Matronics Email Lists :: View topic - WRT M3X prop boom measurements.

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

WRT M3X prop boom measurements.
Goto page Previous 1, 2, 3, 4 Next

Matronics Email Lists Forum Index -> Kolb-List

View previous topic :: View next topic

Author Message

captainron1(at)cox.net
Guest

Posted: Sun May 31, 2009 9:23 am Post subject: WRT M3X prop boom measurements.

You got it, but they cost more.

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

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



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




I want a front row seat.

BB

On 31, May 2009, at 12:36 PM, Ron wrote:



 	  Quote: 	
		   



 "First, a prop creates thrust by increasing the speed of air  

 passing through

 it.  It's more efficient to accelerate a lot of air a little bit  

 than to

 accelerate a little bit of air a lot.  Thus a larger prop is better. "

 ============== above is a quote==============

 that's actually incorrect, it may be correct if we were talking  

 about a Rocket motor or say a Turbo Jet but not a conventional  

 propeller. The propulsion that a prop creates is directly  

 proportional to how much lift the prop airfoil creates. Now if you  

 look at the mechanic of lift you will see that to top of the prop  

 creates a low pressure area. the air movement that you notice as  

 the prop blast is to a large extent a stream of onrushing air  

 filling in the low pressure area that the blades created. It can be  

 accomplished by a large blade or many small blades. In fact the  

 many small blades are way better at creating a vacuum in front of  

 the propeller than a fewer blades attempting the same thing. This  

 is not an opinion this is a fact of aerodynamics ( all else being  

 equal ).

 I sense that people have some problems in letting go of some  

 constants in their minds, one of them is notion that a large  

 because its large creates more propulsive force than an equally  

 sized volume disc with multiple blades. Anyway I really gave out  

 more information then I want, since who knows I may want to have a  

 Kolb Air Race and I want to compete against the folks who hold a  

 different concept.  






	




--

kugelair.com

rowedenny

Joined: 09 Mar 2008
Posts: 338
Location: Western PA

Posted: Sun May 31, 2009 9:23 am Post subject: WRT M3X prop boom measurements.

---

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Sun May 31, 2009 9:47 am Post subject: WRT M3X prop boom measurements.

[quote]   I want a front row seat.

BB

On 31, May 2009, at 12:36 PM, Ron    wrote:



 	  Quote: 	
		   --> Kolb-List message posted by: Ron <captainron1(at)cox.net (captainron1(at)cox.net)>


	


 	  Quote: 	
		   I    sense that people have some problems in letting go of some  

    constants in their minds, one of them is notion that a large  

    because its large creates more propulsive force than an equally  

    sized volume disc with multiple blades. Anyway I really gave out     

 more information then I want, since who knows I may want to have    a  

 Kolb Air Race and I want to compete against the folks who    hold a  

 different concept.  




	


    

   By all means Capt Kangaroo, show us where we are wrong.    I look forward to seeing the outcome. Its only money, and worse comes to    worse, you will have a spare three blade prop.

   Larry

[b]

_________________
do not archive

Dana

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

Posted: Sun May 31, 2009 1:52 pm Post subject: WRT M3X prop boom measurements.

At 12:36 PM 5/31/2009, Ron wrote:

 	  Quote: 	
		  



"First, a prop creates thrust by increasing the speed of air passing through

it.  It's more efficient to accelerate a lot of air a little bit than to

accelerate a little bit of air a lot.  Thus a larger prop is better. "

============== above is a quote==============

that's actually incorrect, it may be correct if we were talking about a 

Rocket motor or say a Turbo Jet but not a conventional propeller. The 

propulsion that a prop creates is directly proportional to how much lift 

the prop airfoil creates. Now if you look at the mechanic of lift you will 

see that to top of the prop creates a low pressure area...


	


Which are you saying is incorrect?  That a prop creates thrust by 

accelerating the air passing through it (true, or you can look at in the 

opposite direction, that the thrust accelerates the air) or that larger is 

better (true in most cases).



