I'm planning a build around the Recursion Scythe frame. I mostly flew two AOS35 builds last year but they don't have any weight margin left since I want to stay sub250g. I recently put together a Naked Hero8 to replace my Runcam Thumb Pro and hence need to build something lighter. I briefly debating going with a smaller prop size but ultimately decided to go for a lighter 3.5" frame. That's where the Scythe comes in.

I have a JHEMCU F411 HD AIO already I plan on using. I also have an HDZ whoop kit to put on it. I was hoping to reuse some 1505 motors but the motor bolt spacing is too large. I ordered some t-motor 1404 3800kv motors to use instead. Receiver will likely be a HappyModel ELRS EP1 and the GPS an HGLRC M100. I have 650mah and 720mah 4S batteries I can use as well.

Wiring should be straightforward. HDZ vtx can connect to the 10V pad and one of the UARTs. I probably wont bother with SmartAudio. RX is 5V and a UART. Same for the GPS. Naked GoPro record button will likely connect to a remapped LED pad and the GoPro powered straight from the battery.

I'm just playing the waiting game now while the missing parts are on the way. Although I suppose I should find and print an action camera mount.

Edit: I notice the AIO I have only has 2 uarts and would require the GPS to be wired to a soft serial port. Is that a good idea or no?

Not a good idea to put GPS on soft serial if you plan to use GPS Rescue. Happymodel sells a CruxF405HD board which has a VTX plug, 3 UARTS (one is used for ELRS), and built in ELRS with ufl antenna. It is a 20x20 board and I think fits the Scythe frame better than a 25x25. It also has 20A ESCs, but motor pads are very tight and slim so take note of that.
Also the Scythe frame has two top plates, the wider one has 25x25 holes so if your HDZ VTX is that size, you can mount it to the top plate.

(24-Apr-2024, 10:08 PM)mstc Wrote: Not a good idea to put GPS on soft serial if you plan to use GPS Rescue. Happymodel sells a CruxF405HD board which has a VTX plug, 3 UARTS (one is used for ELRS), and built in ELRS with ufl antenna. It is a 20x20 board and I think fits the Scythe frame better than a 25x25. It also has 20A ESCs, but motor pads are very tight and slim so take note of that.
Also the Scythe frame has two top plates, the wider one has 25x25 holes so if your HDZ VTX is that size, you can mount it to the top plate.

I ordered the JHEMCU AIO thinking it was a 20x20 style but ended up with a 25x25. I'm going to try and make what I have work first. My other options are a NeutronRC AT32 AIO (I have zero experience with AT32 boards) and a HAKRC F411 20A AIO. I was wary of the HAKRC because I wasn't sure if 20A would be sufficient.

20A should have no problem for 1404s. I just used the NeutronRC board in two slightly larger builds and for its low price it is quite a good board. You are a little limited in the firmware selection, either ATBetaflight 4.3.2 or BF 4.5 up which is still RC. The board has enough UARTS, VTX plug, a nice layout and is easier to solder than the micro AIOs, and they are a bargain when you find them for $30-40. If you get it, make sure you get the v1.2 board, not the older one.

If you don't need GPS rescue, then I guess you can make your F411 work.

(25-Apr-2024, 12:07 AM)mstc Wrote: 20A should have no problem for 1404s. I just used the NeutronRC board in two slightly larger builds and for its low price it is quite a good board. You are a little limited in the firmware selection, either ATBetaflight 4.3.2 or BF 4.5 up which is still RC. The board has enough UARTS, VTX plug, a nice layout and is easier to solder than the micro AIOs, and they are a bargain when you find them for $30-40. If you get it, make sure you get the v1.2 board, not the older one.

If you don't need GPS rescue, then I guess you can make your F411 work.

The HAKRC F411 has 3 uarts so GPS rescue should work with that. I forgot I also have a SpeedyBee F411 20x20 stack but I'm not sure it'll fit the frame with a HDZ Race v3 board in there as well. Maybe if I stack everything on the same screws rather than trying to top mount the VTX and bottom mount the FC.

Stack will be tighter, but should still fit. It fits a vista plus AIO, so essentially a 3 board stack. If your VTX is 25x25 then it would be difficult to put it on the same screws (probably not enough room for an adaptor). You can still mount it to the wider top plate, just use low profile bolts and have the nuts on top of the top plate, that way you get more clearance for the stack.
But a stack will add a few extra grams to your build compared to an AIO.

A 20x20 stack won't fit if I use a "golden nut." The gummies should be able to squish enough to fit but the connectors between the FC & ESC bottom out first. I'll probably end up using the NeutronRC AIO once it arrives. I like the SpeedyBee solely because it has a 4.5V pad that can power up a GPS with USB power. I haven't found an AIO that does this yet.

The top board is the HDZ Race v3.

Just press it down like a sandwich
You could use shorter gummies, but not if the boards are already touching as you mentioned.

It does seem most of the newer AIOs skip the 4.5v pad, but some do have it (for example JHEMCU AIOs). The NeutronRC board is a little odd, the 5v pads are actually powered by USB, some Betafpv AIOs do the same (which I think is a bad design if you have some heavy draw item connected like a 5v VTX). I have a RX/GPS on mine and it powers up with USB which is nice to have that option.

Here it is with an AIO instead. The camera plates are a really tight fit so I'll probably have to file them down a bit. The HDZ nano camera has an annoying mounting hole size so I'm not sure how I'm going to make that work yet.

I think the camera plate holes are cut too small, I had to grind mine down to get them to fit. You can also skip the plates and print a TPU mount (planning that on my next Scythe build), especially if your camera has different mounting dimensions. That will also allow you to use shorter standoffs for a lower profile build since two boards don't need that much space (but props may be a little high in the camera view).

Motors arrived today! Just waiting on the NeutronRC AIO now.

Looking forward to seeing how this build turns out. I've been eyeing the Scythe frame for a while now. A high quality, more durable, Crux35-alike would be awesome.

(Yesterday, 01:42 PM)drumgod Wrote: A high quality, more durable, Crux35-alike would be awesome.

That's my thought as well. I was planning a Crux35 build but I might just get a second Scythe frame instead. Although I already have the Crux35 frame so maybe not.

For anyone interested, the Crux35 is on the left and the Scythe (cut by CNCDrones) is on the right.