I have seen several posts here and on rcgroups asking for the same help but have yet to see any simple specific guidance for the calculation or formulas that arrive at a solid Motor/Propeller/Battery combination for QuadRotor platforms.  Of course the weight, maneuverability and flight times or battery capacities are going to be different for each but there has to be an easier solution than web pages with forty inputs that are unknown to the average person.

Does anyone have a link or some easy formulas for calculating:

  1. Motor specifications
  2. Propeller specifications
  3. Battery capacity
  4. Appropriate ESC specs for Motors/Batteries

With inputs of:

  1. Total weight: 35 lbs (Airframe, 4 Motors, 4 ESCs, 4 Batteries, APM & Electronics, Misc)
  2. Desired flight time: ~ 30 minutes

I would imagine that each Motor/ESC should run on its own battery.  Most motor retailers recommend ESCs for the specific motor, but are there any tips to take into consideration for an Aeroquad?

Thanks in advance for any help and I'm sure that this info will serve many more than just myself.

Views: 2143

Reply to This

Replies to This Discussion

Use motocalc or electricalc to compute static thrust.

These programs have libraries of prop, motor, ESCs and battery models, and you can add your own models, or use user contributed models. Either should get you close enough to start building and then try out some props.


I can't help thinking that for large platforms the energy lost in accelerating the propellers for attitude correction will be significant. We can't recover the energy at the decelerating side (at least not easily). I guess people like the simplicity over the efficiency of a variable pitch system.




Here is another place to download a fine tool for most of what you want. You can quickly compare motors props etc. and notice that it all matters. Because a quad is flying on all motor it makes since to have that part right.



I just checked motocalc website and unfortunately it says it does not include support for helicopters "as yet". Textually, this is what their FAQ section displays:


Question: Can I use MotoCalc to predict the performance of a helicopter?


Answer: MotoCalc does not, as yet, provide support for helicopter performance modeling. However, you can make use of it to do some rudimentary predictions.

The MotoWizard and MotOpinion features won't be of much use, but if you can determine the blade pitch at 75% diameter, you can use this, and the rotor diameter, as the propeller pitch and diameter in MotoCalc's main input window. Then, you can experiment with different gear ratios for a given motor and battery to find a combination that will provide a higher static thrust than the helicopter's weight. Note that this will still only be approximate, because a helicopter rotor has a variable (with respect to time), yet constant (with respect to distance from the hub) blade angle, whereas a propeller has a variable blade angle but constant pitch.


I think the price of $39 USD is alright, if only I could use it for my copter project. Then, on top of this, it does not run on Linux (which is what I use), although they also say it can run on Wine. Wish they had a Linux natural package.

I downloaded Drive Calculator and I think it works pretty decently.  It does the job and definitely helps a lot. It allows to make several useful predictions such as fly time (at WOT) and static thrust. Among other goodies, it allows the user to play with different combinations of motors, propellers and power packs.


It is a very good work of programming and mathematical modeling. Yet, I see some areas where this program could be improved:


1. The program only calculates for a single propeller system. So, some arithmetics needs to be done to estimate total weight and payload of an aircraft meant to have more than one motor and propeller, such as in the case of a quadcopter.


2. The database, although extensive, needs the participation of a wider group of individuals. As it is, it includes among its options for motors and propellers, those available mainly in Germany. As is, it is the result of the work of basically four guys, I guess from Germany. As more people pitch in in improving the database, the more useful it will be for a wider number of people all over the place.


3. The Linux version definitely needs a bit of additional work. As anticipated by the programmers, it did not perform too well on my distro (Mint 9 - 64 bit), but it did the job. The Windows version, on the other hand, worked without a problem at all and the looks is much better (tried on Windows XP - 32 bit).


4. The manuals definitely need improvements in the contents department. The program does a good numbers of things which are not included in the manual. Perhaps a wiki type of manual would be more appropriate. That would relief a single person (Kenneth Myers) from the extensive work of coming up with a comprehensive and detailed manual (also in different languages?).


Congratulations and my most sincere gratitude to Christian Persson, Helmut Schenk, Gerd Giese, and Kenneth Myers for making this software available to all.


Reply to Discussion


© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service