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912ULS fuel consumption

in 912 / 914 Technical Questions 12 years ago
Hello all. I am getting about 5.8GPH of fuel consumption while running 5200RPM at about 1500FT ASL. Rotax says, if memory serves, less than 5GPH at this RPM. I use premium auto gas unless I am traveling but I get about the same with 100LL.

I am swinging a 70" three blade Warp Drive with the pitch set for 5600RPM WOT straight and level, just like Roger Lee recommends.

What kind of fuel burn are the rest of you getting?

Alan

  • Re: 912ULS fuel consumption

    by » 12 years ago

    Hi Alan,

    This can be a tricky subject because it assumes we all have our fuel flow transducers set properly. If yours is set properly then I would think you may be just a tad high, but not much. I think most at 5200 rpm are about 4.8 - 5.2 gph, but again that assumes the fuel reading is correct. There are a few other factors in play and because each plane, prop and fuselage combo is different and the gph will be a little different.
    you should do a good fuel level and use check for about 10 flights to get a good average and flow and then adjust the "K" factor for the transducer.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: 912ULS fuel consumption

    by » 12 years ago

    Hey Roger,

    Thanks for your reply. I do not have any kind of fuel flow system. My Highlander is "old school" with strictly day VFR instruments, no glass, and only translucent fuel tanks for level indications. I have been calculating fuel consumption for several years now and have found that I can fly for 1.6 hours on the Hobbs and use a tad over 9 gallons. I know the exact fuel usage because that is how much fuel is available in one tank. I don't routinely let the engine run out of fuel before swapping tanks but it has happened.

    Alan
      
    Report

  • Re: 912ULS fuel consumption

    by » 12 years ago

    Hi Alan,


    What is you WOT rpm at your average altitude?
    Prop pitch affects fuel consumption. Set the prop to get 5550-5700 rpm at WOT flat and level at your average altitude. A little too much pitch regardless of the cruise rpm will cost fuel economy. You are using about .8-1 gph more than I am for 5200 rpm. Remember there are a few other factors in play here and they aren't something we have control over. Where you are using 9 gph at 1.6 hrs I'm at around 7-7.5 gph. Too compare fuel usage against different planes, different fuselages, different fuel read out systems and weather can be tough to pin down for a comparison.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: 912ULS fuel consumption

    by » 12 years ago

    Hi, I get 4.8 gph with my 912ULS with take off weight of 1270 lbs (solo, full fuel, 30lbs luggage),its

    Kitfox 5 taildragger .

    I have the Ivo inflight adjustable propeller on it so that really helps in all the performance areas

    and with fuel consumtion. At gross weight of 1550 lbs I usually burn 5.0 gph .

    These gph's are with 5100-5150 rpm and 25.5 " MAP cruise and with premium unleaded.
      
    Report

  • Re: 912ULS fuel consumption

    by » 12 years ago

    Hi Roger,

    I have the Warp pitched for 5600RPM at WOT at 1500FT MSL. Since I live on the Gulf Coast, that is also AGL. I have heard it said that the Warp is very heavy and will cause higher fuel burn. Any truth to that?

    Alan
      
    Report
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