On Mon, 05 Apr 2004 12:27:26 GMT, "Charles S"
wrote:

I apologize for posting this 'non-home built' question here.
But I believe here is where I am most likely to discover the answer.
My question involves how the Germans in WWII fired cannon through the
propeller hub of V-12 engines.
I cannot see how this is accomplished, since to my knowledge there were no
gear reduction units on these planes..
I can only suppose that the diameter of the 'throw' journal was large
enough,
that it always included the centerline of the crankshaft. This would be a
hugh diameter.
Thus a hole bored through the centerline of the crank,
would also be through each 'throw' journal. Thereby making a continous
bore,
with no exposure to the crankcase.
This seems unlikely, as it would add tremendous amount of weight to an
engine.
And, those ME-109 cranks I have seen on TV do not seem to have that feature.

So, I am still confused.
Again, sorry about posting here, and thanks.


Ah but your premise is wrong: ALL high performance WWII military
engines used gear reduction to swing the props. That includes the
radials and the inline liquid cooled engines.

The Bf 109 used a Daimler Benze DB601 2,070 cubic inch displacement,
fuel injected inverted engine. The canon used in the models F and G
but not the E used during the Battle of Britain, nestled between the
banks of the inverted V12 and fired through the hollow gear that spun
the prop. It wasn't a terrific idea but given that the wings were
never designed to handle canon within the airfoil (The Bf 109 was
designed in 1935 when most fighters used machine guns mounted in their
nose and Messerschmitt did not want to spoil his wings with wing
mounted armaments). So he designed them very thin. The wing design
proved difficult to put canon into which is why you see canon mounted
on blisters under them, rather than in them.

Corky Scott

PS, google Bf 109 and you'll find lots of information.