For those of you flying extreme 3D maneuvers, servos are now being offered with metal gears. Made from a mixture of aluminum, steel and brass, these gears are 16 times stronger than the standard gears. However, they do have one big disadvantage, and that is they will wear over time. Depending on how hard you use them, you should be able to get 40 to 50 flights before they start to wear to the point they need to be replaced. And the way you can tell the metal gears need to be replaced is when they develop backlash, which will show up as slop in the output arm. To check for slop, turn on the radio and leave the sticks centered while slightly twisting the servo output arm back and forth. If you can feel any slop in the servo, a new gear set should be installed. However, these gears are a replaceable item, and are easy to install by the average modeler.
To meet the higher servo demands of large helicopters performing violent maneuvers, Hitec also offers servos with titanium gears. These gears are actually 48 times the strength of the standard gears, but have the added advantage of performing with absolutely no wear at all. Since they don’t wear, and therefore never need to be replaced, this is a distinct advantage over the metal gears. I like to think of the combination of titanium gears, matched to the overall performance of the servo, as an added insurance policy to keep my helicopter flying incident free for an extended period of time.
Added features of the new high performance servos now available include a heat sink servo case to dissipate the increased heat from the demands placed on the high performance motor. Also, many of the new horn sets are all metal, or at least use a metal ring to support the servo arm to the output shaft of the servo, to keep it from slipping under heavy loads. However, the one part of the servo that has remained fairly standard throughout the years is the servo mounting lugs. I suspect we’ll start to see improvements in this area in the not too distant future to better mount the servo to the helicopter.
In closing, the final point I would like to make is there is no substitute for a good mechanical setup to any helicopter. By this I mean all rates and end points should be set to their max limits, servo arms should be as short as possible, and any reduction in servo travel will also mean a reduction in servo resolution. I would like to thank Mike for his wealth of information on servos, and you can find him at many fun flies and contests throughout the year giving seminars on the subject, or he can also be contacted through Hitec RCD.