Encouraged by Pathfinder075, I'm starting a new project.
My latest build, the 5-inch Bozon One, is too big to fly in my area, so I need something smaller to practice flying.
I decided on an agile 2.5" micro quad.

For now, I have the frame - BetaFPV Twiglet 2.5:

Parts List:

Assumptions

It will be powered with 2S and/or 3S LiPo, 
XTV Walksnail Avatar Mini S1 with Nano Cameras

FC I don't know yet. 
Pathfider075 recommended me AIO from DarwinFPV:
https://darwinfpv.com/products/darwin-el...luejay-aio

I also found BetaFPV which seems to fit my project:
https://betafpv.com/collections/brushles...-aio-fc-v1

I am leaning towards the latter because the price is similar, the weight is almost the same, it is designed for HD, it has a better processor, serial ELRS etc.
Motors I will take the suggested Happymodel 1204 6500kv as I have no experience in that matter

As for the rest, I don't know yet

Here will be the pictures from the build..

So far I have only the frame:



The VTX finally arrived and I already have most of the parts:


After a moment of fear:


I managed to put everything together:


I think it also looks good with blue propellers (here after the maiden flight):

The Darwin board is ok, but it has no current sensor (not necessary but I always prefer to keep an eye on amp draw), has a SPI ELRS (so ELRS version is tied to BF version, but it frees up a UART), comes soldered with the capacitor, and comes with a fairly humongous ELRS antenna (you can swap it though).

The Betafpv board is designed for digital VTX only (no analog OSD), and if you are using WS it even has a plug where you can plug in the 1S VTX without needing to solder which is nice. ELRS is serial so you can update the ELRS firmware independent of the BF version, but it does rob you of a UART, meaning you won't have any free ones to add say a GPS or other serial device. The AIO does extend out the back, but looks like it should fit your frame, and it does come with a lower performance single wire ELRS antenna, but you could solder in a better antenna if you really wanted to.

Yeah, go with an HD 2-3S FC. mstc's suggestion will be better than the Darwin version which is more optimised for analog.

Motors wise, Ali is probably the only place to get 1204's, I think, at the minute. I did see some at a local shop in the UK, but he sold out of them. The ones I've ordered are from here, but they haven't arrived yet so no idea on them, but I've used HobbyFly before and not had an issue. Remember to get the 6500kv and the 4 pack, if you do get them from Ali.

https://www.aliexpress.com/item/10050032...131e6bb7-1

Props wise. GF 2540, Azure Power 2540, HQ 2.5x2x3 or HQ 2.5x3.5x3 - Spec sheet says 8A per motor on GF 3025, so would expect the HQ 2.5x3.5x3 or 2540's to work without issue. Plus the BetaFPV FC has 20A ESC's so should be fine on the power side of things.

I have no experience in Walksnail so mstc (and ph2t) are your experts on that side of things.

GPS is moot on something this size. It doesn't have the efficiency and lift for real LR stuff. It's more of a fairly close in light freestyler sort of build. My videos are a pretty good indicator of what I use mine for. It's basically 200-300m range and lots of acro, but it works well as a cruiser too. But it's still powerful enough to get you into trouble if you want to live on the edge and on 1204 even more so (1202.5 3S is peppy and 1204 3S is on paper about 150-200g more thrust).

Put a buzzer on it to handle when it goes down and you need to go look for it, or if not, BadRaven made the suggestion (that i currently use) of flicking turtle mode on (if upside down) and just flicking the stick so you will hear the motors spin for a millisec, which gives you an idea of where to look, but won't be enough to blow any ESC's. I've been doing it that way now for over 6 months without issue. The other things is to use a bright colour for the canopy and bright colours for the props, ideally two tone props, like say bright blue on the front props, bright red for the back props. Colours that aren't green like grass and look as unnatural and bright as possible.

As to the range of the ELRS, I wouldn't worry. This is a relatively close in sort of quad. You should still be getting 300-400m of range even with the enamel wire, you just might need to experiment with placement to maximise the range. Honestly i don't fly beyond 200m most of the time, because 200m is still a fairly long walk.

(23-Feb-2024, 09:46 PM)Pathfinder075 Wrote: GPS is moot on something this size.  It doesn't have the efficiency and lift for real LR stuff.  It's more of a fairly close in light freestyler sort of build.  My videos are a pretty good indicator of what I use mine for.  It's basically 200-300m range and lots of acro, but it works well as a cruiser too.  But it's still powerful enough to get you into trouble if you want to live on the edge and on 1204 even more so (1202.5 3S is peppy and 1204 3S is on paper about 150-200g more thrust).  

