Today's Message Index:
----------------------
1. 07:03 AM - Re: Prop choice (LarryMcFarland)
2. 07:52 AM - Re: Prop choice (Jim Belcher)
3. 09:04 AM - Re: Prop choice (jaybannist@cs.com)
4. 10:51 AM - Re: Prop choice (Craig Payne)
5. 10:52 AM - Re: Prop choice (Jon Bateman)
6. 10:52 AM - Re: Prop choice (Bryan Martin)
7. 10:53 AM - Re: Prop choice (Bryan Martin)
8. 10:53 AM - Re: Prop choice (Jim Belcher)
9. 12:26 PM - Re: Prop choice (n801bh@netzero.com)
10. 01:25 PM - Re: Prop choice (Carlos Sa)
11. 03:02 PM - Re: Prop choice (Klaus Truemper)
Message 1
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Hi Bill,
70-inch, 3-blade, Warp Drive, 17-degree pitch, 130-mph.
Best advantage of the Warp Drive prop is being able to adjust from
15-degrees for learning to fly the plane, then progressively
adjust the pitch thru 16, and 17 degrees for a best cruise of 120 or
so. I think 3 blades are smoother and quieter. 2-blades are reported
to be more efficient, but if you pick the wrong pitch, it can be an
expensive mistake.
Larry McFarland 601HDS at www.macsmachine.com
Bill Naumuk wrote:
> All-
> I'm interested in hearing about your prop choices for HDSs
> (Corvair or 100hp), size, type, pitch and performance. Thanks, and
> Merry Christmas!
> Bill Naumuk
> Townville, Pa.
> HDS N601MG/Corvair 95%
> *
>
> *
Message 2
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Larry, I'm not an aerodynamicist, but I was once told by one that the most
efficient number of blades was an infinite number. In other words, all other
things being equal, the more blades the better. I would suspect weight
eventually catches up with the advantage gained.
I'm out of my area of expertise, but intuitively, it sounds right.
On Wednesday 23 December 2009 09:01, LarryMcFarland wrote:
>
> Hi Bill,
> 70-inch, 3-blade, Warp Drive, 17-degree pitch, 130-mph.
> Best advantage of the Warp Drive prop is being able to adjust from
> 15-degrees for learning to fly the plane, then progressively
> adjust the pitch thru 16, and 17 degrees for a best cruise of 120 or
> so. I think 3 blades are smoother and quieter. 2-blades are reported
> to be more efficient, but if you pick the wrong pitch, it can be an
> expensive mistake.
>
> Larry McFarland 601HDS at www.macsmachine.com
>
> Bill Naumuk wrote:
> > All-
> > I'm interested in hearing about your prop choices for HDSs
> > (Corvair or 100hp), size, type, pitch and performance. Thanks, and
> > Merry Christmas!
> > Bill Naumuk
> > Townville, Pa.
> > HDS N601MG/Corvair 95%
> > *
> >
> > *
>
--
============================================
Do not archive.
============================================
Jim B Belcher
BS, MS Physics, Math, Computer Science
A&P/IA
Retired aerospace technical manager
Mathematics and alcohol do not mix.
Do not drink and derive.
============================================
Message 3
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Jim,
I'm not an aerodynamicist either, but I've been told the exact opposite --
that is that the most efficient propeller has only one blade (counterbal
anced, of course), and that two blades are more efficient than three. Tho
se big ole' warbirds nearly always had four, but I think that was to take
advantage of the available power while respecting maximum blade length.
>From what I see, I think a lot of it has to do with whether the propeller
is ducted or not. Obviously, ducted fans and turbojet engines have many,
many blades. I have to believe that must be for a very good reason.
Jay Bannister
-----Original Message-----
From: Jim Belcher <z601c@anemicaardvark.com>
Sent: Wed, Dec 23, 2009 10:01 am
Subject: Re: Zenith-List: Prop choice
Larry, I'm not an aerodynamicist, but I was once told by one that the most
efficient number of blades was an infinite number. In other words, all oth
er
things being equal, the more blades the better. I would suspect weight
eventually catches up with the advantage gained.
Message 4
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Actually there was a one bladed prop patented, built and sold in the 30's
and 40's. I believe the idea is to minimize the turbulence that the blade
see from the upstream blade.
