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galinhdz(at)gmail.com
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 Posted: Sun Feb 13, 2011 6:01 am Post subject: CATTO 3 bladed prop |
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Is anybody flying a CATTO 3 bladed fixed pitch prop? I am thinking of switching from my current SENSENICH 2 blade on my TR-4 with a Lycomming O-360.
Galin
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BlueSkyFlier
Joined: 27 Jan 2011
Posts: 74
Location: UK
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| Posted: Fri Feb 18, 2011 12:21 pm Post subject: Re: CATTO 3 bladed prop |
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Hi Galin,
As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models.
To my surprise and contrary to popular wisdom the results showed that
(a) larger diameter is not necessarily always better and
(b) 3 bladed props are rarely (if ever) better than 2 bladed props
At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity.
For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude.
These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together.
Regards,
Alfred
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sstearns2(at)yahoo.com
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| Posted: Fri Feb 18, 2011 3:36 pm Post subject: CATTO 3 bladed prop |
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I remember when the 'new' cessna 182 came out. The 3 bladed propeller was an option. The POH showed no difference in performance between the two and three bladed propellers, except the 3 bladed propeller was 40 pounds heavier and a $10,000+ option. I've never seen a new 182 with a two bladed propeller and a lot of older 182 have converted to three bladed props. It does look cool....
Scott
--- On Fri, 2/18/11, BlueSkyFlier <bleuskyfly(at)teledynamix.com> wrote:
| Quote: |
From: BlueSkyFlier <bleuskyfly(at)teledynamix.com>
Subject: Re: CATTO 3 bladed prop
To: kis-list(at)matronics.com
Date: Friday, February 18, 2011, 12:21 PM
--> KIS-List message posted by: "BlueSkyFlier" <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)>
Hi Galin,
As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models.
To my surprise and contrary to popular wisdom the results showed that
(a) larger diameter is not necessarily always better and
(b) 3 bladed props are rarely (if ever) better than 2 bladed props
At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity.
For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude.
These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together.
Regards,
Alfred
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331443#331443
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[quote][b]
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sstearns2(at)yahoo.com
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| Posted: Fri Feb 18, 2011 4:10 pm Post subject: CATTO 3 bladed prop |
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Also, a one bladed propeller is really best, just a bit hard to do. Some model racing airplanes use one bladed propellers with a counter weight to balance the prop.
Scott
--- On Fri, 2/18/11, BlueSkyFlier <bleuskyfly(at)teledynamix.com> wrote:
| Quote: |
From: BlueSkyFlier <bleuskyfly(at)teledynamix.com>
Subject: Re: CATTO 3 bladed prop
To: kis-list(at)matronics.com
Date: Friday, February 18, 2011, 12:21 PM
--> KIS-List message posted by: "BlueSkyFlier" <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)>
Hi Galin,
As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models.
To my surprise and contrary to popular wisdom the results showed that
(a) larger diameter is not necessarily always better and
(b) 3 bladed props are rarely (if ever) better than 2 bladed props
At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity.
For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude.
These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together.
Regards,
Alfred
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331443#331443
http://www.matronics.com/Nav - MATRONICS WEB &nbsf="http://www.matronics.com/contribution" target=_blank>http://www.matr=====================
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[quote][b]
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galinhdz(at)gmail.com
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| Posted: Fri Feb 18, 2011 4:41 pm Post subject: CATTO 3 bladed prop |
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Yes, I am aware of what you pointed out about the different props. But, I want to use a smaller diameter prop since I fly in and out of runways that are not very well kept. I have a constant struggle with nicks on my 76" prop. I installed prop guard on the leading edge. It lessened the problem, but it still exists more than I like.
That is why I wanted a PIREP if anybody had a CATTO prop and how it performed.
Galin
On Fri, Feb 18, 2011 at 2:21 PM, BlueSkyFlier <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)> wrote:
[quote]--> KIS-List message posted by: "BlueSkyFlier" <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)>
Hi Galin,
As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models.
To my surprise and contrary to popular wisdom the results showed that
(a) larger diameter is not necessarily always better and
(b) 3 bladed props are rarely (if ever) better than 2 bladed props
At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity.
For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude.
These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together.
Regards,
Alfred
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331443#331443
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Robert Reed
Joined: 22 Oct 2009
Posts: 331
Location: Dallas/Ft.Worth
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| Posted: Fri Feb 18, 2011 5:42 pm Post subject: CATTO 3 bladed prop |
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Well, there is one thing you won't have to worry about with the Catto 3 bladed is any significant weight increase. It is a very light prop. I know all the issues of 2 vs. 3 but my main reason for the Catto 3 blade was the quiet operation of the 3 bladed prop. My wife has migranes and I have made several changes to reduce cabin noise. Besides, it's one of the sexiest looking props around.
Bob
Sent from my iPhone
On Feb 18, 2011, at 5:25 PM, Scott Stearns <sstearns2(at)yahoo.com (sstearns2(at)yahoo.com)> wrote:
[quote]I remember when the 'new' cessna 182 came out. The 3 bladed propeller was an option. The POH showed no difference in performance between the two and three bladed propellers, except the 3 bladed propeller was 40 pounds heavier and a $10,000+ option. I've never seen a new 182 with a two bladed propeller and a lot of older 182 have converted to three bladed props. It does look cool....
