Question: What is the name of a German rocket-powered fighter aircraft designed by Alexander Lippisch, the original version being the first to exceed 1000km/h and the subsequent version, known as the Me 263 Scholle having had 3 prototypes, non of which were ever flown?
Sentence (from "Messerschmitt Me 163 Komet"): Designed by Alexander Lippisch, it is the only rocket-powered fighter aircraft ever to have been operational and the first piloted aircraft of any type to exceed 1000 km/h (621 mph) in level flight.
Relevant evidence: Yes