Final answer:
The question about the maximum thickness of a packed automatic back parachute cannot be answered with the provided information, as it does not specify any details about the packed dimensions of parachutes. However, the information does discuss the role of mass, terminal velocity, and drag coefficient in parachute design and function.
Step-by-step explanation:
The maximum thickness of a packed automatic back parachute is not specified in the supplied information. Parachutes are carefully engineered to balance functionality, safety, and packability. Key factors that influence parachute design include the mass of the skydiver, the terminal velocity, and the drag coefficient. The dimensions and specifications of the parachute must also comply with safety regulations imposed by aviation authorities.
In the context provided, we can observe that a skydiver's terminal velocity is significantly reduced once the parachute is deployed. For a 75-kg skydiver, a headfirst fall can yield a terminal velocity of about 350 km/h, which reduces to about 200 km/h in a spread-eagle position. Upon parachute deployment, the velocity decreases even further due to the increased drag.
While the question does not provide the specific details needed to calculate the maximum packed thickness of a parachute, understanding the principles of skydiving and parachute design, which include drag coefficients and terminal velocities, is essential for any approach to parachute engineering.