Hi everyone,

I'm new to these sort of projects, and I'm trying to prepare all the components I need to build a hexacopter. I'm looking to buy the jD-Simplex Hexa (RTF) from jDrones, with the upgraded motors, ESCs, and the 12x45 props. I'm also planning on purchasing the radio set with it. However, I'm in a dilemma about the battery I should get and what the flight time will be. I've read almost everything I can about how to select a battery and how to calculate the flight time.

With the upgraded motors and ESCs, I'm thinking I need a 8000 mAh 3S1P 30C battery, because  8 Ah * 30C = 240 A, and the ESCs run on 30 A (so 30*6=180). Can someone clarify this selection for me?

Also, if I calculated correctly, this copter at 75% throttle will have about 4.5 minutes of flight (with the 8000 mAh battery). Does anyone that has experience with this drone have a longer flight time than that?

Thanks so much,


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Thanks for all the info! So the Iris with the Pixhawk will allow me to also go in and enter my own code with Arduino? 

Get a simulator, they are even cheaper to crash ;-) i've used ccrcsim, but there are many other RC sims on the market. It really helps get muscle memory in controlling a remote vehicle. And crashes don't cost a penny ;)
You can program the Iris with your own code. It uses the Pixhawk autopilot. Which is based on a ARM 32bit processor. Compiling code for it is more involved than the APM2.5/6 hardware, but being more performant, you can do more. See http://dev.ardupilot.com for more info on that

So if I'm understanding this correctly... The IRIS itself is Arduino-based but the Pixhawk is not?

and of course the code in a 3DR copter can be modified and reuploaded :)...


no the IRIS is pixhawk based which is an STM32 processor, the APM line is based on 8 bit processors which are at EOL in the software for the most part.. not enough processor cycles...


That is not correct. The autopilot hardware that is used in Iris is a Pixhawk. The code that runs in the autopilot is Arduino based. And I'm not sure how you got the impression that it cannot be reprogrammed but that is not correct either. An explanation of how to program is here http://dev.ardupilot.com

hi kate,

    there is a vagrant based compile for pixhawk at present. I dont think it will compile for usage on an Arduino as the Arduino/APM hardware is AVR 8 bit based and the pixhawk STM32 based.. entirely different machine code as far as I know.. that being said.. the compile for PIXHAWK is CLI based as opposed to the gui based automation of the arduino.

But YES on writing and modifying and adding to the APM/PIXHAWK code base or any of the more popular Open Source MAVLINK based ground control stations, you will wind up learning and using a variety of tools across different platforms..


I can attest to the IRIS/PIXHAWK  programmability .. I have one myself.. even if they are a bit expensive comparatively. Good platform to learn the PIXHAWK hardware and software on where its already setup and configured for you.

That being said ALL of the 3DR multicopters come with PIXHAWK now  as far as I know and copters like the Y6 and X4/X8 can be folded up a bit smaller than the IRIS which doesnt fold at all and have a GOOD deal more  weight capacity for experiments and are NOT constrained by a HULL as in the IRIS case.

    choices, choices, choices

     hzl :)


Thank you, so glad to finally get a straight answer. I was about to lose my mind in confusion.

@cala: That is just pure nonsense. Carbon fibre props cost more, break just as easily, and are more dangerous than APC props. If you look at the professionals  they are using wood props, as you can get then pre-balanced, and they are quieter.

with an APM running arducopter, the software autotunes the throttle so 50% will give you a hover. I run 3s and 4s batteries on the same frame and it works it out for me... too clever

Hi kate,

your best choice for learning stick skills is to get a cheap hubsan clone or similar (frys 29.95(estes))  and at least 6 spare batteries and wear out as many as you need to before trying  your piloting skills on a flying wallet(full sized multicopter)..

shoot about 1k-4k landings and takeoffs(about 3 complete hubsan copters(worn out) :(  then practice around the bushes and tree branches after that, it takes about 3 weeks to develop skills if not awaiting charging(why you have 6 batteries).

Then try your hand on the flying wallet in a very wide open space.. do NOT initially try ANY GPS/AP navigation until you are complete familiar with the PIXHAWK and its foibles, fly in stabilize only initially.

Always have telemetry up and running prior to ANY initial flying with the PIXHAWK guided multicopter, if your GPS glitches or you somehow  left home set for the backyard instead of the practice field this will help you track your flyaway instead of joining the flyaway club..



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