Doubt about the A6M2 supossed negative G engine cut

Discussion in 'Engines' started by Mad_Dragon, Jul 17, 2009.

  1. Mad_Dragon

    Mad_Dragon New Member

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    #1 Mad_Dragon, Jul 17, 2009
    Last edited: Jul 17, 2009
    Hello!

    I was reading a Wikipedia's article (a featured one by the way) about the Akutan Zero, also known as Koga's Zero and the Aleutian Zero, or simple the first Zero captured by the US when it make a forced landing in Alaska and the pilot died in it when broken his neck because the plane flip over.

    there's a part of it that let me in doubt altough:

    "Also, its engine cut out under negative acceleration due to its float-type carburetor. We now had the answer for our pilots who were being outmaneuvered and unable to escape a pursuing Zero. Go into a vertical power dive, using negative acceleration if possible to open the range while the Zero's engine was stopped by the acceleration. At about 200 knots, roll hard right before the Zero pilot could get his sights lined up"

    Akutan Zero - Wikipedia, the free encyclopedia

    know, I never heard this by Japanese sources and other western ones, this is the first time read something like that. also, some people tell me (know, don't have a realible source is useless, but wheatever) that the carburator was not instaled correct in this aicraft, thefore such supossed disadvantage was wrong constated.

    another thing, also fligth sims content should not be used for solve real life treads in most times, though this is not regarded to performance comparison, but for a simple non complex tecnical representation, so, in IL2 Sturmovik,initially, the Zero came with the negative G cut, but later this was removed because the devolpment team obtain the information that this was historically incorrect, and thefore the A6M2 didn't have negative G cut out according to their source.

    I even start a discuss in the talk page of the article about it, because fear that perhaps people are being provide with a wrong information. but as I don't have any source, my opinion would not be take in consideration, and I also don't have confirmation of that anyway, only are in doubt.

    in the IL2 official forum people tell me to try find wat was the source used by the IL2 team, but didn't manage to find nothing in the internet, nothing.

    maybe sounds ilogic try contest a official US trial report and would be improvable that such thing would happen.

    anyway, would ask to you folks, if possible to answer please, anyone know anything about this subject?
     
  2. vanir

    vanir Banned

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    #2 vanir, Jul 18, 2009
    Last edited: Jul 18, 2009
    From a web search I can only find reference to a "float type carburettor" being used on the Sakae 12 of the Model 21 indeed taken from accounts of the captured example you're talking about. I can't find any blueprints or adequate pictures of the fuel system to confirm.
    Essentially if it used a float type carburettor you've got that problem, if it used a pressurised fuel bowl (vacuum drawn carb) and the fuel pump was strong enough you haven't. I need to see the carb.

    Mismatching a pressurised fuel bowl to an underpowered fuel pump can also give you this issue, this is what caused persistent neg-g problems in Spits even though the float level was done with during '41, especially with early Griffons (being so damn thirsty). They wound up changing the brand of carb to fix it in the MkXIV iirc (SU to Bendix-Stromberg I think, I'd have to look that up but basically pinched the carb off an Allison to feed the Griffon without neg-g cutout and never did identify that it was fuel pump inadequacy, that's my input from race experience with these carbs).

    So...it is possible in Japanese service you don't have neg-g issues which you do in a captured US test example, if any of the fuel system had been changed when making it airworthy again. I know the prop had to be replaced. Does the Japanese fuel pump run off the reduction gear? I don't know without some blueprints to look at. It could've been changed with the switch to the American built Hamilton Standard if that is the case. Which means they may have used a local fuel pump fitted to the Sakae and it may not have been matched to the carb, or had other issues related to improper installation/part-matching.

    That's about as much as I can come up with scratching my brain for you.

    Hang on...aren't the A6M2 versions in IL2 two-speed Sakae 21 engines anyway...? Been a while since I flew them. If so they're a bit off from historical to start with.
    I did a couple of FM projects for IL2 mods and soon found the whole thing is such a mess off the bat it's a matter of accepting an arcade game for what it's worth (not much in terms of flight simming) and wait for the day somebody decides to forego the youth consol marketplace and actually produce a proper "full flight sim" version of a combat flight sim, with all the bells and whistles and some celebrated research and references, but you know, the whole complex engine start routine etc. tossed in, and one hell of a program engine in mathematical physics terms. Oh and an open code for the mod community thankyou very much, none of this "online gaming cheaters" crap, just genuine sim enthusiasts for this baby.
     
  3. Mad_Dragon

    Mad_Dragon New Member

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    #3 Mad_Dragon, Jul 18, 2009
    Last edited: Jul 18, 2009
    thank you very much for your reply and so much dedication in help me!

    gonna keep researching to see if can find something.

    and about IL2, yeah, but as I saied, just cited it because of the change of the engine cut out system that caugth my attention so was wondering to know wat was their source to have make this change

    altough wat let me more surprise is about the Japanese pilot's. today, sadly there's just very, very few early A6M2 pilot's alive or even no one. but some decades ago was never ask to any A6M2 pilot, never, all tecnical reports, everything lost to involve this in mistery?

    hard to belive...

    anyone never ask this to Saburo Sakai? he was one of the first pilot's to flow the earlist operational models, in 1940, over China.

    apparentely don't have logic for me, I'm very confuse about such subject.

    gonna try enter in contact with Japanese aviation entusiasts to see by Japanese sources, though still think it's almost unbeliable a so basic tecnical information like that could not exist with confirmation, and gonna post wat I to find.
     
  4. danjama

    danjama Member

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    I'm also interested, please keep us updated.
     
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