Thrust curve measurement brushed motor

[Astudillo]

Hey Guy's

I just got my Chaoli 08-20's in the mail, and i was wondering how to make a decent thrust curve measurement for them.
A R2V calibration i think isn't possible with the onboard controllers right? should i use a tachometer to measure the rpm or is there another way to do it?

Cheers,

Ray

[Astudillo]

I just did my thrust measurements and put them in the excel sheet. Now im a little bit confused in the wiki about which DEFAULT_MOT_VALUE2T_A1 and DEFAULT_MOT_VALUE2T_A2 i should use, the numbers out of the excel or the ones from the OSx Grapher?

[Max]

I think either result should work. The OSx grapher docs were written first, before the spreadsheet was created. I thought it a bit confusing as well.

BTW would be very interested in your results. What kind of thrust-per-watt are you getting? And which props are you testing with?

-Max

[plexus]

Hi
The two run well. I take those in excel. Be care to take this one noted " use only".
Alain

[Astudillo]

Hey Max and Plexus, thanks for your quick reply's!

Actually the question was for my hexa(with T-motor U3's), as im waiting on my tachometer for the Chaoli motors. But as soon as i have the results ill will share them here.

Here's a photo of my nano quad.

[Kisssys]

The M4 with onboard esc's uses a voltage to thrust relationship and has no need for RPM. In doing so it automatically compensates for battery voltage change and the internal esc code apply's some correction to compensate for the slower response of the brush motor.

The attached xcel file should give you an idea as to what is needed to get a good A1,A2. for the -20 motor. Numbers for a 0820-15 with ladybird prop are attached as a reference. If I was in a hurry I would just raise A1's value by the percentage of thrust that the -20 motor puts out more or less than the -15 motor and you'd probably be close enough leaving A2 alone.

A good test to see how well you've done would be to put the copter on a thrust stand with a variable supply. Set half throttle with 3.5 volts applied and note the thrust. Now raise and lower the voltage to see it the thrust stay's close to what you have set.

Cheers
Steve

2015-04-07_7-48-15.jpg (144.54 KiB) Viewed 11152 times

[Astudillo]

Hey Steve,

Thanks for your reply, ill be giving it a try!

Cheers,
Ray