Some good info in this thread over on RCGroups: https://www.rcgroups.com/forums/showthre...k-LR-build

One advantage of the DarwinFPV AIO that I hadn't fully appreciated is its 15A rating. The motors draw roughly a fixed power at a given thrust output, which means that to maintain hover or forward flight as the Li-ion voltage drops amps must increase. Also, as voltage drops motor RPM decreases and overall efficiency decreases. Thus with a typical 5A whoop FC the ESC can't keep up with the current requirements of the motors as the voltage drops. The link above has a good video showing this.

The FPVCycle 1S board specifies 9A ESCs, but mentions the FETs are 10A+ capable. I wonder if both actually use the same FETs and FPVCycle is just being more conservative with their rating? If the FPVCycle FETs are actually smaller than the Darwin FETs then I would assume they are more efficient, so it will be interesting to see how they compare in practice.

I'm working on a variant of Dave C's frame design using 3mm carbon fiber tubing. Not that I'm not happy with Dave's design; I just like trying my own take. Might end up horribly over-complicated and very little weight saving, but we'll see. This started by me adding tubes to the outside, then I got carried away 

(18-Mar-2021, 02:42 AM)JoyMonkey Wrote: I'm working on a variant of Dave C's frame design using 3mm carbon fiber tubing. Not that I'm not happy with Dave's design; I just like trying my own take. Might end up horribly over-complicated and very little weight saving, but we'll see. This started by me adding tubes to the outside, then I got carried away 

Interesting design! Where are you going to mount the battery?

Could you move the baseplate further back in the design so the FC was centered and the camera was more in line with the front motors? This might give you a better CG and would use equal length arms for the diagonals facilitating replacement.

(18-Mar-2021, 06:54 PM)V-22 Wrote: Interesting design! Where are you going to mount the battery?

Could you move the baseplate further back in the design so the FC was centered and the camera was more in line with the front motors? This might give you a better CG and would use equal length arms for the diagonals facilitating replacement.

Here it is a little more fleshed out. Doing a test print right now using Siraya Tech Tenacious resin.


It's definitely not the most sensible design, but I was trying to keep to Dave C's form factor as much as possible. Maybe for V2 I'll make it more toothpick-like, with uniform tube lengths.

(17-Mar-2021, 06:08 PM)V-22 Wrote: The FPVCycle 1S board specifies 9A ESCs, but mentions the FETs are 10A+ capable. I wonder if both actually use the same FETs and FPVCycle is just being more conservative with their rating? If the FPVCycle FETs are actually smaller than the Darwin FETs then I would assume they are more efficient, so it will be interesting to see how they compare in practice.

The DarwinFPV AIO has a S-H-50 esc setup and the last 2 digits indicates a dead time of 50. The FPVCycle 1s AIO has a dead time of 5.

So clearly they are not using the same FETs or the same ESC layout. 

For a Nano LR build the DarwinFPV AIO should be good enough.

But for a freestyle 1s build the FPVCycle 1s AIO will provide better performance based on the specs and reports by people who report a clear difference in flying characteristics using a different AIO FC/ESC on a 1s babytooth build.

The FPVCycle board is specifically designed with appropriate electrical routing for 1S along with an ESC layout focused on high amp (9A) but low dead time (5).

Adding a bit of extra info here so people are clear on the performance of ESC's on other AIO 1s capable board's on the market:

- NBD's BeeBrain Brushless: 12A esc's but have a deadtime of 40 based on S-H-40 esc layout.

- HGLRC Zeus5 AIO: 5A esc's and although they do not mention the ESC layout, the deadtime has been reported to be 50 being a 1-2S board for people that have the board.

- BetaFPV F4 1S AIO: 5A esc's, dead time 5 based on O-H-5 layout.

- iFlight SucceX F4 V1.1 1S: 5A esc's, dead time 5 based on O-H-5 layout.

- JHEMCU PLAY F4 WHOOP AIO: 5A esc's, dead time 50 based on S-H-50 layout.

Here's a really clever re-think of the design using the battery as a structural member: https://www.rcgroups.com/forums/showpost...stcount=50

Really interesting post there Kafie! You did a JB on me and I learned something today. Had to google what deadtime was. Found this info to help others that may need the extra info like myself:

https://brushlesswhoop.com/namelessrc-nl...412t-jesc/

For the 5V step-up regulator, I have a bunch of these Pololu boards on hand. They are more compact than Dave C's suggested board (0.4g vs 1.5g). The LC filter board can be soldered directly to it. They can supply over 1A with an input of 3.3V, so seems capable. Will do a bench test as soon as I have a Zeus VTX to test.
https://www.pololu.com/product/2564/specs

Yeah, I use Pololu regulators. I agree.

pololu for me as well. i'd just get a inductor/cap and wire together instead of that big ass board.

