Accelerations in Transport-Airplane Crashes Page: 4 of 77
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NACA TN 4158
representing a pressurized low-wing transport is shown in figure 2(a).
This airplane was designed for high-altitude pressurized flight and has
the gross structure characteristic of this airplane class. The airplane
shown in figure 2(b) is representative of low-wing unpressurized trans-
ports. The fuselage belly and undersides of the nacelles are approximately
on the same level, so that in crashes in which the airplane strikes the
ground while moving in its original direction, such as in an unflared
landing, the impact forces will be taken simultaneously by the three sur-
faces. Since this airplane was not designed for pressurized loads, its
structure was quite different from that of the pressurized transport.
The unpressurized high-wing airplane (fig. 2(c)) is a cargo-carrying
airplane having an integral floor and belly structure throughout the main
fuselage. The nose section of the fuselage, however, is a weaker structure
covering the front wheel and strut and also serving as an aerodynamic
fairing. The main fuselage structure is suspended from the wing. If the
main landing gear fails, however, the fuselage structure must support the
entire wing, nacelle, and fuel-tank load.
RESULTS AND DISCUSSION
Accelerations in Horizontal Plane
The variables in a crash that affect the accelerations are the atti-
tude of the airplane during successive impacts, the airplane structure,
the velocity of the airplane, and the type of surface or obstacles the
airplane hits. These are the factors that a full treatment of crash-
impact loads should cover. However, since the number of airplanes avail-
able was limited, the effects of impact velocity and the type of surface
were not studied. Therefore, only the effects of the impact attitude and
the airplane configuration on the crash accelerations in the horizontal
plane are discussed. Accelerations normal to the horizontal plane are
considered in a subsequent section.
Effect of crash attitude on longitudinal acceleration. - During a
crash, an airplane may hit the ground in many ways. The ways that were
studied in this investigation are as follows:
(1) The airplane strikes an object or the ground while traveling in
a straight path.
(2) The airplane strikes obstacles while moving sideways or backward.
(3) The airplane slides along the ground while rotating around its
vertical axis as in a groundloop.(4) The airplane tumbles and rolls as in a cartwheel crash.
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Preston, G. Merritt & Pesman, Gerard J. Accelerations in Transport-Airplane Crashes, report, February 1958; (https://digital.library.unt.edu/ark:/67531/metadc56808/m1/4/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.