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A Super Cool Yaw design ( I think )

n8r

Junior Member
#1
If anyone is looking for another way to make an easy, reliable Tricopter yaw with some other benefits, this is how I am currently running mine.

https://picasaweb.google.com/106432727440071052304/RCStuff#5872362940471051330

I have had bad luck with micro servos and have destroyed 2 Hitec hs-82 mg sevos. Stripped the crappy aluminum half gear inside on both of them. I think the torque load of the dt700 withh 11" props and crashing alot is too much for them.

I had a huge Hitec 645 mg lying around and decided to use it but running it on the rear of the tail put too much weight out there so I decided to make a direct drive extension shaft using an old carbon arrow I had lying around. I made a coupler using wood and a trimmed servo arm that is glued into the wood block. I then just drilled a hole on the other side of the coupler and hot glued in the carbon tube which is then hot glued into the yaw block. Originally I just had the servo shaft going directly into the yaw block.

I figure the advantage of this design is that it moves the servo weight much closer to the center of the copter which takes load while pitching off the tail motor. The carbon shaft only weighs a little over 1g so there is really not much more weight added. Another advantage is that by moving the servo further away from the motor, more of the load is put on the rear yaw pivot and aluminum bracket and less is transferred onto the servo shaft.

Also, I feel the carbon arrow is too strong. In the event of a really bad upside down crash I want the carbon shaft to break and absorb the force rather than transfer it into the servo shaft, so I am going to redo it using a weaker and smaller diameter carbon tube. It's much cheaper and faster to replace a $0.50 carbon tube than a servo.

I have some 10mm square carbon tube coming so when it gets here I'll replace the wood with the square carbon so everything is carbon. The Hitec 645 mg is heavy and overkill, but since I have put it on I've crashed the crap out of it and it is holding strong. I've reduced weight in other areas and with the heavy 55g 645 servo, my tricopters total AUW is 885g, thats flying weight with the 3s 2200ma battery. The 645 is a little slow so I have a Corona 32g servo coming I'm going to try out. I'm not going to screw around with small lightweight servos on the tricopter anymore. They don't last and break too easy in my experience.

I just thought I'd post this incase anyone is having trouble with destroying servos and is looking for an alternative yaw design that is easy to make. Nate
 
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#3
nice setup- looks like alotta work. i would guess your gear stripping has alot to do with the crashes and being direct drive.if ya keep wrecking gears maybe look at putting a short peice of linkage in there to take the beating instead of the heart of the servo- check the post i made earlier today... practically unbeatable.