Double prop still generate rotational torque?

[Jestersage]

So I am makign a plane with double prop, one on each side. I had double checked them such that one is clockwise and the other counterclockwise. Both at maximum output.

The plane still row to the right once it lift off the ground.

Even when I created contra-prop (so total 4 prop) to test the issue, I still have the roll.

Thus, what may cause the issue?

Edited July 18, 2019 by Jestersage

[bewing]

Generally, propellers are not synchronized. That is, they will rotate at different speeds. Which means they will produce slightly different amounts of thrust, and therefore a torque.

[Foxster]

You might just want to double check the deployment of each individual prop. If you missed one then thrust will be unequal. 

[Kryxal]

If you really want to test, switch them to rotating in the same direction and see if it makes a difference, then the other direction and check again.

[AHHans]

You should also check, that the blades on both props have the same amount of pitch (though in different directions). What helped me designing my craft was to switch on the aerodynamic overlay (<F-12>) . (Which made it clear, that one of my props was thrusting backwards...)

Edited July 19, 2019 by AHHans