How Do YOU Design Multicopters?

I originally built my quadcopter using someone else's plans.  It flew well, but I quickly found that it "needed" additional equipment (camera gimbal, GoPro, longer landing legs, FPV transmitter, etc.).  These add-ons seem to have pushed the aircraft past its optimization point and eCalc estimates my hover throttle at 85% and flight time with a 3S/2200mAh battery to be 3.4 minutes for the aircraft's current weight (the flight time seems to be spot on, I need to test out the hover throttle).  I'm in the process of trying to shed weight from the aircraft and am even considering going with larger motors.  Unfortunately, I'm a bit confused about how to spec motors for this thing.

My question for you guys is, how do YOU go about designing a multicopter?  Do you use a proven setup and slap an APM on it?  Poke and prod at eCalc until it spits out something reasonable?  Have a better understanding of motor specs and the thrust capabilities than I'm familiar with?

I'm particularly concerned about how you approach selecting a specific motor/prop combo for your aircraft.

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • I went down this path as well. What I figured out is that there is no best design.

    Nothing gives you long flight times,  no vibrations, acro performance, room for a gimble and so on. Build the lightest thing you can for acro, and big big slow props for AV and mapping. What you can build is probably dictated by cost. More motors is more money.

    Build 3 or 4 machines and you'll probably be able to look at a spec sheet and know if it suits your needs.

    Build smaller cheaper machines until you need something more. You may find a mobius cam on an ecks frame is all you'll ever need.

  • For filming I like using higher Kv's (rpm/Volt). I use 1000Kv with 3s 2200 25c battery, 20 amp esc, 10X4.5 carbon fiber props, and my favorite designs are like a H copter or a TBS Discovery. Those copters let you counter weight the gopro and gimbal with the battery and get the props out of the shot. :)

    P.S. carbon fiber props use less power, are quite,increase performance, and decrease the vibration by alot!


  • start with the load, endurance, pack-ability, and reliability requirements then find a motor prop combination that comes close and design around it.

    The weight can vary greatly. For example, I have two heavy quads with basically the same power system. One is an all metal, collapsible frame made in house from whatever alum material we had around. The other is all carbon, fixed config (arms not easy to remove), and uses off-the-shelf components. The carbon frame is MUCH stiffer, but it is also 300gm heavier for the same size. For us, the cheap in house alum frame is better but the other "looks" better.

    Think hard and define your requirements, no matter what they are. Then go from there. 

    To answer your question, motor/prop comes first and carbon wide blade props always win out over plastic. Same alum quad above, 30+ min on carbon 14x4.7 rctimers. 22 min on APC 14x4.5. go figure. And ecalc does not have good prop data particularly for multirotor optimized carbon props. 


This reply was deleted.