Here are some pictures and original articles on the Everel single bladed
prop:
<http://www.notplanejane.com/aeromatic.htm>
http://www.notplanejane.com/aeromatic.htm
<http://www.notplanejane.com/everel.htm>
http://www.notplanejane.com/everel.htm
-- Craig
_____
From: owner-zenith-list-server@matronics.com
[mailto:owner-zenith-list-server@matronics.com] On Behalf Of
jaybannist@cs.com
Sent: Wednesday, December 23, 2009 8:25 AM
Subject: Re: Zenith-List: Prop choice
Jim,
I'm not an aerodynamicist either, but I've been told the exact opposite --
that is that the most efficient propeller has only one blade
(counterbalanced, of course), and that two blades are more efficient than
three. Those big ole' warbirds nearly always had four, but I think that was
to take advantage of the available power while respecting maximum blade
length.
>From what I see, I think a lot of it has to do with whether the propeller
is ducted or not. Obviously, ducted fans and turbojet engines have many,
many blades. I have to believe that must be for a very good reason.
Jay Bannister
-----Original Message-----
From: Jim Belcher <z601c@anemicaardvark.com>
Sent: Wed, Dec 23, 2009 10:01 am
Subject: Re: Zenith-List: Prop choice
Larry, I'm not an aerodynamicist, but I was once told by one that the most
efficient number of blades was an infinite number. In other words, all other
things being equal, the more blades the better. I would suspect weight
eventually catches up with the advantage gained.
Message 5
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On my first plane I had a 3 blade in-flight adjust IVO prop. It did two th
ings for me. It was quieter and had better prop to ground clearence. After
100 hours I changed it to two blades for better performance. Also running b
ehind a Rotax 503 it didn't sound as much as a flying lawnmower. My 601XL i
s going to be powered by a Lyc. O-290D. I know it is a little heavy but I c
an change out a few heavy items Prop=2C starter=2C alt. and mags and loose
a lot of weight. I am tossing around either a three blade warp or 2 blade E
d Strerba wood prop. I have a freind that has owned two Sterba props on bot
h a Soneri and Thorpe. He can't say enough good about them and plans it for
his next project
Jon Bateman
Subject: Re: Zenith-List: Prop choice
From: jaybannist@cs.com
Jim=2C
I'm not an aerodynamicist either=2C but I've been told the exact opposite -
- that is that the most efficient propeller has only one blade (counterbal
anced=2C of course)=2C and that two blades are more efficient than three.
Those big ole' warbirds nearly always had four=2C but I think that was to t
ake advantage of the available power while respecting maximum blade length.
>From what I see=2C I think a lot of it has to do with whether the propelle
r is ducted or not. Obviously=2C ducted fans and turbojet engines have man
y=2C many blades. I have to believe that must be for a very good reason.
Jay Bannister
-----Original Message-----
From: Jim Belcher <z601c@anemicaardvark.com>
Sent: Wed=2C Dec 23=2C 2009 10:01 am
Subject: Re: Zenith-List: Prop choice
Larry=2C I'm not an aerodynamicist=2C but I was once told by one that the m
ost
efficient number of blades was an infinite number. In other words=2C all ot
her
things being equal=2C the more blades the better. I would suspect weight
eventually catches up with the advantage gained.
_________________________________________________________________
Hotmail: Trusted email with Microsoft=92s powerful SPAM protection.
Message 6
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Most turbofan engines, which are basically a gas turbine running a ducted fan,
are producing thousands of horsepower. They need all those blades to make use
of all that power. On a turbo jet engine, on the other hand, the blades you see
in the intake have little to do directly with producing thrust, they just compress
the air for the combustion process. The jet exhaust produces all the thrust.
Pure turbojets aren't used much anymore, most "jet" aircraft use turbofans.
On Dec 23, 2009, at 11:24 AM, jaybannist@cs.com wrote:
> Jim,
>
> I'm not an aerodynamicist either, but I've been told the exact opposite -- that
is that the most efficient propeller has only one blade (counterbalanced,
of course), and that two blades are more efficient than three. Those big ole'
warbirds nearly always had four, but I think that was to take advantage of the
available power while respecting maximum blade length.
>
> >From what I see, I think a lot of it has to do with whether the propeller is
ducted or not. Obviously, ducted fans and turbojet engines have many, many blades.
I have to believe that must be for a very good reason.
>
> Jay Bannister
--
Bryan Martin, BSAE
N61BM, CH 601 XL,
RAM Subaru, Stratus redrive.
do not archive.
Message 7
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Actually, the most efficient number of blades on a propellor is one. The more blades
you have, the lower the overall efficiency. A single blade prop with a counterweight
has actually been used on some aircraft. There is a recent self launching
glider that uses one, the prop is designed to be folded back inside the
fuselage while soaring. Of course, this is a very low power application. Two
bladed props are the norm for small aircraft because it's the easier to implement.
Instead of engineering a counterweight to counteract the forces of one
blade, you just use two identical blades. It's also minimum number of blades that
eliminates the off-center thrust of a single blade, so it runs smoother.
