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Tricopter YAW servo

#1
Hello ive been working on my tricopter for about 3 months mainly waiting for parts from hk. I need a servo for my yaw. the one that david uses has horrible reviews. does any one have a suggestion of a servo that works good and is not out of stock?
 

JimCR120

Got Lobstah?
Site Moderator
#3
opps sorry i just saw replies to my Q after i posted this and i cant figure out how to delete this
Delete it you say? Hahaha. Pardon my lol. I only laugh because I too prefer cleaning up after myself. I hate to be the bearer of bad news but you should check out this link.

—Jim
 

Burg

Never catch a multirotor
#4
Hi Toby, I have the same thoughts about david windestal his BMS servo. I am now using the 2.8kg Hitec HS-82 Metal gear servo. This is a quality servo and works great. I use the yaw system from RadicalRC dot com. Fits an works perectly. Hope this helps. Mark.
 
#8
Yes i did my original Tri to Davids specs. Can't claim mine as original. I love it because it protects the servo and can take a knock without damage. I came in tail first a couple of times and nothing broke.
 

ananas1301

Crazy flyer/crasher :D
#9
Yes i did my original Tri to Davids specs. Can't claim mine as original. I love it because it protects the servo and can take a knock without damage. I came in tail first a couple of times and nothing broke.
Yeah of course! That way even if you hit the ground your servo won´t get the hit and the wood can nicely absorb the shock.

Ohh and just a little question as I want to build a Tricopter soon as well:

Is it easy to balance the bell of the motor, with the zip tie? I´ve seen some of the red ones in one of your pictures and just wanted to ask how you knew when it is balanced.
 
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#10
As David said in the Tricopter tips video, hold the arm under the motor. You will feel the vibration. Then move the zip tie around till you feel the vibes diminish.
Also with my yaw mech, if i break the arm, i just remove two bolts and put the mech on a new arm in a couple of mins.
Cheers Lee
 
#11
Thank you all i got my yaw servo and got it hooked up. :D ill have to show you my yaw mechanism ive made some small changes that i think will make it more efficient. ill post pics under my other thread of "tricopter pics"
 

ananas1301

Crazy flyer/crasher :D
#14
Any flights done yet?

Looks very nice! I am about to build one and I am going to try to do the yaw servo the way you did it. That way it doesn´t need many extra parts.
 

shelterock

Fly Crash, Rebuild
#15
I too am building a Tricopter. I am using David's model and so far so good. I am curious if anyone had defined specs as to how much torque the servo need sto have to work on a direct drive Yaw mechanism. David had chosen a servoe at 17G that delivered 4.6Kg/cm and the HS81 is 2.6Kg/cm or there abouts. That is a big range and therefore I would think we have room to work with. I was curious if anyone had a servo that was too light fail without a CRASH! Spining props have gyroscopic effect that can create or need quick a bit of force to move off axis. Any thoughts. H
 

ananas1301

Crazy flyer/crasher :D
#16
I too am building a Tricopter. I am using David's model and so far so good. I am curious if anyone had defined specs as to how much torque the servo need sto have to work on a direct drive Yaw mechanism. David had chosen a servoe at 17G that delivered 4.6Kg/cm and the HS81 is 2.6Kg/cm or there abouts. That is a big range and therefore I would think we have room to work with. I was curious if anyone had a servo that was too light fail without a CRASH! Spining props have gyroscopic effect that can create or need quick a bit of force to move off axis. Any thoughts. H
I think the sizes of the props aren´t enough to really kill a servo unless you use a 3,5g servo. It is kinda obvious that such a small servo won´t really deliver those amounts of power needed to move the motor, while its moving.

I would use anything above 2kg/cm. I am going to take a HS81MG, which I luckily havd 2 lying around in my hobby parts area. :D

Anything around that, I´m sure will be fine to go with.

Of course it also depends if you wanna scale up Davids V2,5 to a even bigger version you´ll need bigger servos and with a smaller Tri even less.

In theory you should be able to measure the Power needed to move a running motor, but not really that easy to do for us "normal" users of electronics, I suppose.
 

shelterock

Fly Crash, Rebuild
#17
In theory you should be able to measure the Power needed to move a running motor, but not really that easy to do for us "normal" users of electronics, I suppose.
My thoughts exactly. I have a Turnigy TGY53317M I got everything put together to test the electronics and she's working. Ailerons are working Rudder moves correctly, but the servo doesn't center well. Could be the Turnigy servo, could be a setting. I have a sneaky feeling I have a gyro issue on the front left motor. When I pull back on the elevator the right motor speeds up but the left doesn't. If I push down on the elevator the rear motor speeds up as expected.
I need props to figure it out.
http://www.youtube.com/watch?v=2Z59MTGGa7Q
First Video of my contraption.
 
#18
I started with a $3 HXT900 servo on the tail. It flew fine, but it was NOT good for aerial video as it had way too much slop, so it couldn't find center and would jitter, making the whole tricopter wiggle causing shaky videos. I then tried a $11 HK922MG and got the same results. Was so dissatisfied with the quality of video that I came up with all sorts of ways to reduce vibration (some actually worked well!) but decided it was still time for a different servo. I ALMOST bought the $60 futaba, because I KNOW it's quality, but ultimately the next servo that I'll be using is the $28 TGY-390DMH, which has excellent reviews, stronger than the one David uses, and it's faster too -- only a little heavier. When it arrives and I get my trike put back together we'll see how it flies.