Here is the second servo calibration procedure developed by Bell Electronic Technologies. It is adapted to programming a Hitec digital servo while on the plane. Click here for the on the bench programming method. The AeroPerfect Digital Control Throw Meter is perfectly suited for this because of its high degree of accuracy and ease of use. Also please note that AeroPerfect's new MU-9000X USB and MU-9000X AP3 can also be used while following this servo programming procedure. In the following text, just substitute MU-1800-I with either of these two newer devices. This method will allow you to program your Hitec digital servos using the Hitec HFP-10 programmer without resorting to the "trial and error" method. (Again, we are not in any way affiliated with Hitec. But this just works too well to keep it to ourselves!) Please read our Conditions of Use
As in the on the bench programming method, a preliminary set of calibration numbers are obtained from the HFP-10 programmer. A set of estimated calibration numbers are obtained by multipling the preliminary set of numbers by a scale factor. The scale factor is calculated based on the ratio between your radio's actual pulse widths and the HFP-10 programmer's assumed pulse widths for all radios. Your AeroPerfect Digital Control Throw Meter is then used to measure your control surface deflection. The final programming numbers are then calculated by the spreadsheet based on the measured error.
Please use this Servo Calibration Spreadsheet along with the following procedure. Downloading of this spreadsheet indicates that you agree with the Conditions of Use. You can either "right-click" and select "save target as" or "save link as", depending on your browser.
In the following example, a Hitec HS-5645MG is programmed with the Hitec HFP-10 digital servo programmer while accurately measuring the control throws with the AeroPerfect Digital Control Throw Meter.
As in the previous procedure, it's best to establish a convention as it relates to pulse widths and CW - CCW: If you program your servo for CW (clockwise servo rotation) using the HFP-10, it means that wider pulse widths will cause CW servo rotation. (Conversely, narrower pulse widths will cause CCW servo rotation). Also, if you program your servo for CCW (counter-clockwise servo rotation) using the HFP-10, it means that wider pulse widths will cause CCW servo rotation. (Conversely, narrower pulse widths will cause CW servo rotation). On our Eclipse 7 radio we've observed that, with the servo directions set to "normal", that left stick movement produces narrower pulse widths and down stick movement also produces narrower pulse widths (and the converse of this is true as well).
Set the trims and sub-trims on all channels of your transmitter to zero and make sure the EPA adjustments are where you plan to use them (e.g., 100% or 115%) for all channels. Also, make sure you don't have any mixes activated. (There is an advantage in setting your EPA's near your radio's maximum in order to gain resolution. You can even set your radio's EPA's to maximum, however if you ever need to increase the control throws, the servo would have to be reprogrammed.) Set the direction for the radio channel you plan to use to "Normal".
Connect the HFP-10 to the radio channel you plan to use. Select the Measure Pulse program function. With the control stick at neutral, enter the number of microseconds into the spreadsheet on the "Measure Radio's Pulse Widths" row and in the "Middle" column. Move your radio's control stick in the direction that will yield the smallest pulse width and enter that value into the spreadsheet on the same row, but in the "CW Degrees" column. Lastly, move your radio's control stick in the direction that will yield the largest pulse width and enter that value into the "CCW Degrees" column.
At this point, the spreadsheet shows two scale factors that will be used later to obtain the "Estimated" program numbers.
Make sure the servo is NOT connected to any control surfaces. Remove any servo arms and reset the servo using the Program Reset function on the HFP-10. After resetting the servo, you may need to reverse the direction of your servo. If so, use the Program cw/ccw function at this time. Please refer to the CW - CCW discussion above in deciding the direction of rotation.
Keep in mind that if you need to change the direction of rotation after your servo is programmed, the easiest way is to set the corresponding channel on your radio to "REV". This calibration procedure must be repeated any time the servo direction is changed using the HFP-10's Program cw/ccw function.
Set the HFP-10 to the S-Test Manual program function and set the knob for the number of microseconds that you measured for neutral in step 2 (Probably somewhere close to 1500 microseconds). Push the servo arm onto the servo shaft 90 degrees to the case (as close as is possible). Make sure you orient it in the desired direction. (Since there are a finite number of spline on the servo arm and shaft, it is possible that the angle between the servo arm and the servo case will not be exactly 90 degrees at this time. However, that will not affect the accuracy of the servo programming.)
