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National Advisory Committee for Aeronautics, Technical Notes - Summary of Acceleration and Airspeed Data from Commercial Transport Airplanes During the Period from 1933 to 1945

Normal acceleration and airspeed data collected with NACA VLG
recorders in transport airline operations from 1933 to 19h5 are summa-
rized and analyzed with respect to gusts and gust loads. The acceler—
ations experienced in most operations equaled or exceeded the limit— gust—
load—factor increment, on the average, twice (once pOSitive and once
negative) in 107 flight miles. The gusts experienced in most operations
exceeded 33 feet per second, on the average, twice (once positive and
once negative) in 107 flight miles. The loads experienced for several
operations varied appreciably from average conditions. A predominating
factor causing the variations in the load experience was the difference
in the gust experience, with operating speeds in rough air being a sec—
ondary contributing or moderating factor.

Records of.normal acceleration and airspeed for use in connection
with the study of applied gust loads have been obtained with the NACA
V;G recorder in commercial transport airplanes during a period of 18 years.
Six hundred and fifty—four suitable records representing more than
90,000 flight hours pf operations on six types of transport airplanes
were collected and evaluated from 1933 to l9h5. Analyses of these records
for the gust loads experienced by each airplane type are presented in
references 1 to 6. Estimates of the frequency of equaling or exceeding
stated limit values of acceleration and airspeed were obtained by uti-
lizing statistical methods of analysis. The major implications as to
the effects of route, speed, and other associated conditions on the gust
loads were considered.

Further study was made of‘the V-G data collected from 1933 to 1915
to correlate the gust loads and the gusts experienced during the opera-
tional lives of the airplanes. A method of statistical analysis (refer-
ence 7), which appeared more logical in application to these data than
past procedures and which provided a measure of reliability of the derived,
estbmates, was applied. This paper presents a summary of the imposed '
accelerations, the effective gust velocities, and the airspeeds flown.
The statistical method applied gives some measure of sampling reliability
to determine the significance of observed differences in the results. '
The influences of various operating parameters such as flight airspeed
are analyzed with respect to the accelerations experienced. Differences
in the observed accelerations that could be attributed to differences in
route and period of operation are also examined.