The US-made fifth-generation F-35 warplane reportedly continues to face a raft of mechanical issues, although it has been developed for several decades with a budget of over $1 trillion. The German radar-maker Hensoldt has claimed that it managed to track two US stealth fighter jets F-35 from a pony farm for almost 100 miles (about 150 kilometres) during an air show, the website C4ISRNet reports.