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captainron1(at)cox.net
Guest

Posted: Mon Jun 01, 2009 12:22 pm Post subject: WRT M3X prop boom measurements.

Hi Brad 

We got quite a List with a big library of pictures. If you need info on the Suzuki you can find it at FlyGeo(at)yahoogroups.com



One of the moderators will approve you pretty quick. Have fun and post any questions that you can think of we have some very apt people there about the motor, and even two fellows that will sell you the whole motor package for the Kolb. If you got the money that's probably the best route to go.

You could go back and review the libraries, all the posts are there. I think we have discussed that motor and the different types in great detail. Bob B can correct me but I think the latest motor that is consensus recommended for the big Kolbs is the 1.3l 16V SOHC from the 2000 Model Geo / Sprint. The little Kolbs can probably do fine with the 1. ltr Suzi motor. 

I am sure that pictures of my motor mount are already there but the latest batch has the final configuration with all the bracing that I felt were needed.



I will post my most recent photos today sometime there.



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



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

---- Brad Stump <sky-king(at)inbox.com> wrote: 



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




Hay Ron,Iam thinking about starting to work on a Suzuki 1.3 non turbo to replace my Hirth by some time next year.Would like to see any pics as you progress..Thanks



[quote] --

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Mon Jun 01, 2009 3:47 pm Post subject: WRT M3X prop boom measurements.

At 01:10 PM 6/1/2009, Ron  (at)  KFHU wrote:



 	  Quote: 	
		  My intent was to dissuade others from the notion that a prop is a reaction 

motor such as a rocket, i.e. throwing a mass backwards to cause Newton's 

law of equal reaction.  


	


A prop is not a rocket in that the mass originates in a rocket, but the 

prop does accelerate aft the air passing through it, and Newton's law of 

reaction says that the force exerted in pushing the air back is equal to 

the force the air exerts pushing the prop forward.  Thrust is equal to the 

mass flow times the velocity change, as I said.



I'm not idly speculating... I kinda had to study this stuff when I was 

earning my aerospace engineering degree...



 	  Quote: 	
		  Anyway I am chuckling here thinking that drinking a Heineken after a long 

day and then posting something of a serious nature does not really further 

the cause of science.


	


OK, I'm done with science/engineering for tonight too... don't care for 

Heineken, think I'll go open an Anchor Steam.



-Dana

--

  The greatest threat to western civilization are people whose fear of 

other people's liberty exceeds the love of their own.

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Mon Jun 01, 2009 4:42 pm Post subject: Re: WRT M3X prop boom measurements.

Captain Ron,



It would be a rather expensive test that will surely have poor results.  Lots of prop testing has been done on Kolbs, and lots of other planes by Warp Drive,  Power Fin, And IVO.  These guys know a LOT about props, and have done the research.  Whenever I call any of these companies, they are very knowledgeable about prop/speed/motor combinations and what works, and what does not.  If they could sell more props and make a bunch of money by selling us new multi blade smaller diameter props that would work better, they would !  If you have doubts I would suggest you talk to some of these prop experts.  I'm just trying to save you the trouble and expense of an experiment that has a known outcome...



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Mon Jun 01, 2009 6:01 pm Post subject: WRT M3X prop boom measurements.

Thought some of you may be interested in multiple blade props offered by 

Warp Drive for air boats.  Alabama Power Corp uses air boats on our lakes 

powered by 350 Chevy engines and 8 blade WD props.



john h

mkIII - Only have 3 blades.  



      AIRBOAT AND HOVERCRAFT PROPELLER PRICE SCHEDULE



      NOTE:  These prices are for Airboat and Hovercraft applications with 

direct-drive engines exceeding 80 hp and for engines exceeding 120 hp with a 

PSRU installed.  The price includes the Nickel Leading Edges which are 

mandatory and a Protractor to measure and set blade pitch.

      3 Blade  Up to 72" $1135

      4 Blade Up to 72" $1530

      5 Blade Up to 72" $1840

      5 Blade Up to 80" $1890

      6 Blade Up to 72" $2120

      6 Blade Up to 80" $2175

      6 Blade Up to 90" $2695

      7 Blade Up to 80" $2475

      8 Blade Up to 72" $2725

      8 Blade Up to 80" $2785

      10 Blade Up to 80" $3315



      All Airboat and Hovercraft Replacement Blades are $300.00 per blade 

including the Nickel Edges. (Provide prop serial number)

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

by0ung(at)brigham.net
Guest

Posted: Mon Jun 01, 2009 7:31 pm Post subject: WRT M3X prop boom measurements.

Long winded post about props.  If you are not interest hit delete.



I have seen the charts that show small diameter props turning fast rpm's

reach their maximum efficiencies at high speeds.  AND   large diameter

props reach their maximum efficiencies at slow speeds.



SO   when building a plane the first thing you want to do is to determine

what the plane is to be designed to do.   That will determine the speed

range of the design, the speed of the design will determine the prop

diameter and pitch.    

