Standard sub 250 gr Copter Build and Tune project - 3” Mid Range

Topic:

Due to increasingly restrictive flight regulations, copters weighing less than 250 grams will be increasingly in demand in the future.

Users struggle to configure and tune copter builds, especially very small 3” copters. This proposal is to construct typical copter of a certain class (sub250gr). Where possible/logical partner technology will be used without compromising the quality of the build.

This proposal is to independently build and tune one 3" Mid Range copter sub 250 gr. Mid Range copters play to ArduPilot strengths (autonomous missions, long range, high quality FPV/video, optical flow hold) but also prove quite difficult to tune due to less stiff frames, motors optimized for power consumption and weight (estimated flight time 10/15 minutes).

Proposal type: Hardware [X] , Software [ ] , Other [X] :

Description:

Proposed build:

frame QWinOut 135mm or FEICHAO Merry135 3inch

motor 4pcs FullSpeed 1106 C2 4500KV 2-4S

fc 20x20mm Matek Systems H743-MINI

esc Hakrc 20A Blheli 4in1

gps BN220

compass GY-273

prop LDARC 3045

liion 2x18650 sony vtc6

rx Jumper R1

lidar Benewake 8m TF-Luna ToF

vtx Eachine NANO VTX 5.8GHz 48CH 25/100/200/400mW

cam RUNCAM SPLIT 3 MICRO

optical flow CX-OF or similar

Copter would be tuned against Copter 4.1.

Build would be written up and published on the wiki together with standard configuration parameters

Planned amount $$ (USD):

$360

Estimated time for completion:

About 2 months

This is my current sub 250. Arducopter 4.0.5, flight time 15 minutes, weight 219 grams, fpv 400mW with OSD and telemetry with yaapu script, optical flow, powered 2s Liion.

In this videos it is in “mission auto mode” and “optical flow hold mode”

This is my 5" quad. Arducopter 4.0.7 matek F405 CTR, 18 minutes fly time, wifi telemetry, 2.7k video recording and fpv whith one cam.

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The @Funding_Team is still discussing this.
A sub-250g build would be great, and we’d been discussing with a manufacturer in the background. For this proposal we need to look at availability, whether a vendor would like to offer as a kit, whether it’s better than the configuration we are looking at (a toothpick frame) and a few other things.

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Hi @james_pattison

thanks for the answer!

I believe that it is important a sub 250 built with standard products that can be found in online stores and at low cost. I would have the opportunity to make a frame with CNC but I prefer to use a standard frame so anyone can reproduce the project.

In these months of development I realized that to use the advanced functions of arducopter it is necessary to build a copter that flew at least 10/15 minutes. For this you need to use li ion 2s battery if you want to have that flight time. The ideal frame is a 3" to stay under 250 gr and lift about 100 gr of battery. I don’t think there are any low-cost and easily reproducible alternatives.

For this reason I think a frame like this can be fine. Obviously you could use others, but this one costs little, it’s 3", it could evolve digitally with Caddx Vista.

Here you can see some tests done yesterday of my sub 250 (219gr) Arducopter. Sorry for the non-quality video but I was flying and shooting the video alone, without assistants and also bit of wind as you hear in the video. :slight_smile:

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Nice - you’ve got that flying well!

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For awareness, the sub250 configuration we have been looking at is:

Component Item
Frame Podracer 4"
Motors Podracer motor
GPS M8Q-MSP/CAN
FC/ESC AIO Beast H743
Props Props
RC Tracer Nano
Cam Caddx Ant Lite
FPV TX UnifyPro32 Nano
Alternates
GPS TBS GPS
RC ELRS
VTX OVX300

Which has a weight (without battery, strap and FPV antenna) of between 101.5g and 107.8g, leaving enough headroom for quite a lot of battery (potentially 3x VTC6 18650 if we’re very lucky). It hasn’t been built yet, although the components are on order. I hadn’t thought of adding CXOF flow: that’s a good idea.

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That looks like a nice bit of kit for a sub 250g. I might suggest the 5" version of that frame giving a bit more flexibility. 12g more but I have found low pitch 5" with otherwise the same hardware performs very well with more flight time. 4", 5", 2S-3S, Li-ion/Lipo all can work. I’m using the Betaflight 1404-3800kv motors, I would expect the 1505-3600kv’s to be even better suited to 5".

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It’s really tight on weight. 5” with 2S 18650 would make it in, but I don’t know if it’s worth it.
With 4”, on paper 2S 21700 or 3S 18650 can just make it in - probably at the cost of a lighter gps, and hence not having a compass (no I2C or CAN on the Beast FC, and the Matek unit is the only one I know of with compass over serial).
I’ll see how it goes. 3” might end up having fewer compromises, so we’ll leave this proposal open for a bit.

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Yea, that’s what I typically fly. Compromises for sure at this weight.

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You might want to look at Flywoo Goku 745 AIO FC as well. The board itself is only 8.5 gram and has i2c for GPS and compass.

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Yes, but F745 has only 1MB flash, and I really want to run full ArduPilot. The only AIO 20mm or Whoop footprint option with support for the full Ardupilot feature set is the BeastH7, as far as I’m aware. The Matek H743 Mini, and MRo ControlZero boards are also possibilities (the MRo in particular is a great flight controller), at the cost of separate ESC board.
It’s great that this topic is getting some discussion happening!

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Unfortunately the Flywoo website is now advertising these as 512k flash which is not enough - they are not all like this, certainly the two I got have 1Mb flash, but unless we can get Flywoo to guarantee the part its a bit difficult to base a standard build on it.

