The Reichsluftfahrtministerium (RLM, or Reich Aviation Ministry) first learned of the American B-29 Superfortress heavy bomber in late 1942. Serious concerns as to B-29 capability developed in early 1944, when YB-29 "Hobo Queen" made a well-publicised appearance at RAF Bovingdon, which had been cryptically hinted-at in an American-published Sternenbanner German language propaganda leaflet from Leap Year Day in 1944, meant to be circulated within the Reich.[1]