That said, the most efficient prop is a "1" blade prop... you read it right

"one" blade.  The problem with a one blade prop is keeping things in

balance.  And yes it has been experimented with,  you have to have a counter

balance on the other side,  and by playing with the angle of a pivot you can

make it more or less a constant speed prop.  When it is pulling hard it will

cone forward and if mounted at the correct pivot angle it will reduce the

pitch,,,  when the plane is up to speed the centrifugal force causes it to

run in a flatter coneing angle, increasing the pitch.   Why do I mention the

one blade prop as the most efficient????  because every prop or wing going

through the air has two types of drag acting on it.  



Drag:   drag may de subdivided into induced drag and parasite drag.  Induced

drag is simply the drag created in the process of developing lift / thrust.

In addition to the induced drag caused by the development of lift, there is

parasite drag due to skin friction and form.  This term is used because

parasite drag is not directly associated with the development of lift.

Parasite drag is present ant time the wing or prop is moving through the

air, even in a zero lift condition.



The more blades the more parasite drag.  The more parasite drag, the more HP

will be used up that is not creating lift / thrust,  the more hp not

producing thrust  the less efficient the prop / wing.



Now props work best when set to the best pitch angle at cruise, as to be

able to use up the available HP.  Fast aircraft have a high pitch angle.

And if set as a constant pitch, they have very poor takeoff performance.

That is why they put on a variable pitch prop on fast aircraft.  So they can

maximize the efficiency at both slow and fast speeds.   At the speed that

the kolb line of aircraft fly,,  the variable pitch seems unnecessary.

Because we get good take off performance and flight with one pitch.  Look at

the production aircraft that fly in the speeds that the kolbs fly.  They

have very simple fixed pitch props.  Generally a two blade prop.   Now as

the HP increases and you start to have prop ground clearance problems, and

you cant pitch the prop to use up the available HP in cruise, by setting the

pitch for maximum efficiency,  then you add an additional blade.



Now on a pusher there is a different reason to add the third blade sooner

than you would on a tractor,  that is because of the noise developed by

having a prop with greater pitch go into and out of the disturbed airflow.

The smaller pitch on a three blade seem to make less noise.  But we trade

the quieter operation  for less efficiency caused by increased parasite

drag. 



On most aircraft the prop diameter is limited by ground clearance.    Has

anyone ever  seen a Cessna 150, or a j5 cub with a 45 inch 6 blade prop?  If

it were more efficient it would be the norm. 



Boyd Young

Kolb MkIII C   580+ hours and counting

Brigham City Utah.

russ(at)rkiphoto.com
Guest

Posted: Tue Jun 02, 2009 6:18 am Post subject: WRT M3X prop boom measurements.

Boyd

Excellent comments in re prop blades. Straightforward and, more  

importantly, accurate.

Thank you

Russ K

do not archive



On Jun 1, 2009, at 11:30 PM, b young wrote:



 	  Quote: 	
		   



 Long winded post about props.  If you are not interest hit delete.



 I have seen the charts that show small diameter props turning fast  

 rpm's

 reach their maximum efficiencies at high speeds.  AND   large diameter

 props reach their maximum efficiencies at slow speeds.



 SO   when building a plane the first thing you want to do is to  

 determine

 what the plane is to be designed to do.   That will determine the  

 speed

 range of the design, the speed of the design will determine the prop

 diameter and pitch.

 That said, the most efficient prop is a "1" blade prop... you read  

 it right

 "one" blade.  The problem with a one blade prop is keeping things in

 balance.  And yes it has been experimented with,  you have to have  

 a counter

 balance on the other side,  and by playing with the angle of a  

 pivot you can

 make it more or less a constant speed prop.  When it is pulling  

 hard it will

 cone forward and if mounted at the correct pivot angle it will  

 reduce the

 pitch,,,  when the plane is up to speed the centrifugal force  

 causes it to

 run in a flatter coneing angle, increasing the pitch.   Why do I  

 mention the

 one blade prop as the most efficient????  because every prop or  

 wing going

 through the air has two types of drag acting on it.



 Drag:   drag may de subdivided into induced drag and parasite  

 drag.  Induced

 drag is simply the drag created in the process of developing lift /  

 thrust.

 In addition to the induced drag caused by the development of lift,  

 there is

 parasite drag due to skin friction and form.  This term is used  

 because

 parasite drag is not directly associated with the development of lift.

 Parasite drag is present ant time the wing or prop is moving  

 through the

 air, even in a zero lift condition.



 The more blades the more parasite drag.  The more parasite drag,  

 the more HP

 will be used up that is not creating lift / thrust,  the more hp not

 producing thrust  the less efficient the prop / wing.



 Now props work best when set to the best pitch angle at cruise, as  

 to be

 able to use up the available HP.  Fast aircraft have a high pitch  

 angle.

 And if set as a constant pitch, they have very poor takeoff  

 performance.

 That is why they put on a variable pitch prop on fast aircraft.  So  

 they can

 maximize the efficiency at both slow and fast speeds.   At the  

 speed that

 the kolb line of aircraft fly,,  the variable pitch seems unnecessary.

 Because we get good take off performance and flight with one  

 pitch.  Look at

 the production aircraft that fly in the speeds that the kolbs fly.   

 They

 have very simple fixed pitch props.  Generally a two blade prop.    

 Now as

 the HP increases and you start to have prop ground clearance  

 problems, and

 you cant pitch the prop to use up the available HP in cruise, by  

 setting the

 pitch for maximum efficiency,  then you add an additional blade.



