the cap carries up thrust not down thrust. This allows for cleanier up lines and comps for the stab location in relation to the wing location (one high the other low). its usually takes me 20 or more flights to get a plane line up correctly by changing CG 1st, throws, up thrust or down thrust, maybe servo locatons or adding servo in some case, taking a plane off certain hardware flaws, mixes, to give my true thoughs to the bird.