Custom built APM mini quad.


Just want to share my scratch built FPV quad made with my new CNC machine :) Called "the butterfly" name picked by my Fiance 

This was my first CNC project I gave myself.. It has been a great learning experience learning all the different techniques required to design, and translate that design to a finished CNC'd product.

I wanted to make something very forgiving in crashes for teaching my friends, full featured flight controller, and capable of FPV flight. Just a pure training and fun flying helicopter.

The length of the quad arm end to arm end is 17 inches (including prop guard). I do not have an exact weight, but I can say it hovers at 40-45% throttle and has a flight time of 10 min. The arms are tilted inward 10 degrees on each arm to improve stability. The motors are mounted upside down to avoid prop-wash hitting the arms and creating drag.

The gimbal and video has not been tested as I'm still waiting on the video transmitter and rca-usb video input for tablet to arrive. The plan is to fly it from my surface tablet using a usb hub for video and data radio Tx. I also plan to design a small box for an antenna tracker. There is no traditional Tx/Rx used to control this copter.. It's all done through the data link. Flying this way took a little practice, but it's very nice using the PS4 controller's joysticks. This also helps save a little weight and frame real estate. There is no lag at all between my controller and the heli.

Crash durability has been extensively tested.. The frame is very forgiving in crashes. After many small bumps with objects, crashes, and even being stuck in a tree the props have not even the slightest nicks on them and no broken parts.

Overall I'm happy with the frame. The flight controller is giving me a few issues however. GPS positions jump allover the map frequently, and altitude hold is sketchy at best. I currently only fly in stabilize mode. I'm using the miniAPM flight controller.

3689615343?profile=originalOpinions and thoughts welcome.

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  • nice project congratulations ..

  • very nice, i want it!! can you share 3d files? i guess ti coudl be 3d printed

  • Hi, love the design! Are you thinking to open source the design? I'd be very interested in a frame if you were intending to produce some - otherwise we have some cutting equipment so I could run off one. 5" is a nice small form factor, easy to handle and work on, but I'd also be interested to see something around an 8" or larger prop design too. Inverted prop mounting increases efficiency around 7%, definitely the way to go for longer flight time and when introducing struts to hold a prop guards.

  • alt hold issues can also be because of the exposed baro on the mini APM. It gets affected by prop turbulence. Cover tightly with foam, and see if that improves it.

  • Another question: What program did you use to design it?

  • Off topic: Is that a Surface 3? How do you like it as a  field computer for Mission Planner?

    I have an Asus T100, which is great for battery life, but I use 135% scaling and Mission Planner sucks with scaling (lots of stuff, especially wizards, radio calibration just won't show on the screen).

  • Great looking quad. Love how you placed the motors facing down, I'm no aerospace engineer but it seems like it would be more efficient given the prop wash wouldn't hit the arms.

    I would try using longer spacers under the GPS/Mag plate to avoid interference.

    What material is it made of?

    Please post a video of you flying it with the PS4 controller?

    Great design, keep up the good work :)

  • it mostly helps active flight by decreasing the angle necessary for the fast flight, thus reducing chances of getting props in the view, as well as helping to decrease loading on the "front" motors, which in turns results in lesser amp consumption. 

  • It would help with prop wash on descents in ideal gas. Real flow has turbulence below the craft no matter what you do. It's very easy to test - get it to hover and then get some smoke above it (visco fuses work well). You'll see massive vortices everywhere.

  • The only thing I've heard about tilted motors is that it supposedly helps when the craft is descending into its own prop wash. Supposed to be smoother and less turbulent, for smoother video applications.

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