RunRyder - throttle trim

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Main Discussion > throttle trim

biff74
Heliman
Location: gold coast, australia

Hey,

do i set the throttle trim to full low when setting up my throttle linkage or half way 0 ? on raptor technique he says to set it at half way i think. the radio is a Jr x 378.

i can get perfect equal throws with trim set at half way but when i set the throttle trim all the way down , i can;t seem to get the linkage set right..
it has too much throw one way.

cheers

07-30-2005 Over year old.

Sar
Elite Veteran
Location: Kingston, NY

I haven't read the article on Raptor Technique. Usually I trim my throttle all the way down and then set the endpoints of the throttle, I then bring the trim up to about mid, start the heli in idle and adjust the trim up or down as required to keep the engine running. Make certain to check full open vs. full closed to the engine manual, you don't want to get it backwards.

--
Jon

07-30-2005 Over year old.

HOMEPAGE

ChrisLaFollette
Veteran
Location: Altha, FL

I set mine up at 50% throttle in the radio with the trim centered. I usually mount my ball out about 12-15 mm's so its halfway fast. It doesnt really matter on the throttle. Just gets there quicker.

07-30-2005 Over year old.

biff74
Heliman
Location: gold coast, australia

Hey,
Thanks for your posts.

Girard, i tried your method. i got the pushrod the exact lenght got the servo horn the exact length had equal throws but now the throttle when at 50% is not half way on the carb barrel. (os50) and the arms are not 90degrees . so i am back to square one. what do you think.

(EDIT) Girard, its very close.. very close, i used the adjustable servo horn that comes with the hitec servos got that spot on. got the link length spot on.. equal throws are perfect at both 0 and 100% at 50% on the stick (half wa the throttle arm is just over half way. (near the third mark on the 0S50 barrell and very close to 90 degrees.
.
thanks for your help..

cheers

07-30-2005 Over year old.

SDavied
Senior Heliman
Location: Ellis, Ks

It makes more of a differnce than you may think when you take the time to get the throttle's mechanical set-up just right.

07-30-2005 Over year old.

MicroDOC
Veteran
Location: Goleta, CA

In normal flight mode you want the throttle fully closed when the stick is all the way back and the trottle trim is all the way down, this will kill the engine. With the stick down and the trim advanced about half way or a little more you want a good idle. With the trim all the way up you should get a fast idle, but not enough to engage the clutch. With the trim set half way and the stick fully up you want full trottle. At least that's how I like mine.

Ron…

Experience is something you don't get until just after you need it!

07-30-2005 Over year old.

HOMEPAGE

biff74
Heliman
Location: gold coast, australia

i can get perfectly equal throws with the trim set at 0 (middle) but it seems as soon as the trim is at full low. then the throws immediatly become unequal. with the barrel at exactly half way there is more throw one way then the other becuase of the digital trim being full low.
ive overloolked something no doubt. but at the moment i dont'; see a way around it . Girards throttle geometry doc. doesn;t say anything about the thottle arm and servo arm being at 90 degrees at half way.

anyways i dunno..

cheers.

07-31-2005 Over year old.

Big Edge
Senior Heliman
Location: Palm Harbor, FL USA

My Futaba 9C has digital trims,
I setup my throttle linkage with the trim setting in the middle "0" I get equal ATV settings (96%) and servo arms 90 degrees at 50% throttle.

07-31-2005 Over year old.

biff74
Heliman
Location: gold coast, australia

i found it impossible to get equal throws with the trim at low position whilst having the barrel at 50% with the arms 90 degrees to link.
from middle position it was easy. but for the reasons you just stated i dont want it like that.

07-31-2005 Over year old.

biff74
Heliman
Location: gold coast, australia

i loosened the throttle arm then gave full throttle then moved the throttle arm to match then gave 0 throttle and had a match there, perfect , but as soon as i moved it to 50% half way the arm is no longer 90 degrees to the link and it is not at exactly half way on the barrel. this i gather is not having equal throws.

07-31-2005 Over year old.

biff74
Heliman
Location: gold coast, australia

Girard,

Thanks very much for writing that out. I will do what you suggest when i have some spare time again.

cheers

07-31-2005 Over year old.

Red-Rx7
Senior Heliman
Location: Olathe, KS - USA

Hey gang..

