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Thread: High end needle valve adjust

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  1. High end needle valve adjust 
    #1
    Join Date
    01-23-2013
    Location
    prescott, az
    Posts
    2
    Clarence Lee
    Model Airplane News

    Clarence: Moved from 1000 ft elevation (Phoenix, AZ) to 5200 ft elevation
    (Prescott, AZ) Running an OS .46 2 stroke in a sport plane with 15%.
    Due to the elevation change, do I need to adjust high end needle valve to a richer setting or a leaner setting? Many thnaks
     

  2.  
    #2
    Join Date
    08-19-2002
    Location
    Wichita, ks
    Posts
    27
    Just adjust it as you normally would for maximum rpm minus 500 or so on the ground.

    If you're just looking for what to expect, it will be normal to have to lean the needle compared with where you were. As usual though, a good running engine should at least start and run. You may have to make adjustments after it's fired up and up to temperature, but I would wait until it's running to turn the needle. No reason to loose a good setting and start guessing.

    Not sure how often the editors stop by to say hi so I figured I would answer for you.

    -Eric
     

  3.  
    #3
    Join Date
    01-23-2013
    Location
    prescott, az
    Posts
    2
    Eric: Many thanks for reply. Will adjust accordingly....Bob
     

  4.  
    #4
    Expect less useful power at the higher altitude. The engine has less air to mix with fuel and the prop has less air to "grab" to produce thrust.

    The airplane will fly differently than you are used to.
     

  5.  
    #5
    Join Date
    08-19-2002
    Location
    Wichita, ks
    Posts
    27
    Good point! Also a little less lift from the wings and less authority from the control surfaces!

    -Eric
     

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