An analysis of airspeed, altitude, and acceleration data obtained from a twin-engine transport airplane operated over a feeder-line route in the Rocky Mountains Page: 4 of 24
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NACA TN 3750
Design speed for maximum gust intensity (indicated),
VB (computed according to ref. 6), mph ............. 138
Design cruising speed (indicated), VC (also manufacturer's
design maximum level-flight speed VL), mph .......... . 211
Design never-exceed speed (indicated), VNE, mph . . . . . . . . . 257
Normal acceleration corresponding to the design limit-
gust-load-factor increment, an,LLF (computed according
to ref. 6), g units .......... . . . . . . . . . . . . 2.34
Unless otherwise indicated, the values listed were obtained from the
manufacturer ' s design data.
EVALUATION OF RECORDS AND PRESENTATION OF RESULTS
Frequency distributions of gust and maneuver accelerations, gust
velocities, indicated airspeeds, and pressure altitudes were obtained by
procedures such as those discussed in reference 2. These procedures and
the results obtained are described briefly in the following sections.
Gust accelerations above a threshold of 0.3g were read from the
VGH records by using the steady-flight position of the acceleration trace
as a reference. The resulting frequency distributions of gust accelera-
tions by flight condition (climb, en route, and descent) as well as the
total frequency distribution are given in table I for class intervals
of 0.1g. Positive and negative values of the gust accelerations have
been combined in table I since the distributions were essentially sym-
metrical about zero g. The number of flight hours and flight miles repre-
sented by each distribution are also. given as well as the average indicated
airspeeds for each phase of the operation.
The total gust acceleration distribution of table I is shown in fig-
ure 2 in terms of the average number of accelerations greater than a given
value exceeded per mile of flight. The solid line in the figure was faired
through the data points to represent the distribution. For comparison,
the corresponding gust acceleration distributions for a short-haul opera-
tion (ref. 1) and a long-haul operation (operation A of ref. 2) are also
shown in figure 2. The pertinent operational data and characteristics
of the airplanes involved in the three operations are given in table II.
In order to express these data in a form suitable for load-factor compari-
son, the accelerations in figure 2 were divided by the acceleration anil
corresponding to the computed limit-gust-load-factor increment for each
airplane, and the results are presented in figure 3. The values of an,LI
used in obtaining the data in figure 3 are given in table I.
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Copp, Martin R. & Fetner, Mary W. An analysis of airspeed, altitude, and acceleration data obtained from a twin-engine transport airplane operated over a feeder-line route in the Rocky Mountains, report, October 1956; (https://digital.library.unt.edu/ark:/67531/metadc56182/m1/4/?rotate=90: accessed May 23, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.