500 Tail Setup Trex 500

[Harford]

I have just installed a Spartan Quark on my Trex 500 ESP. As part of this process I am going over the tail setup.
The Trex manual says the pitch slider must be centred. The Spartan manual says for flying in rate mode, the tail blade pitch should be set at approx. 8% to compensate for main rotor torque (leading edge pointing towards tail case?). If I do this, the pitch slider will not be in centre position. I will not be flying in rate mode so do I ignore the reference to 8% pitch and simply centre the slider as the Trex manual says ?

Many thanks

 

[Tony]

Unless you are going to be flying in Rate, I would just ignore that. Center the slider and see how it goes. Now days, the setup is much easier, but back in the day of the Quark, you would spool up the helicopter in Rate mode and adjust the tail linkage rod until you get no drift at the throttle setting you fly most in. So if you fly in IU1 at a flat 85%, you would set your tail with that head speed so there is no drift. A flat curve on these older gyros is a must! And once you do that, you can then switch back into HH mode and you should have a very stable helicopter. Hope this helps.

 

[Harford]

Thanks for this. I almost hate to ask but what is IU1 ?. I understand you are saying use a flat throttle curve.

 

[Tony]

Idle Up 1. Most Tx's now days have the F-Mode switch and you have position 0, 1 and 2. 0 is usually Normal mode, then IU1 and IU2 will have higher flat curves including full negative stick. Normal, or IU0 will have 0% at low stick so that you can shut the motor off.

 

[Harford]

Yes , of course. I am familiar with the flight mode options. Thanks again. I will centre the pitch slider and go from there. Weather no good here so unlikely I will be able to test it until later in the week.

 

[Tony]

Just remember, the Quark is an older gyro so you may have to go through the Rate Mode setup as explained before. Give HH a shot first and if it is stable, fantastic. If you notice some drift or just weird behavior, then flip into Rate mode and start adjusting the tail linkage rod to compensate. But the Quark is a MEMS gyro, so it should do just fine. There are still a lot of people on here that swear by that gyro over the Align tail only gyros. I have run the GP780 on my flybar heli's and it is fantastic.

 

[Harford]

Tony, I have removed the GP780 and replaced it with a new Quark. I have not been successful in completely removing the slow tail wag when using the GP780 so I thought I would try a Quark. Looking at forums generally, there seem to be a lot of people who have this problem with the GP780 and consequently there are those who have a good experience with it (like you). I have a GP780 on my other flybarred heli, the 450 Pro where again it has a small amount of slow tail wag. With all the issues I have had with the tail on my Trex 500 recently, it is interesting (to me at least) that the genuine Align replacement foam pads for the GP780 are vey thin (max 1mm) and quite stiff, whereas the Quark comes with 3mm thick pads which are quite spongy. You may recall I fixed the jittering rudder servo issue by using thicker, more spongy pads under the GP780.

 

[Tony]

Yup I do remember that. And we need to get this issue fixed lol.

 

[Harford]

Just so I do this correctly, can you tell me please how I accurately measure centre point for the pitch slider. I see the diagrams in the Trex manuals but is the measurement on the tail case side taken from the external side of the tail case or from the start of the recess within the tail case side, ie where the shaft first exits the tail case. Hope this makes sense. Many thanks

 

[Tony]

I have always just eyeballed it so that I have equal space on each side of the slider where I can see equal amounts of the tail shaft.

 

[Harford]

Quark fitted and test flown twice. A good result with a stable heli. However still a little tail movement (minor) so still some work to do,