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Revolution Models . CarbonXtreme . Midland Helicopters

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Gasser Model RC Helicopters > Gasser Throttle Linkage Setup
 
 
Magenta
New Heliman
Location: woodridge, illinois - USA



It's not a matter of the servo rotation speed, it's the angular displacement that results.

Assuming that the load is horizontal to the diagram, you'll notice that the shift in position (A vs B) increases as the servo arm approaches 90 degrees to the load
05-31-2008 12:43 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

I have two issues with this concept:

1, In the fully closed position you have basically taken out the spring compensator of the butter fly. That means all the vibration of the engine as it comes to a stop will be pounding the hell out of the servo. Remember throttle servos have failed and this will certainly help do it.

2, At the other end of the servo travel you have decreased the resolution of control where the engine is operating most of the time. You don't fly a heli around the idle position, you fly it or just hover it somewhere between 50% and 75% of the engines capability. So who cares about resolution at the idle end.

I'll stick with a set up of 50% open butterfly at the 90 degree position. And you people don't like metal gears. I stick with them also.

Ace
What could be more fun?
05-31-2008 01:13 PM
 
 
windy62
Heliman
Location: USA

The way I see it, you have BETTER Servo resolution at half throttle and higher, and less at below half.

I have no idea what you mean by removing the spring compensator...Does the engine vibrate more when the throttle is shut down?

As I understand this concept, it is to help prevent the overspeeding when using a governor on the gasser engines. I guess if all that you say is true, then you have to weigh the pro's vs the con's. But I'm not convinced. Overspeeding is way worse on the heli and engine than any trumped up thoery...

windy62
05-31-2008 02:39 PM
 
 
twostroke
Heliman
Location: Elton,LA

Gasser Throttle Link Setup

I don't follow what you are saying about the "spring compensator".The throttle arm is simply repositioned on the butterfly shaft by loosening the set screw and rotating the arm. The spring action is unaffected as far as I can see.
05-31-2008 05:43 PM
 
 
BeltFedBrowning
Senior Heliman
Location: Albany, MO USA

My gassers hover somewhere between 30 and 40% throttle opening. Nitros hover at 60 to 75% throttle opening.
I had my throttle curve set up to take advantage of the gas engines torque. With the stock set up everything above 60 to 70% throttle is basically wide open. Setting up mechanical expo will make the mechanical portion of the throttle opening more linear.
Thanks for the great info guys!
06-01-2008 01:09 AM
 
 
FLAP
Key Veteran
Location: Michigan

Quote 
And you people don't like metal gears. I stick with them also
who are the '...you people..' you are referring to? Does this have anything to do with this thread?
06-01-2008 03:24 AM
 
 
TVAILLANCOURT
Senior Heliman
Location: Edmonton Alberta Canada

metal gear servo's

Not sure what the beef is with the metal gear servos.I run all my gas stuff with metal gear servos on the throttle.Giant scale Aircraft too!Never had an issue or failure????
So what's the Beef?

I like the new throttle set up!
06-01-2008 06:02 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
I have no idea what you mean by removing the spring compensator...Does the engine vibrate more when the throttle is shut down?

It vibrates at a ever decreasing frequency until the engine stops. Typically as the frequency decreases the amplitude increases but not always.

There should be a spring on the butterfly that keeps the slop out of the gear train of the servo. When the butterfly is closed all the linkage slop is gone so as the engine vibrates to a stop it will be transmitting this force right to the servo with no compensation. It can very easily wreck the bearings, or the pot of the servo.

Quote 
Not sure what the beef is with the metal gear servos.I run all my gas stuff with metal gear servos on the throttle.Giant scale Aircraft too!Never had an issue or failure????
So what's the Beef?

I couldn't agree more but post like that will get you insults from the peanut gallery.

Quote 
Does this have anything to do with this thread?

Sure does in my book.

Ace
What could be more fun?
06-01-2008 01:47 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
I like the new throttle set up!

On a plank it has more merrit. Also, the servo is usually behind the engine in line with the crank on an airplane. On a heli it is 90 degrees to the crank which means it gets the full shake of the engine. The servo link of a plank doesn't see any shake of the engine because it is 90 degrees to the link.

