The Revolution Will Not Be Televised wrote:

On Wed, 23 Jul 2003 13:49:11 +0100, John Halliwell
wrote:

They evolved that way, from roughly similar airframes as a starting
point. Lancasters flying by day would soon develop heavier armour,
especially around the engines, less bombload in exchange for more fuel
to burn for higher height on the ingress route, and heavier armament
like .50 calibres in the rear turret - all of which they were adopting
by 1945, which cut into their bombload margin over the B-17.

Interesting point, any sources for this. I haven't heard about
increasing armour for daylight ops, or trading bomb load for fuel.

Look at the trend evident in the Rose turreted B.1/B.IIIs, and the
engine installation in the Lanc IV which directly influenced the
Lincoln (two-stage Merlins with armoured, annular radiators), let
alone the massively increased armament in the Lincoln (e.g. twin 20mm
Hispanos in the mid-upper turret). The only way to get more fuel in
the Lanc for Tiger Force operations was in the bomb-bay, which had
obvious implications for the bombload carried. This just represents a
gradual and evolutionary change in operational emphasis.

snip

The 50s in the rear turrets were IIRC fitted only as a pair instead of
the quad 303s.

Sure, but this still represented an increase in effectiveness at
daylight engagement ranges.

And let's remember that each .50 weighed 65 lb., while each .303 weighed 24
lb. As a perfect example of the apples to oranges comparison I'm talking
about, the 8 .303s carried by the typical Lanc weigh a total of 192 lb.
while the 13 .50s carried by the typical (in late '43) B-17G weigh 845 lb.
Oops, there goes 653 lb. of bombs/fuel right there, and then we've got to
carry extra fuel to haul that extra weight back from the target. And we're
ignoring the extra weight and drag of a ball turret and waist guns plus the
gunners and their equipment, which means carrying extra fuel to haul all
this extra weight both ways, which the night bombers didn't have).

Guy