Hi guys,

welcome to my new Nanolongrange FPV drone design! This is the 4th and most sophisticated iteration. The design builds on my previous completely 3d printed frame NLR35. The goal was to make it lighter, more powerful and yet fully integrate battery and GPS mounts. Moreover, I decided to switch to a new digital FPV link system, Walksnail. It provides better image quality than analog and HDzero and is lighter than DJI. Finally, it records HD footage onboard and on goggle's DVR.

Please feel free to print, mod and share your builds with the hashtag #NLR35.

Key features:

121g AUW with 1s 21000 LiIon (optional 18650 (-18g))
magnetic battery connectors
Walksnail digital FPV system
GPS
ELRS
1203 11500kv motors
3-3.5" props

Flight test results

>23min flight time
>10km distance
>2km range

Supplies

Files for 3d printing and carbon cutting

1x DarwinFPV 15A 1-3s AIO

1x Walksnail 1s lite VTX

4x Flywoo 1203 11500kv motors

4x Gemfan 3018

1x Flywoo Goku Nano GPS V3

8x M2x4 titanium screws

5x2mm neodym magnets

4x M2x20 plastic screws and 8x nuts

Nickel strips

21700 Liion Battery: I recommend Molicel p45b or p42a; Samsung 40T is the low budget option;

Step 1: Print and Cut Frame Parts

You need to cut the main frame from 1.5mm carbon fibre. Use the .svg file on Thingiverse/Printables. There are plenty of local and online CNC shops which can do the job for you. The most affordable option is probably Sunlike/Senlai in China. You can buy from them on Aliexpress too, just message them and ask for a quote. It's around 8$ for the frame + shipping.

3d print the .stl files. The 18650 mount is optional. I printed with PLA+. You can go as low as 20% infill except for the smaller parts (Camera and GPS mount, Walksnail cam lite adapter) where I recommend 99% infill. I'm happy with Esun PLA+.

Step 2: Build Frame

Start by installing the battery mounts. Use M2x20mm plastic screws. Ensure the correct direction, they should fit snugly.

Insert M2x20mm plastic screws on the 2 other mounting holes for the flight controller. Put grommets on top to keep them in place.

Attach the camera mount to the front screw. Again, the camera mount should fit snugly.

Put the GPS mount on the back screw. The mount faces upwards and fits snugly.

The full frame should be around 10g. Make sure that it is as light as possible.

Step 3: Install Flight Controller, VTX and GPS

This is the hardest part of the build, where you need to solder. You need to connect the video transmitter (VTX), GPS and power wires to the flight controller. Take your time, pre-tin wire and pads and it will work even on these tiny surfaces.

Start with the Walksnail VTX. Solder the RX wire to TX1 and the TX wire to RX1 on the flight controller. Then solder the power wires directly to the battery in pads (+ to + and - to -).

Now solder the GPS wires to the flight controller. RX goes to RX2 and TX goes to TX2 on the flight controller. Use the 5V BEC to power the GPS (different GPS may require a lower voltage!). Solder the black wire to GND (ground) and the red to 5V.

Solder the included power wires to the flight controller. Start with red (+). It is supposed to face forward. Continue with the black wire (-) and let it face backwards.

Put the VTX first on the frame. Use grommets, and secure the VTX with M2 nuts on top. Then put the flight controller on top. Ensure direction. Secure with M2 nuts on top.

Cut the GPS wires to size. Solder the wires to the GPS pads. Red wire (5V) goes to V, black wire (GND) to G, RX2 to T, TX2 to R. then insert GPS into the mount. The ceramic antenna faces upwards.

Step 4: Install Motors

This step is easier, you just need to attach the motors with screws and solder motor wires to the flight controller.

Mount all 4 motors to the arms of the frame. Use M2x4mm titanium screws. The motor wires should face towards the flight controller.

Now cut the wires to size. The should easily reach the motor wire pads on the flight controller.

Insert the motor wires from below into the motor wire holes of the flight controller. So you can ensure that the propeller won't touch them. Solder all 3 motor wires to the flight controller. The order doesn't matter, you can correct the motor direction in the drone's software.

Step 5: Install Magnetic Battery Connector

I developed and tested the magnetic battery connecting system. Although it is very simple and lightweight, I'm trusting it. If you want to use a different connector use GNB27 (lighter) or XT30. BT2.0 may work too, but it will probably be limiting the quads power as it may not deliver enough current. I don't recommend PH2.0 due to its current limitations.

For the magnetic connector you need 2 small pieces of Nickel strips and 2 strong 5x2mm neodym magnets.

Start by inserting the LiIon battery. The positive top (+) faces forward. Cut the power wires to size. They should touch battery top / bottom. However, they shouldn't be too loose either, to avoid touching the propellers.

Cut 2 small pieces off the Nickel strip. Solder to the power wires.

Attach the power wires with a magnet on top of the Nickel strip end to the battery. Now your flight controller should power up.

Step 6: Install Propeller

Gemfan 3018 works great. Gonna do more testing, there might be other good options too. Bi-blades are most efficient (or in future toroidal propeller?) Props up to 3.5" will fit.

It's a press fit. You can easily mount the propellers by holding the motor and turning the propeller. Make sure you get propeller with the correctly sized mounting hole. There are 1.5mm and 2mm options. My motors have a 2mm shaft, so I bought propellers with a 2mm mounting hole.

I prefer a props out setup, which means that the 2 front motors spin outwards and the 2 back motors spin inwards. This is not the standard configuration in Betaflight. Ensure you enable this option later in the software.

Step 7: Camera Mount

You need to 3d print the adapter to mount the Walksnail lite camera as it has no mounting holes. If you use other 14mm cameras with mounting holes, you can screw them directly on the camera mount. Use M2x4 titanium screws.

Step 8: Walksnail Setup

You probably need to update your Walksnail VTX. The firmware of your Walksnail goggles/VRX should correspond. I currently use 31.36.8 firmware.

To update, connect the VTX with the included USB cable to your PC/MAC. Power the drone. Now you should see a new drive. Drag and drop the firmware on the drive. Eject drive after copying. Hold the linking button of the VTX for 8 seconds after powering up. Red LED should flash and goes into flashing green after successfull update.

To link with your goggles/VRX shortly press the linking button on your goggles/VRX and on your VTX. After successfully linking, LED should be solid green on the VTX.

Step 9: Betaflight and Bluejay Setup

Here are only a few basic setup tips. This drone uses Betaflight firmware, which is the most popular FPV drone software. So you will find plenty of online tutorials and information on youtube and the internet. If you are a complete novice, please acquire some basic knowledge first.

DarwinFPV uses Bluejay firmware. Connect the flight controller over USB to your PC/Mac. Power the drone up. Go to https://esc-configurator.com Update the ESCs firmware and choose 48kHz which should provide a more efficient flight experience. After updating disconnect the configurator.

Now open Betaflight on your PC/Mac. First you need to align the board in the software so that the software recognises the correct directions when moving the drone.

Go to ports tab and enable GPS in UART 2 and 115200 baud. In Configuration tab enable GPS, UBLOX, Autobaud, Autoconfig and Galileo. Now the GPS sign on the top screen should light up.

In the Motors tab enable bidirectional Dshot. Reverse motor direction for props out setup. then use reorder motors and motor tool to ensure that motor numbers fit to the Betaflight layout and spin in correct direction.

Enable OSD in your Walksnail FPV stream by using the Avatar HD VTXs preset. Map displayport to UART1.

In the OSD tab enable and align the elements you want to display in your goggles. Unfortunately, DarwinFPV flight controller has no current meter. So you can not display amperage draw.

Step 10: Link to ELRS Radio

Attention, there is a bug in Betaflight 4.3.2. The SPI receiver of Darwin FPV/BETAFPVF4SX1280 ELRS SPI will not bind. Use a different Betaflight firmware like e.g. 4.3.1!

Go to https://www.expresslrs.org/hardware/spi-receivers/#uid-byte-generator to create a CLI code for the passphrase you are using on your ELRS transmitter.

Go to the CLI tab enter the code and hit save. Now you should see the stick movement of your radio in the Receiver tab. You may have to adapt the channels by rearranging the order of letters RTAE.