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Software Tools

This section identifies a few software tools that can help you explore how electric power set-ups might work.  You can compare alternatives by calculating the effects of different component combinations to see what fits your need best.  They can also assist you in judging how a particular combination might perform, so you can optimise a solutions, or at least be confident that a given set-up has a good prospect of meeting your expectations.

Some of these tools are downloadable, some are on-line and others you need to purchase and you will need to go to each tool’s site to access it.  We’ve included a link to help.  The ones we’ve included information on are:

  1. Motor Power Train
  2. Prop Power, Thrust and Efficiency
  3. Thrust XL
  4. Drive Calculator
  5. Thrust HP
  6. Motocalc

1 Motor Power Train Calculator


On-line tool. Predicts and graphs key operating parameters for two motor/prop/battery voltage combinations.

Accessible at

By permission Rod Babcock  Nov 2009


2 Prop Power, Thrust and Efficiency Calculator


On-line tool.  Predicts and graphs how a propeller will perform under given conditions (RPM, voltage, current or power) and calculates efficiency.

Accessible at

By permission Rod Babcock  Nov 2009


3 ThrustXL


Downloadable spreadsheet.  Allows a close to optimum prop selection for a given motor and power system without the need for a dedicated thrust test stand. “Static performance is no indicator of how it will perform in flight, but by obtaining a reasonable balance of static thrust and pitch speed, one can at least have a conservative flight-testable system.”

Accessible at

By permission Rod Babcock  Nov 2009



4 Drive Calculator 


Downloadable freeware application.  A tool that can be used for DC motor analysis and as an aid in the selection of the complete power system for electrically powered model aircraft.  Purchasers of commercially available products can use the program to help guide them to a suggested combination of power system components for a given model aircraft. The program can also help motor builders optimise the results of their work.

“I have written this tool some years ago when the fascination of electric flight caught me. I had stumbled over a description in an internet forum on how to recycle a brushless motor out of a CDROM drive as a model airplane drive. We took the stator laminations, re-wound the wire, and learned how to make cans and bearing tubes on a lathe. Since that time I have produced quite a number of motors for my friends, my son, and myself. In the beginning, though, matching the propeller with the motor happened more or less accidentally, by trial-and-error. Later on I was so lucky to get in touch with Helmut Schenk, an engineer, model pilot, and author. He taught me something on the theoretical background of electric machines and supplied me with a set of formulae for the computation. I decided to put all that into a piece of software and combine it with a database engine. That was how the first version of the Drive Calculator came up. Meanwhile, I have received quite a lot of suggestions and wishes from users, so that the software has grown up to what it is today.”  Christian Persson

Accessible at http://www

By permission Christian Persson – April 2010

5 Thrust and Horsepower Calculator


Downloadable freeware application.  Calculates performance parameters (using imperial units). 

 “The program was written for a bit of fun really for a chap in our flying club who was into this sort of thing and was using a spreadsheet, a bit of info which is in the help file about the formulas used.”

“Formulas from AMA magazine in Oct 1986

Load = Prop Diameter^4 * Pitch

Speed = Pitch * rpm * 0.000947

Horse Power = Load * rpm^3 / 1.4 * 10^17

Static Thrust = 0.00000000000283 * rpm^2 * Prop Diameter^4 * Air Density/29.92 * CF value”

“Note:  Regarding thrust to pitch variables, PRACTICAL test revealed very little if any change in thrust due to pitch variation at the same RPM. This I think is partly due to any increase in thrust being negated by blade stalling and a more turbulent influx area with increased pitch. This obviously only applies to static conditions, it's a whole new ball game under dynamic i.e. flying variables. The program is not designed to calculate thrust under dynamic conditions so it may not be of  use for Ducted Fans.”  Barry Hobson Select Goodies in main menu

By permission Barry Hobson – April 2010


6. MotoCalc

 “MotoCalc is a program for predicting the performance of an electric model aircraft power system, based on the characteristics of the motor, battery, gearbox, propeller or ducted fan, and speed control. You can specify a range for the number of cells, gear ratio, propeller diameter, and propeller pitch, and MotoCalc will produce a table of predictions for each combination.”


“MotoCalc will predict weight, current, voltage at the motor terminals, input power, output power, power loss, motor efficiency, motor RPM, power-loading, electrical efficiency, motor RPM, propeller or fan RPM, static thrust, pitch speed, and run time. By producing a table of predictions, MotoCalc lets you determine the optimum propeller size and/or gear ratio for your particular application.”


“MotoCalc can also do an in-flight analysis for a particular combination of components, predicting lift, drag, current, voltage, power, motor and electrical efficiency, RPM, thrust, pitch speed, propeller and overall efficiency, and run time at various flight speeds. It will also predict stall speed, hands-off level flight speed, throttle, and motor temperature, optimal level flight speed, throttle, and motor temperature, maximum level flight speed, rate of climb, and power-off rate of sink.”


“If you are a newcomer to electric flight, MotoCalc's MotoWizard will ask you a few simple questions about your model and your preferences (such as brand of motor), and will then make suggestions as to the ideal power system. You can then use the rest of MotoCalc to investigate one or more of the suggestions in detail, and then use MotoCalc's MotOpinion feature to get a plain-English analysis telling you how the power system, and your plane, will perform.”  Capable Computing Inc


Accessible at

By permission Stefan Vorkoetter,  Capable Computing, April 2010


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