Aircraft Circulars (AC) - Reprints of articles giving specifications of individual aircraft, often from other countries.
Annual Reports (AR) - Contain NACA’s Annual Report to Congress as well as Technical Reports produced in that year.
Control Reports (CR)
Technical Memorandum (TM) - Reprinted reports from other laboratories, often translations from foreign languages.
Technical Notes (TN) - Report partial results or material of narrower interest. Selected information from these reports was often analyzed and refined for later publication in the more formal Technical Report series.
Reports (TR)- Also called NACA Technical Reports (TR). Usually the final report on a project, summarizing earlier interim reports.
Research Memorandum (RM) - Less formal reports issued to meet the need for rapid dissemination of aeronautical information.
Wartime Reports (WR) - Published after World War II to make more widely available wartime research that had been previously issued in restricted series.