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        Discussion e-flight calculators (compilation)

#1 Ron van Sommeren Dec 05, 2006 08:22 AM

e-flight calculators (compilation)
I will compile the calculators mentioned in this thread, in this first message. Please post broken/old/rotten links so I can fix them.

1 - Numbers
  1. Motor and prop database
    Test bench data for several hundred brushless motors and props.
    Several selection options
  2. APC propeller performance data
  3. Flybrushless prop database
  4. Aeronaut, APC & Slowflyprop

    → TM Configurator
    → Aeronaut, APC & Slowflyprop tabs
  5. Determining motor constants
    → motor constants
    Christo van der Merwe a.k.a. RCG user Skylar
  6. Measuring brushless motor resistance
  7. The math behind calculators and motors.
    Brushless motors are just brushed motors with electronic commutation (the ESC) instead of mechanical commutation (the brushes). Math is identical for both types.

2 - Calculators
  1. Drive Calculator
    Motor analysis and computation of the complete power system.
    Christian Persson/Helmut Schenk, English & German, Windows/Mac/Linux
    Download, discussion, help, announcements, moderated by yours truly
  2. Propellor Calculator
    Computes the performance data of propellers with a given geometry, notably in-flight thrust and power drain across the utilizable airspeed range.
    Helmut Schenk, English & German, Windows & Mac
    → propellor calculator (bottom of page)
  3. MM_calc
    Louis Fourdan, English
    → téléchargements (link at top of page)
    → moteurs
    → MM_calc
    → English or French version
  4. MM_Calc derivatives
    All 6 are on rep. websites and/or RC-Groups + electrofly.free.fr
  5. Measuring motor power without standard props, by running the motor with a calibrated "stick" fitted in place of the propeller prop:
  6. eCalc (€/$)
    propCalc, xcopterCalc, fanCalc, heliCalc
    English, Deutsch, Čeština, 中文, Español, Português, Français, 日本語, فارسی, Polski, Pусский, Nederlands
    5$ a year subscription
    xcopterCalc tutorial
    propCalc tutorial
  7. User yomgui's calculator/optimizer, Excel based
  8. Motocalc (€/$)
  9. Elektro-Antrieb (German only, (€/$)
  10. P-calc
  11. E-Calc
  12. Mumtats, user vintage1
  13. user Rod Badcock's thrust-, prop- and motor-calculators
  14. WebOcalc and PowerCalc (Free Open Source Software)
    → software
  15. Adam One Motor/Prop calculator (freeware)
  16. Thrust calculator (freeware)
  17. Thrust calculator (freeware)
  18. Prof. Mark Drela's prop calculator
  19. Jim Banner's (user jrb) calculator
  20. PropEngine, Jim Kitt a.k.a. Aeroplayin - RCG
    Power Systems for Extreme Flight Fanatics! - RCG
  21. RC E-Calc - Electric flight calculator for Android phones

Vriendelijke groeten ;) Ron
Cumulus MFC, Nijmegen, Nederland Drive Calculator group
diy brushless motor group diy motor building tips & tricks

#2 kit Dec 05, 2006 08:48 AM


#3 Dr Kiwi Dec 06, 2006 01:20 PM

Here is another one for thrust/rpm: http://www.gobrushless.com/testing/t...calculator.php

and another estimator: http://www.adamone.rchomepage.com/calc_motor.htm

#4 Fourdan Dec 19, 2007 10:36 AM

Brand dedicated Motor Calc

In the serie you have
MM_Calc (see Ron post #1) on electrofly
You have the cousins in any order
1) Scorpion Calc http://www.scorpionsystem.com/downloads/
here v3.65 (may 2015) : http://www.rcgroups.com/forums/showthread.php?t=736782
SC v4 beta with plane wizard : http://www.rcgroups.com/forums/showthread.php?t=1388429
2) Dualsky Calc v3.24 04 march 2013
3) MotrolFly Calc 2.36 http://www.subsonicplanes.com april 2009
4) ARC Calc http://www.rcgroups.com/forums/showt...819392&page=25 post #373 pg 25
5) Aero-nuts Calc http://www.aero-nuts.com
6) Himax Calc http://www.maxxprod.com/
All 6 are on rep. websites and/or RC-Groups + electrofly
I update regularly

Louis (the author)

#5 jrb Dec 19, 2007 12:34 PM

4 Attachment(s)
Here's my spreadsheet (have EDF version too); its helped me with these and others:

#6 Carl.E Dec 29, 2007 12:52 PM

Prof. Drela has recently released a windows version of QPORP, his motor/prop analysis software. I've found it much better at predictions and efficiency calcs, since it uses a much more advanced prop model (not just thrust coefficients). Here's an exerpt of the manual:

QPROP is an analysis program for predicting the performance
of propeller-motor combinations. Its intent is to provide
an alternative to the existing prop/motor simulation programs,
which use relatively simple propeller models, and assume
a brushed DC motor type. QPROP has a relatively sophisticated
and accurate prop aerodynamic model, and a general motor model
which can be implemented via a user-supplied subroutine
if necessary.

