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CranialRectosis' Alien 4" Build

cranialrectosis

Faster than a speeding faceplant!
Mentor
#61
I'm curious to see how autotune can do on this. With RE1 we've seen a lot of new users to dRonin and some more people with high performance builds experiencing AT issues. Hard to say for sure what's causing them but it's starting to look like most of them are likely vibration related due to AT using leveling mode and the vibrations messing with the accells even if they gyros are ok. This is exacerbated by hard mounted FC's, but is especially bad on frames where the FC mounting bolts double as arm mounting bolts which can transfer more vibration. Last night icee hacked up a version of AT that can run in rate mode but was convinced it would be unusable - this morning one brave tester gave it a go and found it was actually usable. That's only a first step towards solving the issue, but gave a lot of insight as to some approaches for making AT more robust.

Any major AT changes won't reach release for awhile yet. Slight possibility they could make it into the release after the upcoming one, but that's purely speculation on my part. It could just as easily be a release after that, or the experiments could turn sour and it never makes it out of testing.

Next major release is getting close, may be a bit late since there are still some blockers in the queue but there's a lot of cool new stuff for the next release - like expoM - so I'm excited about it making it out of development ;)

Cranaial - I think you'll love expoM. Makes it so much easier to get a nice expo curve with a longer flatter center section for smooth center stick control but still have insane rates at full stick for real fun ;)
I absolutely had trouble with AT on this build in the beginning with the Brain. The problem was vibration and got intensely worse as the C clips on my motors started falling off mid-flight. Root cause was bad Cobra 1806 motors.

As your copter wears and if your props get bent or scraped, you can see the vibration build in the OSD. The horizon starts to tilt while the copter is still. When that happens, it's time to clean the motors out or replace the props.

The wiring diagram for the RE1 doesn't match dRonin. The motors are all wonky. I need to re-map the motors and directions before I heat shrink ESCs and zip tie everything up for a maiden. I also did a really poor job soldering the ESC signal and ground wires to the RE1 as my iron is acting up. It looks like hell and will until I can fix or replace this iron.

Still, I should get a chance to try and am charging 4S lipos now. :)
 

cranialrectosis

Faster than a speeding faceplant!
Mentor
#62
All working smoke tested and I broke a standoff holding the FC to the copter during assembly.

I can either order new standoffs because all the ones I have and all the ones that come with the RE1 are too tall for a 4" Alien. They work on the 6" Alien but not the 4" Alien. Or (when I get my soldering iron back from the shop) I can completely remove the mPB and RE1 and put the Brain and Pololu back on the copter.

One takes 2-3 weeks. The other works tomorrow if I get my soldering iron back and working.

To be honest, I am really not liking the mPB. It is too tall and makes for the messiest build I have personally done since 2013. It removes the LC filter and Pololu but for an Alien which already has a PDB, it brings the power wiring up another 1/4" off the booms and moves the ESC signal wires up by 3/4" off the booms. It makes for a really ugly Alien build.

At any rate, until I have either a working soldering iron or a standoff short enough to make this mPB fit in a 4" Alien, this copter is out of the game.
 

cranialrectosis

Faster than a speeding faceplant!
Mentor
#65
Lightbulb! :D

I saw this episode of RR today. At about the 1:26 mark is a shot of someone stacking the standoffs with O rings (which I stopped doing some time ago) and what looks to be a small, plastic hex nut.


My quad is grounded because I need an 8mm M3 Standoff and only have 6mm and 12mm. The 6mm are too short. When I use them the cap on the mPB hits the bottom of the RE1 and prevents seating. If I use the 12mm standoffs, the RE1 hits the top of the 4"Alien frame where the lipo sits and prevents me from putting on the top plate of the Alien.

All I should have to do is pad the 6mm standoffs with a 2mm nylon nut to raise the FC. If the threads on the 6mm standoffs are long enough, I can fly today instead of waiting for new standoffs or replacing the RE1 and mPB.

I can hardly wait to try it! :)
 

Snarls

Gravity Tester
Mentor
#67
All I should have to do is pad the 6mm standoffs with a 2mm nylon nut to raise the FC. If the threads on the 6mm standoffs are long enough, I can fly today instead of waiting for new standoffs or replacing the RE1 and mPB.
What I do is sandwich my FC on the standoffs between two O-rings and then cap it off with a nylon nut. The O-rings are about 1.5-2.0mm and I just barely thread the nuts on to a point where I'm comfortable they won't come off. If you are also concerned about vibrations, having the FC between the O-rings is better than on top of the O-rings.