Mooney 201 prop

Walking out to my plane yesterday, I had the opportunity to walk
through a number of A/C to get to mine. I passed a Mooney (looked
like a 201) and realized that the width of the prop blades was
significant... It was much wider than my fixed pitch Sensenich,
wider than the blades on the Bonanza sitting next to it. In fact, it
had about the widest blades on the ramp (besides maybe a Navajo and
the turbines). So my question - why?

Blade width should create additional frontal drag. I would think you
would want to minimize that. A 201 has 200hp, so it isn't like it
needs to get several hundred HP transferred to the air.

Since Mooney's sit low, does this mean prop clearance is an issue?
Hence a short prop, hence a fat blade?

Inquiring minds want to know.

Thanks,
Nathan

Since Mooney's sit low, does this mean prop clearance is an issue?
Hence a short prop, hence a fat blade?

You probably have it right.

From my observations, prop design seems to be more of an art than a science.
This topic is very confusing.

An interesting aspect of prop design is not only the chord shape but also
the number of blades. People generally think that more horsepower requires
more blades. But witness the Piper Malibu's two-blader (350 hp) and the
Piper Turbo Seminole's three-blader (180 hp).

Mooney's Ovation was initially sold with a three blade prop but later
changed to a two blade (Ovation 2) and it picked up 8 knots of airspeed.
Evidently this was due to the efficiency gains of the two blade, the same
reason it was chosen for the Malibu.

I believe three bladers are preferred for their reduced vibration, quiter
operation, greater low speed thrust, and appearance. Chord design probably
is the main factor in determining the efficiency of the prop regardless of
the number of blades.

Frankie

Look at the early P-47 Thunderbolt props and their performance.
Then look at the replacement prop and its performance.

Look at the early P-47 Thunderbolt props and their performance.
Then look at the replacement prop and its performance.

....not familiar with this example. Perhaps you could fill us in.

Frankie

Frankie wrote:

...not familiar with this example. Perhaps you could fill us in.

Early P-47s had a fairly typical military prop when they first came out. The
planes were heavy for a single (over 7 tons). They had pretty good high altitude
performance, unbeatable dive characteristics, could take immense amounts of
punishment, but they didn't maneuver well (compared to planes like the Spitfire)
and they guzzled gas. Later in the war, the Thunderbolt was re-equipped with a
prop which had comparatively wide blades -- the pilots called it a
"paddle-blade" prop. Rate-of-climb and maneuverability immediately improved to
the point that a good Jug pilot could out-maneuver a Spitfire. Fuel consumption
also improved a bit. The prop simply made better use of the engine's power.

Not sure this is applicable to the Mooney. I suspect that the short legs on the
Mooney make a short prop necessary, so a paddle blade gets the best results.

Don't forget that a prop is essentially a rotating wing. Increase the width of a
wing and you will increase lift (at the expense of increased drag). When the
wing is your prop, that increased "lift" translates to increased thrust. With
the P-47, the plane had the power to make the increased drag unimportant.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

Specifically, here's the first XP-47 prototype with its conventional
four-blade prop: http://www.warbirdsresourcegroup.org...es/xp47j-1.jpg

And here's the late-war P-47D with the paddle blade prop. Note the cuffs
around the prop roots. http://home.att.net/~historyzone/p-47d-27-re.JPG

"George Patterson" wrote in message
news:qWaOe.2407$SW1.1776@trndny09...
Frankie wrote:

...not familiar with this example. Perhaps you could fill us in.

Early P-47s had a fairly typical military prop when they first came out.
The planes were heavy for a single (over 7 tons). They had pretty good
high altitude performance, unbeatable dive characteristics, could take
immense amounts of punishment, but they didn't maneuver well (compared to
planes like the Spitfire) and they guzzled gas. Later in the war, the
Thunderbolt was re-equipped with a prop which had comparatively wide
blades -- the pilots called it a "paddle-blade" prop. Rate-of-climb and
maneuverability immediately improved to the point that a good Jug pilot
could out-maneuver a Spitfire. Fuel consumption also improved a bit. The
prop simply made better use of the engine's power.

Not sure this is applicable to the Mooney. I suspect that the short legs
on the Mooney make a short prop necessary, so a paddle blade gets the best
results.

Don't forget that a prop is essentially a rotating wing. Increase the
width of a wing and you will increase lift (at the expense of increased
drag). When the wing is your prop, that increased "lift" translates to
increased thrust. With the P-47, the plane had the power to make the
increased drag unimportant.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

George Patterson wrote:
Later in the war, the
Thunderbolt was re-equipped with a prop which had comparatively wide
blades -- the pilots called it a "paddle-blade" prop. Rate-of-climb and
maneuverability immediately improved to the point that a good Jug pilot
could out-maneuver a Spitfire.

How does a prop change make the plane more manuverable?

I don't know about that, I always thought there was a lot of science
behind props. I also drive a Mooney but never noticed my prop having
longer cord than others. However, other than ground clearance (my
Mooney has 13 inches but looks like 2" ) I would imagine that the
cord of the prop would be just like different cord's on wings. Don't
most props include an efficiency index? Perhaps I'm over thinking it
though...

-Robert

One of the reasons that we don't often talk about or compare propeller
efficiency is that almost all modern props score around 82 to 85%
efficiency -- it's very very tough to improve on that. In fact the Wright
brothers did most of the essential design work on props, and one of the
reasons they beat Langley and the Euro experimenters so soundly is that they
built props with 70% efficiency (according to modern testing -- they
themselves thought they had 66%). So the past century has produced only
about a 25% improvement in prop efficiency, and I suspect very little of
that bump has happened since WWII.

See http://www.fluent.com/about/news/new...i2_fall/a2.htm
for a very cool summary of this issue.

Seth
Comanche N8100R

"Robert M. Gary" wrote in message
ups.com...
I don't know about that, I always thought there was a lot of science
behind props. I also drive a Mooney but never noticed my prop having
longer cord than others. However, other than ground clearance (my
Mooney has 13 inches but looks like 2" ) I would imagine that the
cord of the prop would be just like different cord's on wings. Don't
most props include an efficiency index? Perhaps I'm over thinking it
though...

-Robert