We all know that Voyagers warp nacelles angle up when it goes to warp. I have always wondered why don't they just stay at that angle all the time, why do they have to go back down. If there not in warp, then there not it use so why not leave them upright. Does it somehow get in the way of the Impulse engines to leave them angled? I'm not sure if this was ever mentioned on screen. The obvious behind the screen answer i'm sure is that the producers thought it was cool, so they had them do that.