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Thread: Idle RPM


  1. #1

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    Idle RPM

    When properly setup, what RPM do the ZDZ Super 80s usually like to idle at? Right now, 2000 RPM seems to be the lowest that it is happy at, but it still seems to be a little rich on the low end, but also a little easier to start. Thanks.
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    RE: Idle RPM

    i would guess here as my da does 1500 but will go lower along with other singles that I have in this same range. I do a bump up upon flying to about 1650-1800 using a mix.
    smooth as silk!

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    RE: Idle RPM

    2000-2200 is as low as I can go right now, otherwise it dies when chopping the throttle after WOT. Guess we'll see after break-in and a carbon fibre prop.
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    RE: Idle RPM

    Lins how much fuel do u have on this motor at this point? also after you run it and shut it down can you pull the spark plug to see what color it is we are wanting a nice tanish brown only. From here u can see what conditon the motor is running. dying from releasing the throttle sounds like the needles are not were they need to be.
    smooth as silk!

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    RE: Idle RPM

    I have hardly any fuel through it so far, only a couple tanks. I just got the plane running this week. It only dies if it is around 1600-1800 right now. I have it adjusted to where it will idle forever. Plugs after holding it at WOT are a tannish colour. The low needle setting doesn't seem to help keeping the RPM's low at this point. I'm going to try to get a few more tanks through and see where it's at then. I wish I could just fly it, but I'm waiting for my battery setup.
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    RE: Idle RPM

    Well you have some issues going on considering the question in this thread as well as the other one you posted....[8D]

    It will idle slower as it loosens up on break in, usually you'll see a bit of improvement somewhere around a gallon or a bit more and then again somewhere around 5 gallons is about where it should be close to being as loose as it will get.

    The singles will idle just a bit higher than the twins, but my ZDZ-50NG will idle quite happily at 1250-1300 RPM now that it's broke in and my ZDZ-100NG will idle about 1100 RPM. I've got several buddies who fly 80's and I'm sure those are idleing somewhere in the 1300 or so range but I've not actually tached them.

    You're going to find it really difficult to land if you can't get yours running any slower than what you've mentioned.

    While this is the manufacturer support forum for ZDZ, I've not had really good luck with getting questions answered here by RCS. But if you'll e-mail them direct, or even better, give 'em a call I'm sure they'll be more than happy to help out.

    Oh, I too use a "Flight idle" on mine as krayzc-RCU noted. In my experience, the slower you want 'em to idle and still cover the transition to full throttle without dying, the richer the low speed needle has to be. So by kicking up the idle for flying, it doesn't have to be as rich to cover that transition without dying, and it will idle slower to land. I do it the same way, a throttle/throttle mix or a throttle curve setup on a switch on the tx.
    Zeeb

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    RE: Idle RPM

    Well it is actually getting easier to start. The transition from idle to full throttle has no hickups at all. It will idle forever without dying. I can set the idle to 1600 roughly without dying, it's just if I cut the throttle from WOT, the idle drops momentarily enough to quit. Maybe it just doesn't like the Zinger prop. Either way, if I was flying it, I would just bump up the idle for flying, then slow it down for landing. If it's like my other engines, I'll just fly it as much as I can to break it in and then really fine tune it.
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    RE: Idle RPM

    In full scale aviation they say: NEVER panic throttle. If we rc guys would go by the same saying there would be much less problems with our engines. How often do we really need to suddenly close the throttle completely from wot? I never do it. Neither do I suddenly open the throttle from low idle. As a result I can adjust my engines leaner on the low needle and my engines run very smooth on idle and midrange.

    Wait for your engine to break in. DonΒ΄t rush it. Adjust the needles in very small increments at a time, and IΒ΄m sure your engine will turn out great.

    Adjusting the needles so the engine will respond to just flicking the throttle open and shut is IMHO not a properly adjusted engine.


    Lars.

    PS. IΒ΄m from Norway and donΒ΄t always really know how my words come out. But I never try to offend anyone on purpose.
    Happy landings!
    Lars.

    PS. IΒ΄m from Norway and donΒ΄t always really know how my words come out. But I never try to offend anyone on purpose.

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    RE: Idle RPM


    ORIGINAL: Lins

    Well it is actually getting easier to start. The transition from idle to full throttle has no hickups at all. It will idle forever without dying. I can set the idle to 1600 roughly without dying, it's just if I cut the throttle from WOT, the idle drops momentarily enough to quit. Maybe it just doesn't like the Zinger prop. Either way, if I was flying it, I would just bump up the idle for flying, then slow it down for landing. If it's like my other engines, I'll just fly it as much as I can to break it in and then really fine tune it.
    Lars has a point, but the idea behind covering the transition is due to the fact that these little carbs don't have accelerator pumps, so when you crank open the throttle it gets a huge gulp of air and no fuel. Then add in the fact that an engine will usually run somewhere in the 15/1 air/fuel mixture at a constant RPM, but needs about 12/1 for acceleration and the difficulty becomes apparent.

    Bye the way, it's been quite some time since I worked on a full scale with a carb but IIRC everyone I've seen has an accelerator pump.

    I don't wish to be harsh, but most folks who've been around GS stuff for awhile consider the Zingers to be suitable paint stir sticks, but not for aircraft use....

    I know props aren't cheap, but you'll be surprised at the differences in flight performance you'll get with some other brands. The really hard part about prop selection on the GS stuff is that no two setups when combined with different flying styles are the same. So you can ask some questions about what people like, but their favorite prop brand/size may not be the best one for your model/engine combo and flying style.

    Do a few searches on props and you'll find there are some VERY brand loyal folks as well as those who will make some generalized suggestions based on their own experience.
    Zeeb

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    RE: Idle RPM

    YPB wow I never thought of that deal. I do not think I ever go from low to high in a quick move either. I may have when i started flying years ago but never now a days
    smooth as silk!


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