this is advice from experience with scale ships that have wash out built into the wing tips.It is not a good idea to have the airlerons adjusted for trim so that they droop below neutral,as this will remove any built in wash out in that panel and cause a nasty snap at low speeds.It is better to have one airleron raised above neutral for trim for this reason.I learned this on the test flight of my jhh f9f-8 cougar back in 84" It need just a tad of airleron trim that I made with the trim on the tx.flew fine the rest of the flight ,however when I came into land about 2 feet above the runway I started to flare the plane it snapped so fast an unexpectedly there was nothing I could do and it landed on the runway on it's back.I was lucky in that it did not hook a wingtip and cartwheel,only damage was some scraped paint that need to be touched up before the 85 nats.