Plenty of hot air

April 2021

Q. Our fictional slugger who fell just a vote short of the Hall of Fame was once asked to ruminate about the physics of the long ball: “Well, just like saltwater is denser than freshwater, cold air is denser than warm air. We all know it’s easier to swim in saltwater, and it’s kind of like that with a baseball in the cold air. You hit it out toward the fence and let it swim on a cushion of cold air right into the stands. I never believed that the ball carries better on hot days, even if the humidity gives some lift. Those were my days off.” Was our slugger on his physics game or did he miss his chance at the Hall of Fame?

Draft a response of no more than 250 words and email it by noon Eastern April 12 to aeropuzzler@aiaa.org for a chance to have it published in the May issue.

RIGHT STUFF FOR WRIGHT BROTHERS: We asked you why the Wright brothers would be interested in talking to Bob Gilruth in Langley, Virginia, in 1941.

WINNER: In 1941 Gilruth was working for NACA at Langley, where he performed flight research. His research led to NACA Report R755, Requirements for Satisfactory Flying Qualities of an Airplane, published in 1941, in which he defined a set of requirements for the handling characteristics of an aircraft. Until this point, no set of guidelines for pilots and aircraft designers existed. In an interview [for an oral history project at the National Air and Space Museum], he explained: “Of course the way you define it is, you have to be not only able to go to the extremes of the envelope of flight, but you have to be able to do it with precision. You have to be able to make that airplane go exactly the way you want it, point the way you want, which means you’ve got to have not only the ability to go to the boundaries of the envelope, but go there with precision. To do it just the way you want it, that means a very high degree of control, and in order to get that you have to have the right kind of force per g and the right kind of variation of parameters, which is what I tried to put into my requirements.” The Wright brothers, never having taken flight and having no idea what to expect, took flight to find out in a few desperate minutes if they could fly. As they sat in the seat thinking through the controls for their first flight, the data from Gilruth would have been invaluable.

Kevin Burns, AIAA associate fellow
San Diego
kevinrobburns@gmail.com