It's kind of like the Bernoulli (faster moving air over the top of the wing 

creating low pressure) vs Newton (wing lift force from accelerating air 

downward) arguments of lift.  There is no argument, because they're 

different ways of describing the same thing.



The prop blade creates lift-- which is a force (thrust)-- which accelerates 

the air backward.



At low speeds, the larger prop with less blades is more efficient, for the 

same reason that nearly all helicopters have large two blade rotors rather 

than small multi blade fans.



-Dana

 	  Quote: 	
		  . the air movement that you notice as the prop blast is to a large extent 

a stream of onrushing air filling in the low pressure area that the blades 

created. It can be accomplished by a large blade or many small blades. In 

fact the many small blades are way better at creating a vacuum in front of 

the propeller than a fewer blades attempting the same thing. This is not 

an opinion this is a fact of aerodynamics ( all else being equal ).

I sense that people have some problems in letting go of some constants in 

their minds, one of them is notion that a large because its large creates 

more propulsive force than an equally sized volume disc with multiple 

blades. Anyway I really gave out more information then I want, since who 

knows I may want to have a Kolb Air Race and I want to compete against the 

folks who hold a different concept.  




	


--

  When authorities warn you of the sinfulness of sex, there is an important 

lesson to be learned. Do not have sex with the authorities.

Dana

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

Posted: Sun May 31, 2009 1:57 pm Post subject: WRT M3X prop boom measurements.

At 12:45 PM 5/31/2009, Ron  (at)  KFHU wrote:

 	  Quote: 	
		  ...Submarine props are very much multi blade props, they almost look like 

the Propjets from the 80's...


	


Submarine props are optimized for minimum noise.  The propfans are 

optimized for fuel efficiency in cruise, not max thrust at takeoff.



-Dana

--

  When authorities warn you of the sinfulness of sex, there is an important 

lesson to be learned. Do not have sex with the authorities.

jbhart(at)onlyinternet.ne
Guest

Posted: Sun May 31, 2009 2:39 pm Post subject: WRT M3X prop boom measurements.

Dana.



Also there is another aspect to be added.  Over propping.  By this I mean 

you can run a propeller that is too long for your combination of your 

aircraft drag and the available engine torque.



I have run a 72" IVO on the FireFly.  Climb out was impressive, but I could 

not get over 55 mph, due to the fact that I had reduce pitch to get engine 

rpm up.



While working on propeller noise reduction, I used an old IVO prop 56 inch 

two blade IVO and by converting it to "Power Tips", it ended up at 54 

inches.  To limit top engine cruise speed, I had to increase the tip pitch 

angle from 17.25 to 18.75 degrees.  Both of these props would push the 

FireFly over 63 mph, but climb out was not exceptional.



Then I purchased a third blade, and matched it to the original two "Power 

Tip" blades.  I had to reduce the pitch to 15.0 degrees.  This set up flew 

just as well as the two blade.



These short blade props gave very acceptable cruise performance, but they 

had nothing to shout about when it came to climb performance.  



To get away from the 72 inch low cruise speed problem, I started cutting the 

prop.  Currently it is at 64 inches and it gives very good cruise and 

acceptable climb.



For your interest:  

The noise level at 5,200 rpm for the IVO

56 inch two blade square tip - 110 db

54 inch two blade power tip  - 106 db

54 inch three blade power tip - 105 db.

No data has been taken on the current propeller.



Jack B. Hart FF004

Winchester, IN



 	  Quote: 	
		  There are several aspects to this.



First, a prop creates thrust by increasing the speed of air passing through 

it.  It's more efficient to accelerate a lot of air a little bit than to 

accelerate a little bit of air a lot.  Thus a larger prop is better.



Second, there are tip losses, just like a wing.  A higher aspect ratio wing 

is more efficient (look at a sailplane).



Third, the closer together the blades are, the more each blade is operating 

in the air disturbed by the previous blade.  This causes inefficiency in 

the same way that a biplane is less efficient than a monoplane.



The ONLY reason for more than two blades is if you don't have enough room 

for a 2 blade prop that can absorb all the engine's power, or if it's 

turning too fast so that you get tip losses due to sonic effects and you 

can't increase the reduction ratio.



