Development Tools:

• The Firmware was developed in C over a self-developed RTOS.

• Electronics based on Microchip ICs and standard components found on eBay.

• The PC side has several GUI applications: AHRS, FCU, Motor-Controller & 3D-Display.

• They were developed using Python 2.7, wxPython, VPython, and PyGame.

• The custom mechanical parts were designed with FreeCAD and printed with the RepRap Delta-Fisher 3D printer.

Specs:

• Chassis: Based on the Tarot-120 chassis (80x80mm) that I extended to 130x130mm.

• Motors: Original Tarot BLDC MT-4000KV.

• ESC: 3S/6A

• Prop: Original Tarot 3020.

• AHRS: Self developed SmartAHRS (in C with the PIC24F32K302).

• FCU: Self developed (in C over the dsPIC30F6012/14).

• Communication: Bluetooth 2.1 (Serial) or self developed long-range module over IEEE802.15.4.

• Battery: Designed for 3S LiPo (But I am using external power supply during development)

Conclusions:

Most interesting! Demands knowledge, experience & understanding is many fields.

Not easy! I found it very difficult and complicated in all fields (Maybe less on the electronic side because all of the critical sensors have digital interface).

The price tag of $15 for these toys does not represent at all the amount of engineering and science that they are base on.

Go ahead and review the "Quadol" project.