 Now on a pusher there is a different reason to add the third blade  

 sooner

 than you would on a tractor,  that is because of the noise  

 developed by

 having a prop with greater pitch go into and out of the disturbed  

 airflow.

 The smaller pitch on a three blade seem to make less noise.  But we  

 trade

 the quieter operation  for less efficiency caused by increased  

 parasite

 drag.



 On most aircraft the prop diameter is limited by ground  

 clearance.    Has

 anyone ever  seen a Cessna 150, or a j5 cub with a 45 inch 6 blade  

 prop?  If

 it were more efficient it would be the norm.



 Boyd Young

 Kolb MkIII C   580+ hours and counting

 Brigham City Utah.

captainron1(at)cox.net
Guest

Posted: Tue Jun 02, 2009 11:08 am Post subject: WRT M3X prop boom measurements.

A couple of years ago I pretty much had said to Bob B pretty much what I will say again.

The claim that a singe blade prop is more efficient than say a 2 blade prop does not stand the test of reason. I have heard that claim since I was a kid, that a one blade prop is better but never quite understood it even back then. 

As Bob just stated the one blade prop is supposedly more efficient because it always slices in undisturbed air. 

Well !!! As I said a couple of years ago that is false, the claim that a one blade prop is more efficient is false!

Lets for example take my airplane in cruise flight I believe its a 80 inch bore spiral. In any one revolution of the prop you move forward 80 inches.

Okay,,,?  so the second blade is always ahead of where the first blade was by 40 inches. In other words at all times unless maybe right at the beginning of the take off roll the following blade is always in undisturbed air. On a four blade prop each blade is always 20 inches forward  than the previous one and so on.

Why we don't have a 4 blade prop on a J3? Well I doubt it was certified with one back in the Golden days of aviation. But I have seen glider tow airplanes using 4 blades for towing. On a J3 we are not going to see all that much difference in cruise but we will see it in climb. The drag of the airframe gets ever greater as the speed increases so prop efficiency will only help so much, but in a climb where the speed is low there we see the better efficiency, the exponential increase in drag is still less noticed at low air speeds. But in our draggy Kolbs we may see it for other reasons one of which the turbulent air for a pusher, there the multi blade will shine very nicely because it is able to "catch" more of the "crappy" air behind us.

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

---- russ kinne <russ(at)rkiphoto.com> wrote: 



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




Boyd

Excellent comments in re prop blades. Straightforward and, more  

importantly, accurate.

Thank you

Russ K

do not archive



On Jun 1, 2009, at 11:30 PM, b young wrote:



 	  Quote: 	
		   



 Long winded post about props.  If you are not interest hit delete.



 I have seen the charts that show small diameter props turning fast  

 rpm's

 reach their maximum efficiencies at high speeds.  AND   large diameter

 props reach their maximum efficiencies at slow speeds.



 SO   when building a plane the first thing you want to do is to  

 determine

 what the plane is to be designed to do.   That will determine the  

 speed

 range of the design, the speed of the design will determine the prop

 diameter and pitch.

 That said, the most efficient prop is a "1" blade prop... you read  

 it right

 "one" blade.  The problem with a one blade prop is keeping things in

 balance.  And yes it has been experimented with,  you have to have  

 a counter

 balance on the other side,  and by playing with the angle of a  

 pivot you can

 make it more or less a constant speed prop.  When it is pulling  

 hard it will

 cone forward and if mounted at the correct pivot angle it will  

 reduce the

 pitch,,,  when the plane is up to speed the centrifugal force  

 causes it to

 run in a flatter coneing angle, increasing the pitch.   Why do I  

 mention the

 one blade prop as the most efficient????  because every prop or  

 wing going

 through the air has two types of drag acting on it.



 Drag:   drag may de subdivided into induced drag and parasite  

 drag.  Induced

 drag is simply the drag created in the process of developing lift /  

 thrust.

 In addition to the induced drag caused by the development of lift,  

 there is

 parasite drag due to skin friction and form.  This term is used  

 because

 parasite drag is not directly associated with the development of lift.

 Parasite drag is present ant time the wing or prop is moving  

 through the

 air, even in a zero lift condition.



 The more blades the more parasite drag.  The more parasite drag,  

 the more HP

 will be used up that is not creating lift / thrust,  the more hp not

 producing thrust  the less efficient the prop / wing.



 Now props work best when set to the best pitch angle at cruise, as  

 to be

 able to use up the available HP.  Fast aircraft have a high pitch  

 angle.

 And if set as a constant pitch, they have very poor takeoff  

 performance.

 That is why they put on a variable pitch prop on fast aircraft.  So  

 they can

 maximize the efficiency at both slow and fast speeds.   At the  

 speed that

 the kolb line of aircraft fly,,  the variable pitch seems unnecessary.

 Because we get good take off performance and flight with one  

 pitch.  Look at

 the production aircraft that fly in the speeds that the kolbs fly.   

 They

 have very simple fixed pitch props.  Generally a two blade prop.    

 Now as

 the HP increases and you start to have prop ground clearance  

 problems, and

 you cant pitch the prop to use up the available HP in cruise, by  

 setting the

 pitch for maximum efficiency,  then you add an additional blade.



