Aileron servos

[Ponty Bri]

Just coming to the point of servo mounting in my Dawn Flyer and the following point suddenly struck me. Back in the old days we had one servo for the ailerons centrally mounted and two 'snakes' to the ailerons, but nowadays all the models seem to have two servos mounted in the wings, with a Y lead. Can anyone tell me why this change ? It is heavier , more expensive and awkward to fix sometimes.

Brian

[Dave Miller]

It needn't be heavier as normally smaller servos will be used. The main advantage is being able to connect two servos to separate channels so that neutral position can be adjusted easily and mixing and differential movement incorporated. Nothing wrong with a one servo set-up though if that will do the job.

[Simon Chaddock]

Ponty Bri

A wing mounted servo with a direct link to the aileron horn is mechanically more efficient than a snake so even smaller & lighter servos may be used. With this fact in mind and taking into account the cost of the snakes is a single servo set up really cheaper?

Then of course should one servo fail for any reason you do stand a chance of making a successful landing!

[Bob Cotsford]

For small or medium models I see nothing wrong with a single servo as long as it uses decent size torque rods. I know Pete Miller will disagree but I find central servos with long pushrods/belcranks or snakes a disaster area. Hard to eliminate slop, prone to friction, single servo failure means no ailerons - why bother when it's so simple to fit two servos with short, direct, slop free linkages. It was different when servos were relatively expensive but with genuine (insert favourite brand name) servos available for near enough the cost of a packet of snakes it makes sense to me to use two servos.

Bigger models need two servos for the same reasons but even more so.