Question: The Walter HWK 109-509 powered the first piloted aircraft of any type to exceed how many MPH in level flight?
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