Batter up

April 2020

Q: Suppose Major League Baseball executives are considering raising the average seam height on the baseballs thrown to Houston Astros hitters as a punishment for their stealing pitch signs in the 2017 and 2018 seasons. The executives believe higher seams will increase drag and make it harder for the Astros to hit home runs. Explain why they are right or wrong.

Draft a response of no more than 250 words and email it by midnight April 9 to aeropuzzler@aiaa.org for a chance to have it published in the May issue.

FUEL EFFICIENCY: Climate scientists are returning home after delivering a presentation about cirrus clouds. The pilot announces, “Ah, folks, we’re taking the shortest possible route from Washington Dulles to Vienna this afternoon, so sit back and relax, knowing we’ve done all we can to reduce this flight’s climate impact.” The scientists let out a collective groan. Why?

WINNER: The climate scientists groaned, because they were well aware of the North Polar Jet Stream. Taking the shortest geographic route might seem like a good idea to shorten a flight and burn less fuel, but that assumes the atmosphere is stagnant. Solar-powered convection and the Coriolis force created by our spinning planet lead to powerful currents that flow at speeds of 180 km/hr on average, and have been measured at up to 400 km/hr. The North Polar Jetstream, one of the most powerful jets, flows east around 60° N latitude at 9-12 km altitude — where passenger jets typically fly — and is often used by airlines to provide a massive tailwind to eastbound flights. While a direct flight would travel less distance, were a plane to hitch a ride on the jet stream, it would cross the Atlantic in far less time and use less fuel.

Jeffrey J. Mach
Santa Clara, California
Mach works for Sierra Lobo Inc. as a site manager at the
thermophysics facilities branch of NASA’s Ames Research Center.