Supercharger Intake Locations

Discussion in 'Aviation' started by silence, Aug 13, 2013.

  1. silence

    silence Active Member

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    So I was looking at some cutaway drawings...

    Looks like the P-47's supercharger intake is directly under the engine right in front, correct?

    But I can't find for sure the location for the same on the Spitfire, unless its the little bitty scoop above the starboard exhaust pipes.

    And I have no idea where the Mustang's is.
     
  2. swampyankee

    swampyankee Active Member

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  3. razor1uk

    razor1uk Well-Known Member

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    #3 razor1uk, Aug 13, 2013
    Last edited: Aug 14, 2013
    The little scoop on one side of a Spitfires cowling, is for (partial) cockpit pressurisation using a roots type blower - after the war many were used for supercharging drag bikes due to its small size. The carb/supercharger intake is the under nose roughly inline with the wings leading edge on Spits, in Mustangs (with Merlins/Packhards), its by the tip of the nose, or when cold or dusty, fed by the perforated plates behind the spinner.
     
  4. silence

    silence Active Member

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    Ah, so on the Spit the intake is shared. Okay, that makes sense.

    So the Mustangs' would be the small chin scoop?
     
  5. nuuumannn

    nuuumannn Well-Known Member

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    The Spitfire's is the carburettor intake at the wing leading edge under its nose; it's not shared with anything. That's what its for:

    [​IMG]

    [​IMG]

    Yep.
     
  6. GregP

    GregP Well-Known Member

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    The Allison had a downdraft carb and so the intake for the carb is on top in the P-51A. The Merlin has an updraft carb and so the intale is under the spinner on the P-51.

    The intake for the P-38 is a small stand-alone scoop under the traling edge of the wing on the booms. In modern P-38's, nobody is running the turbochargers and the carb intake is in the middle where the intercooler intake used to be.
     
  7. wuzak

    wuzak Well-Known Member

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    The P-38 also had a system which drew air in from the wheel well.
     
  8. silence

    silence Active Member

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    It seems (to me) that razor1uk and nuuumannn are in disagreement.
     
  9. Milosh

    Milosh Well-Known Member

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    They both said the same thing:

    razor1uk: The carb/supercharger intake is the under nose roughly inline with the wings leading edge on Spits

    nuuumann: the carburettor intake at the wing leading edge under its nose; it's not shared with anything.

    Did you actually look for an answer before asking the question?
     
  10. razor1uk

    razor1uk Well-Known Member

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    Thanks Milosh :) Sorry Silence :D English meanings can be usually be written in at least 2 or more ways and still mean the same, this can make translating difficult sometimes, but for those who write books, they find it useful being less bored, or end up with a bigger writers block. Mind due those who read, can find that it is hard at times and sometimes too much.
     
  11. silence

    silence Active Member

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    I think my confusion may be resulting from ignorance on just how the supercharger and carburetor interact with the engine.

    The carburetor mixes air and fuel for the engine. The supercharger is an air compressor used to increase the pressure, temperature, and density of air supplied to an internal combustion engine (per wiki). Therefore the supercharger (my fingers seem to HATE to type that!) feeds INTO the carburetor to keep its air supply at the levels it needs.

    This, coupled with previous posts, leads me to conclude that the supercharger is in front of the carburetor and maintains a strong airflow to the carburetor. (Please excuse me if I'm stating the obvious: typing it out helps my thought processes.) The intake does not feed both simultaneously, but rather the one with then, in turn, feeds the other - a system in series rather than in parallel.

    If this is correct, then it appears that for whatever reason I was thinking (apparently not too well!) that the carb and supercharger operated side-by-side, simultaneously drawing from the same air supply at the same time. I think that rates a big "whoops"!
     
  12. Shortround6

    Shortround6 Well-Known Member

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    Yes and no. The Merlins had a system in which air went from the carburetor to the supercharger and from the supercharger to the intake manifold. Most Allisons did too. German engines used direct fuel injection into the cylinders. Air from the intake went to the supercharger, it was compressed and flowed to the cylinders. French Hispanos ( and Russian VK-105 engines) took air from the intake to the supercharger, blew it through pipes to six carburetors ( one carb fed two cylinders) and then to the cylinders.
    Some engines had one supercharger blowing air into a carburetor mounted on a second supercharger.

    They ALL operate in series except the engine on a F4U Corsair which had a changeable intake. It had two superchargers in series but it could by pass the first one. Not really operating in parallel.

    A number of planes had alternate air intakes like the P-38 in which one faced forward and picked up "ram" pressure from forward speed but was liable to ingest sand, dirt and debris and another intake for use while taking off/landing that was more sheltered or filtered but they joined BEFORE the carb or supercharger.
     
  13. silence

    silence Active Member

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    NOW I get it!

    Thank you all!
     
  14. GregP

    GregP Well-Known Member

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    #14 GregP, Aug 14, 2013
    Last edited: Aug 14, 2013
    All Allisons except some unsupercharged PT boat and tank engines had a carburetor that fed the air fuel mixture directly into the supercharger impeller and was compressed and routed to the cylinder via the intake manifold system. Supercharged Merlins, both single and muilti-stage, were the same except the Allison has a downdraft carb (carb sticks up ... so air intake is routed above the engine and turns downward into the carb) and the Merlin has a updraft carb (carb sticks down ... so air is routed under the engine and turns upward into the carb).

    That's why the ALlison-powered P-51A has the carb intake above the spinner and Merlin-powered units have the carb intake below the spinner.

    The -147 and -149 Allisons (the G9R and G8L for the F-82) had fuel injection, but the supercharger was in the same place with the air being routed to it instead, bypassing the space where the carburetor used to be.
     
  15. nuuumannn

    nuuumannn Well-Known Member

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    Perhaps this confused you, Silence.

    What Razor is referring to here is the intake just below the exhaust ports on the nose above the guy's head, he is obscurting the carburettor intake. This is a PR.XIX photographic reconnaissance Spit.

    [​IMG]
     
  16. silence

    silence Active Member

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    Actually it was another portside scoop I saw on an online drawing. My confusion, I think, really just boils down to the complexity of the English language. I tend to read very literally.

    Damn, those are some BIG underwing radiator scoop thinigies!
     
  17. nuuumannn

    nuuumannn Well-Known Member

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    Yep, its got a big engine to keep cool; 36.7 lt two-speed two-stage supercharged Griffon 65.
     
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