-Dana

John Hauck

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

Posted: Sun May 31, 2009 3:42 pm Post subject: WRT M3X prop boom measurements.

> At low speeds, the larger prop with less blades is more efficient, for 

the

 	  Quote: 	
		   same reason that nearly all helicopters have large two blade rotors rather 

 than small multi blade fans.



 -Dana


	




I am from the old days of helicopters, mostly two blades, except the CH-47 

Chinook, which had two each three blade main rotors.



However, today things have changed a bit.  Most have gone to ridgid rotor, 

hingeless, multiblade main rotors of at least 4 blades.



The little TH-55, or I think the civilian designation is Hughes 269 or 369, 

had a three main rotor blade system.



The main rotor blades have become multi-blades and the rotor diameter has 

shrunk, but they are still pretty big props.



Take care,



john h

mkIII

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

Dana

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

Posted: Sun May 31, 2009 4:03 pm Post subject: WRT M3X prop boom measurements.

At 07:36 PM 5/31/2009, Jack B. Hart wrote:



 	  Quote: 	
		  Also there is another aspect to be added.  Over propping.  By this I mean

you can run a propeller that is too long for your combination of your

aircraft drag and the available engine torque.


	


Absolutely.  As in everything, there are limits.



 	  Quote: 	
		  I have run a 72" IVO on the FireFly.  Climb out was impressive, but I could

not get over 55 mph, due to the fact that I had reduce pitch to get engine

rpm up.


	


Yes, I should have mentioned that the larger slow turning prop may make 

more static thrust, but it has a lower efficient speed range.  Big slow 

turning flat pitch props are great for climb, but less good for cruise.



 	  Quote: 	
		  While working on propeller noise reduction, I used an old IVO prop 56 inch

two blade IVO and by converting it to "Power Tips"...


	


Dunno if I mentioned it to you, I did the Power Tip mod to one of my PPG 

props after chewing it up flying at the beach (pebbles get kicked up during 

takeoff).  Rather than fill the damaged area, I cut it away (diameter at 

the trailing edge tip is unchanged).  I can't say if it's any quieter, that 

single cylinder engine is pretty loud anyway, but I picked up maybe 

1-200rpm at WOT with no loss in thrust, and (though I've made no accurate 

measurements) a bit better fuel consumption.  A side benefit is that it's 

much easier to wrap the polyurethane leading edge tape around the tip!  I'm 

debating making the mod to my UltraStar prop.



-Dana



--

  I love my country, but I fear my government.

Dana

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

Posted: Sun May 31, 2009 4:03 pm Post subject: WRT M3X prop boom measurements.

At 07:32 PM 5/31/2009, John Hauck wrote:



 	  Quote: 	
		  I am from the old days of helicopters, mostly two blades, except the CH-47 

Chinook, which had two each three blade main rotors.



However, today things have changed a bit.  Most have gone to ridgid rotor, 

hingeless, multiblade main rotors of at least 4 blades...


	


Yes, but I suspect the multi blades are for space or controllability 

reasons, not aerodynamic efficiency.



-Dana



--

  I love my country, but I fear my government.

captainron1(at)cox.net
Guest

Posted: Sun May 31, 2009 5:22 pm Post subject: WRT M3X prop boom measurements.

Remember the boat prop was not my example!

I just run with it because it was a good example that even in boats they went to multi blade props.

but the observation is correct to the same extant as a wood screw needs much less blade length to dig its way through the way more dense wood. 

The fact though is that propulsion is not by and large a consequence of  throwing the air back to create high pressure behind the prop to Push it forward, that is false. Because for example an airplane that moves at 300 kt will never be able to throw back enough air to move it forward.. On the ground at full power the max velocity of the air that you throw back or move back is maybe 30-40 mph at most. If you are moving at say 300 kt it is obviously impossible that 30-40 mph is pushing you at 300kt. It is something else then. And that something is of course the lift that the prop is generating and not the air that it moves. Say you have a big two blade prop moving the air at 15 mph it is still impossible for it to move you forward at say 70mph.

