Mar 30, 2007, 07:51 PM Planes from 1oz to 55lb's USA, FL, Orlando Joined Aug 2004 1,278 Posts Alert 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, 08:08 PM
Planes from 1oz to 55lb's
USA, FL, Orlando
Joined Aug 2004
1,278 Posts
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,

# Images

 Mar 30, 2007, 08:11 PM Suspended Account Fountain Valley, California Joined Feb 2004 10,765 Posts I don't think I've seen a test stand to measure torque before...intriguing. Will
 Mar 30, 2007, 08:16 PM Planes from 1oz to 55lb's USA, FL, Orlando Joined Aug 2004 1,278 Posts Inspiration came from this guy http://www.unitedhobbies.com/communi...ts.asp?TID=308
 Mar 30, 2007, 08:18 PM Suspended Account Fountain Valley, California Joined Feb 2004 10,765 Posts Nice. I look forward to your tests. Any chance there'll be a video? Will
Mar 30, 2007, 08:27 PM
Member
Edina, MN, USA
Joined Oct 1999
11,841 Posts
Very nice!

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

# Images

 Mar 30, 2007, 08:38 PM Suspended Account Fountain Valley, California Joined Feb 2004 10,765 Posts That motor is GINORMOUS! What was it used in? Will
 Mar 30, 2007, 09:42 PM Member Edina, MN, USA Joined Oct 1999 11,841 Posts 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, 06:51 PM
Planes from 1oz to 55lb's
USA, FL, Orlando
Joined Aug 2004
1,278 Posts
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!

# Images

Mar 31, 2007, 06:58 PM
Planes from 1oz to 55lb's
USA, FL, Orlando
Joined Aug 2004
1,278 Posts
and i finally mounted the scale correctly. I have a lab quality 10kg 2gram resolution scale coming for thrust measurements.

# Images

Apr 07, 2007, 11:02 AM
Registered User
Blackpool, Great Britain (UK)
Joined Dec 2003
1,342 Posts
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, 11:05 AM
Suspended Account
Fountain Valley, California
Joined Feb 2004
10,765 Posts
Quote:
 Originally Posted by peterangus Then you have not searched this website.
Never thought to.
Apr 07, 2007, 11:07 AM
Registered User
Blackpool, Great Britain (UK)
Joined Dec 2003
1,342 Posts
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, 11:32 AM Suspended Account Fountain Valley, California Joined Feb 2004 10,765 Posts What's up peterangus?
Apr 07, 2007, 12:56 PM
Registered User
Chattanooga, Tennessee, United States
Joined May 2003
27,210 Posts
Here is a picture of my thrust stand modified as a crude Torque Measuring rig.