Surviving the fall
Q: You’re buckled in a helicopter when the hum of the engine disappears from your headset. You feel yourself lift from your seat slightly, and you realize the aircraft is accelerating toward the ground. The pilot moves his hands and feet quickly, but not frantically, as the aircraft turns toward an open field. Near the ground, G-forces push you into your seat, and then the aircraft settles to the ground. What maneuver did the pilot perform to control the descent, and what explains the G-forces?
Draft a response of no more than 250 words and email it by midnight May 7 to firstname.lastname@example.org for a chance to have it published in the June issue.
PUNISHING PITCHERS: We asked you whether hypothetical baseball executives would be right or wrong to think that higher seams on baseballs would make it harder to hit home runs.
Your answers were reviewed by Barton Smith of Utah State University and author of the blog, Baseball Aerodynamics (see posts 36, 38, and 54).
WINNER: As a member of the NCAA Baseball Research Panel, a technical advisory group, we had virtually the same problem, but in reverse. We had decreased the performance of non-wood college bats to the level of wood bats. But home run production had also greatly decreased. Fans and coaches complained. To remedy the situation, and on the basis of careful aerodynamic research, we lowered the seam height of the college ball to match the seam height of major league baseballs. The result: ball aerodynamic drag decreased, hit distance increased, but the ball exit velocity (hit speed) did not change. Player safety is intact, but the game is more exciting.
So, the answer to the question is that, based on the aerodynamic research that has been done and on the results in college baseball, it is very likely that higher seams will increase the drag of the ball and will decrease home run production in major league baseball. There will be an effect on pitch speed, very slightly increasing the time of flight.
Keith Koenig, AIAA senior member
Starkville, Mississippi; email@example.com; Koenig is a professor emeritus of aerospace engineering at Mississippi State University.