Ace
What could be more fun?
06-01-2008 01:55 PM
 
 
Malorie
Elite Veteran
Location: Paw squared, MI

Well I can help with any proposed failures due to this setup. I flew this setup hard for a couple of seasons since this thread and NEVER had any issues with burned up servos or ruined gear trains in those servos. So theorize all you want, the field test says it works just fine with no ill effects.

This is still the ultimate setup for a gasser throttle even if you don't run a governor, IMHO.

Malorie

Life's a journey, NOT a destination.
08-26-2008 12:23 PM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

Malorie

Well said Malorie,Going to change my gassers tonight.
08-26-2008 02:23 PM
 
 
shawmcky
Veteran
Location: Isle of Wight,United Kingdom

Linkage set up

I have changed the linkages on my gassers and immediately noticed a big difference.Strange how such a small detail can make such a big change to the characteristics of the heli,s.They both seem much more responsive with this set up.
08-28-2008 12:00 PM
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

Thanx Mal !!!

I converted to Mal's mechanical expo the day it came out on RR at least 3 year's ago or longer. Gosh it's good to here from you Mal - thanx for your contributions.

Did it after losing a BSN " bran spanking new 9252" Thought it was value enough to print it and place it in the great 3 ring book of copter knowledge. The mechanical expo trick is really great especially on a gas motor due to where power curve actually developes in relationship to the butterfly opening, and where the high speed and low speed needles transistion in the carb circuit.

After that servo oddesey I know run a budget servo on the throttle upon the reccomendations of Mr Ra.

What's interesting is a while back I was defining the pitch curves on my SE trying to get more resolution and was posting both set's of curves, pitch and throttle.

At the time my concern was defined over resolution pitch issues, so I didn't get into my throttle configuration, but one individual whom's pretty darn sharp indeed did make a comment about the throttle numbers showed the mechanical expo in the numbers.

It's kinda like having a soft foot on the accelerator on a car with a big motor hot cam.

greyeagle
08-28-2008 02:14 PM
 
 
ccm15
Senior Heliman
Location: Lake Ariel, PA

I wish I had read this post earlier. I can't wait to try this setup on my Spectra. I am running the GV-1 and Stator gator and have experienced the overspeed problem. This makes so much sense. Thanks.

One mile of road will take you one mile. One mile of runway will take you anywhere in the world.
09-01-2008 06:56 PM
 
 
Excalibur
Veteran
Location: Destination: Earth

Hi ccm15:

I was looking at doing this on my Spectra-G as well, but it's not going to be as easy to implement because the carb throttle arm is rotated 180 degrees from normal. In other words, it points TOWARDS the engine, not AWAY from it as depicted in the drawing. This will cause control rod binding on the throttle arm at extreme throws as shown in the diagram, but you may get close enough to call it good.

I'll be looking at this a little more in the next week or so, and will see if it's doable. Let us know how it works for you.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
09-02-2008 05:49 AM
 
 
BeltFedBrowning
Senior Heliman
Location: Albany, MO USA

On my JR I loosened the set screw on the throttle arm and put it where I wanted it.
09-03-2008 05:23 AM
 
 
ccm15
Senior Heliman
Location: Lake Ariel, PA

What do your endpoint settings look like? I am thinking on a Spectra and Futaba 10C 100% low and 140% high.

One mile of road will take you one mile. One mile of runway will take you anywhere in the world.
09-06-2008 03:04 PM
 
 
ccm15
Senior Heliman
Location: Lake Ariel, PA

I tried this setup today and it workes great. Thanks so much.

One mile of road will take you one mile. One mile of runway will take you anywhere in the world.
09-08-2008 02:37 AM
 
 
Excalibur
Veteran
Location: Destination: Earth

ccm15:

Please post a couple of pictures of the throttle and servo linkages so everyone can take a look at it - thanks.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore
09-08-2008 05:18 AM
 
 
ccm15
Senior Heliman
Location: Lake Ariel, PA

Ok, here are my pictures on the throttle setup on the Spectra.
The first picture is Closed throttle position.
Second picture is Mid stick.
Third picture is Full throttle.
I hope this helps.

09-08-2008 12:40 PM
 
 
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Gasser Model RC Helicopters > Gasser Throttle Linkage Setup
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