RCHeliGears: How to get rid of tail bounce after pirouette stop(right or left rudder)? T-Rex 550L with GPro as an example.

Sunday, January 31, 2016

How to get rid of tail bounce after pirouette stop(right or left rudder)? T-Rex 550L with GPro as an example.

For some unknown reason, maybe because of the 550L speed fuselage increasing the weight of the tail, I found the tail of my T-Rex 550L had a little bounce back while it was stopped from right pirouette, which I did not notice before...
I follow the guide of the parameters of GPro to decrease the value of the "Rud Right Stop"; but the bouncing remained even the value was down to 0, which meant the tail bounce couldn't be fixed by the settings of GPro, so I went to the mechanical....
Let's see why the tail is bounced back while it's stopped from the right pirouette:
When we move the rudder stick to the right, the heli is spinning clockwise, when the stick is released to central, there's no "move" signal to the rudder of the heli, so the gyro GPro takes over the rudder control and "tells" the  rudder to go to the neutral position which was set up by us originally. So if the neutral position is not "neutral enough" and lean to the "left rudder" side, the tail will be acting like a we send a "left rudder" signal to the heli, and then GPro is detecting the bounce; so a "right rudder" correction by GPro is sent to stop the tail until it stays still.
So the solution is easy:
Change the neutral position of the tail from the current position to a little "right rudder" mechanically;
which can be done by shortening the tail control rod; make 2 turns of the ball link clockwise each time, and hover your heli to check whether the bounce is gone, make another 2 turns until the tail is stopped still & solid.
In my case, I made 4 clockwise turns of the ball link on the tail control rod, and the tail is not bounced after pirouette any more.
P.S. If you heli tail is bounced at left rudder pirouette, lengthen the tail control rod following the same procedure above.

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