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Old May 01, 2012, 07:34 PM
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United States, FL, Pembroke Pines
Joined Aug 2008
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Originally Posted by 1bwana1 View Post
I just finished programming my F-4. I used the AR-8000 DSMX RX as suggested in the manual, and set my servos up as recommended in the manual. This means that the aileron servos are set up with opposite orientation so they can run off a "Y" harness.

My guess is that HH did this to support the DX-8 Spektrum radio, not because it gets you the best setup. When you get to the reccommended throws for the ailerons the manual calls for a couple of millimeters of differential. More throw up than down. This is usually done to take caare of rolling issues that cause the plane to pull slightly off line during rolls. However, since the ailerons are on a "Y", you cannot put in this kind of differential. I ended up having identical throws up and down. I'm not sure if this will be an issue because I haven't flown the plane yet. Hoefully it won't matter much. Still, for those that have a high channel radio like the 11X, I suggest you use at least a 9 channel RX. This way you will have complete control of the entire setup.

I also found that even with the longest arms on the Hitec HS-85 servos you will have trouble getting the full 30mm of throw for the flaps. I ran out at about 28mm. Once again, it probably won't matter.

One final thing. The manual calls for Up Elevator compensation with flaps. The habu-32 required down Elevator compensation which worked perfectly. Have you guys who have flown this plane think the Up Elevator is correct for this jet?

I will post my 11X file as soon as I have done the maiden and gotten it all dialed in.

You can still achieve Aileron Differential using Aileron servos on a Y harness, reset you neutral point on both your servo arms towards the front/nose of the airplane or away from the aileron (move the servo arms one or two notches on the spline and lengthen your push-rods). The more you move them the more differential you will get. Play with the angles until you get the recommended differential and then when you fly the plane you can increase or decrease it to your liking.

The right hand side of this picture illustrates this:

- Birger
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