 Now on a pusher there is a different reason to add the third blade  

 sooner

 than you would on a tractor,  that is because of the noise  

 developed by

 having a prop with greater pitch go into and out of the disturbed  

 airflow.

 The smaller pitch on a three blade seem to make less noise.  But we  

 trade

 the quieter operation  for less efficiency caused by increased  

 parasite

 drag.



 On most aircraft the prop diameter is limited by ground  

 clearance.    Has

 anyone ever  seen a Cessna 150, or a j5 cub with a 45 inch 6 blade  

 prop?  If

 it were more efficient it would be the norm.



 Boyd Young

 Kolb MkIII C   580+ hours and counting

 Brigham City Utah.


	




--

kugelair.com

sky-king(at)inbox.com
Guest

Posted: Tue Jun 02, 2009 11:34 am Post subject: WRT M3X prop boom measurements.

Hi Russ,

I hope i'am not asking a dumb question here,but I need some advice.My engine's peak Hp is at 6500 rpm,I climb out at 700-800 fpm,and cruse at 65-70 mph.If I increase the pitch of my 3-blade prop, will I increase my cruse or climb rate?



[quote] --

slyck(at)frontiernet.net
Guest

Posted: Tue Jun 02, 2009 11:56 am Post subject: WRT M3X prop boom measurements.

Ron, you are referencing the the wrong "Bob"

I have stayed out of this pointless joust fest (with the exception of  

the heli viewpoint)  because

it has gone beyond my attention span.



Important update:  between beers I have managed to complete the steel  

gear leg installation with a healthy

guess as to alignment, hauled the old beast up the hill to the summer  

bug infested shelter (carpenter bees the size of wrens) and somehow  

managed

to avoid dinging another delicate surface.  I have a Powerfin 2 blade  

hub creeping via UPS across the USA that I will be

comparing with my current 2 blade WD setup.  To be fair it will be  

65" powerfin against 70" WD so it really isn't

apples to apples.



By the time I get the wings back on with the assistance of my  

brother, the summer should be half over. With any luck I may? get as  

much time

in this season as John H. did in one week.  -nahhh

BB



On 2, Jun 2009, at 3:07 PM, Ron (at) KFHU wrote:



 	  Quote: 	
		   



 A couple of years ago I pretty much had said to Bob B pretty much  

 what I will say again.

 The claim that a singe blade prop is more efficient than say a 2  

 blade prop does not stand the test of reason. I have heard that  

 claim since I was a kid, that a one blade prop is better but never  

 quite understood it even back then.

 As Bob just stated the one blade prop is supposedly more efficient  

 because it always slices in undisturbed air.

 Well !!! As I said a couple of years ago that is false, the claim  

 that a one blade prop is more efficient is false!

 Lets for example take my airplane in cruise flight I believe its a  

 80 inch bore spiral. In any one revolution of the prop you move  

 forward 80 inches.

 Okay,,,?  so the second blade is always ahead of where the first  

 blade was by 40 inches. In other words at all times unless maybe  

 right at the beginning of the take off roll the following blade is  

 always in undisturbed air. On a four blade prop each blade is  

 always 20 inches forward  than the previous one and so on.

 Why we don't have a 4 blade prop on a J3? Well I doubt it was  

 certified with one back in the Golden days of aviation. But I have  

 seen glider tow airplanes using 4 blades for towing. On a J3 we are  

 not going to see all that much difference in cruise but we will see  

 it in climb. The drag of the airframe gets ever greater as the  

 speed increases so prop efficiency will only help so much, but in a  

 climb where the speed is low there we see the better efficiency,  

 the exponential increase in drag is still less noticed at low air  

 speeds. But in our draggy Kolbs we may see it for other reasons one  

 of which the turbulent air for a pusher, there the multi blade will  

 shine very nicely because it is able to "catch" more of the  

 "crappy" air behind us.

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

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

 ---- russ kinne <russ(at)rkiphoto.com> wrote:



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

 



 Boyd

 Excellent comments in re prop blades. Straightforward and, more

 importantly, accurate.

 Thank you

 Russ K

 do not archive



 On Jun 1, 2009, at 11:30 PM, b young wrote:



> 

>

> Long winded post about props.  If you are not interest hit delete.

>

> I have seen the charts that show small diameter props turning fast

> rpm's

> reach their maximum efficiencies at high speeds.  AND   large  

> diameter

> props reach their maximum efficiencies at slow speeds.

>

> SO   when building a plane the first thing you want to do is to

> determine

> what the plane is to be designed to do.   That will determine the

> speed

> range of the design, the speed of the design will determine the prop

> diameter and pitch.

> That said, the most efficient prop is a "1" blade prop... you read

> it right

> "one" blade.  The problem with a one blade prop is keeping things in

> balance.  And yes it has been experimented with,  you have to have

> a counter

> balance on the other side,  and by playing with the angle of a

> pivot you can

> make it more or less a constant speed prop.  When it is pulling

> hard it will

> cone forward and if mounted at the correct pivot angle it will

> reduce the

> pitch,,,  when the plane is up to speed the centrifugal force

> causes it to

> run in a flatter coneing angle, increasing the pitch.   Why do I

> mention the

> one blade prop as the most efficient????  because every prop or

> wing going

> through the air has two types of drag acting on it.

