Two planned new models.
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Thread: Two planned new models.

  1. #1

    Two planned new models.

    Hello folks,
    There are two Russian airplanes that have caught my attention to build models
    of in the near future: The Il-2 Shturmovik and the Petlyakov PE-2.

    IL-2 Shturmovik
    ---------------
    The Il-2 Shturmovik fighter seems to have been quite a remarkable WWII fighter,
    tuned for low-altitude ground attack. It was difficult to shoot down and posed
    a strong rival to the Luftwaffe. There is only one fying example nowadays,
    but several are displayed in museums.
    36,183 units were built making it one of the most produced fighters in history.
    At a MTOW of 10300 lb, its armoured shell was 15% of this weight.

    A two-seater prototype flew in 1939, and went through several improvements.
    In 1940 a high-altitude version came out with original Mikulin AM-35 1,370 hp.
    improved versions of the Hispano Suiza Y12.

    However, it was decided to have a lighter, single-seat design, with the more
    powerful 1,680 hp Mikulin AM-38 engine, optimised for low level operation.

    It proved devastating for ground attack missions, against road convoys, railways
    and tanks, but was vulnerable against air-attacks, so the two-seater version was
    re-instated in 1943, with an aft-firing machinegun, and an upgraded Mikulin AM38F
    engine that conferred a Max. speed of 257 mph.

    This engine had a geared supercharger, working at 53.54 in. Hg for take-off,
    giving 1720 Hp at 2350 RPM, whereas for normal maximum continuous operation it
    operated at 47.24 in. Hg, giving 1500 Hp at 2050 RPM at 2500 ft.

    Petlyakov PE-2
    --------------
    The Petlyakov PE-2 was a twin-engined fighter/dive-bomber, remarkably fast,
    manoueverable and durable. It started out as a high-altitude fighter-escort. The
    prototype had a pressurized cabin, superchargers and many electrically actuated
    systems. Because a tactical bomber was deemed more necessary, the design was then turned
    into a heavy fighter/dive bomber, and production started in 1941.
    11427 units were built.

    The most-produced version was the PE-2FT, with 2Ũ1210 hp Klimov M- 105PF liquid-
    cooled V-12 engines, which had a 2-stage supercharger:
    (Data for the M-105R)
    > 1,100 hp at 2,700 RPM for take-off, boost rated at 1.27 Atm (38.00 MP)
    subsequent variants had 43.3 and 47.2 MP
    > 1,050 hp at 2,700 RPM at 13,123 ft, boost rated at 1.21 Atm (36.22 MP)
    subsequent variants had 43.3 MP
    > 500 hp at 2,700 RPM at 31,168 ft (9,500 m)
    >Emergency boost (maximum 2 minutes): 1,100 mm Hg (43.30 MP) at 2,800 RPM.
    subsequent variants ??
    >Critical altitude: 2,000 m (6,561 ft) at 1st speed, 4,000 m (13,123 ft) at 2nd speed.

    (I still have to see which variant is the M-105PF, which had 100 Hp more, but it seems
    to have been a maximum of 43.3 MP for the engine in question.

    As CFS1 only allows single-speed superchargers, for the moment I have decided to
    put take-off and emergency power into WEP, totalling 43.3 MP, leaving altitude boost
    power within
    normal operation at max. throttle - 36.22 MP.

    In my opinion, these would be two very interesting models to make for CFS1!
    Cheers,
    Aleatorylamp
    Attached Thumbnails Attached Thumbnails Ilyushin01.jpg   Ilyushin02.jpg   Petlyakov_Pe-2.jpg   Petlyakov_Pe-2_Muzeum_Wojska_Polskiego.jpg  
    "Why make it simple if you can also make it complicated?"

  2. #2

    The Supercharger on the Petlyakov PE-2

    Hello Folks,
    The two stage supercharger on the Klimov VK-105PF engine of the Petlyakov PE-2
    is certainly a headache, as it is impossible to make such a thing for CFS1.

    The corresponding graph on the chart attached is the one marked in red.
    It would continue downwards as the black line does for the M-105P.

    Translated into numbers, altitudes/Hp are the following:
    _S.L. ...: 1210 Hp
    _2300 ft: 1260 Hp
    _3280 ft: 1225 Hp
    _5500 ft: 1140 Hp
    _6500 ft. 1160 Hp
    _8850 ft: 1180 Hp
    _9840 ft: 1160 Hp
    12467 ft: 1060 Hp
    16404 ft: 980 Hp
    19685 ft: 825 Hp
    23000 ft: 720 Hp

    In order to achieve the best possible performance equivalent for this engine
    using a single speed supercharger, the first thing to do would be to try and
    bend the graph into a convenient shape, but this is easier said than done.

    The problem is that too much power around the medium altitudes comes out.
    It appears that the low and high altitudes will be a little easier to do...

    For the moment my efforts have produced the green graph line - one can
    recognize a single-engine supercharger pattern, with the obvious deformation
    at mid altitude.

    This is for WEP. In this case, with the adjustments, the Manifold pressure settings
    do not coincide with the WEP MP on the specs and is 3 in. Hg lower, at 40.3 in. Hg.
    Also, Boost Gain and WEP Pressure Change rate had to be lowered so much that
    critical altitude is no longer at 13120 ft, but much higher.
    Problems, problems...

    Cheers,
    Aleatorylamp
    Attached Thumbnails Attached Thumbnails Kilmov_Engine_Graph.jpg  
    Last edited by aleatorylamp; May 15th, 2018 at 22:00.
    "Why make it simple if you can also make it complicated?"

