Failure - Interactions

Air Safety Board,   Public  Hearing,   March 30, 1939.

B-307,   Stratoliner,  NX19901,   Inflight LoC -- Breakup

Within the Boeing Company,   Eddie Allen   and   George Schairer  worked   in the wind tunnel    to discern  the design variables affecting the human's control of yaw-rate,  while operating at  combinations of  high alpha  and beta.  Testing  involved various iterations of  sizing-shapes of the Fin-Rudder,  Hinge placement,   and  resulting  rudder Hinge Moment  (thus avoiding non-linear Pedal-force curves).

  Schairer's  paper was  presented at the Aerodynamics Session of the   IAeS-  gathering in NY, January 31st, 1941.   Skip ahead two pages to read excerpts from George Schairer's work,  describing lesson learned and design modifications  [the revolution in Fin-Rudder design after 1939].

  Visitor-in-cockpit,       Visitor-in-seat,

     pilot-not-qualified for planned testing

 These factors would be  cited in  other cases of inflight upset in later decades

 --  Test Plan Reviewed   --

During the  preflight  meeting  to confirm the Test Plan,  Von Baumhaure (a visiting Dutch engineer) said he wanted to see  what took place at 110 to 115 mph  when one outboard motor was cut  and  Pedals were held-in-position,  and when completely stalled.