BackyardRC

A practical approach to RC planes

Thurst Rig – Motor Efficency Testing

BackyearRC Thrust Rig

BackyearRC Thrust Rig

Head to any of the popular RC forms and one of the hottest topics is always is what is the best motor prop combo?

This isn’t always an easy question to answer. When it comes to determining the best motor and prop for a given airframe a lot of factors come into play. Style of airframe (high/mid/low wing), overall weight, wing surface, desired performance (slow fly/trainer/war bird/jet), and on and on.

So what is a pilot to do? Troll the forums? Try every combo out there? Blindly trust the manufacturers?

There is a better way. Build a thrust rig and do some empirical testing of your own. But who has time for that? Well here at BackyardRC we are making time for just that. Motor efficiency testing.

Today we’ll be starting an ongoing series to test electric motors. With each new motor we purchase we’ll first run it through a series of tests and share our results. We’ll post our findings here and in the comment section of the seller’s website. Our goal is to simply share our data. We are not looking to definitively find the best motors out there..

So without further delay let’s get started by reviewing our newly designed BackyardRC Thrust Rig.

The rig is fairly simple design where the RC motor is bolted to the top of a pivoting arm, on the other end of the arm is a scale, The electronics are wired through a watt meter. When a motor is throttled up the thrust from the motor is transferred through the arm and onto the scale.

Storage Drawer

Storage Drawer

The key is simplicity. The rig takes an all in one approach, measuring all the key data points in one quick test. And with 3D printed interchangeable motor mount plates make for easy motor swaps. The base has a built in drawer store everything you need to quickly run through a series of tests.

Solidworks CAD Model

Solidworks CAD Model

All the complex connecters were designed in Solidworks and printed on our Cube 3D printer. 1/2 inch steel square sock is used in the arms for ridiculous levels of strength. The ESC is only held on by zip ties and can be changed within minutes.

3D Printed Parts

3D Printed Parts

Ok enough about the build of the rig. Let’s get to testing. In our next post we’ll be reviewing the NTM Propdrive 28-36 1000kv motor sold on Hobbyking.com.

Thanks for reading and if you have any questions please post below.

-Miles

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