also really surprised an LC filter is needed

(19-Mar-2021, 03:39 PM)JoyMonkey Wrote: For the 5V step-up regulator, I have a bunch of these Pololu boards on hand. They are more compact than Dave C's suggested board (0.4g vs 1.5g). The LC filter board can be soldered directly to it. They can supply over 1A with an input of 3.3V, so seems capable. Will do a bench test as soon as I have a Zeus VTX to test.
https://www.pololu.com/product/2564/specs

Have you verified it can supply 1A at 3.3v? From the specs, it looks like it tops out a bit lower than that:


Please report back when you get the Zeus VTX! If the U1V10F5 works well I may switch to that just for the 5% bump in efficiency

I went with the U3V12F5 instead for my build. The efficiency is a little lower, but it provides a higher output at lower voltage:

(19-Mar-2021, 04:29 PM)p-i-engineer Wrote: pololu for me as well. i'd just get a inductor/cap and wire together instead of that big ass board.

also really surprised an LC filter is needed

In my experience the Pololu regulators have a pretty clean output, so I agree you could probably skip the filter.

Success! I'm back in the air and just did a test flight with iNav. Temperature was 40F with a 10mph wind gusting to 20mph. Total flight time was 10 mins (~16 min total power on time due to messing with settings). Battery was sagging at the end, but I'm charging it up now to see how much capacity I used so I can better calibrate my current sensor. Min voltage during the flight was 2.8V, but resting voltage when I went to charge the battery was 3.5v so I don't know if that's accurate either. I'm wondering whether the nickel strip I'm using to extend the battery terminal is causing too much voltage drop under load? I'm going to make another 1S 18650 "pack" with 16 or 18 gauge wire and see if that is any different.

Position hold and RTH are working well, and I have a waypoint mission loaded up for a local park later today.

I'm getting a little bit of warble from the props, so I may need to play around with my PIDs a bit. Motors aren't getting warm, but considering how small they are and how cold and windy it is I don't know if that means anything.

Since I installed the FC upside down in order to be able to access the pads, I needed to remap the motors. And since iNav does not support motor remapping, I had to edit and build a custom iNav target for it. I have attached it here if anyone runs into the same issue. Note: You will need iNav Configurator 2.7.0 to install and configure.

(19-Mar-2021, 05:01 PM)V-22 Wrote: Have you verified it can supply 1A at 3.3v? From the specs, it looks like it tops out a bit lower than that:

Please report back when you get the Zeus VTX! If the U1V10F5 works well I may switch to that just for the 5% bump in efficiency

As luck would have it, the Zeus VTX (and DarwinFPV AIO) was sitting on my doorstep today.
I ran it through a few tests using a cheap benchtop power supply, so numbers may be a little fuzzy, but this should be a decent ballpark.
The U1V10F5 (with LC filter inline) did a good job, and I'd imagine results would be better on a quad with air from the props assisting with cooling.
The VTX doesn't like when its input voltage drops to around 4V.
With the VTX set to 350mW mode, with 2.5V 1.6A (4W) coming out of the power supply, the regulator runs pretty hot, but video is still stable.
At 2.4V, things become unstable; video cuts out, mA jumps between 1A and 1.5A.

So ~2.5V seems to be the low voltage limit in 350mW mode when using the U1V10F5 regulator.
In less power hungry modes I could get the voltage down further and maintain stable video signal (1.7V in 25mW mode, 2.1V in 100mW mode, 2.3V in 200mW mode).

To do: Come up with better GPS mount 

So they waypoint test was interesting   I fully charged the 18650 cell to 4.2v this time, after realizing that my other charger was cutting off at 4.1v. This was my first flight in the present configuration with the new motor, and the quad immediately felt way more powerful than before. I'm not sure if fighting the wind during the earlier flights was causing two motors to saturate or what, but it felt much peppier and had a respectable vertical climb rate. I flew a lap LOS then realized I had forgotten to load the waypoint mission in iNav (throttle down, pitch forward, roll right when disarmed) so I landed and did that. 

I took off again and switched into position hold near my first waypoint, but when I switched to waypoint mode the quad immediately rolled left into the ground. It cartwheeled for a bit along the grass then came to a stop at the edge of the field. No physical damage, and the single rubber band 'battery strap' kept the battery restrained, but the GPS disconnected and was flung off in a random direction. I searched for 20 mins, but eventually gave up hope of finding the 1" x 1" GPS in the grass

A few important lessons learned here: always get a few mistakes high before trying anything new and be ready to recover, make sure everything is securely fastened to the quad, and bring backups for everything. 

While I'm waiting for a new GPS, I'm considering swapping in an OpenLager on that UART to do some tuning. I might just flash back to Betaflight now that I know iNav (kinda) works, and get some more flight time on it.

Any ideas for a secure but lightweight mount for a M8Q-5883 GPS?

Shrink tube and double sided adhesive to the frame for the GPS. It weighs just about nothing and it works as long as flying style is not too aggressive. Also have to consider any sort of heat sources affecting the frame.