Check out the latest Futaba 8FG Programming Installment, all about Rates:
How much your controls move is of top importance in getting your airplane to “feel” right while you’re flying it. How they move can make the airplane feel “twitchy”, with a very loose feel, giving you the impression that it’s unstable; you can get control movements that make you feel “locked in”, with a very high stability. Control movement can also help you fly more smoothly. It’s all in how you set things up.
How much a control surface moves for each bit of stick movement is called the “Rate”. When you set up an airplane with a pushrod connecting a control surface to a servo, you are setting a rate. That’s before anything is done in the transmitter’s programming. When you set up a model, you want the controls to have the maximum amount of movement possible BEFORE you do any programming. That’s especially true if you want to do 3D-type maneuvers.
With our model, we set the ailerons, elevators, and rudder so that they all will move 45-degrees from center when the stick is moved all the way over. We do this by putting the pushrod in the innermost hole of the control horn on the control surface, and the outermost hole on the servo. If that gives us too much movement of the control surface, then we move in one hole on the servo, or out one hole on the control surface, or some combination. We can only get close.
Make sure the control surface is perfectly-centered when you get done. Get as close as you can. Sometimes, you’ll notice that the servo arm is not perfectly perpendicular to the servo case. You can fix this by removing the arm and turning it 180 degrees. Futaba servos have an odd number of splines, so you can center the arm by putting it in one position or the other. To fine-tune the controls, adjust the subtrims a bit. You should not need much at all. Too much subtrim means you haven’t done your job on getting the pushrods adjusted properly.
The subtrim adjustments are in the Linkage Menu. Here are some we’ve adjusted for our example:
Once you get close to the amount of control surface movement you want, go into the Linkage Menu, and then the “END POINT” menu selection. Adjust the travel amount up or down to set each endpoint for full-stick travel. You should not need much at all. This fine-tunes the controls so that they are moving exactly how you want them to move. Here’s a pic of the End Point section showing slight differences in the aileron, elevator, and rudder settings to get things dialed-in:
Once you have the controls moving the proper amount for your maximum movement, you can have switch-selected settings that allow you to reduce the amount of control movement to tone down the feel. For most flying, 3D rates are just too high, so a lower rate is needed for general flying, and maybe even a lower rate for extra smoothness during takeoffs and landings. When we add two more rates, we wind up with a total of three: basic rate, reduction #1, and reduction #2. You don’t have to have two additional rates, you can have only one. You can have more, too, if that’s how you want to set things up. Just remember, you have five rates to add to all of the functions of the airplane.
Adding a rate:
Adding a rate is easy.
Enter the Model Menu, and then the Dual Rate section. Move the cursor down to the dotted lines below the number “2″ at the bottom of the screen. Touch the dial. This brings up the “H/W Select screen. In our example we chose “SA”. Go to the “on” position setting section and set the switch so that it is “off-on-off”. The makes the middle position turn on the rate.
Do the same for the number “3″, and set the same switch (SA) so that it is “off-off-on”. You now have three positions: default rate, rate #2, and rate #3…or three different amounts of control movement.
To adjust the amount of movement for any of the rates, move the switch to the position that turn on that rate (you’ll see it become highlighted under the cursor), and adjust the amount in the fuel rate screen. Leave it at 100 for the basic, but when you move to the #2 and #3 positions, you’ll be able to adjust eh amount to whatever you desire for that rate. Confirm the rate by holding the stick at full travel and move the rate switch. You’ll see the affected control surface move to each of the three extreme positions you’ve just set. You now have triple rates on that control function. You’ll also see the graph change, too, as you move the switch.
The basic rate is 100%. That’s going to be your 3D control movement:
Rate #2 will be somewhat lower. We set our transmitter to 70% for the example:
Rate #3 is the lowest, at 40% for the example:
You can do this for the other controls you want to set.
……And that’s how you set the rates.
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