I have a Starfire II with some problems. My right aileron servo decides to strip when it wants to. I have a JR3301 in it with a dubro control horn. Last flight i had with it flew very nice with no abuse to the plane. I fuel up to go again, check the controls and the right one is not responding. This is the second time this has happened to my 3301's with the same situation "no damage". Any suggestions would be appreciated. Pics below.
Jester

Right Bay

Servo and Horn

Left wing assembly is the same as the right and does not strip.

That is a long friggin servo arm you have there!!!
What are your ATV's set at to get normal control throws on the ailerons?
JR lists the torque spec. for the 3301 as only 60 oz inches, this is less than 10 ounce inches more torque than their standard (527) servo (and I wondered why my Bobcat runs out of elevator sometimes ).

I would guess that with that long of a servo arm you had to turn the ATV on the aileron channel WAY down in order to keep the throws manageable, but this does nothing to control the actual force that is being applied to the servo.
A longer servo arm equates to more mechanical advantage that the control surface has over the gears (and the motor) in the servo. I would guess that for some reason the flight loads of your Starfire are just a little higher on the right aileron than they are on the left, and you have just been very lucky that you have only exceeded (more than once, it sounds like) the limit of what the right aileron servo can handle.
I would highly suggest that you shorten the servo arm length on both of the aileron servos (and any other similar "high load" surfaces) before your luck runs out.

It seems like you could easily have different flight loads on the ailerons. If the wing isn't symmetrical (it's not), and the pilot flies in one direction (left or right pattern) more than the other, then one aileron could be having a much more rigorous life than the other. Just a thought.........

I agree with Kevin W, but even with the shortest servo arm possible, you may still strip a servo occasionally. Back when several of us flew JMP Starfires on a regular basis, we were all stripping servo gear trains on a semi-regular basis. Then Futaba came out with a metal gear servo (3002) that was a direct replacement for the servo we were using and we all switched. No more problems after the switch.

What always amazed me, was that we usually would not realize we had a stripped servo until we saw the aileron drooping as we were taxiing back or as in your case, when we were getting ready for another flight.

By looking at the photos, it shows the cut out on the servo cover is very long in one direction but very short in the other direction. When you move the stick full travel does the servo arm hit the cover? The servo arm needs to be free to travel without binding on the servo cover.

Just a thought.

Turbine or Fan?
I had the same exact problem on my JMP Starfire. I'm flying DF power. After replacing gear sets about 3 times I figured I'd better try something else before my luck runs out. Repaced them with 517's, no problems yet. Vibration maybe? The 3301 is side mount, thats why I used them, but they don't have the rubber grommet mount.

Are any of you guys running a 5 cell 6v batt sys with regualtor....i know that will give you about a 10-15% increase in torque and speed.. I wonder if that will be enough...

I have a starfire that will be making its maiden soon and i have ds 3301's for ailerons, flaps, and rudder......

i would sure hate to loose it due to a failed servo. After how many flight are yall noticing that the gears are stipping out.

I find it real odd that so many are reporting servo gears stripping but no one is loosing the aircraft over it.

Thanks in advance
sean

My first failure was the second or third flight. I have 3321's for flaps and rudder, same servo only not digital. HMMMM.

The Starfire is ducted fan. I had heard some of the same suggestions all of you have said from one person. The problem I had with it is that I have used these horns on weaker standard servos, which have been skipped slammed and drilled into the earths crust and the servo never striped. So what can be done to the servo with the other suggestions to allow this not to happen again in? (are their metal gears available)
Thanks

No metal gears for this servo. I modified the servo bay and installed the much cheaper 517.

Yeah that sounds about right but I think my first striped servo was on the 2nd flight and then I changed the gears and it happend again on the 7th.
Jester

Quit while your ahead.
Randy

I am not familiar with that servo. Is about the same size as the 3301 torque and size. I am using a 6volt jr pack.

It's quite larger. Standard size servo. About $60 cheaper and plenty of power for aileron.

Are any of you guys running a 5 cell 6v batt sys with regualtor....i know that will give you about a 10-15% increase in torque and speed.. I wonder if that will be enough...

I have a starfire that will be making its maiden soon and i have ds 3301's for ailerons, flaps, and rudder......

i would sure hate to loose it due to a failed servo. After how many flight are yall noticing that the gears are stipping out.

I find it real odd that so many are reporting servo gears stripping but no one is loosing the aircraft over it.

Thanks in advance
sean

4 cell for me. I tried the 5 cell early on, thought it might be part of the problem. No reg. though. I like 4 cell better.
Is yours DF or turbine? Keep us posted how it turns out.

This is exactly what happens.

Ditto Jester22
I'm planning to use them in rudders on my Hot Spot. Alot less vibration.

This is a os 91 dynamax setup.... i was hoping it would last long enough to get a turbine waiver....

How many flights did you put on it with 6v? Any reason why you didn't like the 6v setup ?

instructions call for the jr 3321 which is right at 60 oz ...and if im not wrong the ds 3301 was a direct replacement for it just DIGITAL NOW....You would think all the more better...go figure.

I thought the same as you, exactly. Spent the cash to make it right. In the end, it nearly cost me alot more. I think it's a combination of several things. The exact holding power of digital, mounting so far out on the wing, maybe the arm length, vibration, etc. My solution has worked so far, over 50 flights, maybe more. Fix it now, or forever hold your peace.
Randy

Jetfreak
Sounds like we have a similar setup I am running an OS 91 and JR servos throughout. I am using a 6V system and have not had any problems so far. I have had about seven flights. I grounded the plane until I can figure out a solution to the problem. I was also hoping to use this for my waver if it will corporate.

Randy M-
I put the voltz servos in my hotspot very thin. I had also heard good things about them.

Jester

Tried it for a while, maybe 8-10 flights. Made things a little zippier than I like, I'll try it next time with regulator and see how that goes.