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HeliHobby . Ron’s HeliProz South . Century Helicopter

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Gasser Model RC Helicopters > Gasser Throttle Linkage Setup
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

hookmaker

Just to make clear that the carb has less movement in relation to the throttle servo now.Your governer needs to relearn the new positions.I am set up to hover at just over mid stick now.
09-13-2008 11:25 AM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

There are a 100 ways to do this

Paul has his setup all over the place and I redid it for him last weekend.

Basically the way I do it is:

Engine idles at mid trim
Engine dies at full low trim
Throttle curves are at 0 on low
ATV's are anywhere from 100/100 to 130/130
Throttle hold is at 0%

The way Paul had it his throttle low point was 27%, his throttle hold was 20% or something like that.

I like things to be neutral and start as normal as possible, so with above settings the throttle curves come out to about 0, 20, 22.5, 25, 100 or something similar for normal mode. This is with a G26 motor. With a G231 motor the numbers will be slightly higher.

So if you're idling at 38%, then your whole throttle curve is off.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
09-13-2008 03:37 PM
 
 
BeltFedBrowning
Senior Heliman
Location: Albany, MO USA

Thanks Raja, I have printed this out and added it to my set-up book
09-13-2008 04:26 PM
 
 
hookmaker
Heliman
Location: Copenhagen, Denmark

Raja, I don´t get this at all:

I use the 14MZ. I setup the mechanical linkage as close to the above diagram as possible.

I have a throttle curve that is linear from 0 - 100%.

I pull the starter handle with throttle at 0 and then go up. At the same time I observe the butterfly valve and try to start. It starts at throttle about 35% (and valve equally open). It can not start with the valve more closed than that.

At about 38% it idles pefectly.

So I don´t understand that you can start with the valve almost closed???

/Henrik
09-14-2008 07:14 PM
 
 
TooBizzy
Senior Heliman
Location: Georgetown, Ohio USA

Try adjusting the length of your control rod so your engine idles at "0" on your throttle curve. Sounds like you need to shorten it a bit. By having your first point set at 38%, your loosing what you are trying to gain by setting up mechanical expo.

Once you have this set, you'll need to make sure you can shut the motor off with the trim.

Can you post a picture of your setup?

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...
09-14-2008 09:57 PM
 
 
hookmaker
Heliman
Location: Copenhagen, Denmark

Not realy necessary to post a pic, it´exactly as in the diagram. BUT big difference to nitros is that on a nitro the carb only has to be less than about 10% open to be able to run, it´s considerably more on the gasser. I´ll just have to setup mechanically for this.

So I still don´t understand how you can run the setup as pictured, have a throttle curve linear from 0-100 and be able to start and idle the engine at around 5-15% throttle, thats impossible unless you would use a LOT of trim.

/Henrik
09-14-2008 10:42 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
So I still don´t understand how you can run the setup as pictured, have a throttle curve linear from 0-100 and be able to start and idle the engine at around 5-15% throttle, thats impossible unless you would use a LOT of trim.

/Henrik

You're right in that it will take more travel to reach idle if you have set up the mechanical expo. If I take 38% of 90 degrees I get 34 degrees; it could happen.

Ace
What could be more fun?
09-14-2008 11:09 PM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

You should...

Set throttle curves with the first point at 0
Mechanically setup throttle arm as said above.
Adjust ATV so the carb if full open at full throttle, full closed at full trim down.
Hover and adjust mixture or adjust mixture from before.
Adjust link length so engine idles reliably at mid trim.
Throttle hold should be at 0% and no change in rpms when enguaged equal to mid trim setting.
Engine will die before the carb is closed all the way but ignore that. As long as it dies at full down trim you're good.

You should not be starting/idling the engine at 38%.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
09-15-2008 01:35 AM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

hookmaker

What you are experiencing here is the altered movement ratio.With the std set up the linkage moves the carb end linkage at exactly the same time as the servo.With the set up you now are using there is a dwell period as the throttle servo rolls over the peak of the servo horn.you are in effect starting in the same original carb position but the percentages are showing higher because of this dwell period.Watch the operation of the new set up and you will see what i mean.The throttle servo is moving some time before the carb spindle starts to move.This is why you are seeing the higher % ratio.You can alter the linkage position on the throttle servo horn if you want to reduce this,this set up is meant to incorporate the dwell period.
09-15-2008 09:14 AM
 
 
aarinsingh
Veteran
Location: Thompson, MB

I just recently came across this thread, and was curious. Long story short, I set it up last night.