Scott
--- On Fri, 2/18/11, BlueSkyFlier <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)> wrote:
| Quote: |
From: BlueSkyFlier <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)>
Subject: Re: CATTO 3 bladed prop
To: [url=mailto:kis-list(at)matronics.com]kis-list(at)matronics.com (kis-list(at)matronics.com)[/url]
Date: Friday, February 18, 2011, 12:21 PM
--> KIS-List message posted by: "BlueSkyFlier" <[url=mailto:bleuskyfly(at)teledynamix.com]bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)[/url]>
Hi Galin,
As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models.
To my surprise and contrary to popular wisdom the results showed that
(a) larger diameter is not necessarily always better and
(b) 3 bladed props are rarely (if ever) better than 2 bladed props
At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity.
For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude.
These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together.
Regards,
Alfred
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331443#331443
http://www.matronics.com/Nav - MATRONICS WEB &nbsf="http://www.matronics.com/contribution" target=_blank>http://www.matr=====================
|
[b]
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wschertz(at)comcast.net
Guest
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| Posted: Sat Feb 19, 2011 4:12 am Post subject: CATTO 3 bladed prop |
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Galen,
I have no experience on a KIS with a 3 blade prop, but a friend of mine has an E-racer that he used a Catto 3 blade prop on, and he was very pleased with the performance.
Bill Schertz
KIS Cruiser #4045
N343BS
Phase I testing
From: Galin Hernandez (galinhdz(at)gmail.com)
Sent: Friday, February 18, 2011 6:39 PM
To: kis-list(at)matronics.com (kis-list(at)matronics.com)
Subject: Re: Re: CATTO 3 bladed prop
Yes, I am aware of what you pointed out about the different props. But, I want to use a smaller diameter prop since I fly in and out of runways that are not very well kept. I have a constant struggle with nicks on my 76" prop. I installed prop guard on the leading edge. It lessened the problem, but it still exists more than I like.
That is why I wanted a PIREP if anybody had a CATTO prop and how it performed.
Galin
On Fri, Feb 18, 2011 at 2:21 PM, BlueSkyFlier <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)> wrote:
| Quote: | --> KIS-List message posted by: "BlueSkyFlier" <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)>
Hi Galin,
As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models.
To my surprise and contrary to popular wisdom the results showed that
(a) larger diameter is not necessarily always better and
(b) 3 bladed props are rarely (if ever) better than 2 bladed props
At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity.
For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude.
These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together.
Regards,
Alfred
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331443#331443
===========
rget="_blank">http://www.matronics.com/Navigator?KIS-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
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sstearns2(at)yahoo.com
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| Posted: Sat Feb 19, 2011 9:54 am Post subject: CATTO 3 bladed prop |
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3 bladed props look cool, no doubt about that. I think that's basically why they are used on most piston airplanes.
I think it really helps with the pushers to reduce noise and vibration since you don't have both blades hitting the wake of the wing at the same time. Anyhow, just trivia..
Scott
--- On Fri, 2/18/11, Robert Reed <robertr237(at)att.net> wrote:
| Quote: |
From: Robert Reed <robertr237(at)att.net>
Subject: Re: Re: CATTO 3 bladed prop
To: "kis-list(at)matronics.com" <kis-list(at)matronics.com>
Date: Friday, February 18, 2011, 5:39 PM
Well, there is one thing you won't have to worry about with the Catto 3 bladed is any significant weight increase. It is a very light prop. I know all the issues of 2 vs. 3 but my main reason for the Catto 3 blade was the quiet operation of the 3 bladed prop. My wife has migranes and I have made several changes to reduce cabin noise. Besides, it's one of the sexiest looking props around.
Bob
Sent from my iPhone
On Feb 18, 2011, at 5:25 PM, Scott Stearns <sstearns2(at)yahoo.com (sstearns2(at)yahoo.com)> wrote:
| Quote: | I remember when the 'new' cessna 182 came out. The 3 bladed propeller was an option. The POH showed no difference in performance between the two and three bladed propellers, except the 3 bladed propeller was 40 pounds heavier and a $10,000+ option. I've never seen a new 182 with a two bladed propeller and a lot of older 182 have converted to three bladed props. It does look cool....
Scott
--- On Fri, 2/18/11, BlueSkyFlier <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)> wrote:
| Quote: |
From: BlueSkyFlier <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)>
Subject: Re: CATTO 3 bladed prop
To: kis-list(at)matronics.com (kis-list(at)matronics.com)
Date: Friday, February 18, 2011, 12:21 PM
--> KIS-List message posted by: "BlueSkyFlier" <bleuskyfly(at)teledynamix.com (bleuskyfly(at)teledynamix.com)>
Hi Galin,
As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models.
To my surprise and contrary to popular wisdom the results showed that
(a) larger diameter is not necessarily always better and
(b) 3 bladed props are rarely (if ever) better than 2 bladed props
At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity.
For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude.
These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together.
Regards,
Alfred
--------
_________________________________________
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331443#331443
http://www.matronics.com/Nav - MATRONICS WEB &nbsf="http://www.matronics.com/contribution" target=_blank>http://www.matr=====================
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