| 摘要 |
A football having a prolate spheroidal shape including longitudinally spaced apart first and second ends. The football is capable of being analyzed under computational fluid dynamics analysis, and includes upper and lower central regions. Each positioned between first and second upper and lower end regions, respectively. The football further includes a bladder, a cover, a plurality of boundary layer trip mechanisms coupled to the upper and/or lower central regions, and a lacing coupled to the upper central region. The analysis includes first and second configurations. The first configuration is conducted on the football with the trip mechanisms, and the second configuration is conducted on the football without the trip mechanisms. The first and second configurations provide first and second drag coefficients, respectively. The first coefficient is at least 3 percent lower than the second coefficient. The length of the upper and lower central regions is defined by the lacing. |
| 主权项 |
1. A football having a generally prolate spheroidal shape including a major dimension about a longitudinal axis, and longitudinally spaced apart first and second ends, the football capable of being analyzed under computational fluid dynamics analysis conducted at a Reynolds Number of approximately 270,000 having input parameters of a thrown speed of 60 mph, a rifle spin of 10 revolutions per second and a 0 degree angle of attack to airflow, the football comprising:
a bladder; a cover positioned over the bladder and including at least four cover panels, the football including an upper central region positioned between first and second upper end regions, and a lower central region positioned between first and second lower end regions, at least four longitudinally extending seams being formed between the four cover panels, the cover including a plurality of boundary layer trip mechanisms coupled to at least one of the upper and lower central regions, the plurality of trip mechanisms being spaced apart from the longitudinally extending seams, the computational fluid dynamics analysis including first and second analysis configurations, the first analysis configuration conducted on the football with the plurality of boundary layer trip mechanisms, and the second analysis configuration conducted on the football wherein the plurality of boundary layer trip mechanisms are removed, the first and second analysis configurations provide first and second airflow separation lengths, respectively, the first and second airflow separation lengths being measured from the leading one of the first and second ends to first and second airflow separation planes, respectively, each of the first and second airflow separation planes orthogonally extending with respect to the longitudinal dimension, the first and second separation planes positioned at the locations where the airflow in the computational fluid dynamics begins to separate from an outer surface of the cover, the first airflow separation length being at least 2 percent greater than the second airflow separation length; and a lacing coupled to the upper central region of the football, the length of the upper and lower central regions being defined by the length of the lacing with respect to the longitudinal axis. |