If your servo isn't already installed in your aircraft, go ahead and install it and connect the linkage to the servo arm. Rotate the knob of the HFP-10 so that the servo arm is exactly where you want it (probably 90 degrees to the servo case). Mechanically adjust linkages so that the control surface is zero. Establish a zero reference angle by placing the AeroPerfect MU-1800-I onto the control surface (that is still set to neutral) and push the reset button on the AeroPerfect AP3 display.
Select the Program EPAneuFS program function. Decide on the range of control throw travel and enter it into the spreadsheet on the "Enter Desired Range" row. Enter the value for both the "CW Degrees" and "CCW Degrees" columns (The CW and CCW values do not have to be the same).
While holding the AeroPerfect MU-1800-I onto the control surface (the included clamps and plates work well for this), rotate the HFP-10's knob until the control surface reaches its neutral position. Enter the initial program number from the HFP-10 display into the spreadsheet under the "(M)" column and on the "Initial Program Numbers" row. Push the "M" button on the HFP-10.
Rotate the HFP-10 knob left until the AeroPerfect AP3 display reads the desired angle you entered under the "CW Degrees" column on the spreadsheet on the "Enter Desired Range" row. Enter the initial program number from the HFP-10 display into the spreadsheet under the "UP/L" column (and on the "Initial Program Numbers" row). Press the UP/L button.
Rotate the HFP-10 knob right until the AeroPerfect AP3 display reads the desired angle you entered under the "CCW Degrees" column on the spreadsheet on the "Enter Desired Range" row. Enter the initial program number from the HFP-10 display into the spreadsheet under the "DN/R" column (and on the "Initial Program Numbers" row). Press the DN/R button.
The spreadsheet now holds the "Estimated" program numbers which are based on two things: The scale factor between your radio's measured pulse widths and the pulse widths that the HFP-10 assumes for all radios and the initial program numbers you just entered into the spreadsheet. Before proceeding, it is imperative that you disconnect any linkage from the servo arm. Programming the Estimated numbers will require the servo arm to travel farther than it would under normal operation.
Use the Program EPAneuFS program function as before to program the "Estimated" numbers into the servo.
Disconnect the servo from the HFP-10 and connect it to your receiver. Reconnect your servo arm linkage. Use your AeroPerfect Digital Control Throw Meter to measure the control throw deflection for each of the stick positions (neutral, both extremes). Enter the angular values into the spreadsheet on the "Measured Angles Using Radio" row. Be sure to enter the values in either the "CW Degrees" or the "CCW Degrees" column, depending on which direction the servo arm was rotating (not whether the AeroPerfect AP3 is displaying a positive or negative number).
For your radio's neutral stick position, take note of any error from zero. If the error you measured is that the servo arm is too far CW (Clockwise), enter a positive number into the spreadsheet. Otherwise, if the error you measured is that the servo arm is too far CCW (Counter-clockwise), enter a negative number into the spreadsheet. Again, use the "Measured Angles Using Radio" row and the "Middle" column.
The spreadsheet now has the final calibration numbers. Use the Program EPAneuFS program function to program the "Predicted Numbers" from the spreadsheet. Before proceeding, it is imperative that you disconnect any linkage from the servo arm. The final calibration numbers will require the servo arm to travel farther than it would under normal operation.
Rotate the knob until the predicted number for "M" shows on the HFP-10 display. Push M. Then rotate the knob left until the predicted number for "UP/L" shows on the display. Push UP/L. Rotate the knob right until the predicted number for "DN/R" shows on the display. Push DN/R.
Disconnect the servo from the HFP-10 and connect the servo to your radio receiver. Reconnect any servo arm linkage at this time. Use the AeroPerfect MU-1800-I to measure and verify the neutral and the control surface deflection in both directions.
You have now successfully programmed your Hitec digital servo using your AeroPerfect Digital Control Throw Meter ! HAPPY FLYING!
This calibration procedure and the accompanying servo calibration spreadsheet are provided by Bell Electronic Technologies "as is". In no event shall Bell Electronic Technologies be liable for any direct, indirect, incidental, special, exemplary, or consequential damages arising in any way from the use of this procedure and/or spreadsheet.
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