Originally Posted by dayhead
Perhaps you're familiar with the Swift hang glider design. The name stands for "Swept Wing with Inboard Flap for trim".
If your planform has enough sweep, you can lower the trailing edge in the inboard, or root area of the wing to get a nose-up pitching moment. In many cases this is better than increasing reflex in the outboard, or tip area of the wing. I use this to get better sink rates from my Sling Wings.
i built a small free flight balsa glider that had inboard flap trim. it made for a very nice flight envelope, on launch it would fly fast and a mild pitch up and then transition to a slow stable glide. the only explanation i could come up with was that during high speed flight, the flaps' upper airflow separated until it slowed down enough to reattach. wore out my arm throwing that little thing many times