After almost at year with a strange servo jitter that was taking all the fun out of my UAV hobby i finally found the source. A bad servo.
The jitter was intermittent and made and erratic +- 5 mm throws on the elevator or rudder even when i tried flying in "manual mode".
The little bastard finally decided show its real face today by giving a "full down" (and i mean FULL) right after start, giving my Easy Star a nice sucker punch right on the nose.
So, Turnigy S 3317 S. Your life was short and noisy, and you will not be missed.
I am moving on now and will look for a more dependable partner. :-)
I know some of you are doing UAV flying for a living. What brands of servos are you using?
Comments
I've had a "bad servo" occurrence about a couple months back.
I was a spektrum dsp75 servo.
It was is installed in a seawind foamy and connected to the APM while bench testing.
Take note that I had removed the power jumper on the APM board so that the RX & servos would be power seperately.
Well at some point during testing, with everything connected I powered up the APM after powering up the RX and the little sun of a gun went clear on past the mechanical end stops only to be stopped by the rudders' unwillingness to to go further.
This occurred during the first 1/4 second of the APM power up.
After replacing the servo with a brand new one a week later it happened again.
I'm not sure if the DSP servos are acting on brief fluctuations from the APM when it gets powered up or what??
So now I'm scared of them & I replaced the with some HS55's.
Now I'm wondering about the HS55's cause of this posting.
???
@ I.S.: I think all Hitec Servos that end in HB, such as HS-635HB have carbonite gears. I found some german reports on carbonite being to some degree brittle. However, I have no own experience with this type of gears.
@ Davey: Plastic and carbonite servos weight less, but the difference is in my opinion too small to make a true difference at the airframe level. Take for example the HS-81 with 16g weight against the metal gear version HS-82MG with 19g. That's only 3 g of difference and these type of servos are used in a 1000 - 2000g airframe. So by using plastic gear servos, one would save less than 1% of weight... I was discussing just about this topic yesterday with a friend, who is a mechanical engeneer. In his opinion the gears should be made of steel. The difference in wieght between the different materials is too small. He said also that titan gears are only good for one thing, namely to be sold for much money than steel. At least plastic has less backlash. The argument about wearout is a good one, though. However, in my experience, the airplanes "wear out" faster than the servos ;)
@I.S
Yes, I believe its called karbonite, but believe other manufacturers are also releasing similar:
http://www.modelzone.co.uk/hitec-635-high-torque-karbonite-gear-ser...
What about the famous HXT900 servos?
They are dirty cheap, but people use to like them.
@Davey
you mean the carbon enriched plastics or alike?
could you give us some item examples of those new plastics servo?
@Stefan
There are also some new gear materials that are the best of both worlds coming out from suppliers. Metal gears have a tendancy to wear quite quickly, plus they are heavy. The new plastics are tougher than nylon but wear less....
This is a nice way to tune your servo power voltage.
http://www.robotshop.com/dimension-engineering-de-swadj.html
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