  3. #3

    WEP Pressure Change Rate

    Hello Folks,
    The "small" issue of Critical Altitude being altered by entering
    values lower than 0.528 into "WEP Pressure Change Rate" was
    solved by simply leaving this field at Zero - it did not impair
    the functioning of WEP. In effect, it made it more understandable!

    So, it seems that this parameter does not need to be zero only
    for non-WEP .air files, contrary to what Iīd thought before.

    Anyway, with a Zero entry here, it is easier regulate Boost and
    WEP with the usual parameters. I also noticed entering different
    low values here had a strange effect on Boost Gain, and not only
    Critical Altitude.

    The comment in Air Ed that the minimum entry for this parameter
    is 0.528 seems to mean that a smaller value will have the same
    increase effect as 0.528.

    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  4. #4
    Hello Aleatorylamp,

    I was wondering if you would figure this out or remember what we did earlier.

    If you check the last post on this thread (The infamous "Engine Performance Tuning Tutorial"):
    http://www.sim-outhouse.com/sohforum...Tutorial/page2

    You will find that there is a description of these parameters in greater detail.
    We (actually you) came across some weirdness with this parameter back when working on the Martin Baltimore and I took it quite a bit further in testing with my P-40N to see exactly what it was doing. Afterwards, I wrote up what I had found during the testing.

    This is what you posted at the time (Post 77 on the Martin Baltimore thread):
    http://www.sim-outhouse.com/sohforum...altimore/page4
    Quote Originally Posted by Aleatorylamp
    Update:
    The main problem with F10 WEP is that in order to get the right Manifold Pressure readings at altitude, WEP and NON-WEP require different Boost Gain entries in the .air file!
    Rather frustrating, I must say! Iīll have to see if thereīs a way round this... Thatīs why it worked so much better with the WEP-Within-Throttle-Lever.
    At the moment Iīm drastically reducing Emergency Power Press Change Rate parameter, which seems to be doing something. I wonder...
    There was a lot more discussion after that.

    It seems like most of the issues you are currently asking about or running into were covered in pretty good detail in that thread.

    Using the stock AIR files as examples isn't always a good idea. Many of them are not very well behaved.

    It seems like the designers of the AIR file system created a useful feature but the authors of the stock CFS AIR files didn't really understand what the parameters were used for. We have already had plenty of discussions about other places where the stock AIR files are broken.
    The comments in the AIR file editors were probably based on guesses and are often not entirely accurate.

    Coincidentally, the relevant post in the Engine Performance Tuning Tutorial was on May 16, 2016 -- EXACTLY Two Years ago and it was about a week or so after the discussion in the Martin Baltimore thread.

    - Ivan.

  5. #5
    Hello Aleaorylamp,

    Here is another useful conclusion from the Martin Baltimore thread on Post 79:
    http://www.sim-outhouse.com/sohforum...altimore/page4

    Quote Originally Posted by Aleatorylamp
    Halving Emergency Power Pressure Change Rate value had produced no satisfactory results, and leaving it at one tenth was better, although I didnīt understand what was happening very well, so I left it at zero, discovering that above critical altitude, WEP falls off very rapidly! This seems to point towards a possible solution.


    This was on May 9, 2016 or about a week before I posted to the Engine Performance Tuning Tutorial.
    I had figured from your posts that you understood the basic concept.

    The entire section on Page 4 is worth reading because it covers in great detail what it appears you are trying to do now with ta different aeroplane.

    - Ivan.

  6. #6

    Better with non-zero small values...

    Hello Ivan,
    Yes indeed!
    My memory is not very good anymore. In fact, it was always quite mediocre...

    Anyway, yesterday evening I remembered both the Baltimore WEP issue

    and the WEP extension to your tutorial, looked that up and I saw what you
    are mentioning. It says exactly what Iīm finding again right now!


    So itīs not strange that now, it turns out that the performance envelope is
    overall better
    as I already had it on the graph I posted, using small values in
    WEP Pressure Change Rate and adjusting Boost Gain a little.

    Note: The small glitch about the change in Critical Altitude, is in fact rather a
    benefit than a bother, because as WEP still works above Critical Altitude, it
    compensates very nicely for the low non-WEP performance there!

    Well, at least we CAN use this feature to our benefit, contrary to what one
    is lead to believe from the vague AirEd indications.


    Leaving it at zero at first seemed promising, and lowered the unwanted peaks
    between
    6000 and 9000 ft a bit. However, it did so at the expense of lower
    and higher altitude performance -
    both came out low. Hence, Iīm reverting
    back to using the WEP Pressure Change Rate with small values.

    It IS a quirky issue, isnīt it, this busines of trying to figure out how to use a
    single-speed
    supercharger because a 2-speed one isnīt to be got.

    So... What do you think of the green line in Post #2?
    Iīm still trying different things but so far, itīs the nearest Iīve got.

    OK, then! Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  7. #7
    Hello Smilo,
    Perhaps it would be a good idea to change the name
    of this thread to Petlyakov PE-2 Dive-Bomber.
    If you think so too, perhaps you could do it,
    as I havenīt got the capability.
    Thank you for your kind attention!
    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

  8. #8
    SOH Staff
    Join Date
    Jul 2005
    Location
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    Posts
    3,757
    hello Stephan,
    i don't believe i have the capability
    to edit a thread title.
    i would suggest just starting a new thread.
    sometimes the magic works.
    sometimes it doesn't.

  9. #9
    Hello Smilo,
    OK, thanks. Iīll do so as soon as I start building the model!
    Cheers,
    Aleatorylamp
    "Why make it simple if you can also make it complicated?"

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