In the late-1950s, surplus B-17 Flying Fortresses used in the air-sea rescue role found their way into the hands of civilian fire bomber operations that offered a quantum leap in performance carrying significant loads of fire retardant. Prior to the arrival of the B-17s (and PB4Y-2s), no other civilian fire bomber in use approached the retardant capacity of the converted four-engined bombers. By 1960, the first of about two dozen B-17s were converted with bomb bay retardant tanks.
Stripped of non-essential equipment, the B-17 offered a significant increase in power in the typical-high altitude areas that most forest fires were found. Most of the conversions flew on contracts with the US Forest Service.
The fire bomber B-17s were retired in the late Sixties as aircraft like the Douglas DC-6 were converted for the role. In addition, the radial engines of the B-17s were increasingly difficult to support with spare parts.
One enterprising outfit got around this issue by re-engining their B-17 with four Rolls-Royce Dart turboprops that once belonged to Vickers Viscount. As the Dart engines were much lighter than the Wright Cyclone radials, the nacelles had to be extended far forward to maintain the center of gravity with the spinners being nearly in line with the nose.
Only one B-17, N1304N, was converted in 1970. Some sources indicate that the aircraft had the nickname "Batmobile" and she was so overpowered, that with both outboard engines shut down and feathered and carrying a full retardant load, she was still faster than a stock B-17. When the pilots made their drop, they had to shut down and feather the outboard engines to keep from overspeeding the airframe.
This unique B-17 Flying Fortress was unfortunately lost in the same year it was converted. While fighting a fire near Dubois, WY, the engines lost power due to excessive ingestion of heated air and smoke from the fire and the aircraft failed to pull out of a retardant drop.