Mac OS X Motor Performance Utility - RC Groups
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Sep 14, 2004, 09:20 PM
Registered User

Mac OS X Motor Performance Utility

I've just made available a small OS X utility that calculates the thrust and power consumed by a two-bladed propeller driven by an electric power system. It's available at:

This is the text from the "Read Me" file that is included with the application:

AMP (Aircraft Motor Performance) estimates the thrust produced and power consumed by a propeller for an electric aircraft.

I wrote AMP so that I did not have to purchase PC emulation software, or bother someone in my club with a PC to run some numbers for me. I am making this early version available publicly so that it might be used for "rough" estimates - proven software must be used for any final calculations.

I spent most of the development time on the Propeller model, which is based on N.A.C.A. Technical Note Number 698. Right now, it only supports two bladed propellers up to 25 degrees in pitch measured at .75r. If there is sufficient interest, I will add data for three-bladed propellers and ones of higher pitch or different aspect ratio.

The Battery model is loosely based on Sanyo specifications for NiMh chemistry. It still needs some work, but should do well for most common conditions.

The models for the Gearbox and Speed Controller are overly simplistic. Again, though, they should work for initial estimates.

Of course, after experimenting with this application, users are encouraged to confirm assumptions and results using proven software (by either purchasing PC emulation software or bugging friends to run the numbers).

Feedback would be appreciated. I would also be very interested in empirical data to compare with the predicted results.

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Sep 14, 2004, 09:50 PM
Suspended Account
Thanks, from a Mac user.
"If you haven't had a Mac you have never really had a computer"
Sep 15, 2004, 07:35 AM
100% electric since 1990
twest's Avatar
Sep 16, 2004, 12:42 AM
Registered User
BEC's Avatar
Cool!! I'll grab it and give it a try!

Sep 16, 2004, 01:02 AM
Goekeli's Avatar
Thanks for this!!! I love my mac too!

Sep 16, 2004, 07:39 AM
Hogster's Avatar
Looks interesting ... I'll download it anyway, just to show my support for Mac programmers - Macs rule!

Good work!
Sep 16, 2004, 07:54 AM
slow but inefficient
Ron Williams's Avatar
Hi Craig -

I tried downloading the program but just got an Explorer window full of code. I'm on the latest OSX. ???

Sep 16, 2004, 09:57 AM
How am I not myself?
Park_Pilot's Avatar
Thanks a lot!

Sep 16, 2004, 10:02 AM
Registered User

That's odd. I had done my testing with Safari; when I tried Explorer, I saw a window full of code, too.

The workaround in Explorer: 'control-click' on the link and select 'Download Link To Disk'. That works.

Thanks for the interest!

Sep 16, 2004, 11:08 AM
Plane dodger
KillerAir's Avatar
Does it work for OS9? Not on 10 for NT stability reasons, can't afford to have any downtime:O from doing client work.

Sep 16, 2004, 11:26 AM
Registered User
Unfortunately it can't run under OS 9 - it is a 'Cocoa' application from the ground up.
Sep 16, 2004, 05:50 PM
slow but inefficient
Ron Williams's Avatar
Hi Craig -

Thanks. That worked fine. Looks good.

Killer -

I switch back and forth between the latest OSX and 9 all the time. Very stable so far. The new OSX is light years ahead of the last one (a mess). Maybe you need one of the new G5 imacs?

I enjoy seeing your art/graphics when they show up. Nice stuff.

Sep 16, 2004, 11:18 PM
Got more toys than my kid
macr0t0r's Avatar
Not a bad program. May I make a request? Aallow me to specify volts per cell. Having to convert LiPo cells' voltage and internal resistance into NiMh values is a little tiring.

Are you sure you should auto-calc .75r angle? This will vary from prop to prop, so you may want to let the user override the default value (perhaps a checkbox stating "auto-calculate generic value").

Nonetheless, this is excellent work with a clean interface. It'll help me narrow the field as I try to engineer the next powerplant for my project. I REALLY like the ability to calculate estimated values at a given airspeed. Thanks!
Last edited by macr0t0r; Sep 17, 2004 at 12:02 AM.
Sep 17, 2004, 03:46 AM
Registered User
jojonz's Avatar
Thanks for thinking of us Mac users, Craig.
It looks and works great.
Sep 17, 2004, 11:50 AM
Registered User


Just downloaded using Safari and 10.3.5, no problems seems to run fine. Thanks!


Mike D.

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