I used the toy helicopter - WLtoys XK K120 (120mm Blades), with the Holybro KakutaF7mini, burned the ArduPilot Copter 4.0rc2 Heli FW, and added the ultra-small brushed ESC to drive the helicopter tail made up of the hollow cup 8250. After carefully reading the official Documentation, as well as patient debugging, finally succeeded in flying. I think the world’s smallest ArduPilot Helicopters
Below, I have provided some pictures and videos to share with everyone.
Awesome work, as usual 
And great description and pics!. Thanks for sharing.
beautiful build, I’m really jealous of your heli!
Or do you also do one?
Pictures can be used on the official ArduPilot page!
I’m not great at building unfortunately.
Install the FC（KakuteF7mini） on the basis of the WLtoys XK K120
What GPS unit is this?
Matek M8Q-5883 GPS unless @zhangsir corrects me. Nice and small, 20x20mm board including mag, smallest I know of. One thing to like also are the thin and flexible silicon wires, compared to cables provided with most of the larger and no name equivalents. From an Ardupilot partner to boot. 
Yes, it is the Matek M8q-5883 confirmed by @OlivierB ，the smallest GPS I can find, and the electronic compass 5883
Nice! How well does that GPS work? I should pick one up for my Goblin Fireball.
The number of satellites is about 17, and the HDOP is about 0.7. It is slightly weaker than the M8n star search capability of the standard ceramic antenna.
Continue to install the camera, Video Tx, Blheli Gov ESC, Brushed ESC for 2s power supply，everything is ready, let us FPV style
Smallest FPV ArduPilot helicopter indoor flight:nerd_face:
Great work!!! Wow!
Max fly time? battery?
Works only with Futaba?
The original battery 2s1p 300mAh flight time 5 minutes, the deputy factory 2s1p nominal 550mAh battery, flight time 7 minutes. For supported transmitters, see the receiver model you are using. The flight controller can directly input sbus or ppm.
The latest test video this morning, the outdoor temperature is -7 degrees Celsius, there is no wind, and the battery’s endurance is reduced, but it is enough to test the fully automatic flight mission (curve waypoint, do jump 3 times flight). The DVR image of the on-board FPV camera is shown in the video.
Thank you for your attention, and share with you the joy of successful debugging, very happy, cheers
Do you have the dataflash logging? Seems it’s not working with the F7 Mini from Master.
I’m just working on a patch now to enable logging via the SPI blackbox chip on the board.
Hello Everyone,
@zhangsir, awesome work. appreciated.
Can you please share the params file, I want to perform similar project.
Thanks in advance
