Reverse Thrust???
 

Hi all,

I just completed building my J-3 Cub 25 and finally got my lipo and when I gave it power, it was pushing air not pulling air?! In other words, it wanted to go backwards. At first I thought I must have the prop backwards but after examining it it seems I have it on the right way.

Can anyone help me troubleshoot this?

Thanks in advance.

RE: Reverse Thrust???
 

In general, there are three leads to the motor, and this occurs, just switch two of the leads (it doesn't matter which two), and the motor will rotate in the opposite direction.

RE: Reverse Thrust???
 

Thank you sir!

I did that and it works!

RE: Reverse Thrust???
 

Just a quick note about the prop orientation.

Putting the prop on backwards does not change the direction in which it pushes the air. But the amount of air being moved will decrease, often dramatically, because the prop is less efficient when it is mounted backwards.

For most props, the rule is that the side of the prop with the writing on it should point forward, toward the front of the plane. This is true whether the prop is on the front of the plane or on the rear.

- Jeff

RE: Reverse Thrust???
 

> At first I thought I must have the prop backwards <

Take a close look at your propellor and you will see that turning it around does not change the incidence of the blades.

RE: Reverse Thrust???
 

Another interesting fact leaned on RCU, thanks guys!