My new glider uses a V-Tail, and I was wondering about the setup for this. The "default" V-Tail mix on my TX is 50% throws for full stick throw.

This works, but means that only half the servo travel is used when applying just one control, such as full up/down elevator with no rudder input (or vice versa).

If it's not required to have the capability for both full rudder and full elevator at the same time, would it be better (more accurate, better centering) to reduce the mechanical throws and increase the amount of stick to v-tail response?

From : Don Stackhouse

A V-tail must have the same rudder AND elevator authority SIMULTANEOUSLY as an equivalent conventional tail if it is to have equivalent handling. There are many maneuvers (spin recovery in particular) where full COMBINED rudder plus elevator may be necessary.

If your V-tail is sized properly, the required throw for ful elevator will not be as great as that required for an equivalent conventional tail; the same is true of rudder. Although that 50% default mix on your transmitter may not be exactly correct (depending on tail angle), it should be roughly in the ballpark for most tails. In general, because of the longer wings and higher aspect ratios typical of sailplanes, they do tend to have a greater need for rudder, but a lesser need for elevator throw. You might need to adjust the ratios a little till you get the control response that matches your flying style.

In our experience, ruddervator angular travels for rudder alone and for elevator alone are generally similar to the same travels for the rudder and the elevator of an equivalent conventional tail, although ruddervator trael for rudder may be a little less in some cases. For example, on our 2-meter Chrysalis (on both the 2-meter and the HLG Chrysalis the kit includes parts for both a conventioanl tail and a V-tail, and the two variations have been designed and tested for essentially identical stability and control authority), the ruddervaor ntrael for elevator and for the conventional tail elevator are both +/- 3/8". The ruddervator travel for rudder is also +/- 3/8", but the travel for the conventional tail rudder is +/- 1/2".

The exact details of this relationship will vary with each design. However, what will not vary is the need to have full rudder and full elevaator authority SIMULTANEOUSLY.

Don Stackhouse
DJ Aerotech