Bitcraze Forums

I try to experimentally measure torque ( in gramm ) of all 4 engines like this:http://www.bitcraze.se/2015/02/measurin ... pm-part-3/
I put my quadcopter on bottle, bottle on scale and get, that when PWM = 30000 created torque is just 18 gr.
But, with this ratio my quadcopter move up from floor, and his weight is 30 gramm. Does this mean, that there is some other forces is present during vertical motion when starting from horizontal place? What is this forces? Is some idea?

did you zero out the weight of the bottle?
what you are measuring is actually thrust, not torque

what you should do is put the cf upside down on a scale, zero out and then go to full power and read the scale
that will give you a thrust measurement

Without changing PWM ratio:
1) Put quadrotor on the floor and he is move up from the ground to air. His weight is 30 gr.
2) I put quadrotor with bottle on the scale ( quadrotor placed upside UP) and when i power on quadrotor i see -20 gr on the scale.
3) I put quadrotor with bottle on the scale ( quadrotor placed upside DOWN) and when i power on quadrotor i see +20 gr on the scale.

So, the 20 gr thrust is not enough to move up from the ground but it do it. How?

something is still not right,

make sure the scale says 0 if it is empty

measure just the quad, lets say it is 10g

measure just the bottle, lets say 20 g

put the bottle and quad up side down on scale, it should say 10+20=30g

go quad t full power, should lets say 50g

50-30=20g is the thrust

thrust should be more than weight 10g weight, 20g thrust

1. scale say 0 if empty.
2. quad only on scale. Scale says 30 gr.
3. bottle only on scale . Scale says 140 gr.
4. bottle + quad ( turned OFF ). Scale says 170 gr.
5. bottle + quad ( turned ON ). Scale says 190 gr. Quad placed upside down.
So, thrust = 190 - 170 = 20 gr. Less than his weight ( 30 gr ). But with that thrust this quad can fly ( move up from the floor ).

It is ground effect.
https://www.deepdyve.com/lp/institute-o ... kk6VCiUX58

almaz_1c wrote:It is ground effect.
https://www.deepdyve.com/lp/institute-o ... kk6VCiUX58

i dont think so, but still an odd and interesting question

This is how I did it:
1. Disable the stabilization to have the same output on all motors by replacing the line with this: distributePower(actuatorThrust, 0, 0, 0);
2. Put everything on the scale, then tare it (zero it).
3. The scale should now read zero and when you increase thrust it should start displaying negative numbers = thrust. If it can't display negative numbers put the CF upside down to make it push down on the scale.