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National Advisory Committee for Aeronautics, Technical Notes - An Analysis of the Airspeeds and Normal Accelerations of Martin M-130 Airplanes in Commercial Transport Operation

Acceleration and airspeed data taken on three Martin M—l30 airplanes
operated on trans-Pacific routes during the prewar and wartime periods
have been analyzed and the results support previous indications that air-
plane speed in regions of turbulent air is a significant factor in the
life of airplanes. During the prewar period greater route roughness is
indicated in trans-Pacific operations than in operations over transconti-
nental routes of the United States or over Caribbean routes.

Acceleration and airspeed data obtained from V—G records collected
during commercial transport operations (references 1 and 2) are being
analyzed in some detail to determine the flight loads and operating speeds
as functions of airplane, route, season, and prewar and wartime operations.
References 3 and 1; used the available data for four routes and two air-
plane types to summrize the results of operations in the Caribbean area
and to compare results of domestic operations within the United States.
Results have indicated that airplane speed in rough air is a significant
parameter in airplane Life, that the change from prewar to wartime opera-
tion had an appreciable effect on the structural life of aircraft and that,
for transcontinental routes, other factors so compensate for route
roughness that route may be neglected as' a significant parameter of airplane
life.

V-G records taken during operations of three Martin M-l30 flying
boats in trans-Pacific service during the period from 1936 to 1911-5 have
been analyzed to investiyte the factors previously mentioned. The avail-
able M-l30 data are summarized and the flight load results are compared
with the results of analyses made in the past.

One-hundred ninety—two V—G records representing 22 ,37’+ hours 01'
flight were available for anaJJ'sis. The records, summarized in table I,
were obtained during the period from 1936 when the airplanes went into
service to the time when use of the airplanes on the trans—Pacific routes
was discontinued. The records were supplied to the NACA with the instal-
lation and. removal dates, routes flown, and. flight hours per record.
Supplementary information regarding unusual experiences was supplied in a
few cases. No information was provided on actual operating weights.