TUBA-4 Motor Test Stand

[Bartman]

It seems that if you really want to try to understand what's happening with your motors, props, and batteries you have to eventually build yourself a test stand and do your own experiments. If nothing else it allows you to verify the manufacturers' claims so you can feel more confident when you're trying something new.

There's been a lot of discussion about coaxial motors and props and I got to the point with it where I wanted to see for myself what was going on inside the vortex (maybe it's not a vortex, who knows, right?) so I built a test stand. It has affectionately been named the TUBA-4.

On hand is a small collection of stuff with which to begin testing. I've got two Tiger 4008-18 (360kv, 3S-8S), one Tiger 4008-12 (700kv, 3S-6S), one Tiger 3515-15 (400kv, 3S-8S), multiple Tiger 2814-10 & 11's, plus a small assortment of Tiger and Turnigy ESC's. I have on hand at the moment 4S and 6S packs with enough to make other combinations if I have to.

I've got specific goals, one of which is to see what is the most efficient way to make about 800g of thrust out of one motor/prop. From there I want to see what is the best way to get about 1600g of thrust out of a coaxial pair of motors/props.

To monitor everything I've got two Eagletree e-logger's and I hope to be able to optimize the coaxial motors and props to get the combined thrust I'm looking for.


I'm willing to run tests on your motors, props, and ESC's if you don't mind sending them to me. PM if you're interested. I'll post videos and data for the runs I do.

View attachment 8019

That's it for now. I'm still getting acquainted with the e-loggers so once I'm comfortable there the testing will begin.

Bart

 

[kloner]

awesome. if you got any questions about the loggers let me know. i've been screwing with em for a few years now and got a pretty decent understanding of em. That one i sent you was calibrated to the exact amperage used..... the v.4 ones like the other you got are alot closer to true out of the box but you'll still want to verify it before you give the numbers too much weight. hook up a logger and run it in live mode on a pc, stop the run when you hit 1000mah and recharge the battery to see if it says you used 1000 mah. it has a spot in the setup to make that exact

 

[Bartman]

thanks Kloner, that's a great tip and I'll definitely do it. what I'm looking forward to most is being able to see what different props are producing in terms of thrust while also seeing what's going on with the power parameters. I've got my suspicions but I'll wait to see what the facts are before I start blabbing about it.

Want me to run one of those Leopards on there?

Bart

 

[kloner]

i'll see if i can get a spare to send ya

from my plane what i've noticed is when a props too small, it doesn't utilize the motors full watts, when it's overpropped, it hits max speed low on rpm and the rest is wasted energy any more than 3/4 throttle, amp draw goes up but speed doesn't usually follow. propped just right it has a full speed range that goes along with the amp draw having a nice smooth amp draw curve.

on quads all i see is not enough power in the form of amp draw too low, too much amps and the difference in the sky is it'll shake violently over propped. but it's dji arms and all i've messed with on an osd for multirotors. the xy8 is fully outfitted with one of them loggers with 150 amp service and the full sat/barometer/osd so i'll have all the info as soon as it flies. Waiting on a video transmitter today or tomorrow then i think it is totaly built and setup. As soon as i can walk half way comftorably i'll toss it up.

 

[Bartman]

do you really plan to "toss it up" or will it be more like a smooth liftoff from a flat surface?

maybe i'll try a few demo runs tonight.