Does this gun belong in the Macross scenario, or Robotech, or Gundam, or what? What is it? I found it online as a CGI model for Poser (http://en.wikipedia.org/wiki/Poser). Its readme file called it a "V-Gun". It is about 4 feet 5 inches long; it was texture-mapped with 'U N SPACY' (http://en.wikipedia.org/wiki/U.N._Spacy) along each side in big uppercase.
When I found it I interpreted it as a raygun and named its 3 main parts from back to front "powerpack, reactor, ray generator".