It's a little more complex than motocalc, but pretty simple to use once you climb the learning curve.


#7 Truglodite Jan 06, 2008 02:12 AM

Eagle Tree Spreadsheet
i rigged up this spreadsheet for use with my eagle tree micro logger (with temp and rpm expanders):

Excel Spreadsheet (freeware)
Example Spreadsheet (freeware)

it supports quick & simple copy/paste operation directly from the eagle tree software, and outputs thrust, efficiency, kV, Io, Rm, max efficiency, max power, pitch speed... pretty much everything. for kicks i included standard deviations for every number.

it is based on rod badcock's spreadsheet (see post #1), and includes a few other calculations based on these equations. keep in mind it's in beta stage at the moment, and i'm not 100% sure if it'll work with pre o2k3 excel. the example sheet shows what it looks like with all the data entered from a bench test i did on a custom bluewonder.

just like badcock's spreadsheet, both of these spreadsheets include macros, so you may have to modify your security settings for them to work properly.


[edit: i just found an error in the spreadsheet which will cause it to be inaccurate if the logger is set to record temperature in farenheit. it works perfectly with the logger set to celcius. i'm working on a temperature unit selector, but until i update use celsius please.;)]

#8 BlazerB52 Jan 24, 2008 08:10 PM

1 Attachment(s)
Nice converter program:

#9 creyes123 Mar 07, 2008 08:04 AM

www.RCadvisor.com - new free model airplane calculator
My new free online calculator (www.RCadvisor.com):
  • designs efficient electric power systems
  • teaches you using interactive Tutorials and ToolTips
  • flies your model in a virtual wind tunnel
  • predicts airfoil performance
  • shows you the right tradeoffs for your scale model
  • displays graphs that update in real-time
  • runs on Windows, Linux and Mac OS X

#10 creyes123 Mar 27, 2008 11:06 PM

My calculator (www.RCAdvisor.com) includes the estimated Climb Rate. The Climb Angle seemed less useful. I don't provide feet/minute (easy to add), but I have MPH and feet/second among other units.

#11 Ron van Sommeren Jul 09, 2009 04:45 PM

Measuring motor power output using a calibrated dummy prop:

Vriendelijke groeten ;) Ron

#12 Truglodite Aug 08, 2009 07:29 PM

I'm in the process of moving all my "freeware", including MotorXLT2 and TurnCalculator3, to my blog for easier maintenance. Here's the link:


Note that I recently updated MotorXLT2 with my latest version, which includes calculations based on up to 4-props and no-load. This makes the calculations much more accurate. I also made the no-load page more "printer/screen grab" friendly, for easy posting of test results. Unfortunately, I still haven't got around to making a temperature unit selector, so you'll have to record temps in Celsius.

A general tip to those who benchmark:
Just like any other motor constant calculator, when setting up a series of tests you need to avoid using 2 props that are nearly identical (with respect to RPM, A, and V). Use of similar props often leads to inaccurate calculations of Rm, Kv, and Io. An example of this would be the apc5x5e and apc5.5x4.5e. While they fly very differently, both will give nearly identical RPM and current on the bench, which will confuse a motor calculator.


#13 peterangus Oct 15, 2009 01:38 PM


Originally Posted by Ron van Sommeren
Measuring motor resistance without standard props, by using a dummy prop:

Post 11

Should read "measuring motor power output using a calibrated dummy prop".

#14 Ron van Sommeren Oct 15, 2009 03:14 PM

Brainfart :confused::D Thank you Peter, I corrected it.

Vriendelijke groeten ;) Ron

#15 rotagen Mar 06, 2010 08:53 PM

What cracks me up about a lot of these calculators is they only have very expensive brands of components in the database.

Its like an advertisement. Nowadays things are great for the consumer, i've found some amazing good deals on very well engineered power systems, at about 1/10 the cost of hackers, scorpions, etc...certainly in the same performance ballpark at least.

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