Anyway one fellow (Larry Cottrell I think he was at MV but I don't exactly remember the face with that name),, is getting irate so to make sure we don't degenerate here into negativity I am dropping this subject. 

Or you come over to Geo group and we can continue there. There are no personal attacks allowed there, as a moderator I make sure of that.



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



However a fluid is a fluid, and true

---- Denny Rowe <rowedenny(at)windstream.net> wrote: 



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


---

Dana

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

Posted: Sun May 31, 2009 6:12 pm Post subject: WRT M3X prop boom measurements.

At 09:21 PM 5/31/2009, Ron  (at)  KFHU wrote:



 	  Quote: 	
		  The fact though is that propulsion is not by and large a consequence 

of  throwing the air back to create high pressure behind the prop to Push 

it forward, that is false...


	


The thrust produced by a propeller is equal to the mass flow rate 

multiplied by the change in velocity.  Remember Newton's laws:  For every 

action there is an equal and opposite reaction.  The propeller is pulling 

the plane forward; thus the propeller must be pushing the air back with 

equal force.  If you exert a force on the air (or anything!) it will 

accelerate (that's the change in velocity).  I didn't say that the velocity 

change is the _cause_ of the thrust, you could just as easily say that the 

velocity change is caused by the thrust, but it's an essential part of the 

picture.



Just like wing lift, you can describe it by downwash and Newton's law or by 

Bernoulli's principle and air velocities and pressure distribution, but 

they're just two different ways of describing and calculating the same 

phenomenon.  Using one description or method doesn't mean the other is 

incorrect.



-Dana

--

  Black holes are where God is dividing by zero.

slyck(at)frontiernet.net
Guest

Posted: Sun May 31, 2009 6:55 pm Post subject: WRT M3X prop boom measurements.

The larger heavy lift helicopters use more blades, especially the  

russians.

To harness all that power while maintaining reasonable  

maneuverability, to avoid retreating blade stall they have to keep  

the rotor diameter down.

-not a problem we have to contend with on our Kolbs.

BB



On 31, May 2009, at 7:54 PM, Dana Hague wrote:



 	  Quote: 	
		   



 At 07:32 PM 5/31/2009, John Hauck wrote:



> I am from the old days of helicopters, mostly two blades, except  

> the CH-47 Chinook, which had two each three blade main rotors.

>

> However, today things have changed a bit.  Most have gone to  

> ridgid rotor, hingeless, multiblade main rotors of at least 4  

> blades...



 Yes, but I suspect the multi blades are for space or  

 controllability reasons, not aerodynamic efficiency.



 -Dana



 --

  I love my country, but I fear my government.

captainron1(at)cox.net
Guest

Posted: Sun May 31, 2009 7:02 pm Post subject: WRT M3X prop boom measurements.

Okay fine, however that statement could also apply using  your reasoning to a multi blade prop of equal volume as to one of less blades with the same total airfoil volume. 

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

---- Dana Hague <d-m-hague(at)comcast.net> wrote: 



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




At 09:21 PM 5/31/2009, Ron  (at)  KFHU wrote:



 	  Quote: 	
		  The fact though is that propulsion is not by and large a consequence 

of  throwing the air back to create high pressure behind the prop to Push 

it forward, that is false...


	


The thrust produced by a propeller is equal to the mass flow rate 

multiplied by the change in velocity.  Remember Newton's laws:  For every 

action there is an equal and opposite reaction.  The propeller is pulling 

the plane forward; thus the propeller must be pushing the air back with 

equal force.  If you exert a force on the air (or anything!) it will 

accelerate (that's the change in velocity).  I didn't say that the velocity 

change is the _cause_ of the thrust, you could just as easily say that the 

velocity change is caused by the thrust, but it's an essential part of the 

picture.



Just like wing lift, you can describe it by downwash and Newton's law or by 

Bernoulli's principle and air velocities and pressure distribution, but 

they're just two different ways of describing and calculating the same 

phenomenon.  Using one description or method doesn't mean the other is 

incorrect.



