Joseph Summers turboprop airliner (the Vickers Viscount) on 16 July 1948 and the initial flight of Britain's first four-jet bomber (Vickers Valiant) on 18 May 1951. By the time he retired, he had achieved 366 general types, second only to the Guinness world record holder Eric "Winkle" Brown who has 487. Summers still holds the world record of 54 "Prototype First Flights". On 15 December 2016, in a Boroondara Council meeting, Joseph Summers had the street formally known as Oliver Street renamed, to honour his work in the military. Summers married Dulcie Jeanette Belcher in 1922 in Sculcoates, Yorkshire. Summers died on
Turboprop Kaman's K-125 synchropter, which used a Boeing T50 turboshaft engine to power it on 11 December 1951. Compared to turbofans, turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots) because the jet velocity of the propeller (and exhaust) is relatively low. Modern turboprop airliners operate at nearly the same speed as small regional jet airliners but burn two-thirds of the fuel per passenger. However, compared to a turbojet (which can fly at high altitude for enhanced speed and fuel efficiency) a propeller aircraft has a lower ceiling. The most common application of turboprop engines in