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Thread: Prop governor question

  1. #1

    Default Prop governor question

    The following question came up in a warbirds discussion and I couldn't find a definitive answer from a web search:

    For a P-51 with a Hamilton Standard prop, if the engine loses all oil pressure (such as when Dago Red blew the side out of its motor prior to the lap record attempt in 2000), does the prop pitch go to full coarse setting (assuming it isn't already at that setting), full fine, or does it just remain at whatever blade angle the prop is in when the governor looses pressure? An answer from any team members with knowledge on this subject would be greatly appreciated.

    thanks
    Low
    Last edited by Low-n-Slow; 01-30-2014 at 10:14 AM.

  2. #2
    Join Date
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    Default Re: Prop governor question

    You might be getting a couple of things mixed up.

    A.) Loss of engine AND oil
    B.) Loss of the governor itself

    Maybe some of the guys will chime in with the particulars.

    - Joseph

  3. #3

    Default Re: Prop governor question

    Quote Originally Posted by Idaho_cowpony View Post
    You might be getting a couple of things mixed up.

    A.) Loss of engine AND oil
    B.) Loss of the governor itself

    Maybe some of the guys will chime in with the particulars.

    - Joseph
    What he said

  4. #4

    Default Re: Prop governor question

    OK,now I'm even more intrigued. Doesn't the prop governor on the Merlin engined P-51s use the engine oil pressure system as the supply source for the oil that it uses to control the pitch of the blades? So if the engine looses all its oil, so does the governor, yes/no?

    I know some Rotol and Aeroproducts props used an external oil source for the governor, but thought that the Hamilton (at least on the P-51D) used engine oil.

    Looking forward to information on both this and the original question.

    cheers
    Scott
    Last edited by Low-n-Slow; 01-30-2014 at 08:28 AM.

  5. #5
    Join Date
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    Thumbs up Re: Prop governor question

    Quote Originally Posted by Low-n-Slow View Post
    The following question came up in a warbirds discussion and I couldn't find a definitive answer from a web search:

    For a P-51 with a Hamilton Standard prop, if the engine loses all oil pressure (such as when Dago Red blew the side out of its motor prior to the lap record attempt in 2000), does the prop pitch go to full coarse setting (assuming it isn't already at that setting), full fine, or does it just remain at whatever blade angle the prop is in when the governor looses pressure? An answer from any team members with knowledge on this subject would be greatly appreciated.

    thanks
    Low
    In the case of Hamilton Standard P51. Oil pressure boosted by the prop governor drives the propeller to high pitch low RPM. Therefore if engine oil pressure or governor fails blades go flat and overspeed is a coming. That is why the Aero Products propeller is the best in a engine failure mode as the Aero Products has its own propeller oil res and pump internal to the propeller. This allows full propeller control through the failure mode regardless of engine oil pressure. Some propellers have counter weights that drive propeller to corse pitch and oil takes them to fine pitch or high RPM. Therefore in their case of loss of oil pressure the propeller will go to high pitch low RPM. Just depends on what you got!! If you will remember Kevin Eldridge propeller failure at Reno. His propeller was like P51 Ham Standard that when he lost oil pressure the prop quickly over sped departing the aircraft.

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