Hi,

Setting up a Sprit in a Trex 450; in the old days of rate gyros we would set the rudder so that when the sever was centered the rudder horn was perpendicular to the boom which gave about 8 deg of rudder at the server centre position which was about what was needed to counteract the the rotation and roughly hold steady. However that leaves very little rudder slider travel to the right, so if I set it up that way I end up with a left limit of 132, and a right limit of just 32, and the software advises that no value should be under 75.

So should I set it up mechanically so when servo is centered, the rudder slider is mid position (0 deg of rudder), and leave it to the Spirit unit to figure out that it always needs to apply rudder just to hold stationary?

Thanks

Hi
Set the servohorn 90deg to the pushrod,fold the tailblades toghether and asdjust the length of the pushrod so its abaout 6mm betven the tailbladestips.
If the values in software is out of range you have to adjust the length of the servohorn.
Then folow the tuningguide to get the tail holding good.
Fly safe
//Lars
.

My understandig of the manualis, that I should set the rudder to 0° pitch when the servo is 90° to the pushrod:

Some helis has the tailservo mounted at an angle to the boom(Goblin 420 570).Perhaps its only bigger helis
that will have som 3-5deg angel prepitch.

Hi,

Sorry, maybe I didn't word the question very well...

Servo horn is centered in all cases, then I adjust tail linkage length so either:
1) Tail rotor is at 0 deg, slider is approx in the middle, and travel is set to L 110, R 100 which is as far as slider can travel without hitting ends. Cant hover like this mechanically, Spirit would have to add approx 8 deg of tail to stop spinning in a hover.
2) Tail rotor is at approx 8 deg, slider is towards one end, and travel is set to L 160, R 35 which again is as far as slider can travel without hitting ends. It would hover like this mechanically, Spirit would only have to add or remove tail angle hold position.

Linkage is already in closest hole on servo horn, as you can see in (1) the amount of throw is about right end to end, its just whether centered servo should result in 0 deg centered tail blades, or 8 deg required to counteract rotor in a hover.

The more I think about it the more I am presuming (1) is correct, and (2) is just the old way we used to do it with rate gyros, is that correct?

Thanks

I tend to go with what the heli manufacturer recommends - I saw a thread a while back where someone else asked the same question regarding an OXY 3 and that was Tomas's suggestion.

BTW - it's not normally as much as 8 degrees - more like 3 or 4 usually, which means that the slider will be offset, but nowhere near as much as you are saying - if you need that much then it sounds as if your tail is underpowered, or your headspeed is very low.

I certainly wouldn't try and fly with my limits at 35 and 160

I think you are right, not sure where I got 8deg from, so I set it to around 3deg with servo centered which gives me L 140 R 73. I also setup gyro gain to be set from the transmitter rather than unassigned and value just set in the settings (with Tx set to +60%, same as the setting previously was), and it flew fine. Will expermient and see if unassigning gyro gain and leaving it to the setting makes any difference.

Still would be good to have the documentation say whether the rudder should be 0deg or the 3-4deg when the servo is centered, or if it doesnt matter.

Thanks

Ants