22

    The preliminary design of the Pak-VTA/new Il-106 should be ready by December 2020 .. and the next phase of design will start in 2021...

    If so 5 years could be realistic for the introduction of the aircraft in the fleet...

    It depends also on when they will realise the first experimental aircraft for the ground and flight tests...
    It will be probably at least 3 to 4 years from the first flight test to the entry into service...



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