Zenoah engines !!! - Page 2
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  1. #21
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    Quote Originally Posted by Peter View Post
    Pretty sure you'll find it'll be lots better when you get the carb butterfly setup right , it'll need a retune; start with both needles at a tad under 1.5 turns open ..

    my throttle "curves " are like 10 , 15, 25, 35 , 100 , in " normal ; 100 , 45 , 100 in idle up... that's for 3/4 stick hover position ..

    don't use a governor until the motor is run in , usually about 5 litres!!


    I like to get the runout at no more than 1 thou , 2 thou is too much !! ( I reckon anyway!!)
    Thanks for the info Peter.

    I checked the butterfly and it appeared to be about 40% to 45% at hover, but more of an issue was that the throttle servo was not moving linearly and this was due to the end points incorrectly set, with one at 105% and the other at 65% !

    I reset them both to 100% and now at least there is linear movement so got stuck into getting the 30% at hover opening with throttle linkage length and little if any end point changes.

    Finally, the only way I could do this is by changing the throttle curve accordingly so now at mid stick the butterfly is about 30% open.

    Haven't run the heli yet so don't know if this will fix the problem.

    Slowly slowly I guess !!

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  3. #22
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    Finally in the air after almost 1 year !

    As suggested by Peter, I got the butterfly open at around 30% hover, re tuned her a bit and the foaming was not as bad and managed a 20 min flight.

    Flew ok, with reasonable power, not like a nitro but I knew that already and for scale flying is perfect. Did notice a slight porpoising of the nose, ie nose /tail going up down at the odd moment. Not too sure what could be causing it but then........................

    Lucky the sun was getting in my eyes which prevented any high altitude flights because as she came past me at about 6ft off the ground and while pulling slight back cyclic to slow her down, suddenly engine died. To make matters worst on the way down she turned clockwise around facing me but somehow managed to land square on the skids


    Waited for the rotor to slow down, and then the post mortem.

    No servo throttle movement and no tail servo movement a double wammy.

    The throttle problem was easily identified as the servo plug had come out of the receiver about 3 mm. Not obvious until I pushed it back into the receiver and presto, throttle control. What amazed me is that the throttle spring on the butterfly had enough pull to shut it completely even with the 'dead' servo attached. I guess this would be preferable than the throttle staying open right!

    Now the tail problem. It ended up being the servo, a Align DS620 which just simply stopped working at the same time the engine quit.....how weird. I opened the servo and instantly the burnt smell was obvious. I assumed the motor has burned out as the components looked fine after inspecting using a powerfull eyeglass.

    I must admitt I did notice when the helicopter was on the ground idling/running up that the tail servo was vibrating about 4 mm left/right and I think this was caused my mounting the gyro on soft rubber foam. The foam most probably amplifying the engine vibrations causing the tail servo motor to be working overtime and burning out.

    I guess in the end the heli did not crash which is a good thing. I will remove the foam and mount the gyro a little more rigidly, followed by getting another servo real soon. As I don't have the need for super 3D fast tail response, perhaps a simpler non digital servo may be a better choice.


    Cheers.

  4. #23
    Senior Moderator Peter's Avatar
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    Hate it when servos die; had a couple of throttle servos do that .. Now running el cheapo hitec 422's on throttle, last much better than digitals there ..

    But I'd stick with a decent digi servo on the tail, I really hate a lazy tail these days . Back in " the good old days " , 30+ yrs ago when I first decided that R/C helis were a good way to keep the bank balance low, there weren't even gyros , let alone good servos! I'm spoilt now...

    Had a funny with one of my Zenoahs yesterday .. It's had a bit of a rattle for a while , but power was still good, so I kept flying it .. it wouldn't start after its first flight yesterday , spark was good , plug was wet , had a couple of us thinking hard !! Found today after removing it from the Spectra G , and removing the fan etc , that the top bearing is loose in the case . There's two bearings at that end of the crankshaft , the lower one is open , top one is sealed to maintain c/case pressure; and thats what it wasn't doing ,... Seems the rattle was the bearing bouncing against the metal fan !! I'm tempted to leave the bearing out and fit a full seal in its place ; think the marine motors have that ...

    Theres always something more to learm with these things !!
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    MA Spectra G's ;Stratus's ; Extreme, E Razor , N Razor, Fury 55 ;Furion 6; Electric , Nitro & Gasser Whiplash's; ,Aeolus 50 3D ; TSA 600N ; TSA 700N; BeastX FBL electronics... XPS 2.4 GhZ radio........ lots of ignored planks


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  6. #24
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    Ye helicopters are real fun arn't the? Sometimes I ask myself how much actual flying time I have had the past 20 years versus repair time!

    Don't do the comparison, it sucks.

    Anyway, and BTW, it was only the rudder servo that burnt out. The throttle servo was fine, it was the servo plug falling out of the receiver that stopped it from working.

    As far as the new slightly lazy [analog] tail servo I have fitted, for my part I'm not that concerned. Flew fine with much slower servos on the tail going back 25 years ago, and given the scale like flying I do they are just fine.

    Reliability is my main concern, as is with all the other flyers out there. If I could buy 100% guaranteed ultra reliable servo's, [no such luck] frankly even if they only moved at a snails pace they would be preferable to the ultra/fast units with unknown service life ...............

    Haven't had a chance to run the heli after replacing the tail servo as we have been very busy doing some jet car shows up in Brisbane lately.

    Hopefully soon.

    cheers

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