Thursday, August 30, 2012

Nice Things Tricopter

Up until now, I've made all of my tricopters out of cheap materials like golf club shafts, bamboo, and balsa.

  Recently, I got a hold of a little bit of scrap left over from some really nice quadrotor frames.  The stuff is a laminated sheet of carbon fiber and stiff foam.  A high tech sandwich if you will.
I mentioned that I might try to make something similar in a previous post with balsa rather than foam, but having it turn up pre-made isn't a bad thing.

So I drew up some rough plans, cadded them, and got straight to milling.  I used the free 2D version of HSMxpress to get from .sldprt to G code.

Since I got scraps of varying sizes, I designed the frame to be a number of smaller pieces, bolted together by 4-40 hex-head nylon cap screws.  I didn't really have any other options to get the desired frame size, and I figured the screws might provide some level of crash protection if they choose to shear before the arms suffer any damage.

Here's a shot of the larger piece of scrap on the CNC router.  This piece will become the center of the frame.

skip ahead a day or so and here it is:
I borrowed the multiwii setup back from the quadrotor, restoring it to its tri-rotored glory of yore.  
some specs:
Motors:  old Ascending Technologies motors.  They're wound star wye and were made specifically for multirotors.  I like them.
Props: also AsTec.  Still sold here.  Also multirotor specific.  Very nice props, virtually unbreakable as they are made of a very dense and pliable plastic.  quiet, haven't had vibration issues yet.
ESCs: CC 10A Phoenix
Battery: ancient (3 years?) HK 2200mAh 3s LiPo

Aerial video to come