Differential

Study this animation and understand it.

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It doesn't look all that bad, right? We're only coming up 2.5 degrees short on the left and going over 1 degree on the right.

We could adjust our travel to 107 and 97 and get the original full travel on both sides. Then we could make some adjustments in our pitch or throttle curve to compensate. We could do that.

However, if we do, the machine might feel a little off because we're altering the speed that things change. The farther an arm gets from it's "square" position, the less change it makes to the linked arm per degree of travel. It's not too obvious in the top animation, but look at the next one and it will be very clear.

The arm on the left represents a servo going through 60 degrees of travel. Notice that as it moves toward the right, how much faster the arm on the right goes.

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You think you'll never have anything that far off, but it doesn't have to be very far off to make a big difference in the way your model flies.

It's Not Always Bad

Differential can be used for good. You just have to understand it!

I asked Elevated R/C to make this little square to help get linkages square. It doesn't work on all linkages, but it does work well in most throttle applications.

ELRC200

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