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That’s unfortunate. Mine also has 1MB. I was able to build a sub 250g quad with it. I hope that Goku or some other will be able to offer more small AIO FC that is compatible with Ardupilot in near future.

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It is great to see this post and the interest it is building up(pun intended),with the dark cold nights ahead of us in uk any way an other very interesting project to look forward to and I see this as an other project to get more ardupilot users,so hope it gets the green light,

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Hi @james_pattison and hi all,

I had seen the IFlight Beast H7 too, but then in the wiki I read this and discarded this FC. Compass is obviously fundamental, how do you plan to solve it?

" This board has no compass and no way to connect an external compass. Applications requiring accurate heading information must rely on ArduPilots [Compass-less Operation]"

That frame does not seem suitable for me as a structure. All too compact in the center. Better to have more space to have more distance between components and less interference (see Andy with his GPS that doesn’t have a good fix).

In my project I was planning to insert a split cam to have full HD (or 4k) recording. It doesn’t seem possible with that frame.

In my tests the separate compass is quite immune to noise even on a small frame, on that frame it seems difficult to install a separate compass.

A 3s ​​liion battery weighs 155 grams (approximately), about 100 grams remain for the rest of the quad that I remember must weigh max 249 grams and fly max 19m / sec to be in category C0.

My 3 “exists and already flies well for 15 minutes (max), weighs 219 grams at take off, why use a 4” that risks going over with the weight? What are the real advantages of 4 "?

The frame I proposed weighs 38 grams (35 TBS) but could use the caddx vista to have FPV in HD! Weights to be checked.

My current 3 ”(not optimized) weighs 219 g at take off and I have installed the TF luna lidar (5 grams 8 meters) with precision altimeter function. Tested, it read perfectly outdoors up to 8 meters. Unfortunately in copter 4.0.5 it introduced some strange behaviors. I crashed and asked for help on the forum but didn’t get much feedback (I’m afraid arducopter code problems). We should investigate more because with 10 grams of extra weight we could also have a precision altimeter and front or rear obstacle avoidance.

Attached is a screenshot of the log of the recent flight you saw. You can see the number of satellites being received (max 21 with Galileo!) And the very low value of the vibrations (rubber everywhere in the quad). These are two critical elements in a quad sub 250, can you do the same with that TBS 4" frame?

My 3s li ion 18650 vtc6 156gr!

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Here the problems with TF Luna lidar on my 3" copter

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Re compass on the Beast H7, my build list uses this GPS: http://www.mateksys.com/?portfolio=m8q-can which can output using MSP (serial), so GPS, compass and second baro all over a single uart. Being an AP_Periph node I can also use it to connect I2C devices (like some rangefinders) and also send over serial.
I don’t have a TF-Luna so can’t really help with that.
Re benefits of 4” over 3”: as per my earlier posts, there might not be any in the sub250 space, but we were already working on it. What it does give is flexibility. Basically sub250 is possible, but if you don’t need/want that restriction the quad is still highly useful and fun.
No decision has been made. I’ve ordered parts as per your build spec so we can look at both. It might even be that we don’t choose between the two, as they meet different needs.

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If there is a way to link a compass maybe the wiki needs to be corrected. In any case, putting on a sub 250 a gps 29 * 29 * 9.7 mm especially on that frame seems to me quite difficult.

In my opinion, to eliminate esc4in1 there are too many limitations with that FC. In general the porting of the ardupilot code on the rare FC 20 * 20 with baro should be expanded. I put esc HAKRC on my list because I wanted to experience something very important. Exclude via jumper, the esc voltage regulator in order to exclude the low voltage cutoff of the esc and use the 18650 up to 2.8V and extend the flight time in 2S mode (only possibility sub 250 liion).
If there are no weight limitations, but you just want a small quadcopter, I would look at the DIATONE ROMA frames. In my list I did not select those because of the cost (I tried to keep the price low), or for reasons of weight. But in any case there are Rome 3 “4” 5 "frames.

For small quads, ardupilot porting is also useful for F4 cards with less than 2MB. Even if the code will not be complete, with the new server allowing you to insert only the required features (often few on small quads), even the old F4s can still be very useful, in my opinion.

You could also do a low budget sub 250 configuration, only analog FPV (no recording HD), with Kakute F4, GPS BN220, compass.

In any case it is useful to remember what DJI did with his FPV drone (750 grams not sub 250gr). He created an easy-to-fly FPV drone (with gps assistance). With a sub 250, we can do something similar, with the advantage of the sub 250 (no license, flight in an urban area).
DJI is probably already thinking about it

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Hi Alberto,ive just ordered the Roma 3 inch frame the other one that interests me is the hollybro 3 inch Kolpis,I will use a Matek H743mini fc,Aikon 40 amp 4 in 1 escam undecided yet on camera and vtx,will probably use crossfire radio but would love to squeeze a RFD micro 868 onto this,GPS will be matek,will also as time goes by fit opti flow and a lidar and finally 21700 2s li-on batts this will keep me busy through the winter what a great project

Hi Marty, if your target is a sub 250, carefully consider the weights. The 21700s are heavy enough for a 3 "and maybe 3s 18650 would be better to be able to drop with the cell voltage at around 2.5V.
I still think that 3 "and 2s 18650 Vtc6 is the winning combination for the sub 250. Possibly with esc capable of going below 3V per cell

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o/k and thank you,ile order 18650 cells,what esc would you recommend please 20x20 stack