This Day in McDonnell Voodoo History: July 14

In 1955, a conference at the NACA facility in Langley, VA is convened to determine the cause of the 15% range discrepancy noted during USAF Phase II testing.  One of the contributing factors was a poor “Area Rule” distribution and poor flow around the aft fuselage and empennage of the airplane, leading to an increase in base drag.  NACA suggested that a “boat tail” fairing could be added over the existing structure to improve airflow, reduce cruise drag, and minimize the disturbing, continuous buffet often encountered during cruise conditions at altitude.

Photo: Area Rule distribution of F-101A model from a NACA study.  The red line is the author's estimate for added cross sectional area from the Model 96 store, which in mid-1955 was considered the primary armament of the F-101A strategic fighter.

Photo Credit: NASA, with additions by author.