Hello there, please login! Home | Why R/C Heli's? | Getting Started | Set up | Flying Lessons | Articles | Newsletter Archive
Product Reviews | Links | Glossary | Buy/Sell Market | Find a pilot in your area | Login
Set up
Pitch Setup
Throttle Setup

Setting up the throttle curve

Just as crucial as setting up the pitch curves correctly is setting up the throttle curves. Throttle curves work in similar fashion to pitch curves.

In the same fashion as pitch curves, a throttle curve determines how far the throttle body of the carburetor opens based upon the position of the collective/throttle stick.

You can set up different throttle curves for different flight modes. For example in Normal flight mode, where you do most of your hovering, you'd probably want to set your throttle curve up so that the helicopter isn't screaming when it's hovering. Correspondingly, when doing aerobatics and such in Idle Up One or Two, you want all the power and headspeed you can, so you set your throttle curves accordingly.

A good 'Normal' throttle curve is very nearly linear. This means for each movement of the throttle/collective stick, there's an equal movement of the throttle servo no matter where on the curve the stick is. This means that there is a consistent movement in engine revolutions. An Idle Up One curve can be whatever you feel you like with the style of flying you like, and a usual Idle Up Two curve very much resembles a 'V' because it has 100% power at both ends (for flying upside down etc.).

Governors are cool little boxes of electronic wizardry that monitor the helicopter's headspeed and manage the throttle servo to keep the headspeed within predefined parameters. You set them to keep the headspeed at a certain level and it increases or decreases throttle to keep the headspeed at your defined level. This means that instead of your throttle curves managing the engine speed, the governor is. However, it is still important to have good curves because when governors fail, they revert back to the curves you set up.

Throttle Linkage
As with all linkages on a helicopter, it is important that you set up the linkage between the throttle servo and carburetor arm correctly. Ideally, for every degree the throttle arm travels, you want the carburetor arm to travel the same distance. This means that both the servo arm and the carburetor arm should be the same length. The illustration below outlines an ideal setup...

Notice the throttle and carburetor arms are the same diameter and that the throttle are is of such a size that for every degree the throttle servo travels, the carburetor arm moves an equal amount. Having your linkage setup in this way will allow you to set your throttle curves more precisely.

Setting up your throttle linkage in this manner will allow you to accurately program all your throttle curves. In some cases however, you will not be able to achieve the above result and you will have to make adjustments to your curve to compensate.

This graph shows a typical throttle curve for the 'Normal' flight mode where you do most of your hovering.

The benefit of a curve like this for hovering is that it is smooth. For example, moving the stick will give an even movement on the throttle, i.e. it won't suddenly increase, or move more slowly.

There are many differing opinions as to what your Idle Up One curve should look like, some have theirs looking like a 'tick', while others just program theirs to their own taste.

The curve illustrated here is what I use to fly my Ergo 46, the heli flies how I like it with this curve so that's why I use it. I have it setup like this cause I like the headspeed to be high at hover for launches or for when I'm doing maneuvers that require high headspeed.

Here you see why it's called the 'V' curve. With this curve, the machine hovers at around 70% power both inverted and right side up. Also, 100% power is present at both top stick and bottom stick for climbouts and inverted climbouts respectively.

You can also see that the throttle is more sensitive with this curve as the throttle servo moves more with each movement of the collective/throttle stick than any of the other curves.

Featured Link!
Micro Helicopters NZ
Welcome to the first New Zealand website dedicated to the hobby of building and flying miniature rad...

Suggest a link

Free newsletter!
Register for the monthly newsletter, pilot locator & Market
Click here


Email this page to a friend!
Click here

© Copyright LittleRotors.com 2001 - 2004
Contact simon@littlerotors.com for comments/questions.