It looks beat-up because it’s not so easy to keep a B-29 in flying order. The original Curtiss-Wright R-3350 engines were 1940s-era turbo/supercharged radials, and finding components to repair them was a full-time job. “In 2006 we had just overhauled our last serviceable spare,” flight engineer Don Obreiter told us as we stared up at the exhaust-smudged nacelles. “It came with a five-hour warranty, and in our sixth hour of break-in time we had a failure.” The plane’s crew chief had the idea to create hybrid replacement engines, not in the electric/gas way, but from a mix of parts from later 1950s Skyraider and Boxcar engines, supercharged only, and much easier to repair and maintain. Each engine has a 13.5-inch-diameter supercharger impeller driven off the back end of the crank and spinning at 6.45 times the crankshaft rpm. Originally fuel injected, they have been retrofitted with Bendix PR-58 pressure-injected carburetors. Sometimes, you just can’t beat a carb. The 18-cylinder engines are made of steel and magnesium, with a bore of 6.125 inches, stroke of 6.312 inches, displacement of 3,347 cubic inches and a dry weight of 2,670 pounds.
Here’s a pretty nifty article on some of the tricks and cheats CAF has to go through to keep FiFi flying. I’m not a gearhead, so some of it goes right over my head.
But the last part of the article talks about the challenge of the APU. Which, it was, if memory serves, an APU fire that caused the loss of Kee-Bird in Greenland.