Advancement of prop blade in flight, new information

Karl

You are looking at the data wrong.

The rear engine on a 337/0-2 'sucks' air over the wing center section,
increasing lift that the front engine does not generate. With this
increased lift, the bird will climb faster and in general perform
better on rear engine when on single engine.

Data I was given on check out when I flew the 0-2 .

Big John
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On Wed, 18 Aug 2004 12:14:12 -0700, "kage"
wrote:

The rear engine supplies more thrust on a Skymaster.

See:

http://www.skymaster.org.uk/perform.asp


Karl


"Peter Duniho" wrote in message
...
"AJW" wrote in message
...
I agree with some of your observations, but re efficiency -- the
airflow into the loow pressure area around the prop comes from
pretty much everywhere, but the exit flow is directed backwards.
I think props don't get much thrust from 'suck' as opposed to 'push'.

I never said they did. However, an airplane flying 100mph through the air
WILL necessarily have significant flow through the prop from the front.
If
an airframe is in the way of that airflow, it affects the airflow and in
turn the prop.

[...]
Didn't the Skymaster do better with the rear prop, and the Rutan around
the
world airplane?

I don't know much specific about Voyager. I'd say the fact that it was
the
rear engine they used in cruise, not the front, says something about that
particular design. Note, of course, that the rear engine of Voyager was a
smaller engine; it was the one used in cruise for fuel efficiency reasons,
and its location may have been dictated by CG issues or something else,
rather than efficiency per se.

Only Rutan could answer for sure why exactly the lower horsepower engine
was
put at the back, and whether that was a significant issue or not.

As far as the Skymaster goes, everything I've heard about the 337 was that
the rear engine/prop was always a problem. Thrust was worse and the
engine
had cooling problems.

In any case, as I said before, it's not like rear engines are impossible.
There are numbers of aircraft out there flying with rear engines. It's
just
that a rear engine is not the miracle worker one might think it is.

The other issues re having the engine visit the cockpit during a crash
surely bear thinking about.

Certainly a concern, but I'm not aware of any data that indicates
rear-engine aircraft are significantly less crash-worthy. In a crash
where
the engine is likely to actually shift all the way into the cabin, the
cabin
is not likely to have survived the crash in any case, whether the engine
is
in front or the rear.

It's also true that propwash does a good job of keeping the Mooney's
windscreen clear during rain.

This is only a concern during ground operations. In flight, and in fact
quite early in the takeoff run, the relative wind due to the aircraft's
movement is sufficient for keeping the windscreen clear.

Pete