The main reason multi-bladed props are used is that, with more powerful engines
it gets tough to get the prop to absorb the extra power and still have adequate
ground clearance unless you add blades. A three blade prop can absorb the same
power as a much longer two blade prop. Another reason for using a three blade
prop where a two blade prop will do is that the three blade prop will run
smoother and can greatly reduce propellor noise. Some aircraft make a gawd-awful
racket on takeoff with a two blade prop due to sonic effects at the tips. Using
a shorter three blade prop can greatly reduce the noise and keep the neighbors
happier. And some people think a three blade prop just looks cooler.
>
> Larry, I'm not an aerodynamicist, but I was once told by one that the most
> efficient number of blades was an infinite number. In other words, all other
> things being equal, the more blades the better. I would suspect weight
> eventually catches up with the advantage gained.
>
> I'm out of my area of expertise, but intuitively, it sounds right.
>
--
Bryan Martin
N61BM, CH 601 XL,
RAM Subaru, Stratus redrive.
do not archive.
Message 8
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On Wednesday 23 December 2009 10:24, jaybannist@cs.com wrote:
> Jim,
>
> I'm not an aerodynamicist either, but I've been told the exact opposite --
> that is that the most efficient propeller has only one blade
> (counterbalanced, of course), and that two blades are more efficient than
> three. Those big ole' warbirds nearly always had four, but I think that
> was to take advantage of the available power while respecting maximum blade
> length.
It has little to do with Zeniths, but Piper once tried a single blade prop on
the J3 with a couterweight. Their reasoning was yours: a single blade would
be better. For whatever reasons, things didn't work out. I doubt any of those
J3s survive today.
--
============================================
Do not archive.
============================================
Jim B Belcher
BS, MS Physics, Math, Computer Science
A&P/IA
Retired aerospace technical manager
Mathematics and alcohol do not mix.
Do not drink and derive.
============================================
Message 9
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One blade is optimum,, two is faster, three is ALOT smoother,,,, Pick yo
ur poison.
do not archive
Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: Jim Belcher <z601c@anemicaardvark.com>
Subject: Re: Zenith-List: Prop choice
>
Larry, I'm not an aerodynamicist, but I was once told by one that the mo
st
efficient number of blades was an infinite number. In other words, all o
ther
things being equal, the more blades the better. I would suspect weight
eventually catches up with the advantage gained.
I'm out of my area of expertise, but intuitively, it sounds right.
On Wednesday 23 December 2009 09:01, LarryMcFarland wrote:
om>
>
> Hi Bill,
> 70-inch, 3-blade, Warp Drive, 17-degree pitch, 130-mph.
> Best advantage of the Warp Drive prop is being able to adjust from
> 15-degrees for learning to fly the plane, then progressively
> adjust the pitch thru 16, and 17 degrees for a best cruise of 120 or
> so. I think 3 blades are smoother and quieter. 2-blades are reported
> to be more efficient, but if you pick the wrong pitch, it can be an
> expensive mistake.
>
> Larry McFarland 601HDS at www.macsmachine.com
>
> Bill Naumuk wrote:
> > All-
> > I'm interested in hearing about your prop choices for HDSs
> > (Corvair or 100hp), size, type, pitch and performance. Thanks, and
> > Merry Christmas!
> > Bill Naumuk
> > Townville, Pa.
> > HDS N601MG/Corvair 95%
> > *
> >
> > *
>
--
========================
====================
Do not archive.
========================
====================
Jim B Belcher
BS, MS Physics, Math, Computer Science
A&P/IA
Retired aerospace technical manager
Mathematics and alcohol do not mix.
Do not drink and derive.
========================
====================
========================
===========
========================
===========
========================
===========
========================
===========
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Message 10
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There's an interesting overview of this subject here:
http://www.gnrtr.com/Generator.html?pi=211&cp=3
Carlos
Message 11
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Hi,
Recently I replaced the original 3-blade GSC propeller with a
2-blade composite Sensenich propeller. Both propellers are ground
adjustable,
but the Sensenich propeller is substantially more efficient. Pictures and
preliminary flight data are on the website
http://www.utdallas.edu/~klaus/Airplane/airplane.html
At 5400 rpm of the 80 hp Rotax, having done 1220+ hrs, the 601HDS
achieves 115kts = 132 mph. This with a climb setting, where max rpm in level
flight is somewhere between 5500 and 5600 rpm.
Adjustment of the Sensenich propeller is very easy since a center delrin
piece assures symmetric adjustment of the two blades, just the way
a constant speed prop does though not with delrin material.
Finally, the blades are extremely light, which is a big advantage for
geared engines.
Happy flying,
Klaus
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