pilotpete2

I disagree with gas engine vibration stripping a throttle servo, at least not when the servo is back in the fuselage and you use nyrods or the Dubro flex throttle cable in a tube that I favor. I also use IBECs in all my gas ignition powered models, so I have an alternate method of killing my engine in the case of a throttle servo failure. Any servo can fail, I know, I lost my beloved Goldberg Extra 300 to a servo failure. I had just swapped out an original aileron servo the week before the crash, since the old servo started to get jittery at neutral due to a worn/dirty pot. I put a NIB servo in off the shelf and put one in that suffered an early life failure of the electronics. So much for trying to be pro-active with the maintenance
I will agree that MG servos are probably the best bet when mounting the servo near the engine with a heavy unsupported metal linkage that can vibrate or resonate violently at certain engine RPM's. I just won't go that route when mounting my throttle servos for gas engines.
I also think that keeping the throttle spring engaged acts to bias, or damp out some of the vibration on the gears.
Pete

speedracerntrixie

My Feedback: (29)

Back in the day when it was common to use a single servo in the wing center with bell cranks out at the aileron it was always a pain to get them to work bind free. Really rough on servos. Phil Kraft had the right idea with the original Ugly stick to run them external. I have seen throttle servos fail on gassers regardless of the linkage except the pull cable set up. Gas engines bounce around a bit and that can be transmitted to the servo especially if the servo is over driven by just a touch. If mounted on the motor box one has to worry about heat as well. Dirty, thank for the explanation, for reasons you describe I use high discharge rate batteries to overcome the resistance of the regulator and you are correct that I am less likely to have an issue with the Smart Fly regulator then a different unit. Although on my 50cc airplane I ran a single 3000 mah battery with an MPI regulator and IBEC and had no issues there either. Then again at less then 40 flights the airplane was sold so not really a good example of long term reliability. Lots of different ways to skin a cat. Sometimes when looking for every last bit of performance we have to go the route of slightly higher risk, all part of the game.

pilotpete2

+1 on the pull cable setup for throttle!
The old Goldberg Extra 300 that I lost due to an aileron servo, came with all the hardware for a single aileron servo, only recommended if you used a .60 size engine for power. Yeah, those were the days.......as Edith Bunker used to sing at the end of each show

One of the main reasons I prefer the A123/LiFe packs for receiver duty, is that you can strap them in just like old school Nixx packs, and even balance charge them through the charge jack on a HD charge/switch unit if you run the three wire switch harnesses, though you do have to break the "signal" wire in the lead to the receiver with that setup. Also there's the issue of not leaving high C rated Lipo cells fully, or near fully charged for extended periods. With an electric powered model, most times at the end of a flight the battery is below storage voltage, so after the last flight it's easy to just charge them up on the chargers storage mode. With Lipos for receiver duty, the chances are greater that you may wind up with the battery too high for long term storage.
Pete

speedracerntrixie

My Feedback: (29)

Pete, good points and being in California there really never is a time when I would need to store an airplane. The Lipo equipped airplane makes it out to the field at least 3 times a month. The other airplanes, a classic pattern airplane and my pylon airplanes all run an 850 mah LiFe battery. All batteries do get balance charged every few months though.