I assume you tried the magical website "google" before asking for an answer to your homework problem? I had no idea what a launching nose was but google told me more than I needed to know.
GOOD ANSWER! It seems that 90% of the questions posted could be answered by a Google or other search. Maybe the people do not have a computer and cannot do a Search,
Whoops! They must have one or they could not post these questions!
I for one read these forums for the questions asked that I would never think to ask, but none the less find interesting. I suppose I could start with wikepedia on page 1 and read it, but I find this more interesting because there are people on the other end.