Here is a great place to start:
http://nwcintranet/content/library/studentpapers.aspx (Works best while on campus, off-campus requires CAC authentication)
Use the Green DTIC button to do a search or browse older papers lower on this Web page.
DTIC also has
- Unclassified defense information
- Data on a wide range of defense and defense-related topics
- Technical reports and contractor studies, many in full-text PDF format
- Student papers originating at the various service schools
- Naval War College JMO student papers [plus other War Colleges too]
From off-campus:
http://www.dtic.mil/dtic/search/tr/index.html
Also visit the Classified Library for paper copies to look at.