I am putting together a Lanier Sea Bird and what to know if I can use a 9g servo for the throttle. I want to mount the servo in the engine pod and I don' have room for the mini or standard servo. Powered by a 91 4 stroke

I went to do something similiar on a larger engine. After I posted a photo of my setup, I was immediately told to use a bigger servo.

I was very glad I listened to the advice.

A glow engine can produce strong short pulse vibrations, that will strip the gears off a 9g servo.

Don't do it.

OK enough said. I will have to work out something different. I don't like the way they show in the plans. Maybe I can snake a cable up inside the pod. My SeaMaster 120 had all kinds of room so I could put the servo in the pod.

Yeah I use the Sullivan flex cables for throttles all the time... they work great in tight spots.

I would 2nd the idea of a beefier servo, and the flex cable...
The vibration really beats up the throttle servo in that sort of installation.

However...one other consideration might be something like a vibration insulator, similar to a profile 3D type throttle servo installation?
I lost a Hitec HS-81 in my Tribute...then used an HS-85 and a "servo saver" to help cushion the pushrod to output arm linkage. That servo still lives after a couple hundred or so flights.
http://www3.towerhobbies.com/cgi-bin...?&I=LXD646&P=7

Do you have room in the pod for an HS-85 size servo?

i have used the hxt 900 (9g servo) for a number of engines, mainly .46's but ive used it on a magnum .91 fs and it worked just fine.

some of these servos are over a year old and still working great as throttle servos.
one thing i do use is thin wire for most of the servos so its much harder to transmit vibration through and damage the servo

might be close. Think I will use the flex cable. The pod support is already cut out for a solid rod to use for the throttle. I have lots of standard servos that I could use. Thanks

The HS-85 is a 20g servo, making it LARGER than your HXT-9g's...

I used a Hitec HS-81 on my Sea Bird with a K&B 65 Sportster. The servo was short lived about 20-25 flights around there, I think the vibration got to it. As it would start wandering all by itself like a bad pot.
According to Hitec the HS-82MG has the the better electronics like the HS-85 and should work better.

Adding a weight to the pushrod to lower the frequency that the rod will respond to will protect a servo.

An old post that shows this concept.

http://www.rcuniverse.com/forum/m_83...tm.htm#8393174

I have used a 9g servo a few times with any problems. Just make sure the carb barrel is easy to turn. I had to free off one with a little fine wet and dry.

I can't see that using a 9gr servo would be a problem. I'd opt for metal gear. There are quite a few aircraft that use these servo's successfully. The trick is isolating the sources of vibration.

Would using something like the golden rod reduce the vibration.

I wouldn't go less than HS-85. The reason being the 81's 82's are mostly made for electric
planes and their pot is subject to "quit" due to vibrations.

I have a mini std GWS bb that I cut the mounting hole brackets off and I am going to mount it on the side. I will attach it with E-6000. I think that will take care of any vibration and it will have enough torque 47 oz/in.

I have an HS-81 that has been used as a throttle servo for a DL-50. I have well over 1,000 flights on the plane and I have only gone through one. I haven't had any problems with HS-81's as throttle servo's since then. Hope this helps.

Hi NateFlite, thanks for the information. All of my planes have a earlier expiration date than 1000 flights.