Ron Wanttaja wrote:
On Thu, 13 Dec 2007 21:53:23 +1000, Michael Henry
wrote:

The Wikipedia article on "V Engine" is quite short but it includes this:

"Certain types of V engine have been built as inverted engines,
most commonly for aircraft. Advantages include better visibility
in a single-engined airplane, and lower centre of gravity."

OK, these are two pretty good advantages! There are no disadvantages
listed. So why isn't the Lycoming O-540 or the Continental O-520 an
inverted V?

The practical difference in visibility between an inverted-V and a horizontally
opposed engine is minor, especially when the airplane they're used on has
tricycle gear vs. a taildragger. An inverted-V engine has a significant
visibility advantage over a radial, but they're no longer common in light
aircraft.

Same holds true for the lower CG: The inverted-V is much better than a radial,
but not that much better than the horizontally opposed engine. If you're
speaking of an air-cooled engine, much of the mass is in the crankcase, anyway,
irrespective of which way the cylinders poke.

And as you say: There are no disadvantages *listed* in a short Wikipedia
article. That does not mean there are no disadvantages. Access to the carb and
other elements that mount below the crankcase is probably more awkward; the
spark plugs may be more susceptible to oil fouling. For that matter, the
inverted-V may have the same problems with hydro lock as a radial...probably in
itself enough of a reason to favor horizontally opposed.

Ron Wanttaja
Is this thread dead yet?

Actually, there is a real structural advantage to the flat engine over
the V. The block can be lighter in the opposed configuration, for the
same strength.

Charlie