I built a four star 60 and it has about 15 flights on it. Someone who is a lot better flyer than myself flew it today and stated that when he used the rudder, the plane dropped significantly. Since I don't use the rudder much yet, I hadn't noticed, but after he mentioned that, I tried myself and yep, it drops big time. All other control surfaces operated as expected.

Does anyone know what could be causing this? The plane has an OS 91 FS with a 14 x 6 prop.