1st quadcopter build causing a variety of issues.

[Nightham]

My roommate and I decided 2 years ago that it would be a fun challenge to learn about and build a quadcopter from scratch. We even planned on making our frame from scratch with 3D printed parts, but eventually settled on a premade one.

This is the parts list we drew up

Turnigy 850kv brushless moters
Cc3d flight controller
20c 6s 5000MaH Lipo
A small ni-cad battery to power Flight Controller
30A ESC x 4
11in props (don't remember pitch)
Simple wire splicing in place of a store bought power distribution board
A fairly cheap reciever/transmitter

(Sorry I don't have brands or exact figures, if these can help with the debug process I'll get back with them when I get home)

We wanted to sort of go big or go home with this build. The end weight would be somewhere in the ballpark of 3.5lbs or so, but the lift generated by each motor/prop combo was calculated to be around 2lbs each, so the lift should be more than enough to maneuver and to maybe lift a moderate payload.

From the get-go we had some problems, our flight controller had a defect on it somewhere where we powered it up and it began to get really hot and eventually shorted out. We replaced the board and the new one we got worked just fine (so we knew we werent overloading it with too high of a voltage or anything).

So we finally get it all assembled, and now comes the calibration side of things. Libre pilot seemed like the best choice since it was the software recommended with the Cc3d board. But after calibration, we had a problem where when the throttle was activated, the motors would spool up to max speed over the course of a few seconds.

We thought we had solved this with a recalibration, but then, after attaching the props, we found that the minimum rpm I could get the motors at was enough to rapidly lift it off of the ground. (Esentially, the lowest possible motor voltage I could get was too high to be an idle speed).

Now we think we're having a problem with (what we think) is a burned out esc, and the idle speed still seems to high when we attach props to the quad.

I guess I was just posting hoping that there was some problem with our combination of parts that was the cause of all of these problems. At its best, it seemed that if we just attached more inefficient props to it, it would idle and attach low enough thrust to not take off. But in its current state, we have 1 broken esc and a number of problems with just trying to get it too respond to controller input.

 

[Jackson]

A small ni-cad battery to power Flight Controller

First time I heard of such a thing.

 

[Nightham]

First time I heard of such a thing.

The esc's that we bought were a kind that only power to be supplied to the motors from the battery. Basically when we first hooked everything up, the flight controller was receiving no power. We found a guide that showed that an external dedicated power source for just the flight controller and reciever would work with our setup, so we just bought and small battery to do just that.

Edit: they are "non-BEC" esc's, which mean they do not supply a constant enough voltage to reliably power the on board flight controller

 

[mozquito1]

Playing with 11" props on a first build is asking for a trouble. Simple wire splicing can turn into finger wrist or limb slicing Get yourselves a tiny whoop each.

 

[Nightham]

Playing with 11" props on a first build is asking for a trouble. Get yourselves a tiny whoop each.

Would simply switching to smaller/more inefficient props be the way to go then? Ideally I would like to somehow lower idling speed so we aren't wasting battery power on inefficient thrust.

 

[mozquito1]

What exactly do you intend to do with it?

 

[Nightham]

What exactly do you intend to do with it?

At the moment we really just want to see it fly and have it be able to maneuver normally. Eventually we wanted to mount a gopro to it or a camera of some sort.

I guess our only criteria is we want it to have a decent battery life.

 

[mozquito1]

Your going to need a very sturdy frame for them 11" props.

 

[mozquito1]

just start with something like this til u get the basics down. The bigger they are the harder they fall the dearer they are. I get 7min on a 1300mah. I can get a gopro on this aswell as fpv cam. If it's eventually photography you want then an octo copter would be a more stable platform.

 

[Nightham]

View attachment 2718 just start with something like this til u get the basics down. The bigger they are the harder they fall the dearer they are. I get 7min on a 1300mah. I can get a gopro on this aswell as fpv cam. If it's eventually photography you want then an octo copter would be a more stable platform.

Given that money is a bit tight with college at the moment, I was hoping for advice on how to alter our current build as opposed to changing the fundamentals of it completely

Do you see any problems with voltages or power? Can you recommend a different flight controller software for the cc3d board? If so how do I switch over?
I tried cleanflight but for some reason, the cc3d rejected the firmware change. Does anyone who uses a cc3d have a better alternative to LibrePilot?

 

[Jackson]

Does anyone who uses a cc3d have a better alternative to LibrePilot?

For what you are trying to do the CC3D with LibePilot is fine. You don't need a more advanced FC or slicker FW, you need to watch some videos and master what you have.

I'd also dump the NiCD and get the 3A version of this (or something similar.) It' only 5 grams which always is a good thing. Hook it to your main power then plug into an empty ESC port. You can also plug into your RX if the CC3D is full.
https://www.banggood.com/3A5A7A15A-BEC-Brushless-UBEC-For-FPV-Receiver-p-1007444.html?rmmds=search

If you are having a hard time calibrating your ESCs try it this way.

 

[Nightham]

For what you are trying to do the CC3D with LibePilot is fine. You don't need a more advanced FC or slicker FW, you need to watch some videos and master what you have.

I'd also dump the NiCD and get the 3A version of this (or something similar.) It' only 5 grams which always is a good thing. Hook it to your main power then plug into an empty ESC port. You can also plug into your RX if the CC3D is full.
https://www.banggood.com/3A5A7A15A-BEC-Brushless-UBEC-For-FPV-Receiver-p-1007444.html?rmmds=search

If you are having a hard time calibrating your ESCs try it this way.

When we had it "working" at its best, this is actually the technique we used to calibrate them, so we know that this method works well with our quad, the problem was even with this method, lowest throttle caused it to lift off the ground fairly rapidly. We even had friends take turns holding onto it from the bottom while we gave it the smallest increment of thrust, after about 25% throttle, it became nearly impossible to hold onto.

Do you think that this strong thrust might come from us overtaxing the motors? I know when I've worked on airsoft guns before, that putting in a higher voltage battery increases fire-rate, but some gearboxes can fail from too high of rpm. For instance, would a different battery/lower voltage help tone down the power a bit and perhaps even give us a bit longer battery life?

 

[Jackson]

Make sure the arrow on the CC3D is pointing forward.

Run thru this again.

 

[Nightham]

Make sure the arrow on the CC3D is pointing forward.

Run thru this again.

Yup, I've gone through the whole calibration, the problem continues to be that at the lowest possible activation point for the motors, it still spins way too much/produces too much lift with the props to work as an idling speed. Not to mention one of the motors/esc's has stopped working and might need replacement.
Again, if someone could confirm that they dont see any problems with voltages or the amount of power being delivered to the motors, that would be helpful. An esc failing combined with too much power makes me think that voltages or something are too high for the equipment, but this is my first build and I really dont know.