-Dana

--

  Black holes are where God is dividing by zero.

--

kugelair.com

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Mon Jun 01, 2009 5:54 am Post subject: Re: WRT M3X prop boom measurements.

 	  captainron1(at)cox.net wrote: 	
		  



On the ground at full power the max velocity of the air that you throw back or move back is maybe 30-40 mph at most. If you are moving at say 300 kt it is obviously impossible that 30-40 mph is pushing you at 300kt. It is something else then. 



- 	




You could not be more wrong about this.  In a high performance propeller plane, at full power you can easily flip over GA planes over by doing a full power runup in front of them, and it take a hell of a lot more than 30-40 MPH to do that.  Ever stand behind a Cessna 150 or 172 during a full power runup, it is a like a hurricane, WAY more than 30-40 MPH.   Now I am starting to understand why you are making some bad assumptions about different props and their effects on performance here.  You do not have an understanding of some of the basics.



 	  captainron1(at)cox.net wrote: 	
		  



It can be accomplished by a large blade or many small blades. In fact the many small blades are way better at creating a vacuum in front of the propeller than a fewer blades attempting the same thing. This is not an opinion this is a fact of aerodynamics ( all else being equal ). 



	




Many of your " facts " are wrong, and the facts you do know you have used to come to some very wrong conclusions.  You are not the first person to take a fact, and make very bad assumptions based on that.  For the last 80 years or more, smaller props would have allowed shorter and lighter landing gear on many military fighters and WWII, shorter gear on many prop transports, better engine placement on modern  low wing turboprops instead of having to mount engines above the wings, more prop clearance on the ground resulting in less FOD, and much better engine placement on pusher type airplanes.   



Captain Ron, it is really plausible that airplane designers have just overlooked all of this and never thought about using small multi-bladed props ?   This issue has been very carefully studied, and researched for many years, and the FACT is that aircraft designers don't use large props just to make planes heaver and harder to deal with.



Mike

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

Kolb MK-III Xtra, 912-S

mdnanwelch7(at)hotmail.co
Guest

Posted: Mon Jun 01, 2009 6:40 am Post subject: WRT M3X prop boom measurements.

Mike B.

    Eloquently put.  That's why I decided to not participate in this debate.  When someone says "On the ground at full power the max velocity of the air that you throw back or move back is maybe 30-40 mph at most" C then you have to realize your opposition in the argument.

 To belabor the point is futile C really.

   I recall doing a full power runup with an ultralight I had one.  440 Kawasaki 40 HP C seems like all hell was breaking loose.  Yeah C I know C it was only 40 horses C but the wind that sucker blew back moved trees 100 feet away.  Maybe it got to 42 mph.

 Mike Welch

 MkIII Geo Turbo C blows back air 24 mph 

[quote] Subject: Kolb-List: Re: WRT M3X prop boom measurements.

 From: orcabonita(at)hotmail.com

 Date: Mon C 1 Jun 2009 06:55:00 -0700

 To: kolb-list(at)matronics.com

 --> Kolb-List message posted by: "JetPilot" <orcabonita(at)hotmail.com>

 captainron1(at)cox.net wrote:

 > 

 > 

 > On the ground at full power the max velocity of the air that you throw back or move back is maybe 30-40 mph at most. If you are moving at say 300 kt it is obviously impossible that 30-40 mph is pushing you at 300kt. It is something else then. 

 > 

 > -

 You could not be more wrong about this. In a high performance propeller plane C at full power you can easily flip over GA planes over by doing a full power runup in front of them C and it take a hell of a lot more than 30-40 MPH to do that. Ever stand behind a Cessna 150 or 172 during a full power runup C it is a like a hurricane C WAY more than 30-40 MPH. Now I am starting to understand why you are making some bad assumptions about different props and their effects on performance here. You do not have an understanding of some of the basics.

 captainron1(at)cox.net wrote:

 > 

 > 

 > It can be accomplished by a large blade or many small blades. In fact the many small blades are way better at creating a vacuum in front of the propeller than a fewer blades attempting the same thing. This is not an opinion this is a fact of aerodynamics ( all else being equal ). 

