F4U inverted gull wings

In article ,
Steve Hix writes:
In article ,
Orval Fairbairn wrote:

They wanted to keep the main landing gear as short as possible, to
simplify structural loads. The Hellcat had a relatively long main gear
leg.

A four-bladed prop for the same power output should be shorter than the
three-bladed equivalent.

But somewhat less efficient. Each blade added to a propeller knocks
the efficiency down. Later model Corsairs with the more powerful
R2800 'C' series engines had a 4 blade prop, but the diameter is
essentially the same - 13 ' 2".

You also have to tune 'J', the Advance Ratio of the propeller (A
product of propeller rotational speed, propeller diameter, and the
forward velocity of the propeller (and the airplane it's attached
to.) in order to get teh best performance. reducing the diameter for
a given horsepower may have beneficial effects at high speed, but
severely affect the propeller's performance below, say, about 350 mph.

It's all a balancing act - but in ggeneral, you're best off going with
the largest diameter propeller with the fewest number of blades that
you can practically manage.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster
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