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HelicopterGasser Model RC HelicoptersOther › Minor throttle and tail problems
09-06-2009 08:49 PM  8 years agoPost 1
gramey

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United Kingdom

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I 'm having a slight problem with my Spectra in so much as when the engine is warm I ahve to raise the throttle trim up to maximum to keep it ticking over. I tried leaning the low end needle off just a touch which made it slightly easier to start but when I landed if I didn't raise the trim it would cut out.
The other problem I'm having is with the tail drifting to the right, I have a CSM SL 720 gyro. I've tried resetting it then the quick set, I've tried raising and lowering the gain and for the love of me it still keeps drifting to the right.
Does anybody have any idea's as to what may cause both or either of these problems?

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09-06-2009 09:24 PM  8 years agoPost 2
SeismicCWave

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Hilo, Hawaii

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As long as you can raise the trim and the engine ticks over it is a good thing. So move the engine trim before you take off every flight so you know the engine will tick over when you land. It is a good work around. Maybe you are losing compression when the engine is hot.

CSM drifting. You didn't say if the tail drift right or the heli drift right. Either way, set the gyro to NON heading hold. Adjust the tail rotor linkage so you have just a small amount of positive pitch at neutral rudder. That is the tail rotor blows air to the right side of the heli with the positive blade pitch.

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09-06-2009 10:23 PM  8 years agoPost 3
gramey

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United Kingdom

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Tail is drifting left when in normal rate and right when in heading hold? I'm hoping the engine isn't losing compression as it's only had a few tanks through it. If I've managed to mess it up a again then it's day's could be numbered and I'll switch to a 90 nitro, the fuel may cost more but at least they're easy to set up.

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09-06-2009 10:31 PM  8 years agoPost 4
pgkevet

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Wales

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...if this sounds stupid then ignore..

Is this throttle behaving markedly differently from first install of the rebuilt motor or just an issue from that point?

If changing then it could just be because you're running in. If not changing then it could simply be your new throttle setup.

If tickover isn't engaging the clutch then I don't see why you can't just adjust the mechanics of the linkage to give more flexibility on the tx at the low/trim end and just tickover at higher revs... Assuming you can cut the engine still.

pgk

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09-06-2009 10:40 PM  8 years agoPost 5
gramey

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United Kingdom

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I can't remember but it's quite possible that it's since I changed my throttle linkage over, what I need is to find someone that makes a decent carb for these engines that you can put a straight forward linear throttle curve in.

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09-06-2009 11:05 PM  8 years agoPost 6
pgkevet

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Wales

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linear curve.. supposedly with the malorie linkage...

pgk

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09-06-2009 11:26 PM  8 years agoPost 7
SeismicCWave

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Hilo, Hawaii

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>>Tail is drifting left when in normal rate and right when in heading hold?<<

That's your mechanical linkage. Adjust like I described in my earlier post. Try to the tail to stay neutral at rate mode and it should be fine at heading hold.

>>I'm hoping the engine isn't losing compression as it's only had a few tanks through it.<<

Don't be so gloom. Your engine is still breaking in. Play with it for a while then adjust. The gas engine is suppose to last forever if you do it right.

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09-06-2009 11:47 PM  8 years agoPost 8
Fixit

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UK

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linear curve.. supposedly with the malorie linkage...
Yep very close anyway.

I only like to fly gassed up

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09-07-2009 03:42 PM  8 years agoPost 9
gramey

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United Kingdom

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Sorry about the gloomy posts I think it's a result of being on night shift this week and getting tired and fed up. I'll double check the tail linkage if not the CSM will be making way for a JR 770. Not sure on the tick over falling off when warm, temps don't seem too far out the way, I'll see what happens this afternoon.

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09-07-2009 04:24 PM  8 years agoPost 10
rbort

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Franklin, MA - USA

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This is all normal if I understand you correctly

Tail drifting to the right in normal mode. Hover it, if nose goes right then it needs left rudder. Left rudder is tail pushrod away from the main body to pop the link off the tail and unscrew it 1 turn or 2. Try again to hover in normal mode and you'll see the drift will stop. Make sure you didn't unscrew the link too far so that there isn't any threads left for it to hold on in 3D flight that could be very bad!

On the motor, they ALWAYS start fast and slow down when they warm up. Adjust your throttle linlkage so that its a stable idle at mid trim when hot and kills the motor when pulled all the way down. I always start my motor on Kill (trim all the way down when cold), and as it starts to slow down I raise the trim gradually to maintain engine idle until I'm back to mid trim.

