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Weight & Balance

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  • Weight & Balance

    I would like to get the empty balance location on any completed Patrol. Anyone responding please list your engine and prop specifics.


  • #2
    Eric posted his here, and also on his web site. Search is your friend.
    Jim Parker
    Farmersville, TX (NE of Dallas)
    Patrol Quick-Build Serial # P312


    • #3
      I am building a conical mount for my Patrol's 0-320 and I have two questions:
      1: On plans page 17 it shows the thrust line down 1 degree below horizontal and located 18.5" above horizontal datum line, I am not sure where that 18.5" is measured ... at the firewall, prop-flange, or somewhere else. The 1 degree down-angle could give me a half-inch error if I measure in the wrong place.
      2: The Bearhawk newsletter shows forward placement of engine at 56" to 58" in front of the datum line as measured to the prop-flange. I assume one would use the front surface of the flange. If I keep my O-320 light with no electrical and use a lightweight fixed-pitch prop, I would guess that I should use the 58" figure or even slightly more.
      Your opinions are appreciated.


      • JimParker256
        JimParker256 commented
        Editing a comment
        For something like this, I would call Bob Barrows and ask his advice.

    • #4
      Mine is as follows;

      1259# / 14.45"
      Lycoming O-360 full oil
      MT 2 blade 80.5" C/S prop
      Bearhawk Tundra tailwheel. (Notably heavier than the smaller ones)
      PC680 battery - full electrics - 2 A/P servos



      • #5
        N180PB weighs 1178# with cg of 10.4" Superior XP-360, Sensenich prop, 8:00-6 tires, Bob's tailwheel, skylite, PC680, full electrics


        • #6
          Regarding #2.

          The FAA has a weight and Balance manual.

          I recalled using formulas in the previous century when taking a commercial written test. I just scourged around the FAA manual and found one in that you might be interested in.

          The change in CG =

          Engine Weight x Distance it will be shifted
          Total Aircraft Weight

          So, if you have a 1000 pound Patrol, and shift a 250 pound engine ahead 2 inches, it will shift the CG .5 inches forward.

          There are a lot of other formulas that apply for adding or subtracting weight that could be applied using some known airframe numbers to predict an optimal location for your engine in your lighter aircraft. Sometimes I think we just build and at the end we find out what CG we got, kind of like having a baby. Surprise!! But we can use these formula's in the FAA manual and predict and thus control the outcome.
          Brooks Cone
          Southeast Michigan
          Patrol #303, Kit build