Buzzard Droppings November 2002

 Hitec Digital Servo Programmer by Ron Swift

As modelers, we get challenged by solving technical problems as we assemble our newest aircraft. One of these can be the need to match servos when two or more are used for a control surface.

Until recently, setting up a large scale aircraft like a Reno Racer or 3D aerobatic model meant matching servos by buying a large number of the same servo and testing them, matching them up as closely as possible. This process wasn’t ideal and not always successful. Also, it cost lots of dollars!

So what to do when you can’t find a good match among 10 or more of the same model and brand servo?

If you are planning to use digital servos, Hitec has a solution, the HFP-10 Digital Servo Programmer.

The photo shows this “gotta have” tool. Out of the box, the onboard 1100 ma battery needs to be charged. The unit is powered by its internal battery, no AC allowed on this unit. Once fully charged, the tool can be used with Hitec digital servos to reset to the factory defaults (make sure you detach  all linkages from the servo before you do this or major bending of balsa and other stuff will occur!)

For an Extra 260 model, I chose the HS-5625 (0.13 sec/94 oz. in. at 6.0 VDC) and HS-5925 servos (0.08 sec/128 oz. in. at 6.0 VDC). For a Giles 202 model, I plan to use the HS-5945 (0.13 sec/181 oz. in. at 6.0 VDC), as well.

The servos  must be matched or they will fight each other, rapidly depleting the batteries.  Matching the pull-pull rudder servos and

elevator servos are especially important. The aileron servos are not as critical, but why not match them as well?

Besides resetting to the factory default, this programmer allows you to set the rotation direction, speed, zero (neutral) point, dead band width, and the end points. You can also enable or disable the fail safe as well as setting the “failsafe” point preset for the Hitec digital servos.

It is also a servo tester for all brands of three wire servos. With a protractor and an extended  servo arm as a pointer, any servo’s center, dead band, and end points can be measured. With those measurements, servos can be selected as matched pairs. Or with digital servos, you can match them.

A programmer will be at our club meeting for the Show & Tell part of the meeting.

Well, with this stuff, servo mismatch won’t be the reason for those inadvertent vertical landings and fly aways!

 

Also new is this pilot from LitePilots. They have various styles of pilots from 25% to 50% scale. Check out their stuff at http://www.litepilots.com. This 33% pilot is for a winter project and will look super nice in the cockpit.