Hi Guys,

My goal is to build a quadcopter with the HobbyKing X650F frame, with capabilities of adding AP/FPV equipment to it in the future.

Being totally novice in the area of RC and quads and all that, I've been reading up on the subject of quadcopters through serveral tutorials, blogs, forums, youtube etc. After many hours and days trying to figure out which parts to use, I’ve come forward with this setup.
Frame: Hobbyking X650F Glass Fiber Quadcopter Frame 550mm 
Flight Control Board: Hobbyking KK2.1 Multi-rotor LCD Flight Control Board With 6050MPU And Atmel 644PA
Motor: NTM Prop Drive Series 28-30S 900kv / 270w (short shaft version)
ESC: Turnigy Multistar 30 Amp Multi-rotor Brushless ESC 2-4S 
Prop: 12x4.5 SF Props 2pc Standard Rotation/2 pc RH Rotation
Battery: Turnigy 5000mAh 3S 20C Lipo Pack

To be added in the future: Gimbal, GoPro, FPV Transmission Equipment

Calculated weight (incl. Gimbal, GoPro and FPV): 1700-1800g

I have heard about the equation Req. thrust = (AUW x 2) / 4.
But cannot seem to get the math right.

I’ve learned that if you want an acrobatic quad you should go with faster motors and smaller props and the opposite if you’re going for a AP/FPV quad (which is what I’ve gone for).

Could someone please point me in the right direction by answering my questions below.

1) Will my setup work and is it reasonable for a 1700g FPV quad?
2) I can’t seem to get the math right with the ”required thrust equation” mentioned above? I am attaching my results from playing with the ecalc.ch. Is there something wrong? Or is there something I should watch out for?

I would be grateful if someone could help me answer these questions.


// Joel

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If the list of parts above fits your budget, go for it!

I don't see anything terribly wrong. Because it will be your first RC flying machine of any kind, don't put heavy expectations on yourself and consider this your 'Training Quad'. You will need to develop some hobby skills and acquire some tools to be able to assemble the parts into a working system.

You did not mention what RC Transmitter and Receiver you were planning to purchase.

Your local laws will determine the types of RC systems you can employ.

Good Luck!


Thanks for your answer Doug, appreciate it your tips.

You're saying you can't find anything terribly wrong with my ecalc results, but are you seeing anything which could be easily improved? I tend to be very careful in my planning to make this as much a success it could be ;)

I have chosen the Turnigy 9XR Transmitter with the OrangeRx R800X Receiver, they seem to be using 2.4GHz which is legal in here in Sweden. Any Thoughts on that combo?

Thanks again!

// J

The HK airframe you list is a pretty standard 'tube & plate' style; no surprises in design methodology. I scratch build/modify most of my aircraft and it looks like those parts will allow you to do the same.

Weight aside, motors, ESCs and propellers and their combinations will have to be a knowledge/experience process. If you use the 3DR motors and ESCs as a base to compare, you should be fine.

Again, this aircraft should be viewed as your trainer...in many aspects.

Do not go cheap on the battery charger. The Hitec units are very good and flexible.

Happy New Year!


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