Wat does a balancer bar thats on top of a helicopter do?

Question

I hav a syma heli and the bar with 2 weights on top came off and i cant put it back, jst wondering if it must be fitted. heres a link were thers a pic of it http://www.emaxinc.com/9sydrrche.html

Answer 1

The bar acts as a gyroscope. In simple terms it acts as a stabiliser system feeding directly into the rotor disc. Without it the rotor disc is much more unstable and difficult to control. If you look at early Bell helicopter designs you'll see the same system.

Answer 2

Keeps it going straight instead of straight up. Try it without, you'll find out.