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National Advisory Committee for Aeronautics, Technical Notes - An Analysis of the Normal Accelerations and Airspeeds of a Two Engine Type of Transport Airplane in Commercial Operations on Routes in the Central United States from 1948 to 1950

Normal-acceleration and airspeed data obtained from NACA V—G recorders
installed in a two-engine type of transport airplane, employed in routine
commercial operation on a north—south route in the central part of the
United States from 19h8 to 1950, are analyzed to determine the gust and
gust-load experiences of the airplane. The accelerations experienced
equaled or exceeded the limit-gust-load—factor increment, on the average,
twice (once positive and once negative) in about 2.8 x 106 flight miles,
and an effective gust velocity of 30 feet per second was equaled or
exceeded, on the average, twice in about 0.7 X 106 flight miles.

A comparison of these values with corresponding values from the same type
of airplane during past operations indicates that the gust and gust-load
experiences for the present operation agree well with the wartime (l9hl
to l9h5) experiences but were about 20 percent larger than the prewar
(1937 to l9hl) experiences.

A general investigation has been under way for a number of years
to determine (from V—G data) the magnitude and frequency of occurrence
of gusts and gust loads experienced by transport—type aircraft in
routine postwar commercial operation. This investigation was designed
to supplement previous research of this type, as it was felt that changes
in operating conditions since the prewar period might be reflected in
changes in the gust and load experiences. The results of some.earlier
phases of the current program are reported in references 1 and 2.

This paper presents the results of an analysis of V-G data obtained.
from a two—engine type of airplane, operated by a commercial transport
airline on north-south routes in the central part of the United States,
from 19h8 to l950. The data on the gust, gust-load, and airspeed
experiences of these airplanes are compared with similar data obtained
from airplanes of the same type during operations from 1937 to l9h5.
These data are also used to predict the gust-load experience of another
type of transport airplane of more recent design flown in somewhat
similar airline operations.