 > 

 > 

 Many of your " facts " are wrong C and the facts you do know you have used to come to some very wrong conclusions. You are not the first person to take a fact C and make very bad assumptions based on that. For the last 80 years or more C smaller props would have allowed shorter and lighter landing gear on many military fighters and WWII C shorter gear on many prop transports C better engine placement on modern low wing turboprops instead of having to mount engines above the wings C more prop clearance on the ground resulting in less FOD C and much better engine placement on pusher type airplanes. 

 Captain Ron C it is really plausible that airplane designers have just overlooked all of this and never thought about using small multi-bladed props ? This issue has been very carefully studied C and researched for many years C and the FACT is that aircraft designers don't use large props just to make planes heaver and harder to deal with.

 Mike

 --------

 &quot;NO FEAR&quot; - If you have no fear you did not go as fast as you could have !!!

 Kolb MK-III Xtra C 912-S

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=246290#246290

 &g============

Hotmail® goes with you.  Get it on your BlackBerry or iPhone.   	  Quote: 	
		  [b]

lucien

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

Posted: Mon Jun 01, 2009 7:17 am Post subject: Re: WRT M3X prop boom measurements.

 	  mdnanwelch7(at)hotmail.co wrote: 	

 > On the ground at full power the max velocity of the air that you throw back or move back is maybe 30-40 mph at most. If you are moving at say 300 kt it is obviously impossible that 30-40 mph is pushing you at 300kt. It is something else then. 

 > 

Er, maybe if the AOA of the prop blades is low enough, yeah, you could get a wind of only 30-40 mph..........

The way I learnt it, a prop is basically just a rotating wing. It's a little different because the airflow over the different sections of the blade varies due to it rotating, but the same principles concerning efficiency and mechanical limits applies to it.

I.e. high-aspect ratio wing sections tend to be more efficient (i.e. have high L/D ratios) but have lower mechanical limits due to their structure. Low aspect-ration wing sections are less efficient (low L/D ratios) but have higher mechanical limits due to structure as well.

This is why, for example, the warp drive prop is so efficient, probably the most efficient prop you can buy for our light a/c applications. It's got a high-aspect ratio blade platform with a very thin cross section. Ideal for high L/D and thus very efficient at producing rotating power into thrust. The main compromise is blade area to maintain the high AR and keep the diameter within mechanical restrictions. Blades stall at static and low speed regimes - big whoop, easily compensated for by correct power usage on the takeoff roll.

Short, stubby props, OTOH, are less efficient for the same reasons (low aspect ratio) but are used on high-power applications because they can be built strong as an ox...... That's why fighters have those short low-efficiency wings on them. Less efficient but that is overcome simply by applying enough power into the equation .

LS

_________________
LS
Titan II SS

captainron1(at)cox.net
Guest

Posted: Mon Jun 01, 2009 9:11 am Post subject: WRT M3X prop boom measurements.

It was a poor choice of words and no sooner I sent it I thought it probably will cause a bit of a prop blast in my direction. 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.  



I guess we can argue about my less than brilliant example, but that will not change any facts about the efficiency of a multi blade prop as compared to a two blade prop of equal volume of displacement.



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.



---- JetPilot <orcabonita(at)hotmail.com> wrote: 



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


captainron1(at)cox.net wrote:

 	  Quote: 	
		   

 

 On the ground at full power the max velocity of the air that you throw back or move back is maybe 30-40 mph at most. If you are moving at say 300 kt it is obviously impossible that 30-40 mph is pushing you at 300kt. It is something else then. 

 

 -


	




You could not be more wrong about this.  In a high performance propeller plane, at full power you can easily flip over GA planes over by doing a full power runup in front of them, and it take a hell of a lot more than 30-40 MPH to do that.  Ever stand behind a Cessna 150 or 172 during a full power runup, it is a like a hurricane, WAY more than 30-40 MPH.   Now I am starting to understand why you are making some bad assumptions about different props and their effects on performance here.  You do not have an understanding of some of the basics.

captainron1(at)cox.net wrote:

 	  Quote: 	
		   

 

 It can be accomplished by a large blade or many small blades. In fact the many small blades are way better at creating a vacuum in front of the propeller than a fewer blades attempting the same thing. This is not an opinion this is a fact of aerodynamics ( all else being equal ). 