>

> Drag:   drag may de subdivided into induced drag and parasite

> drag.  Induced

> drag is simply the drag created in the process of developing lift /

> thrust.

> In addition to the induced drag caused by the development of lift,

> there is

> parasite drag due to skin friction and form.  This term is used

> because

> parasite drag is not directly associated with the development of  

> lift.

> Parasite drag is present ant time the wing or prop is moving

> through the

> air, even in a zero lift condition.

>

> The more blades the more parasite drag.  The more parasite drag,

> the more HP

> will be used up that is not creating lift / thrust,  the more hp not

> producing thrust  the less efficient the prop / wing.

>

> Now props work best when set to the best pitch angle at cruise, as

> to be

> able to use up the available HP.  Fast aircraft have a high pitch

> angle.

> And if set as a constant pitch, they have very poor takeoff

> performance.

> That is why they put on a variable pitch prop on fast aircraft.  So

> they can

> maximize the efficiency at both slow and fast speeds.   At the

> speed that

> the kolb line of aircraft fly,,  the variable pitch seems  

> unnecessary.

> Because we get good take off performance and flight with one

> pitch.  Look at

> the production aircraft that fly in the speeds that the kolbs fly.

> They

> have very simple fixed pitch props.  Generally a two blade prop.

> Now as

> the HP increases and you start to have prop ground clearance

> problems, and

> you cant pitch the prop to use up the available HP in cruise, by

> setting the

> pitch for maximum efficiency,  then you add an additional blade.

>

> Now on a pusher there is a different reason to add the third blade

> sooner

> than you would on a tractor,  that is because of the noise

> developed by

> having a prop with greater pitch go into and out of the disturbed

> airflow.

> The smaller pitch on a three blade seem to make less noise.  But we

> trade

> the quieter operation  for less efficiency caused by increased

> parasite

> drag.

>

> On most aircraft the prop diameter is limited by ground

> clearance.    Has

> anyone ever  seen a Cessna 150, or a j5 cub with a 45 inch 6 blade

> prop?  If

> it were more efficient it would be the norm.

>

> Boyd Young

> Kolb MkIII C   580+ hours and counting

> Brigham City Utah.

 --

 kugelair.com

russ(at)rkiphoto.com
Guest

Posted: Tue Jun 02, 2009 2:10 pm Post subject: WRT M3X prop boom measurements.

Brad

You should be asking Boyd Young or John  Hauck. They're much more  

informed than  I am.

In any case I think testing is the only way to know for sure.

Russ K



On Jun 2, 2009, at 3:35 PM, Brad Stump wrote:



[quote] 



 Hi Russ,

 I hope i'am not asking a dumb question here,but I need some  

 advice.My engine's peak Hp is at 6500 rpm,I climb out at 700-800  

 fpm,and cruse at 65-70 mph.If I increase the pitch of my 3-blade  

 prop, will I increase my cruse or climb rate?



> --

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Jun 02, 2009 3:09 pm Post subject: WRT M3X prop boom measurements.

At 03:07 PM 6/2/2009, Ron  (at)  KFHU wrote:



 	  Quote: 	
		  A couple of years ago I pretty much had said to Bob B pretty much what I 

will say again.

The claim that a singe blade prop is more efficient than say a 2 blade 

prop does not stand the test of reason. I have heard that claim since I 

was a kid, that a one blade prop is better but never quite understood it 

even back then...


	


For aircraft like ours, I agree that there wouldn't be much if any 

measurable advantage to a one blade prop, and the associated problems would 

outweigh any slight advantages.  However, they have been used to advantage 

on some model airplanes... control line "speed" ships that can do 200mph, 

with engines turning around 30,000 rpm.  With such tiny props turning so 

fast, the blades ARE close enough together that going to one blade helps.



-Dana



--

  A goverment that fears arms in the hands of it people should also fear ROPE!

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Jun 02, 2009 3:10 pm Post subject: WRT M3X prop boom measurements.

At 03:35 PM 6/2/2009, Brad Stump wrote:



 	  Quote: 	
		  I hope i'am not asking a dumb question here,but I need some advice.My 

engine's peak Hp is at 6500 rpm,I climb out at 700-800 fpm,and cruse at 

65-70 mph.If I increase the pitch of my 3-blade prop, will I increase my 

cruse or climb rate?


	


If your prop is already pitched optimally for climb, increasing the pitch 

will improve your cruise at the expense of climb.  If it's pitched too flat 

for best climb, you'll improve both.  If you already have too much pitch 

for best cruise, both may suffer.



Generally a prop is pitched for a good compromise between climb and cruise, 

often a bit more one way or another... so you hear people talk about a 

"climb prop" or a "cruise prop".  On a typical small slow plane, IIRC the 

difference is about 2" of pitch.



-Dana



--

  A goverment that fears arms in the hands of it people should also fear ROPE!

captainron1(at)cox.net
Guest

Posted: Tue Jun 02, 2009 3:51 pm Post subject: WRT M3X prop boom measurements.

Sorry about the mix up. 



Its kinda fun but its getting boring, I think I have reached the end of my stamina on this subject. 

Good for you about the gear legs, I am ever more worried about the ones that came with the kit on my M3x. with the big motor which I estimate my power unit flying weight complete to be around 200 pounds. Them skinny 7075 legs will not take much to start looking like a soggy noodles.

