I had been looking back at Oli's other thread ( http://www.rcuniverse.com/forum/m_92...tm.htm#9257664 ) and questions from Tassos about the flap, see post #25 onwards. Both Tassos and Oli are running into the same problems I had with flap, and neither solved it. They were using flap and servo travels of zero in one direction from centre, and massive (impossible) travels in the opposite direction from centre, as per Oli's suggestion a few posts above this one of using servo values of zero and 90. It can't work like that, the Rs+ and Rs- values are degrees of rotation either side of servo centre, so zero and 90 means no servo rotation one way, and 90 degrees the other way from centre.

So, rules of thumb for using the spreadsheet:

The values for Rs+ and Rs- are degrees of rotation either side of centre and should be in the region of 40 for both. Not +40 and -40, just plain 40 for both. Using a minus value in one of the boxes will make the servo rotate the same way no matter which way you move the stick! The actual value will be whatever servo travel you have available and whatever travel % value you have set in your Tx, your servo may travel 45 degrees each side of centre, maybe space limits mean it can be 45 one way and 30 the other etc etc. But something in the region of 40 to 45 for both directions is a good starting point. Neither of them should be a zero, as this means no rotation away from centre. Neither of them can be 90, as 90 degrees either side of centre would give a servo with 180 degree rotation, and I am not aware of any that do that apart from retract servos.

The Rc values behave the same way and should not be a zero. Setting flap Rc+ to zero does not mean it is horizontal (i.e flaps up) at one end of travel, it means it has zero travel away from the centre of travel. If you have flaps on a 3 position switch, switch at centre is where the black line on the diagrams should be (assuming you have not adjusted the centres and travels away from default values in the Tx) and the Rs and Rc values are travels either side of this. Clearly you don't want a servo travel of zero or a control travel of zero when the switch is in the up position.

The value for Oc is where the control surface is sitting when the servo is at centre, 0 being horizontal, minus values being angled downwards. So for example an elevator might expect an Oc value of 0, but a flap connected to a servo that is at its servo centre will be (roughly) half way down. Remember that the servo at centre (black line) is where the servo and flap will be when flap switch on the Tx is at mid position (assuming the tx values for centre and travel are at default, you can of course alter these in the tx to give a different mid switch position).

So, to simulate flaps in the spreadsheet, lets try an example. You want a flap travel of 45 degrees down. In that case the centre of flap travel is roughly half that, 22.5 degrees down. So the centre value for the control, its "Origin" angle called Oc in the spreadsheet, is not zero (horizontal is defined as an Oc of zero), its centre value is minus 22.5 degrees and that is the value that goes in the Oc box. Immediately you will see the black line at the control surface go to flaps half down position. Now put in 22.5 to each of the Rc values, and see how the flap travels 22.5 degrees either side of its origin. This makes the flap travel from horizontal, to 45 degrees down. You should not make the flap control horn simply at right angles to the flap, it should be raked back or forward a bit so that roughly when the flap is half down, the horn is at right angles to the pushrod. Do that in the Xc box. As explained above, the Rs values should ideally both be in the region of 40 to 45. Rc and Rs values of zero or close to zero should not be allowed.

Harry