Let's introduce a little context, shall we?
When the Devastator was designed and entered service it was the most advanced torpedo
bomber in the world, bar none. The aircraft was ordered in 1934, first flight 15 April, 1935,
production began February 1936, first delivery June 1937, service entry was November 1937.
The fact that it was still in service five years later, and actually acquitted itself fairly well, is down to
USN and pre-war procurement realities, and the basic soundness of the design.
A the time of the Pearl Harbor attack sixty-nine TBDs were assigned to operational squadrons and
another thirty-one were in second line units undergoing overhaul. That was the total extent of
USN torpedo aircraft strength, everybody was waiting for the TBF, so the USN went to war with
what they had.
Yes, a different, more powerful dash number of R-1830 would have helped, but, re-engining is
not as simple as modellers think. The -64 of the TBD was 55.5 inches long, the -86 of the F4F-3,4,7
was 67.44 inches long. So you need to find twelve inches in the nose, or do a major rearrangement
of existing components. Frankly, an R-2600 is out of the picture, as it's not only longer it's also
seven inches larger in diameter and much heavier, over 2000 lbs (as used in TBF) versus 1295 for
the R1830-64 of the TBD.
The corrugated skin added strength without increasing weight, and was a necessary compromise
in the period, the small amount of added drag being considered the lesser of two evils.
Douglas had proposed a larger follow on aircraft in 1939 with an R-2600 and tricycle gear.
