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Old Sep 14, 2004, 09:20 PM
rccraigb is offline
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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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Old Sep 14, 2004, 09:50 PM
Eljimb0 is offline
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Thanks, from a Mac user.
"If you haven't had a Mac you have never really had a computer"
Old Sep 15, 2004, 07:35 AM
twest is offline
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100% electric since 1990
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Old Sep 16, 2004, 12:42 AM
BEC is offline
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Cool!! I'll grab it and give it a try!

Old Sep 16, 2004, 01:02 AM
Goekeli is offline
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Thanks for this!!! I love my mac too!

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

Good work!
Old Sep 16, 2004, 07:54 AM
Ron Williams is offline
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slow but inefficient
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Hi Craig -

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

Old Sep 16, 2004, 09:57 AM
Park_Pilot is offline
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How am I not myself?
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Thanks a lot!

Old Sep 16, 2004, 10:02 AM
rccraigb is offline
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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!

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

Old Sep 16, 2004, 11:26 AM
rccraigb is offline
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Unfortunately it can't run under OS 9 - it is a 'Cocoa' application from the ground up.
Old Sep 16, 2004, 05:50 PM
Ron Williams is offline
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slow but inefficient
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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.

Old Sep 16, 2004, 11:18 PM
macr0t0r is offline
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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!
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Last edited by macr0t0r; Sep 17, 2004 at 12:02 AM.
Old Sep 17, 2004, 03:46 AM
jojonz is offline
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Thanks for thinking of us Mac users, Craig.
It looks and works great.
Old Sep 17, 2004, 11:50 AM
mdiehl is offline
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Just downloaded using Safari and 10.3.5, no problems seems to run fine. Thanks!


Mike D.

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