The  Naval Torpedo Station Branch Post Office, (Newport, Rhode Island) was established on April 28, 1936 and disestablished on November 27, 1941 according to the "Checklist of Rhode Island Post Offices 1794-1994" by Del Beaudreau.  However the Stations & Branches section of "Rhode Island Postal History - the post offices" by Merolla, Jackson & Crowther, lists the U. S. Torpedo Station as 1916 to 1930. I have also seen a Torpedo Station cover with contents dated October 25, 1924.

The cover above is dated February 14, 1936 - over 2 months before the listing in the "Checklist." It is franked with the 2-cent Red National Parks (Grand Canyon) issue of 1934 - Scott #741. (The date on this cover might have been added at a later date, although I believe the CDS itself is authentic.)