fbpx

 

Today I experienced a performance issue with my 912ULS (Pipistrel Virus SW), at least I think I did. Took off from my home field, elev 180', QNH 1020, Temp 14C. Takeoff performance was normal, 5750RPM, Ts  and Ps in the green, normal acceleration and takeoff distance (3kt headwind). Started the climb out and noticed that the aircraft wasn't accelerating past 80kts on the normal 90kt climb attitude. I reduced the climb angle, and at 80kts I was only getting 200fpm climb when I'd normally be getting close to 1000fpm. I elected to stay in the circuit and even with 5500rpm (19MAP) I was only getting 90kts on downwind. All engine monitoring indications were in the green. I flew a normal circuit but remained high for most of finals as I was unsure of what to expect. Completed a normal flaps +1 landing. Taxied off and conducted engine runs. Normal in dictations for everything. I called it a day and am now scratching my head about what could be the cause. The prop remained in full fine throughout except during the run up check when it cycled normally. I repeated the run up procedure before shutting down. Thoughts?

  • Re: Climb performance

    by » 3 months ago


    I think before I worried and started to mess with things I'd give it another flight. It may have been something on the atmospheric side.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Climb performance

    by » 3 months ago


    Seems odd because if the prop is turning at the desired speed, it seems it should produce the thrust. If the engine wasn't producing the power, it wouldn't turn the propeller the desired speed. Might want to look at the propeller.

     


  • Re: Climb performance

    by » one month ago


    The weather conditions you describe should not make that dramatic of a difference. I wonder about the pitot static system. Was your ground speed correct as compared to your indicated speed? There is a lag, but was your gps altitude somewhat matching your altimeter and VSI?


  • Re: Climb performance

    by » one month ago


    "Takeoff performance was normal, 5750 RPM"

    Just at face value, it appears your prop needs a pitch adjustment. I think your takeoff RPM is way too high. If you increase the pitch some (to reduce the above takeoff RPM), I think your climb and cruise speeds will see quite an improvement, towards normal performace targets.

    I fly a Flight Design CTSW (912 ULS) and my takeoff RPM, at rotation, is about 5025 RPM. My full throttle RPM at 3,000 MSL, std temp, in level flight, is 5700 RPM.

    My prop is pitched for slightly better climbout than max cruise airspeed, which I prefer.

    Hope that helps.

     

     

     

     


    Bill Ince
    CTSW (E-LSA)
    Retired Heavy Equipment Operator


You do not have permissions to reply to this topic.