hmmm. So as you increase engine size, you need to increase the down angle of the engine(negative thrust angle or negative engine incidence). Is this to somehow offset the negative pitching moment of the wing,because of increased thrust vectoring? Point the lift vector forward thus giving a postive pitching moment to offset the weight or??????????????????? I have allways been interested in this. What happens if you don't point the engine down after adding a larger engine? Any help or input appreciated.