 

 


	




Many of your " facts " are wrong, and the facts you do know you have used to come to some very wrong conclusions.  You are not the first person to take a fact, and make very bad assumptions based on that.  For the last 80 years or more, smaller props would have allowed shorter and lighter landing gear on many military fighters and WWII, shorter gear on many prop transports, better engine placement on modern  low wing turboprops instead of having to mount engines above the wings, more prop clearance on the ground resulting in less FOD, and much better engine placement on pusher type airplanes.   



Captain Ron, it is really plausible that airplane designers have just overlooked all of this and never thought about using small multi-bladed props ?   This issue has been very carefully studied, and researched for many years, and the FACT is that aircraft designers don't use large props just to make planes heaver and harder to deal with.



Mike



--------

&quot;NO FEAR&quot; -  If you have no fear you did not go as fast as you could have !!!



Kolb MK-III Xtra, 912-S





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 46290#246290



--

kugelair.com

John Hauck

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

Posted: Mon Jun 01, 2009 9:40 am Post subject: WRT M3X prop boom measurements.

This argument has gotten way off the subject line.



I don't intend to be a part of it, but I will throw this in to think about.



When it comes to Kolbs, especially the mkIII, a model that has been out 

since 1991, there isn't a whole lot that can be done to it to improve on a 

proven design.  That includes available, reliable, efficient power plants 

and props.  For what it is worth, I think I have the best of the 

combinations available.  In my travels, I haven't found another Kolb mkIII 

that will out perform Miss P'fer.  There may be some out there, but we have 

not encountered them yet.  That includes the newest model MKIIIx that I had 

the privelege of testing last year.



I have done side by side comparison tests for slow flight and also top speed 

with other mkIII's.  I think I did as well at slow speed as the much lighter 

competition, and I also out ran a mkIII powered with a 912uls and an IVO two 

blade, heavy duty prop.  I haven't raced with other mkIII's with 912uls's 

and three blade fast taper Warp Drive blades, so I don't know how I would 

perform with them.  My mkIII is an 80 mph cruise hog, that carries all the 

weight I ask her to.  She does quite well as a super STOL aircraft, even 

with out the aid of VGs.



This last flight was 60 hours with no maintenance of any kind to aircraft or 

engine.  She flew in some extreme weather conditions and survived.  She got 

me home safe and sound.



I might note, most of this argument about props has been voiced by folks 

that don't have a whole heck of a lot of experience with Kolb aircraft. 

They don't necessarily get into step with all the other aircraft in the 

world.  They are a special breed, and have there own very special quirks 

that are hard for a lot of engineers to understand.  I know they do them and 

can not tell you why.  Guess that is why I like flying my Kolb.



john h

mkIII

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

sky-king(at)inbox.com
Guest

Posted: Mon Jun 01, 2009 10:57 am Post subject: WRT M3X prop boom measurements.

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] --

HShack(at)aol.com
Guest

Posted: Mon Jun 01, 2009 12:14 pm Post subject: WRT M3X prop boom measurements.

Yeah, 'cause instead of 250 hp, they have 1500 turbo horses [maybe two of  them].

  

 Howard  Shackleford

FS II

SC   

  In a message dated 5/31/2009 8:03:18 P.M. Eastern Daylight Time,  d-m-hague(at)comcast.net writes:

  	  Quote: 	
		  Yes, but    I suspect the multi blades are for space or controllability 

reasons, not    aerodynamic  efficiency.



	




 We found the real 'Hotel California' and the 'Seinfeld' diner. What will you find? Explore WhereItsAt.com.

  [quote][b]

Display posts from previous:

	Matronics Email Lists Forum Index -> Kolb-List	All times are GMT - 8 Hours Goto page Previous 1, 2, 3, 4 Next
Page 2 of 4

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum