EMAX NightHawk 250 Mini Quad by Neil – Group Build Log Contest Entry

This page is written by a group member who entered our build log contest. We are sharing the info hope it would be useful to someone.

Hi all – here’s my entry for the build contest log; my first 250 size racing quad! I’ve been watching videos of 250 FPV racing, rolling and flipping thinking that I really need to try this! I spent far too long looking at options and finally settled for the kit at 4 props. The value for money is fantastic, I was worried it was too cheap but the reviews for the frame have been good, it’s a solid piece of kit (so far!). I was considering 4S but 3S seems pretty zippy for a first 250 build, especially if you have a high C rating. An important part of the build for me was to make sure it looked tidy, so the ESCs are hidden underneath. I was also keen to try out a Naze32 and cleanflight as I had read good things.

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Part list of this EMAX 250 Nighthawk full carbon build:

• EMAX Pure Carbon Fibre 250 Sized Frame – cheap, light, strong
• DYS 1806 2300kv Brushless Motors x 4- seem to work well
• EMAX SimonK 12A ESC’s x 4 – light weight
• 5″ x 3″ props (Qty 2 Packs) – option to upgrade later
• Power Distribution Board – makes wiring easy
• Black Nylon Flight Controller Fixing Kit
• XT60 Male Battery Connector
• Black HeatShrink – different sizes
• Turnigy nano-tech 1300mAh 3S 45~90C Lipo Pack (flight time 5 mins)
• WS2812B RGB 10 LED strip – each one can be programmed a different colour
• Naze32 Full with Cleanflight (I like the LED control!)
• Male & Female Plug JST battery pigtails for wiring up FPV gea
• Immersion RC Vtx 5.8GHz & antennas
• Fatshark Dominator goggles
• frsky d4r-ii RX – fantastic value, small, lightweight and telemetry!
• 808 key chain cam with D lens for recording (tried using it for FPV but dynamic range is terrible)
• SONY 639 700TVL 1/3-inch CCD Video Camera PAL – better

Here are the steps how the quad was built.

Step 1 – work out where the PDB and ESCs will go. I’ve placed the PDB underneath: bolt -> PDB -> nut -> chassis (i.e. the nut is the spacer)

Step 2 – cut ESC wires and solder to PDB

Step 3 – wire up XT60 battery connector and 2 pin JSTs for powering FPV gear later. I’ve soldered everything to one side of the PDB to keep it low profile an in-line so that I can heat shrink cover it to insulate from the carbon frame.

Step 4 – Heat shrink cover the PDB or use black electrical tape.

Step 5 – check out it looks. Bolt on the motors and solder to the ESCs. DON’T finish the heat shrinking just yet, you need to check the direction of the motors is correct first!

Step 6 – download the cleanflight software and use it do download the firmware. Set rotation to 90 degrees if you want the USB port to one side. Wire up the motor ESCs and test they spin with the GUI motor controls. No props at this point! Calibrate the ESCs if necessary, again use the motor control on the GUI.

Check for spin directions and make a note of which ones are going the wrong way (swap 2 of the 3 wires to change direction). Note – for the EMAX ESCs they have a LINEAR regulator so it’s OK to have all BECs connected in parallel to the flight controller.

https://www.youtube.com/watch?v=81JPX1_qugI

Step 7 – swap wires as necessary to get the correct motor direction. Tidy away the wires, in this case they can fit between the bolts and spacers to make a really clean looking wiring. I’ve taped it down briefly during assembly but replaced this with a cable tie.

Step 8 – Finish building the lower frame – TIDY!! :D

Step 9 – mount the control RX (I’ve currently got this at the front, just behind the FPV cam). wire up to the flight controller, single cable for PPM carrying ALL 8 channels!

Step 10 – calibrate the flight controller, calibrate and setup the TX/RX check for correct directions of servos, map TX switches to AUX channels etc and map those to flight modes, e.g. angle/horizon etc depending on your flight controller. Wire up a 5V buzzer/beeper. Wire up Vbat to the Naze32 for battery voltage monitoring,

Step 11 – finish building the upper frame – note – no FPV gear on for the maiden flight… keep it simple!

Step 12 – add FPV gear and try out FPV flying!! FPV cam is temporarily held with black tape to get a feel for the right angle. 808 is mounted on top for recording. Immersion RX Vtx is at the back to balance out the weight a little. Battery on top, both 1300 and 2200 seem to work ok. 12V cam and Vtx powered from battery with custom lead.

Step 15 – I also added WS2812B led strip underneath. Cleanflight lets you assign a colour to each one, they can also act as warning lights (e.g. low batter) and indicators. I’ll eventually move them to a row on the front and rear but for prototyping/testing I placed them underneath. Here is a tutorial how LED can be setup in Cleanflight.

Step 16 – let your dad have a go at flying so you can take a picture of it in flight!

Step 17 – upgraded this Quad with an LED light strip attached to the back