I've noticed on a/c with only two wing mounted engines that they tend to be closer to the fuselage than the wing tip. There must be some reason for this, and so I guess my question is why? Does having them farther out on the wing create too much stress? I would assume if a/c manufacturers could put the engines closer to the wing tip they would (for cabin quietness/comfort) so it must be a structural thing. If a four engine a/c was forced to run on just two engines (one on each side), would they then rather have the two closest engines running, or the two outward engines? Thanks for any answers!