With Andre’ Borschberg recuperating in Switzerland, Bertrand Piccard flew Solar Impulse 2 on the last leg of its China stay, making a 17 hour, 22 minute, 1,344 kilometer (725.7 nautical mile) flight between Chongquing and Nanjing. The plane is being readied for its biggest leap so far, from Nanjing to Hawaii, a five-day mission that will test the endurance of the pilot and all systems of the giant ultralight aircraft. The Star, a Malaysian newspaper, reported what could be a growing concern. “’Can we make the pilot sustainable as well?’ Andre Borschberg said by video link from Switzerland, where he is receiving treatment for health problems.” He described his problems as “shingles,” with frequent migraines, both painful inflictions. “’This will be the human challenge when we tackle the next leg,’ he told an audience of reporters.” Borschberg is scheduled to rejoin the airplane in Nanjing, where he and Piccard will plan the Pacific crossing. This may be a greater issue …