Saturday, 8 March 2014

Tricopter frame V2.0

Spontaneous Projects is a chronicle of all of my projects, a reference for me, and a way to prevent others from making the same mistakes. 

Given that the V1.1 frame keeps falling apart in every crash, was unstable in the air, heavy and difficult to carry I started on model 2.0. It's still made of bits and piece I had lying around, and there are a lot of improvements still to be made, but it seems to be a bit more solid. 
Just a few different options, old tent poles.

I have a lot of old aluminium tent poles lying around, that will make perfect arms, And I like the look of the foldable Tricopter design by David. The only suitable material I have though is some 3-4mm MDF... not ideal, but it'll work for a test run.
MDF with basic design, at the moment Arms are at 0, 150, 210 degrees.

Design at this point, with bolt placement



Attaching the poles is all pretty simple, on this prototype version I didn't really think about where everything else was going to go until the arms were attached, I'll do better on the next one. 
Two of the objectives of changing the design were to reduce weight, make it easier to carry and make the center of mass lower so that the tricopter is more stable. Basically, putting the battery under the frame.


I made it a little smaller

Fully packed up

Frame Only
Final Weight
v1.0
588g
1.37kg
v2.0
271g
1.04kg

I succeeded on all of these fronts, and once I get some better material for the plates I'll get it down a bit more, as well as increasing the strength and slimming the design down a bit. 

The two front arms are designed to pivot around and lock in beside the tail when not on use, this should mean that it can be packed inside some PVC pipe for transport into and out of a cave, or thrown in the back of a car. 

It's now taken a few crashes, as I still can't control it, and the frame has stood up well, so with some better materials I think it'll get even better.

Trying to keep the motors straight might be causing some of my issues, and I know some of the early ones were caused by the arms moving about. That was fixed by tying them together with shock cord... seemed to do an adequate job. 







I took a bit more time routing the wiring on this one, as I think that it'll be a platform to be tweaked rather than retired. At the moment it looks like this:
Top

Bottom


Edit: 2 hours later it looks like this


Not sure if it's the wind screwing with the auto level, but something is... I've tried dropping the P gain a little, but no cigar. Stick scaling I've seen mentioned somewhere, but seemed to do nothing... I'll post more when I get it to fly nice and stable... 


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