I wouldn't discount GPS for this size (if you had the desire), there are teeny tiny modules now that work fairly well. Some pilots have taken a 1S 3" setup with GPS out past 8km. I have a GPS on my 2S 3" pick (analog) 1103 motors and it gets more than 12 minutes of flight time. But different setups for different uses.

I don't know i'm still learning about LR. I know for me if I was going to do a LR build it would be 3" minimum in size, just to maximise the thrust efficiency and I probably wouldn't run 12xx, instead opting for a much more efficient motor that was more suited to LR usage. The other thing I would do is make it as light as humanly possible and would probably not use a pick frame.

But yes, accepted you could run GPS on pretty much anything. To do it on one of these frames would only need an acceptable canopy or maybe something custom you 3D printed yourself to allow the module to be mounted behind the camera.

Although most of my builds don't have GPS, it definitely is not only for LR. Extra safety to have RTH, or simply an arrow in the OSD pointing you back home if you get disoriented, sending GPS coordinates to your radio to help recover a quad lost in tall grass with disconnected lipo, or maybe some like the extra speed/distance readings? But yes if its only going to be a backyard trainer then better to leave it off.

I'm not going to mount gps on this thing foe now but if I change my mind this FC gives a possibility to unlock uart 3 by removing one resistor.
I've already ordered the motors in 4-pack on Ali.

Sorry my bad memory, it is a F405, it has 4 UARTS so plenty for everything. Don't remove the resistor, that is UART 3 and connects to the onboard ELRS RX. UART4 is for the VTX, then you have UART1 and UART6 free.

I don't have this FC yet, but thanks for the warning. I skimmed through the description quickly, without understanding what UART 3 release actually means.
Either way, I'll think twice if I really need it before I use my soldering iron on SMD.
There is another R that can be re-soldered to change the VTX voltage from 9V to 5V, but fortunately I don't think I need to do that either, because the new version V3 of WS mini 1S VTX accepts voltage in a wide range of 3.1-13 V

I set mine to 5v as that moves some of the voltage regulation off the VTX, hoping that will also take some heat off the VTX which already gets very hot very quickly. But yes the newer V3 boards will work fine with 9v so it is not necessary. That resistor can be a bit of a pain to remove as it is right next to the plug.

Hi Bozon,

I would go with the BetaFPV for several reasons:

1) The F405 chip is better than an F411 and it DOES have the extra 
    hard UARTs. Of the 6 or so, I see breakout pads for UART1, UART3, 
    & UART6, plus UART4 is in the HD connector. So, plenty for the GPS.
       
2) It is a 20 Amp board vs 15 Amp.

3) It has an HD connector. 

4) The USB connector on the BetaFPV is a JST so my guess is that the
    board comes with a standard USB connector cable. Plus the USB
    connector is out the back. I am not a fan of the downward USB
    connector and shoved right up against the FC mount bolt. 

5) The BetaFPV board has a 9V BEC in addition to a 5V BEC. 

6) The BetaFPV board has 16 MB of BlackBox memory. Some folks
    use this for tuning. Even if you don't (yet), it is nice to have in
    case you ever do. 

For the tiny price difference, this would be a no brainer for me. Actually,
I stopped buying boards with the F411 chips a long time ago. Although
I might consider one if the price was really right, in this case it isn't. 
When you can get an F405 for the same money, well, no contest.

Just my 2 cents worth.

Later, iFly  

Thanks iFly!
In fact, I have already decided on the
BetaFPV and have even ordered it. Exactly for the reasons you listed, (maybe except the USB plug, which I didn't think about)

the very special thing on darwin aio is that it can do 1s up to 3s, there arent other aios does support 1s and a voltage range up to 3s. there might be still no reason for it in your case.

i would suggest to stay away from proprietary betafpv products.
that board design does increase the risk for damage enormous. it doesnt fit most frames well.
its designed for the pico series, it really doesbt match the requirements for a simple 25mm pod on top, it would need to be covered more.
low durability, no versatility, than betafpvs quality controll..

sorry, i would highly suggest to choose another board for that frame

(24-Feb-2024, 11:49 PM)hugnosed_bat Wrote: [...]

would suggest to stay away from proprietary betafpv products.
it really doesbt match the requirements for a simple 25mm pod on top, it would need to be covered more.

[...]

sorry, i would highly suggest to choose another board for that frame

Thanks for your comment.
I guess you have had a bad experience with betafpv products.

Sorry for the stupid question, but is there a specific reason why this particular FC needs to be covered?

What would you recommend for that frame instead?
AIO, 2-3S, UART ELRS 2.4HGz on board, BEC suitable for VTX Avatar Walksnail