Futaba has an (air brake) selection that works very well. I set my Edge up with 10%down ailerons and 5% up elevator activated during low rates on switch (G). Used them a few times during zero wind conditions. Can't be used with a Y-harness on ailerons. Flaperons and duel channel ailerons only. "Hope this helps."
Well I never use Y harnesses anymore. I rather do everything on my TX. The Airbrake function is i believe on the sail plane programming right?