A young woman employee of North American Aviation Incorporated, working over the landing gear mechanism of a P-51 fighter plane, Inglewood, California, 1942. (Photo by Alfred T. Palmer/Buyenlarge/Getty Images)

Aerobatic aircrafts fly during a performance at the Airshow Zhengzhou 2017 in Zhengzhou, capital of central China's Henan Province on April 27, 2017. The 5-day air show kicked off in Zhengzhou on Thursday, aiming to build a general aviation gathering center for business and communications. (Photo by Li An/Xinhua via ZUMA Wire)

A US Marine leads two Viet Cong suspects in restraints during the Tet Offensive on February 20, 1967. (Photo by Bettmann Archive/Getty Images)

Bathing suit models are shown listening to the radio on the beach, circa 1940's. (Photo by Bettmann Archive/Getty Images)

An American soldier walks ahead of an MKIV (Mark IV) British-made tank, circa 1918. (Photo by Hulton Archive/Getty Images)

A member of the Air Force's Wings of Blue Parachute Demonstration Team salutes as he jumps out of an aircraft, during the opening ceremony of Aviation Nation 2017 Nellis Air and Space Expo at Nellis Air Force Base, Nev., November 10, 2017. (Photo by Senior Airman Kevin Tanenbaum/Reuters/U.S. Air Force)

Aviator Frantisek Hadrava moves Vampira, an ultralight plane based on the U.S.-design of light planes called Mini-Max, out of a garage in the village of Zdikov, Czech Republic, August 23, 2016. Frantisek thought driving to work for 14 minutes was too much, so he built an plane to cut the commute by half. (Photo by David W. Cerny/Reuters)

A red fox sits in front of a Eurofighter Typhoon combat jet on the grounds of the 2014 ILA Berlin Air Show, in Selchow near Schoenefeld, Germany, Thursday, May 15, 2014. The International Aviation and Aerospace Exhibition ILA will take place from May 20 until May 25, 2014. (Photo by Patrick Pleul/AP Photo/DPA)