This of course assumes you've set the low needle properly, and you set that for flight at hover, not for idle speeds to starting ease. Once its set correctly so in a hover the tail is how you like it and its burping when cold but less when warmed up, then you're good. At that point you adjust the link as said above to get the reliable idle.

-=>Raja.

MA 1005 Hanson 280, 4129 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 Hanson 300, 1425 flts
Whiplash V2 Hanson 300, 185 flts

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09-07-2009 08:57 PM  8 years agoPost 11
gramey

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United Kingdom

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Went out this afternoon and initally still had probelms with the tail drifting. Sorry I should have said the nose drifts left in heading hold and was driftig right in normal mode.
I tried shortening the tail push rod, lengthening it, increasing & decreasing gain etc. etc. I finally ended up getting it to fly properly with 7 clicks of right trim on the rudder and 11 on the sub trim. The instructions for my CSM gyro say that you shouldn't use any sub trim but I couldn't get the servo horn at 90 degrees without it. If I moved it one spline it was too far so I had to resort to TX adjustments. I shall have another look tomorrow and see if I can ge it nearer mechanically.
As for my engine I took the plug out and it was indicating the engine was running rich so I gave 1/8th of a turn in, in two 1/16th increments, and it now ticks over fine at mid point as it much smoother picking up. Down side is that I temped the engine, next to the exhaust port, on landing and it was 309 degs. Fahrenheit (154 C) am I right in thinking this is too high? I'm not sure if I'm reading too much into that as apart from the temperature the engine seemed to be running really sweet.

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09-07-2009 09:13 PM  8 years agoPost 12
SeismicCWave

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Hilo, Hawaii

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>>I should have said the nose drifts left in heading hold and was driftig right in normal mode.<<

Thank you. That is a lot easier to understand. As far as tail drift. I pay more attention to the drift in rate mode. The servo will center in rate mode when you let go of the rudder stick. So that needs to be trimmed first. Canopy drift right meant you have too much positive pitch on your tail blades. Reduce the pitch by adjusting your tail control rod. After the mechanical setup is done then you are stuck with using rudder trim on the Tx. My JR 770 is the same way. It drifts one way in heading hold and another way in rate mode. So I have to figure out which mode I use more and mechanically trim for that mode. I fly heading hold mostly so I trim for neutral in heading hold.

Engine at 300 degree F by the exhaust doesn't seem too hot to me.

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09-07-2009 09:13 PM  8 years agoPost 13
Fixit

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UK

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309 degs. Fahrenheit (154 C)
I wouldn’t be happy with those temperatures and I doubt the engine will either. I measure the temp on the underside and two fins in from the case with an e-station temp meter so you might get a hotter reading from the exhaust side than I do but thats way too hot

Is the engine run-in?

I would back the low needle back out and wait a bit longer, the motor will idle smooth once its run-in.

I only like to fly gassed up

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09-08-2009 01:40 AM  8 years agoPost 14
rbort

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Franklin, MA - USA

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You're gonna toast the motor soon

Maybe you got away with it for now because you're using more oil in the mixture, but over time you're gonna kill it if you're habitually running at 300+ degrees. Richen it up and get those temps down before the motor will be down and out for repairs.

You can't use sub-trim for the rudder. Neutralize the rudder subtrim and the trim on that channel as well and rotate the hord around on the spline of the servo until you get it to where it needs to be. If all else fails use a servo wheel and drill it yourself in the right spot.

Getting rid of subtrim is the first step to get rid of drift, and lowering the motor running temp (trust me, they run THE BEST lean before they die - its like a last hoorah!) will keep your motor and you happier.

-=>Raja.

MA 1005 Hanson 280, 4129 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 Hanson 300, 1425 flts
Whiplash V2 Hanson 300, 185 flts

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09-09-2009 12:02 AM  8 years agoPost 15
gramey

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United Kingdom

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Raja, I appreciate that's all it may take to screw the engine up but this was the first flight I've done where the temperature has been anywhere near this high. I'm usually getting around 200 - 220 is that nearer the figure I should be looking at, also when Fixit said measure it on the underside and two fins in from the case how do you do that? From underneath you've got the base plate in the way and above you've got the fan shroud there so I'm not quite sure where he's meaning

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09-09-2009 12:16 AM  8 years agoPost 16
Fixit

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UK

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Gramey
Sorry if it sounded misleading.

I was just stating were I take the measurement and I can do this because mine is a custom build with a large cut-out under the engine to help cooling and access.

I only like to fly gassed up

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