Sunday, June 23, 2013
Weight R-3350 engine start-up
video courtesy Aero Telemetry
The Wright R-3350 power plant was the engine of choice by Kelly Johnson of Lockheed. His aim was to provide the most horsepower available for the new L049 Constellation in order to attain maximum load capacity and speed.
Early versions of the R-3350 were equipped with carburetors, though the poorly designed elbow entrance to the supercharger led to serious problems with inconsistent fuel/air distribution. Near the end of World War II, the system was changed to use direct injection where fuel was injected directly into the combustion chamber. This change improved engine reliability. After the war the engine was redesigned, and became a favorite for large aircraft, notably the Lockheed Constellation and Douglas DC-7.
18 cylinders, 2500 horsepower
Following the war, to better serve the civilian market, the Turbo-Compound system was developed to deliver better fuel efficiency and thus economy. In these versions, three power recovery turbines (PRT) were inserted into the exhaust piping of each group of six cylinders and geared to the engine crankshaft by fluid couplings to deliver more power. The PRTs recovered about 20 percent of the exhaust energy (around 450 hp) that would have otherwise been wasted, but reduced engine reliability. The fuel burn for the PRT equipped aircraft was nearly the same as the older Pratt and Whitney R-2800, while producing more horsepower.