It works better then I thought it would, my machine was running good to begin with, so I won't say it transformed it, but it "felt" happier. I have had issues with the engine hiccoping when coming off of full throttle, and that seems to be gone. I only had enough daylight to run 4 flights on it, but so far so good.
09-21-2008 03:39 AM
HOMEPAGE  
 
 
KarbonBird
Key Veteran
Location: Australia

I have set mine up according to this too:

http://www.youtube.com/watch?v=gjzeFTB0b48

Anyone care to comment on how it looks in action...
09-21-2008 08:41 AM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

Karbonbird

Looks spot on to me.If you differentiate from this set up is does not work as it should.
09-21-2008 08:51 AM
 
 
KarbonBird
Key Veteran
Location: Australia

Thanks shawmcky.

It certainly is running the best it ever has - apart from the times when it appears to lose power. I'll make it a bit leaner then see how it handles (and check the plug also). I am just doing some low level hovering during the testing phase so hopefully I'll be able to correct the problem without doing any damage should it cut out or something.
09-21-2008 09:56 AM
 
 
hookmaker
Heliman
Location: Copenhagen, Denmark

I have flown too much nitro the last week, so haven´t had time to fiddle around, but mine does not work as intended.
I set mine up exactly as in the diagram - and as your vid, but with a 0-100% linear throttle curve (ATV +- app. 100%) my engine can only start and iddle at around 36% - everything below and it dies, period.
I actually thought the gasser carb butterfly valve had to be only minutely open to run at idle, but that´s not the case on mine, it has to be something like 30 degrees open (full open is 90 degrees)

This is without any kind of trims etc. I use trims for minute detail adjustments, so this comes after it runs +- okay.

/Henrik
09-21-2008 04:41 PM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

Karbonbird

Recheck your throttle and pitch curves,you might have to readjust after changing the linkage,too much pitch at the wrong point in your throttle curve could be causing the power loss.I have had to reset both my gassers .I have a rotary dial on my Futaba 7C so it was quite easy to reduce the pitch slightly to overcome this.My engines were bogging due to too much pitch and taking a while to catch up,made it seem like fuel starvation.
09-21-2008 06:02 PM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

Karbonbird

The mixture being too rich will make your engine bog down and if indeed it is slightly over pitched it will make it appear ten times worse.
09-21-2008 06:11 PM
 
 
hookmaker
Heliman
Location: Copenhagen, Denmark

Can´t realy use this at the stage I´m at right now. Could you guys verify that your engines do not start unless the butterfly valve is about 30 degrees open from completely shut? If yours start at only I tiny valve opening, then theres something wrong with mine
/Henrik
09-21-2008 09:14 PM
 
 
KarbonBird
Key Veteran
Location: Australia

Quote 
Recheck your throttle and pitch curves

OK, but my understanding is that the pitch curve is to first set up the mechanical arms on the servos - including the throttle. Then, get the pitch curve + and - travel required correct. Lastly play with the throttle curve until the headspeed is at 1550.

Like some others here my throttle pitch curve starts at aound 28 (not 0 as has been suggested). Does that indicate something perhaps??
09-21-2008 10:55 PM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

hookmaker

Neither of my gassers will start with the throttle bottomed out,i always have to lift the throttles to a lesser or greater extent to start especially as the weather changes.
09-22-2008 09:23 AM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

Karbonbird

I take it your heli was fine before you changed your linkage set up.I use governers on my heli,s to maintain my desired headspeed.I think your throttle position is lagging behind your pitch curve,in effect too much pitch for too little throttle opening causing the engine to bog down.It does take a bit of fine tuning to get this right.Check your pitch curves with a pitch guage.You will have to tweak your throttle curve up at certain points to overcome the bogging,best done whilst flying to get it just right.
09-22-2008 09:59 AM
 
 
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Gasser Model RC Helicopters > Gasser Throttle Linkage Setup
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