We use the same design in the big brother for 5" propellers and double the weight of ArduBee. We make this development for our main focus about performative drone for swarm choreographies, its 2 years working with the fleet testing everyday to improve the quality of the performance. We had a lot of crashed indoor, and the pcb never had serious harm. We do not race obviously or high speed onto the wall!

That's great to hear that you haven't seen any issues with the PCB design. Thanks for all the great work!

I don't really concern PCB drones to be long-term type drones. I have a few, and they're not too bad, as long as you don't fly them full speed at a wall.

Another? There is one already? Can you please provide info about it?

I agree bitcraze its a great nano drone, but the first version has 3 minutes flight time and it can not be used outdoor, furthermore, Ardupilot is far more advanced and offers a lot more potential and with a huge community of experts, developers and user

UWB is really impressive and I see you have a optical flow positioning add-on board as well. Would like to play around with the current state-of-the-art, curious is fetting things to position indoors got easyer in the last 4 years, since last time I played with it.

Something I was thinking recently is using a lighthouse positioning system from Valve for indoor positioning. They have permissive licensing terms and the tech looks very promising:

https://partner.steamgames.com/vrlicensing

Yes! Lighthouse positioning system from Valve for indoor positioning it's so interesting, swarm compatible, easier to setup, cheaper and higher precision!

UWB is our present solution, its already easily in the 10cm accuracy in LOS scenario, it also enables complex indoor space with different connected rooms you want to cover, and you could cover easily 30m between each beacons.

We are discussing the option to integrate the optical flow directly into the ArduBee base. If you have suggestions, your contribution is highly appreciated.

There are also skyrocket drone, lastest serie is also running ArduPilot and most of the code is open both for autopilot and radio system

The next step up for rigidity is usually low-cost carbon fiber.

True, carbon fiber composites nearly always have greater stiffness and ultimate strength vs fiberglass

However, carbon fiber is also electrically conductive, vs fiberglass which is insulating, so that might be just a bit of a problem for a circuit board base... (perhaps solvable, but not the usual near-drop-in upgrade)

Yes carbon fiber its an amazing material for lightness and robustness, but we cannot see a way to innovate there with the usual separate parts and its needed cables. ArduBee its without a single wire, ready to fly, apart the motors wires. This in particular for micro drone is really a weakness in terms of flight time and aerodynamics.

Why would the PCB flex? A quadcopter doesn't have that much of a twisting force being applied to it, no?

It flexes in flight (under power load, especially with a battery). The BeagleBone quadcopter we built with plexiglass flexed noticeably. FR4 is better, but it still will flex.

Fr4 material is basically fiberglass, and at 1.6mm thick it doesn't take much to bend it if it isn't supported. I think the weight of the motors could be an issue.

While flying, the whole thing is suspended by the motors. It'd only be the weight of the centre components (mostly battery) that'd be flexing the arms.

(While crashing, all bets are off. But way back when I used to fly RC gliders they had a saying "If you build them to crash, they won't fly well. If you build them to fly well, they won't crash.")

Also, it's not like anyone expects thousands of hours of flight worthiness out of a consumer or even semi-pro drone. Sure the military might spec that for their Predator replacement, but most drone hobbyists I know end up with a bunch of perfectly serviceable old drones which they no longer fly because their gear became obsolete well before the mechanics failed irrepariably.

When resting, possibly. In flight, the weight of the battery would probably be the bigger concern, though I think you can get 2mm PCBs.

Thanks! this could be a great idea,the 2mm PCB could be an interesting option! We are devoted to 1.6mm PCB since the 5" version that weighs 220g and we haven't had any broken or issue on the PCB piece. The battery is well attached, fixed in 6 well distributed points on the PCB and aligned perfectly in the center of the 4 motors.

That's great then, if it works for you that's all that matters. I'm glad you guys are doing this.

Vibration can be a concern with quadcopters especially if the motors and propellers are not properly balanced

Till 1 year ago it has been a great concern, especially for small drone. Now thanks to andyp1per, new Ardupilot dev, we have amazing results with dynamic filtering gyroscope noise, we could even track the mechanical noise peak based on actual RPM or live FFT.

Harmonic Notch Filter in Ardupilot https://ardupilot.org/copter/docs/common-imu-notch-filtering...

new and ongoing development

https://github.com/ArduPilot/ardupilot/pull/13121

https://github.com/ArduPilot/ardupilot/pull/14010

This was about mechanical strain from vibration.

You have to consider under the selected IMU, in the center, there is the most of the mass, made by the single 18650 Li-Ion battery. This solution is working, ArduBee is already flying good with the low pass filter in the gyro sets at 110Hz, if vibration would be an issue I guess it cannot fly

https://discuss.ardupilot.org/t/ardubee-a-ready-to-fly-micro...

Again, this issue is not the IMU, it's the whole thing breaking mechanically.

I guess that's true, and they are using brushless motors so you have quite a bit of power there. Hmm.