I know I have asked these simular questions before, and many knowledgable people have responded (ie Girard Ibanez). Yet, I have also been fighting this, trying to get it setup right as well.

I followed the steps above, and the end result is that my atv's are now dead equal... Yet, they are way off from what I have read to have them at.

They are dead equal at 63% for both High and Low stick on my 9303. I am glad I finally got them all equal, and having the center stick be in the middle carb rotor tick. But, I don't see how I can get my ATV above 80% like people say. In the document example setup, it mentions on step #13 to move the ball on the servo arm "In or Out" to achieve optimal ATV values. In reviewing the pictures below, would I need to move them out further? In doing that, I would need longer servo arms. I can't move them in any closer. Is 63% really that bad, and why?

Picture example:
{Here is center stick, trim down, 63% ATV's both High/Low)

{Here is High stick (Full Throttle), trim down, 80% ATV's both High/Low)

{Here is Low stick (Closed Throttle), trim down, 80% ATV's both High/Low)

Thanks,
Mike

08-01-2005 Over year old.

Ali92124
Senior Heliman
Location: San Diego, CA

Red-Rx7

To get closer to 100% atv, you can
1) move the ball link closer to center on the servo arm or
2) move the ball linker further out on the throttle arm (will not work for your case, as the ball seems to be on the last hole).
---
Ali

I dont need no stiiiiiinkin signature.

08-01-2005 Over year old.

TMoore
rrProfessor
Location: Cookeville, TN

Ali is right. At some point you might want to fly this thing and stop messing with the throttle.

08-01-2005 Over year old.

ChrisLaFollette
Veteran
Location: Altha, FL

Just leave it where it is and go fly. The smaller the EPA number the faster the throttle will be. Just run that itll be fine.

08-01-2005 Over year old.

zoom boy
Key Veteran
Location: N.E. Lincolnshire UK

The way I found best for me is to remove the servo horn, set throttle ATV to 100/100 and put the trim to the bottom, manually close the carb, then drill a hole in the servo horn so that the ATVs stay at 100/100, the only down side is that makes the servo lop sided in regards to linearity, but thats not a problem.

That makes sure that the engine not quitting is not a problem.

Linearity is not an issue on the throttle servo, because the throttle curves can take it out like putting expo does with cyclic, also its a complete non issue with a govener installed.

In also set the throttle cut switch to move the servo to the fully closed postion regardless of the trim

08-01-2005 Over year old.

Big Edge
Senior Heliman
Location: Palm Harbor, FL USA

Just like to point out,
I use the method found on Michael Prewitts RaptorTechnique.com web site.
You don't have to set the first point on the throttle curve to 0.

Binding, I dont get any binding and I do use the throttle cut.

And yes, there is more than one way to skin a cat, or Raptor.

08-01-2005 Over year old.

TMoore
rrProfessor
Location: Cookeville, TN

Quote
Achieving your goal in a linear setup is the basic building blocks to a good foundation on any mechanical setup.

Now that's a good one. In my experience a linear setup is an unachievable goal. The problem with the term linear as it relates to model helis, is that it assumes that pitch and throttle can be linear quantities. Pitch could be but throttle, definitely not.

The engine is an unknown quantity vis a vis the power output relative to the air/fuel ratio and whether or not it truly makes 50% power at 50% barrel opening.

I would never recommend anyone rely totally on the power of the radio as I have demonstrated on several occasions that throttle differential is more powerful than throttle curves alone with a so called linear setup.

The problem with the internet is that it takes longer to write this stuff up and explain than if you just jump in your car and go to an event to ask for help. Few want to do a search for information and even fewer folks like to be challenged to think.

TM

08-01-2005 Over year old.

zoom boy
Key Veteran
Location: N.E. Lincolnshire UK

Ah, but thats why we have tachometers, using an onboard one lets you account for non-linearity very well.

08-02-2005 Over year old.

Big Edge
Senior Heliman
Location: Palm Harbor, FL USA

Linear setup! good points TMoore.

Thats why I use zero, center trim on the 9C, for ease of setup.

When you put the trim all the way down, this introduces differential throws, makes setup a PITA.

Very nice graph by Girard Ibanez,
The box setup works excellent and is very easy to setup when your servo throws are equal, no differential.

08-02-2005 Over year old.

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