---- robert bean <slyck(at)frontiernet.net> wrote: 



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




Ron, you are referencing the the wrong "Bob"

I have stayed out of this pointless joust fest (with the exception of  

the heli viewpoint)  because

it has gone beyond my attention span.



Important update:  between beers I have managed to complete the steel  

gear leg installation with a healthy

guess as to alignment, hauled the old beast up the hill to the summer  

bug infested shelter (carpenter bees the size of wrens) and somehow  

managed

to avoid dinging another delicate surface.  I have a Powerfin 2 blade  

hub creeping via UPS across the USA that I will be

comparing with my current 2 blade WD setup.  To be fair it will be  

65" powerfin against 70" WD so it really isn't

apples to apples.



By the time I get the wings back on with the assistance of my  

brother, the summer should be half over. With any luck I may? get as  

much time

in this season as John H. did in one week.  -nahhh

BB



On 2, Jun 2009, at 3:07 PM, Ron (at) KFHU wrote:



 	  Quote: 	
		   



 A couple of years ago I pretty much had said to Bob B pretty much  

 what I will say again.

 The claim that a singe blade prop is more efficient than say a 2  

 blade prop does not stand the test of reason. I have heard that  

 claim since I was a kid, that a one blade prop is better but never  

 quite understood it even back then.

 As Bob just stated the one blade prop is supposedly more efficient  

 because it always slices in undisturbed air.

 Well !!! As I said a couple of years ago that is false, the claim  

 that a one blade prop is more efficient is false!

 Lets for example take my airplane in cruise flight I believe its a  

 80 inch bore spiral. In any one revolution of the prop you move  

 forward 80 inches.

 Okay,,,?  so the second blade is always ahead of where the first  

 blade was by 40 inches. In other words at all times unless maybe  

 right at the beginning of the take off roll the following blade is  

 always in undisturbed air. On a four blade prop each blade is  

 always 20 inches forward  than the previous one and so on.

 Why we don't have a 4 blade prop on a J3? Well I doubt it was  

 certified with one back in the Golden days of aviation. But I have  

 seen glider tow airplanes using 4 blades for towing. On a J3 we are  

 not going to see all that much difference in cruise but we will see  

 it in climb. The drag of the airframe gets ever greater as the  

 speed increases so prop efficiency will only help so much, but in a  

 climb where the speed is low there we see the better efficiency,  

 the exponential increase in drag is still less noticed at low air  

 speeds. But in our draggy Kolbs we may see it for other reasons one  

 of which the turbulent air for a pusher, there the multi blade will  

 shine very nicely because it is able to "catch" more of the  

 "crappy" air behind us.

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

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

 ---- russ kinne <russ(at)rkiphoto.com> wrote:



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

 



 Boyd

 Excellent comments in re prop blades. Straightforward and, more

 importantly, accurate.

 Thank you

 Russ K

 do not archive



 On Jun 1, 2009, at 11:30 PM, b young wrote:



> 

>

> Long winded post about props.  If you are not interest hit delete.

>

> I have seen the charts that show small diameter props turning fast

> rpm's

> reach their maximum efficiencies at high speeds.  AND   large  

> diameter

> props reach their maximum efficiencies at slow speeds.

>

> SO   when building a plane the first thing you want to do is to

> determine

> what the plane is to be designed to do.   That will determine the

> speed

> range of the design, the speed of the design will determine the prop

> diameter and pitch.

> That said, the most efficient prop is a "1" blade prop... you read

> it right

> "one" blade.  The problem with a one blade prop is keeping things in

> balance.  And yes it has been experimented with,  you have to have

> a counter

> balance on the other side,  and by playing with the angle of a

> pivot you can

> make it more or less a constant speed prop.  When it is pulling

> hard it will

> cone forward and if mounted at the correct pivot angle it will

> reduce the

> pitch,,,  when the plane is up to speed the centrifugal force

> causes it to

> run in a flatter coneing angle, increasing the pitch.   Why do I

> mention the

> one blade prop as the most efficient????  because every prop or

> wing going

> through the air has two types of drag acting on it.

>

> Drag:   drag may de subdivided into induced drag and parasite

> drag.  Induced

> drag is simply the drag created in the process of developing lift /

> thrust.

> In addition to the induced drag caused by the development of lift,

> there is

> parasite drag due to skin friction and form.  This term is used

> because

> parasite drag is not directly associated with the development of  

> lift.

> Parasite drag is present ant time the wing or prop is moving

> through the

> air, even in a zero lift condition.

>

> The more blades the more parasite drag.  The more parasite drag,

> the more HP

> will be used up that is not creating lift / thrust,  the more hp not

> producing thrust  the less efficient the prop / wing.

>

> Now props work best when set to the best pitch angle at cruise, as

> to be

> able to use up the available HP.  Fast aircraft have a high pitch

> angle.

> And if set as a constant pitch, they have very poor takeoff

> performance.

> That is why they put on a variable pitch prop on fast aircraft.  So

> they can

> maximize the efficiency at both slow and fast speeds.   At the

> speed that

> the kolb line of aircraft fly,,  the variable pitch seems  

> unnecessary.

