Servo sizes - again!

I’ve just had yet another conversation about servo sizes with somebody with a Footy, a huge sail servo and huge problems.

When the sheets are hard home, they should lead along the line of the servo arm. This means that the servo has the greatest mehanical advantage when the sheet loads are highest. Compared with many of the layouts that appear here with the servo arm across the direction of the sheet with the sheet home, this is a big, big gain.

There is no reason for using anything but a very small servo indeed for steering. Rudders that lie entirely behind the pivot place high loads on the servo. Ones that have a jaunty aft sweep look good, work worse and impose even higher loads. Rudders should be balanced with the pivot about 33% back from the leading edge. This is further aft yhan full size but ‘feel’ ir irrelevant. Helm forces should then be very small indeed.

Sorry - it weas a long and tedious phone call with an idiot and I’m sure all you nice people knew the answers already: just getting it off my chest.

Totally agree! any weight that can be removed, should be! Start at the top down, of course, but even servos can be replaced. I’m using an Eflite s25 sub micro, about 7.5 gms, for the rudder, and just got a Hitec hs-225bb mini for the sails. THe 225BB has 54oz-in torque at 4.8v and only weighs 27gms.

I’ll add weight in the bulb if need be :slight_smile: