Methods for Calculating Motion Induced Interruptions as Applied to a Space Capsule After Splashdown
Abstract
The introduction of calculation methods for motion induced interruptions (MII) in 1984
introduced a new way to quantify human factors in addition to the motion sickness index
(MSI). The 1990 Graham method for calculating MII uses a combination of a vessel\'s
acceleration and roll to determine a tipping" factor to calculate MII per minute. The
Applebee-Baitis (AB) method considered that the motions are implicitly considered in accelerations, and therefore did not require roll to calculate MII. This thesis examines and
analyzes the di"erences between the AB and Graham methods and compares their results
for a unique hull form shape, a cylindrical capsule, in rough seas to determine which method
is preferred. Two tests were performed by the Naval Surface Warfare Center, Carderock
Division (NSWCCD) for the National Aeronautics and Space Administration (NASA) on
the Orion Crew Exploration Vehicle (CEV) in post-splashdown conditions. A one-quarter
scale model of the CEV was tested at the Aberdeen Test Center in Aberdeen, Maryland.
Direct comparison of the analyzed data, MII sensitivity to location, and scaling analyses are
examined and future work to further the application of MII calculation methods are proposed.
The symmetry of the capsule leads to the assumption that roll and pitch-dominant
MII calculations should be on the same order of magnitude. They are not because both MII
methods only take roll-motions into account. The inclusion of both pitch and roll motions
for the MII calculations is proposed as future work. The Graham method was found to be
the more appropriate calculation because it is more conservative, and therefore preferred in
the context of crew safety.
introduced a new way to quantify human factors in addition to the motion sickness index
(MSI). The 1990 Graham method for calculating MII uses a combination of a vessel\'s
acceleration and roll to determine a tipping" factor to calculate MII per minute. The
Applebee-Baitis (AB) method considered that the motions are implicitly considered in accelerations, and therefore did not require roll to calculate MII. This thesis examines and
analyzes the di"erences between the AB and Graham methods and compares their results
for a unique hull form shape, a cylindrical capsule, in rough seas to determine which method
is preferred. Two tests were performed by the Naval Surface Warfare Center, Carderock
Division (NSWCCD) for the National Aeronautics and Space Administration (NASA) on
the Orion Crew Exploration Vehicle (CEV) in post-splashdown conditions. A one-quarter
scale model of the CEV was tested at the Aberdeen Test Center in Aberdeen, Maryland.
Direct comparison of the analyzed data, MII sensitivity to location, and scaling analyses are
examined and future work to further the application of MII calculation methods are proposed.
The symmetry of the capsule leads to the assumption that roll and pitch-dominant
MII calculations should be on the same order of magnitude. They are not because both MII
methods only take roll-motions into account. The inclusion of both pitch and roll motions
for the MII calculations is proposed as future work. The Graham method was found to be
the more appropriate calculation because it is more conservative, and therefore preferred in
the context of crew safety.
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