My new test stand measures effciency by using torque and rpm measurements. - RC Groups
Mar 30, 2007, 08:51 PM
Planes from 1oz to 55lb's

# My new test stand measures effciency by using torque and rpm measurements.

I just built a new test stand that measures efficiency of the whole powertrain (including prop!!) by measuring torque and rpm. When all the units are converted to SI, Grams of torque to Newton/meter and rpm to radian/second (rad/s) all you have to do is multiply the revolutions by the torque and it gives you output in watts! Then just divide Output/Input and you will get a percentage.

I will get pics up in a few minute, let me find the camera.

simo10
Mar 30, 2007, 09:08 PM
Planes from 1oz to 55lb's
Here are the pics. The entire motor rotates on an old crankshaft and 2 bearings. The connecting rod is used and that pushes down on the scale and measures torque.

RPM's, amps, volts, estimated efficiency, time, and watts are measure by the E-meter. Please realize it still needs a little more work and an extra scale so I can measure thrust as well. The pictured balance will eventually go between the support brace and the base and move with the stand.

simo10
Thanks for checking out my project,

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 Mar 30, 2007, 09:11 PM Suspended Account I don't think I've seen a test stand to measure torque before...intriguing. Will
 Mar 30, 2007, 09:16 PM Planes from 1oz to 55lb's Inspiration came from this guy http://www.unitedhobbies.com/communi...ts.asp?TID=308
 Mar 30, 2007, 09:18 PM Suspended Account Nice. I look forward to your tests. Any chance there'll be a video? Will
Mar 30, 2007, 09:27 PM
Member
Very nice!

Though, but you can only get total system efficiency if you measure both thrust and velocity off the back of the prop.

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 Mar 30, 2007, 09:38 PM Suspended Account That motor is GINORMOUS! What was it used in? Will
 Mar 30, 2007, 10:42 PM Member Assume you mean my motor? Its used for prop testing – 22” shown. Since its synchronous, its rpm remains constant! Tells a lot about props (dia & PITCH) when run at constant rpm.
Mar 31, 2007, 07:51 PM
Planes from 1oz to 55lb's
A few tests with a park 480 1020kv with a 10x7 prop, tested with a 3s 3300 20c pack and a CC60. Remember the efficiency is for the WHOLE power system, so naturally, it's a little lower than what it is spec'd at.

Have fun!

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Mar 31, 2007, 07:58 PM
Planes from 1oz to 55lb's
and i finally mounted the scale correctly. I have a lab quality 10kg 2gram resolution scale coming for thrust measurements.

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Apr 07, 2007, 12:02 PM
Registered User
Quote:
 Originally Posted by willhaney I don't think I've seen a test stand to measure torque before...intriguing. Will
Then you have not searched this website.
Apr 07, 2007, 12:05 PM
Suspended Account
Quote:
 Originally Posted by peterangus Then you have not searched this website.
Never thought to.
Apr 07, 2007, 12:07 PM
Registered User
Quote:
 Originally Posted by simo10 A few tests with a park 480 1020kv with a 10x7 prop, tested with a 3s 3300 20c pack and a CC60. Remember the efficiency is for the WHOLE power system, so naturally, it's a little lower than what it is spec'd at. Have fun!
The efficiencies you quote in post #9 are motor efficiencies.
 Apr 07, 2007, 12:32 PM Suspended Account What's up peterangus?
Apr 07, 2007, 01:56 PM
Registered User
Here is a picture of my thrust stand modified as a crude Torque Measuring rig.