> Because we get good take off performance and flight with one

> pitch.  Look at

> the production aircraft that fly in the speeds that the kolbs fly.

> They

> have very simple fixed pitch props.  Generally a two blade prop.

> Now as

> the HP increases and you start to have prop ground clearance

> problems, and

> you cant pitch the prop to use up the available HP in cruise, by

> setting the

> pitch for maximum efficiency,  then you add an additional blade.

>

> Now on a pusher there is a different reason to add the third blade

> sooner

> than you would on a tractor,  that is because of the noise

> developed by

> having a prop with greater pitch go into and out of the disturbed

> airflow.

> The smaller pitch on a three blade seem to make less noise.  But we

> trade

> the quieter operation  for less efficiency caused by increased

> parasite

> drag.

>

> On most aircraft the prop diameter is limited by ground

> clearance.    Has

> anyone ever  seen a Cessna 150, or a j5 cub with a 45 inch 6 blade

> prop?  If

> it were more efficient it would be the norm.

>

> Boyd Young

> Kolb MkIII C   580+ hours and counting

> Brigham City Utah.

 --

 kugelair.com






	




--

kugelair.com

by0ung(at)brigham.net
Guest

Posted: Wed Jun 03, 2009 7:51 am Post subject: WRT M3X prop boom measurements.

 	  Quote: 	
		   Hi Russ,

 I hope i'am not asking a dumb question here,but I need some  

 advice.My engine's peak Hp is at 6500 rpm,I climb out at 700-800  

 fpm,and cruse at 65-70 mph.If I increase the pitch of my 3-blade  

 prop, will I increase my cruse or climb rate?


	


 	  Quote: 	
		  >>>>>>>>>>>>>>


	


Brad



Lets think out loud here.



With a plane with a constant speed prop they always set to  a fine pitch for

takeoff allowing max rpm.   This equals max take off performance, climb

rate.



When the same plane gets up to speed they increase the pitch, reducing the

rpm.  This gives them a little faster cruse.  It allows the prop to use up

the HP with out over reving.  



This becomes a larger factor when the aircraft speed is above 130 - 150   or

so.   



In your case,  if you climb at 6500 at wot,,, then at straight and level you

will be over reving.   So you have to pull the power back.  If you increase

the pitch you will climb at (lets say for example)  6250 rpm..  at that rpm

your engine is not putting out the full rated hp.(slower climb)   But in

straight and level flight you will pull 6500  and put the full hp to the

prop. Thus going faster, because you have not had to pull the power back.



Boyd Young

by0ung(at)brigham.net
Guest

Posted: Wed Jun 03, 2009 3:47 pm Post subject: WRT M3X prop boom measurements.

For aircraft like ours, I agree that there wouldn't be much if any 

measurable advantage to a one blade prop, and the associated problems would 

outweigh any slight advantages.  However, they have been used to advantage 

on some model airplanes... control line "speed" ships that can do 200mph, 

with engines turning around 30,000 rpm.  With such tiny props turning so 

fast, the blades ARE close enough together that going to one blade helps.



-Dana

 	  Quote: 	
		  >>>>>>>>>>>>>>>>>.


	


Dana 



For a 1 blade to do its job effectively I would think that it should be

installed on a slick go fast plane.  The cruise would be in keeping with the

large pitch angle needed to use up the HP. And less of the HP being used up

as parasitic drag.  To put it on a slow aircraft the prop would use up the

hp but be stalled,  therefore not creating the thrust that it could do on a

faster craft.



And as for the 1 blade design being the most efficient,,  I should have

clarified it by saying in cruise,  and in a tractor configuration, where it

is not slapping the large pitch against the disturbed air,,   climb would

probably not be as good even with the pitch reducing coning angle.  



Boyd Young

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Wed Jun 03, 2009 5:33 pm Post subject: Re: WRT M3X prop boom measurements.

[quote="by0ung(at)brigham.net"] 	  Quote: 	
		   Hi Russ,

 I hope i'am not asking a dumb question here,but I need some  

 advice.My engine's peak Hp is at 6500 rpm,I climb out at 700-800  

 fpm,and cruse at 65-70 mph.If I increase the pitch of my 3-blade  

 prop, will I increase my cruse or climb rate?



	




That sounds about like the envelope of my old FSII. Mine had the 503 with 3.47:1 C box and 68" WD 3-blade taper tip. I'd say thats about the best combo you can get on the FSII, tho admittedly I only had one other FSII in my area to actually compare to. He had the 2.58 B box and a 2 blade woody, I could outclimb him just a little bit, tho he seemed to have a little higher top end than my best climb pitch setting.



For a while I ran about 6400 on climbout on mine but it would easily get to redline in level flight. The rule of thumb of bumping just up to redline at WOT straight and level will give the best compromise. With the prop set that way on my FSII that gave me about 6200 on climbout which was still plenty good climb and gave a comfortable 65mph cruise at about 5300. Just under 3 gph.



I sure kinda miss that plane.... don't know if I ever mentioned that.... 



