Farri,
I understand the aerodynamics and forces involved, which is why I brought this up. Having a trim tab is generally not a bad thing, however all aircraft of the same type and equipment should require a similar trim tab. IE: If one Drifter SB582 should have one, all of them operated the same way should have them also. At least in a perfect world. That said, we all know that individual aircraft have their own quirks. But having a huge tab on mine and no tab on another seems excessive, indicating something is amiss.
I've been inspecting mine and measuring things to make sure it's straight. I've found a few things that concern me:
My sails are worn, so I'm replacing them. This might be a small factor as the tail sails are a little loose. The Right inboard batten has poked through in the front, reshaping the wing a tiny bit.
Inside the rudder, one of the lower ribs (made of styrofoam) was broken. I fixed this and I think it helped a bit.
I measured the wires from the mid trailing edge of the wings to the tail where they tie into the tail bracing wires. The left wire is 1/4" longer than the right. They're both semi-snug without being to tight. I'd say there's 2-3" of movement in the middle if that makes sense.
I'm not sure what the offset angle of the engine should be, or if there's any way to change it.
My main tube is straight and has no cracks. Inspected it with a digital inspection camera.