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Prop choice

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naumuk(at)windstream.net
Guest

Posted: Tue Dec 22, 2009 3:25 pm Post subject: Prop choice

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%

   [quote][b]

larry(at)macsmachine.com
Guest

Posted: Wed Dec 23, 2009 7:03 am Post subject: Prop choice

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:

 	  Quote: 	
		   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%

 *



 *

z601c(at)anemicaardvark.c
Guest

Posted: Wed Dec 23, 2009 7:52 am Post subject: 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.



I'm out of my area of expertise, but intuitively, it sounds right.



On Wednesday 23 December 2009 09:01, LarryMcFarland wrote:

 	  Quote: 	
		   



 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.

=============================================

jaybannist(at)cs.com
Guest

Posted: Wed Dec 23, 2009 9:04 am Post subject: 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

 

   

 

   

 

  --

craig(at)craigandjean.com
Guest

Posted: Wed Dec 23, 2009 10:51 am Post subject: Prop choice

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/everel.htm



--  Craig

   From: owner-zenith-list-server(at)matronics.com  [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of  jaybannist(at)cs.com

Sent: Wednesday, December 23, 2009 8:25  AM

To: zenith-list(at)matronics.com

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.



 	  Quote: 	
		  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(at)anemicaardvark.com>

To:  zenith-list(at)matronics.com

Sent: Wed, Dec 23, 2009 10:01 am

Subject: Re:  Prop choice



  	  Quote: 	
		  --> Zenith-List message posted by: Jim Belcher <z601c(at)anemicaardvark.com (z601c(at)anemicaardvark.com)>



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.

	




[quote]



href="http://www.aeroelectric.com">www.aeroelectric.com

href="http://www.buildersbooks.com">www.buildersbooks.com

href="http://www.homebuilthelp.com">www.homebuilthelp.com

href="http://www.howtocrimp.com">www.howtocrimp.com

href="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?Zenith-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com



[b]

jonbateman(at)HOTMAIL.COM
Guest

Posted: Wed Dec 23, 2009 10:52 am Post subject: Prop choice

 On my first plane I had a 3 blade in-flight adjust IVO prop. It did two things 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 behind a Rotax 503 it didn't sound as much as a flying lawnmower. My 601XL is going to be powered by a Lyc. O-290D. I know it is a little heavy but I can change out a few heavy items Prop C starter C alt. and mags and loose a lot of weight. I am tossing around either a three blade warp or 2 blade Ed Strerba wood prop. I have a freind that has owned two Sterba props on both a Soneri and Thorpe. He can't say enough good about them and plans it for his next project 

  

    Jon Bateman

 

  To: zenith-list(at)matronics.com

Subject: Re: Prop choice

Date: Wed C 23 Dec 2009 11:24:49 -0500

From: jaybannist(at)cs.com



 Jim C



I'm not an aerodynamicist either C but I've been told the exact opposite --  that is that the most efficient propeller has only one blade (counterbalanced C of course) C and that two blades are more efficient than three.  Those big ole' warbirds nearly always had four C but I think that was to take advantage of the available power while respecting maximum blade length.



 	  Quote: 	
		  From what I see C I think a lot of it has to do with whether the propeller is ducted or not.  Obviously C ducted fans and turbojet engines have many C many blades.  I have to believe that must be for a very good reason.  


	


Jay Bannister



 



 



 --

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Dec 23, 2009 10:52 am Post subject: Prop choice

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(at)cs.com wrote:



 	  Quote: 	
		   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.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Dec 23, 2009 10:53 am Post subject: Prop choice

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.



 	  Quote: 	
		   

 

 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.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

z601c(at)anemicaardvark.c
Guest

Posted: Wed Dec 23, 2009 10:53 am Post subject: Prop choice

On Wednesday 23 December 2009 10:24, jaybannist(at)cs.com wrote:

 	  Quote: 	
		    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.

=============================================

n801bh(at)netzero.com
Guest

Posted: Wed Dec 23, 2009 12:26 pm Post subject: Prop choice

One blade is optimum,, two is faster, three is ALOT smoother,,,, Pick your poison. 

do not archive



Ben Haas

N801BH

www.haaspowerair.com



--------

carlossa52(at)gmail.com
Guest

Posted: Wed Dec 23, 2009 1:25 pm Post subject: Prop choice

There's an interesting overview of this subject here:

[url=http://www.gnrtr.com/Generator.html?pi 11&cp=3]http://www.gnrtr.com/Generator.html?pi 11&cp=3[/url]

Carlos

  [quote][b]

klaus(at)utdallas.edu
Guest

Posted: Wed Dec 23, 2009 3:02 pm Post subject: Prop choice

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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