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.

When you apply rudder, the secondary effect of that is for the plane to roll, and yaw is the secondary effect of roll. Which is what could be happening to your plane. The effects are more pronounced if your plane has wing tip stalling tendencies.(maybe different angle of incidence on each wing panel).

Not sure, but the plane was my first build, it was pretty close but the wings could be off. I wasn't too happy with the way the wing sat in the saddle. I do know that it takes quite a bit of up elevator trim to keep level. Also, loops are great, the plane doesn't bail out.

welcome to the world of 4*s every one ive ever seen or flown does a dive when rudder is applied . neat note though go inverted and apply a little rudder and it will fly level.

That's the first I've heard of that for four stars. Makes me feel a little better though. Do you know what causes it?

i dont know what causes it but on the up trim you might double check your balance it sounds nose heavy . also you can check the ailerons to see that they are in line with the flat bottom of the wing if it isnt it creates a flap effect and requires up trim and also makes it very pitch sensitve which would probably exaggerate the rudder problem i described earlier . take a straight edge and with trim centered place it on the bottom of the wing from le to te there should be no gap if there is adjust it out.

A question. When you apply rudder are you saying the airplane pitches nose down or is it just losing altitude in a fuselage level flight condition.

Moving the CG aft would make the airplane more pitch sensitive.

The nose pitchs down. For example, when flying level and apply right rudder, the plane rolls right slightly while the nose drops.