I built a Motor Test Tower

I started building the MTP II this week, but based on my experience and your feedback on hot glue's weaknesses, I decided to wait to put the pieces together until my CA foam safe glue arrives in the mail.

In the meantime, I wanted to do some some testing on my motor as many of you said it appeared too weak for the airplane. As I got started thinking of ways to test the motor, I realized how many different elements go into a motor/prop efficiency/power/thrust/etc.

So I built the Motor Testing Tower, a tower that allows the motor to mounted on top and while its running the tower simultaneously measures the force generated, the watts/volts/amps consumed, the speed of the air flowing from the propeller, and the temperature of the motor (or ESC, battery, etc.).

I was VERY surprised with the results, as it showed that my old brushed set up generated more thrust (9 oz) than my brushless set up (6 oz). After reviewing the data and the motor specs I am not surprised, the brushless motor is much smaller than the brushed motor, and was not designed for that prop size or the amount of watts that I was putting through it, no wonder it got so hot after a few moments of running that I couldn't touch it without being burned.

I ordered a larger motor yesterday that should be a much more appropriate fit for this airplane, and hopefully it will get here in time for next week's episode.

What do you guys think of the tower? Anything else I could add? I was thinking a RPM measuring device could also be added to complete the set up.

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Comments

Trent at MyGeekShow July 3, 2011 at 11:31am

Thanks guys! I'll have to post some of my test results for future reference. I'll look at adding a RPM gauge when the budget permits, right now I've saving up for my FPV equipment and better electronics.
Kyle Pace July 3, 2011 at 10:03am

I agree with Philippe, avoid the ground effects. Try to have everything (batteries, receiver, & miscellaneous wires) off of the ground and on the scale; the wiring will effect your readings slightly. I just noticed on one or two of your tests.
Another item that could be of interest would be a RPM meter, like Jani.

Keep up the good work.
Bernard Michaud July 3, 2011 at 6:34am

Real DIY imagination

Very helpfull for me and my team of determined newbies.
Developer

Jani Hirvinen July 3, 2011 at 2:38am

Cool, a bit similar system that we are using for testing quad and other motors here. We also have pressure sensors measuring changes on thrust, rpm measurement and heat.
Philippe Petit July 2, 2011 at 1:56pm

Hey, wow looks really cool, with that tower you could really do some cool and helpful measurments! Really helpful if you want to determine the forces! I like it.

But as you asked for it: to avoid ground effects and other unwanted aerodynamic influences, you could firstly mount the propeller in such a way that it pushes instead of pulling. Also some streamlining of the tower would certainly help. And most important, place the amemometer somwhere nearer the propeller, the ground effect here will certainly affect the measurment.

Keep on the good work, I like the setup
T3

Sami Finnila July 2, 2011 at 10:09am

Looks like you need a PowerLog 6S or the sorts. Really nice tool for measuring pretty much everything going on in your plane both in flight and on the ground. Anyways nice setup. :)

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