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Thread: Cooling air inlet duct opening.

  1. #21
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    Default Re: Cooling air inlet duct opening.


  2. #22
    Senior Member jrevens's Avatar
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    Default Re: Cooling air inlet duct opening.

    I left a gap between the bottom cowl & radiator... don't recall exactly how much. I sealed that gap with some nice soft silicone rubber "D" section that I glued to the cowl w/ silicone sealant. The cowl comes off & re-installs very easily.

    Carl - I flew this morning when it was in the low 30's, and I was up to adequate temperature by the time I taxied to the run-up area, but I do have oil & water thermostats.

    IMG_1392.jpgIMG_1390.jpg
    Last edited by jrevens; 01-20-2020 at 09:25 PM.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  3. #23
    Senior Member efwd's Avatar
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    Default Re: Cooling air inlet duct opening.

    My firesleeve is just wedged into the space and secured from coming back the way it went in by a piece of velcro. The gap is too close fitting to allow it to go through toward the exit.
    The Rotax manual states that the engine should be run around 1800 for two minutes. I do that then bump up to 2200 and that is enough to taxi (too much) but like John, It is warmed up by the time I get to the run up area. It takes about 4-5 min run time.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  4. #24
    Senior Member Cherrybark's Avatar
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    Default Re: Cooling air inlet duct opening.

    Thanks for the feedback on time to operating temperature. And I really like these ideas for closing the gap around the radiator.
    Carl Strange
    Flying
    SS7, 912iS, Oratex, G3X

  5. #25
    Senior Member jiott's Avatar
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    Default Re: Cooling air inlet duct opening.

    Eddie, FWIW even though Rotax may recommend idling at 1800, I was taught by Stick & Rudder to never idle below 2000 rpm. Their huge experience with the Rotax 912 indicates 2000 is a definitely smoother idle and easier on the gearbox than 1800. This doesn't mean you can't set your minumum idle below 2000 (mine is at 1600), just don't run it on the ground for warmup, taxi, etc. below 2000 rpm.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  6. #26
    Senior Member efwd's Avatar
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    Default Re: Cooling air inlet duct opening.

    Hmmm 🤔 Paul had me idle at 1800. All in an attempt to protect the gearbox.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  7. #27
    Senior Member jiott's Avatar
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    Default Re: Cooling air inlet duct opening.

    That's very interesting! When I trained with S&R they were running the 914 turbo and 2000 was the number. Maybe with the newer 912is 1800 is preferred. I know with my 912uls there is noticeably better smoothness at 2000 vs. 1800.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  8. #28
    Senior Member jrevens's Avatar
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    Default Re: Cooling air inlet duct opening.

    Paul had me keep the idle above 2000 also. I believe he made the comment that brake pads were cheaper than gear box repairs, or words to that effect. I reason that it is probably to keep solidly driving the prop and help reduce or eliminate any gear clatter due to backlash... I might be wrong. I also read somewhere that warm-up should be accomplished at 2500 rpm. Except for perhaps in very cold ambient conditions, that doesn’t seem an unreasonable rpm to me with these particular engines. I generally taxi at 2100 to 2200 rpm, but my idle stops are set for as low as possible without the engine quitting on short final (like it did on my first test flight), maybe 1550 rpm?
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  9. #29
    Senior Member jiott's Avatar
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    Default Re: Cooling air inlet duct opening.

    My 912uls operator's manual says to idle at 2000 rpm until oil temp reaches 90F, then increase to 2500 rpm until oil is 120F. Then you are good to do the 4000 rpm mag check and T/O.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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