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Dec 05, 2006, 09:22 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
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e-flight calculators, motor- and prop-databases (compilation)

I will compile the calculators mentioned in this thread, in this first message.
Please post broken/old/dead links so I can fix/remove them.

  1. Before you use an e-flight calculator
  2. Calculators
  3. Motor- and prop-databases, prop-tools and -theory
  4. Motor- and calculator-theory
There is some overlap between the three lists, and double entries.

Before you use an e-flight calculator.
Some useful and I hope instructive insights first, before you start plugging numbers in some unfamiliar software. To gain some feeling/insight, and to get rid of a few possible misconceptions.
  1. The simple effect of pitch and number of blades, and the huge disproportional effect of voltage, Kv and prop-diameter on current and power drawn.
  2. Fundamental difference in behaviour under load between e-motor and ic-engine.
  3. The velocity konstant Kv is not related to max.power, nor to several other things.
  4. GIGO: garbage in, garbage out.
  5. Ball park figures. Always measure/check current in a new/changed setup.
1. Calculators
  1. Drive Calculator
    Motor analysis and computation of the complete power system.
    Christian Persson/Helmut Schenk, English & German, Windows/Mac/Linux
  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
    Aero-nuts freeware - RCG
  4. MM_Calc derivatives
    All 6 are on rep. websites and/or RC-Groups +
  5. eCalc (€/$)
    propCalc, xcopterCalc, fanCalc, heliCalc
    English, Deutsch, Čeština, 中文, Español, Português, Français, 日本語, فارسی, Polski, Pусский, Nederlands
    5$ a year subscription
    Youtube channel
    xcopterCalc tutorial
    propCalc tutorial
  6. Online motors and propellers graph tool + theory
    →Online graphing tool for DC motors and propellers
  7. APC-E propeller thrust and absorbed power estimating program - RCG
  8. Measuring motor power without standard props, by running the motor with a calibrated "stick" fitted in place of the propeller prop:
  9. User yomgui's calculator/optimizer, Excel based
  10. Motocalc (€/$)
  11. Elektro-Antrieb (German only, €/$)
    AFAIK the first e-flight calculator, by Wilhelm Geck.
    Site does not exist anymore.
  12. P-calc
  13. ElectriCalc
    Sid Kauffman - ElectriCalc Designer & Friend
  14. Mumtats, user vintage1
    MUMTATS IS HERE! For inveterate experimenters and motor builders
  15. user Rod Badcock's thrust-, prop- and motor-calculators
  16. WebOcalc and PowerCalc (Free Open Source Software)
    ( → software)
    WebOCalc - Free, easy power system help! - RCG
    WeboCalc - Free software for choosing motors - Part III - RCG
  17. Adam One Motor/Prop and Thrust calculators (freeware)
  18. Thrust calculator (freeware)
  19. Thrust calculator (freeware)
  20. Prof. Mark Drela's prop calculator
  21. Dr. Martin Hepperle's prop tools
    → Javaprop
  22. Jim Blanner's (user jrb) calculator
  23. PropEngine, Jim Kitt a.k.a. Aeroplayin - RCG
    Power Systems for Extreme Flight Fanatics! - RCG
  24. RC E-Calc - Electric flight calculator for Android phones
  25. Flight Calc, for props, edf's and helis
    → support
    → tech support
    → Flight Calc
  26. Pitch speed and G-force calculators
  27. By user aeromodel03/Bill
    Excel programs for estimating model in-flight performance- RCG
  28. Franck Aguerre's calculator, he is a renowned French e-flight expert:
    e-flight calculators (compilation) - post #252

