Big radial engines in full song!
Super Constellation take off at dusk.
R-3350s are each fitted with three power recovery turbines (PRTs). Each shrouded PRT is turned by the exhaust of six cylinders and transfers its energy back to the main crankshaft through a fluid coupling, thereby recovering what would otherwise be wasted energy. At take-off, each PRT contributes up to 150hp, adding around 450hp per engine on takeoff. The actual exhaust stacks are only about 2 feet long, hence the unburned fuel/flames out the stacks under full power, which was 59.5 inHg and 3,400 horsepower with 115/145 gasoline. Since 115/145 is no longer available, my understanding is they have derated the engines to something in the 2800 horsepower range and lower pressures.
In this picture, the item circled in red is the actual short stack on an R-3350 installed on a Connie. The lower stack is removed for maintenance apparently…