FSX/FS2004 – Junkers D.1 Updated. The Junkers D.I was a WWI German all-metal monoplane fighter. It entered service in 1918 but reports indicate only some 30 were stationed at the Western Front and there are no reports of encounters with Allied aircraft. Some have called it the Me-262 of World War I – the shape of things to come. Several historical and what if skins included.