I've lately been seeing pictures of and reading that throttle servos are being installed very close (even on the firewall) to the engine. I had always understood that this was a major no-no. Has something changed? Thought all the RC onboard electronics was supposed to be as far away from the engine and componets as possible to prevent interference. Is this possible with good shielding or by using two receivers or just luck? Have had some planes where I would have liked the throttle servo close to the engine but I took the stay away routine as gospel. Whats up with these servos just a few inches from the gasoline engine?

Chances are (assuming they're using elec. ignition type engines) the planes you have seen are using a fiber optic servo extension which allows you to place the servo wherever you want to for balance/simplicity reasons and not have to worry about RF interference. Another neat feature is you can run the throttle servo off of the ignition battery and help balance out some of the servo draw. Aerografix sells the fiber optic ext. (http://www.aerografix.com/) The site is under construction but I'm sure Roger could help you via e-mail ([email protected]).

I'm sure we'll be seeing more and more of these being used as the amount of high quaility light weight engines continues to grow. Always better to move the servo up front than to add lead.

...........Mark

I'd be willing to bet most guys are just mounting the throttle servo near the engine WITHOUT using the fiberoptic extensions. They are running the risk of introducing rf noise into their system. You'd probably be amazed at the way some people set their planes up, it's a wonder more of them don't crash. How about the guy who has radio intereference on ppm and says "I'll switch to PCM to avoid the problem". I think that fiberoptic extensions are great. If you choose not to use them mount the servo at least 12" away from the throttle. In fact it is a good idea to separate all engine componets from the radio components.

Thanks for the info!

Mounting the servo close to the engine or the ignition is a BAD idea. The fact that some have done it successfully doesn't mean its ok, it means they are lucky. There is not one single manufacture that recommends this, and as the ignition components get old the chances for a problem increase. :^)

Just using the fiber optical coupling is not enough. You must use seperate (seperate from the receiver) battery power for that servo also or RF can feed back through the power leads.

I saw this setup on a bunch of planes on-line, I tested it and installed the throttle servo in the engine box on my Pitt's,I have tried everything and still no problem. I am running a brison 2.4 and have a hs85mg servo for throttle the linkage is a 6" nyrod with a ball link attached to the bell crank on the engine. I have run the engine again and again on the ground and flown the plane with this setup and have nothing bad to report. People say an electric smoke pump can cause Rf noise too but people are still using them. I don't know if its wrong or not but it works for me flawlessly.
THIS IS JUST MY OPINION
Fred