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National Advisory Committee for Aeronautics, Technical Notes - An Analysis of the Airspeeds and Normal Accelerations of Boeing B-247 and B247D Airplanes in Commercial Transport Operation

Acceleration and airspeed data taken on Boeing B-2h7'transport air—
planes operated over transcontinental routes'of the united States during
the period from 1933 to 1937 have been analyzed. The results show that,
on the average, the placard speed would be exceeded once in about
9.5 x 105 flight miles and the limit gust load factor would be exceeded
once in about 2.5 x 106 flight miles. The results of operations
of the B—2h7 airplanes in camparison with the results of operations of
other airplanes show larger than average flight loads, a high operating-
speed ratio, but route roughness appears to be about average. These
results together with analyses made in the past indicate that operating
speed in regions of turbulent air is a significant factor in the operational
life of the airplane.

The results of analyses of VLG data given in references 1 to 5 have
shown that the flight loads of airplanes operated in commercial transport
service are influenced by operating speeds and by forcasting and
dispatching practices as reflected in differences between operations
during the prewar and wartime periods. In line with previous investigations
of airplane flight loads and operating speeds, this paper presents the
results of an analysis of VLG records obtained on Boeing B~2h7 transport
airplanes. The available data are summarized and the flight results are
compared with the results of analyses made in references 1 to 5.

Forty-two V-G records representing 12,191; hours of flight were on hand
for the present analysis. The records were obtained from five airplanes
operated by one airline during the period from July 1933 to_ April 1937 on
routes across the United States. Two of the airplanes were operated
as B—2h7 type and, after conversion, were operated as B~2h7D type. The
records were supplied to the Langley Aeronautical Laboratory of the
NACA by the operating airline together with dates of installation and
removal, number of flight hours per record, and occasional supplementary
remarks regarding unusual atmospheric conditions or operating practices.