2. Motor- and prop-databases, prop-tools and -theory
  1. Lots of prop info, data, tests, theory and links in Louis Fourdan's sticky. Links in post#3.
    Propellers (sticky)
  2. Motor Data - test bench data for several hundred brushless motors - RCG (sticky)
    The database, several selection options
  3. Propeller basics, by Stefan Vorkoetter, author of MotoCalc (thanks Christo/Skylar)
    → Electric RC planes
    → Propeller basics
  4. APC propellers
  5. Determining motor constants
    → motor constants
    Christo van der Merwe a.k.a. RCG user Skylar
  6. How to add tested motor data to Drive Calculator by Ken Myers (
    Collecting Motor Data for Input Into Drive Calculator
  7. Measuring Brushless Motor Resistance (Two Digital Meter Method) - WFF
  8. Practical diy dynamometer - RCG
  9. Several diy test rig designs, thrust and dynamoter
  10. Theory and profiles by dr. Helmut Quabeck

3. Motor- and calculator-theory
The math behind it all. Finally
  1. Determining motor constants (Christo van der Merwe a.k.a. RCG user Skylar)
    → motor constants
  2. Feature Article - Motor constants, how to find them and use them - RCG, by Joachim Bergmeyer
    The article is about brushed motors, however, math is identical for both brushed and brushless motors
    A brushless motor in combination with it's controller behaves just like a brushed motor. It is a brushed motor with electronic commutation (the ESC) instead of mechanical commutation (the brushes).
  4. Motor equations by Stefan Vorkoetter, author of MotoCalc (thanks Christo/Skylar)
    → Electric RC planes
    → Motor math
  5. Motor Modellierung Theorie, by Helmut Schenk (pdf, German)
    chapter 3 : Motor + ESC theory and modelization

Vriendelijke groeten Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
e-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
Last edited by Ron van Sommeren; Dec 02, 2021 at 12:39 PM.
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Dec 05, 2006, 09:48 AM
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Dec 06, 2006, 02:20 PM
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Dr Kiwi's Avatar
Here is another one for thrust/rpm:

and another estimator:
Dec 19, 2007, 11:36 AM
Registered User
Fourdan's Avatar

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
here v3.75 (31 december 2019) :
SC v4 beta with plane wizard :
2) Dualsky Calc v3.26 04 feb 2017
3) MotrolFly Calc 2.36 april 2009
4) ARC Calc post #373 pg 25
5) Aero-nuts Calc seems out of service in 2018
6) Himax Calc v2.35
All 6 are on rep. websites and/or RC-Groups + electrofly
I update regularly Scorpion Calc

Louis (the author)
Last edited by Fourdan; Dec 31, 2019 at 12:47 PM. Reason: SC version 3.75
Dec 19, 2007, 01:34 PM
jrb's Avatar
Here's my spreadsheet (have EDF version too); its helped me with these and others:
Dec 29, 2007, 01:52 PM
Registered User
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.
Jan 06, 2008, 03:12 AM
Registered Aircraft Offender
Truglodite's Avatar

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.]
Last edited by Truglodite; Jul 15, 2008 at 04:25 AM.
Jan 24, 2008, 09:10 PM
Registered User
BlazerB52's Avatar
Nice converter program:
Last edited by BlazerB52; Jan 24, 2008 at 09:17 PM.
Mar 07, 2008, 09:04 AM
Carlos Reyes - new free model airplane calculator

My new free online calculator (
  • 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
Last edited by creyes123; Sep 09, 2008 at 08:50 PM.
Mar 27, 2008, 11:06 PM
Carlos Reyes
My calculator ( 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.
Jul 09, 2009, 04:45 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Thread OP
Measuring motor power output using a calibrated dummy prop:

Vriendelijke groeten Ron
Last edited by Ron van Sommeren; Oct 15, 2009 at 03:16 PM.
Aug 08, 2009, 07:29 PM
Registered Aircraft Offender
Truglodite's Avatar
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.

Oct 15, 2009, 01:38 PM
Registered User
peterangus's Avatar
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".
Mar 06, 2010, 09:53 PM
Scratch building addict
rotagen's Avatar
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.
Mar 30, 2010, 03:56 AM
electric power,what else!
eJets's Avatar
it is not a matter of expensive or cheap motors - it's a matter of motor data availability, and this availability is the general problem of cheap motors....

feel free sending PM with motor data (Kv, Internal Resistance Ri, Idle Current Io, Power or Current Limit, Housing length and weight) of cheap motors.

Cheers eJets

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