LS

_________________
LS
Titan II SS

aslsa.rng(at)gmail.com
Guest

Posted: Wed Jun 03, 2009 8:28 pm Post subject: WRT M3X prop boom measurements.

http://www.ultraligero.net/Cursos/varios/helice_de_una_pala.pdf



[url=http://www.ultraligero.net/Cursos/varios/helice_de_una_pala.pdf][/url]Rick

 

On Wed, Jun 3, 2009 at 6:35 PM, b young <by0ung(at)brigham.net (by0ung(at)brigham.net)> wrote:

[quote] --> Kolb-List message posted by: "b young" <by0ung(at)brigham.net (by0ung(at)brigham.net)>

 

 

 For aircraft like ours, I agree that there wouldn't be much if any

 measurable advantage to a one blade prop, and the associated problems would

 outweigh any slight advantages.  However, they have been used to advantage

 on some model airplanes... control line "speed" ships that can do 200mph,

 with engines turning around 30,000 rpm.  With such tiny props turning so

 fast, the blades ARE close enough together that going to one blade helps.

 

 -Dana

 >>>>>>>>>>>>>>>>>>.

 

 Dana

 

 For a 1 blade to do its job effectively I would think that it should be

 installed on a slick go fast plane.  The cruise would be in keeping with the

 large pitch angle needed to use up the HP. And less of the HP being used up

 as parasitic drag.  To put it on a slow aircraft the prop would use up the

 hp but be stalled,  therefore not creating the thrust that it could do on a

 faster craft.

 

 And as for the 1 blade design being the most efficient,,  I should have

 clarified it by saying in cruise,  and in a tractor configuration, where it

 is not slapping the large pitch against the disturbed air,,   climb would

 probably not be as good even with the pitch reducing coning angle.

 

 Boyd Young

 

 

 

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 arget="_blank">http://www.matronics.com/Navigator?Kolb-List

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

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 [b]

sky-king(at)inbox.com
Guest

Posted: Thu Jun 04, 2009 3:09 am Post subject: WRT M3X prop boom measurements.

Boyd,

Thank you and others who have offered advice.Iam going to increase the pitch this week-end and see if this will make go faster.



[quote] --

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Thu Jun 04, 2009 7:12 am Post subject: Re: WRT M3X prop boom measurements.

Prop pitch will have a huge effect on your cruise and top speed.   I have done a lot of experimenting with it on my MK III Xtra with the 912-S and 3 blade Warp Drive prop.



When I pitched for 5800 RPM climb, which is the maximum RPM for the Rotax 912-S, I get the best acceleration and climb, but cruise speed is horrible.  It takes a lot more RPM, power, and fuel to cruise at 75 MPH.  All my high end speeds were way down, top level flight speed is limited by RPM.  If all one ever did was climb, the low pitch / high RPM setting might be ok, but for overall flying, it really sucks 



With the prop set for 5200 RPM climb, I give up a couple hundred feet per minute in climb, but 75 MPH cruise is achieved at a much lower RPM, and  power setting with significantly lower fuel usage, and top level flight speed is much better.   The cruise with lots of pitch in the prop is so much improved, I will gladly give up a couple hundred RPM in climb.    The added advantage is that not running the engine to its absolute maximum RPM should increase its life.   The Rotax 912-S is designed to run at high RPM's, but the 5500 - 5800 RPM range is time limited by Rotax for a reason, and it will probably increase the engines life keep it at 5500 RPM and below and just not to try to get every last HP out of it.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Jun 04, 2009 7:33 am Post subject: Re: WRT M3X prop boom measurements.

 	  JetPilot wrote: 	
		  Prop pitch will have a huge effect on your cruise and top speed.   I have done a lot of experimenting with it on my MK III Xtra with the 912-S and 3 blade Warp Drive prop.



When I pitched for 5800 RPM climb, which is the maximum RPM for the Rotax 912-S, I get the best acceleration and climb, but cruise speed is horrible.  It takes a lot more RPM, power, and fuel to cruise at 75 MPH.  All my high end speeds were way down, top level flight speed is limited by RPM.  If all one ever did was climb, the low pitch / high RPM setting might be ok, but for overall flying, it really sucks 



With the prop set for 5200 RPM climb, I give up a couple hundred feet per minute in climb, but 75 MPH cruise is achieved at a much lower RPM, and  power setting with significantly lower fuel usage, and top level flight speed is much better.   The cruise with lots of pitch in the prop is so much improved, I will gladly give up a couple hundred RPM in climb.    The added advantage is that not running the engine to its absolute maximum RPM should increase its life.   The Rotax 912-S is designed to run at high RPM's, but the 5500 - 5800 RPM range is time limited by Rotax for a reason, and it will probably increase the engines life keep it at 5500 RPM and below and just not to try to get every last HP out of it.



Mike 	




BTW, this is also true of the 2-strokes but a bit higher degree than the 912. It's a common misconception that they last longer running at 6000+ rpm continuously. Actually, the "sweet spot" for continuous operation with them is in the 5200 to 5500 range, at somewhere in the neighborhood of 2/3 throttle. 



Also, they can't run at full throttle on a continuous basis. The TBO goes down significantly when they're run wide open all the time regardless of the rpm and something will eventually give (usually the con rod big end is the first to go). Especially the 582, tho the 503 and 447 can take that for a while longer.



The 912 is sturdier in that regard as they can run WOT continuously below 5500 rpm (IIRC from the operator's manual).



The sweet spot on my 912ULS seems to be around 5050 rpm....



LS

_________________
LS
Titan II SS

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