Hi Guys,

I have some questions about the flight surface servos and linkage. Is it best to hardmount the servos as a precaution to avoid potential flutter or utilize the rubber bushings and grommets (... And yes, the grommets inserted the correct way) ?

Linkage- Is it best (I always thought it to be true) to have the clevis linked close to the servo's output shaft and out on the control surface horn to give the best resolution AND is it less of a 'workload' for the servo like this (starting with ATV's set at 100%)??

Jet- JL T-45 (to maiden in 1 month)
JR 8711-Elevator
JR 8411-Flaps
JR 3421- Ailerons and Rudder

All surfaces have NO gaps. I also have the H9 alumn. servo arms short and long for each servo.

Thanks in advance for any advise or tips.

Others may have more informed opinions, but I still think it is a good idea to use the grommet/eyelets in servo installation for turbine powered models - I'd follow the instructions though, if they say otherwise. Sometimes I will "shim" the servo with some masking tape, on the servo case side, so it will fit snugly in a plywood tray, so the torque load isn't all taken out by just the screw attachments - this can help get rid of slop too.

And what you've mentioned about clevis placement is correct. Closer is better on the servo side (the shorter throw will allow the servo to generate a greater force down the pushrod length, at the expense of pushrod travel distance), and farther is better on the surface side. Pushrod travel distance then can be increased if necessary, by increasing your servo ATV to, say 110%...

On this topic, there are as many opinions as there are flyers. I don't know that my opionion is "more informed" or not, but here how I see it.

People that are relatively new to the turbine scene usually use the cautions they learned from nitro powered engines. That's a good idea.
The rubber grommets were designed into servos eons ago, because the mighty 2 stroke internal combustion engines have a penchant for vibration....you cannot completely balance a single cylinder engine.

Since there is no appreciable vibration with a turbine engine, many of us are rigidly mounting the servos to minimize slop in the control system. In the absence of this vibration, there is no harm in rigidly mounting your servos.

I always use the grommets on my nosegear steering servo to help protect it from taxiing vibration and landing shocks transmitted down the pushrod. The rest are hardmounted.

A loose or sloppy control system will cause no end to your grief until you and your wallet
have recovered from the loss from the crash.
Jet speeds and control surface loads are much higher than most of the IC airplanes, so a slop free control system is a must.

The only servo failure I have had since starting my turbine experience in 1996 was last year. A JR351 on the landing gear valve....it worked one day, but didn't the next.

As Ron indicated, the best setups utitlize all of the torque of the servo....the advertised servo torque is measured one inch from the servo output gear center. This is one case where shorter is better.

When I set up a control surface on any aircraft, I start with the pushrod on the farthest out hole of the control surface horn and use whichever hole on the servo will give me the desired travel with the ATV/Endpoints at 100% or more.
You are better off with the pushrod farther out on both the servo and the horn as this will reduce the effect of any slop in the clevises.
By moving the pushrod farther out on both ends you do not loose any mechanical advantage or resolution, just the effect of any slop.