Today's Message Index:
----------------------
1. 04:12 AM - Re: Re: CATTO 3 bladed prop (Bill Schertz)
2. 06:01 AM - Sun-N-Fun?? (Galin Hernandez)
3. 07:51 AM - Re: Sun-N-Fun?? (ALFRED ROSA)
4. 09:54 AM - Re: Re: CATTO 3 bladed prop (Scott Stearns)
Message 1
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| Subject: | Re: CATTO 3 bladed prop |
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
Sent: Friday, February 18, 2011 6:39 PM
Subject: Re: KIS-List: 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@teledynamix.com> wrote:
<bleuskyfly@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
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Message 2
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Anyone going to Sun-N-Fun this year? I hope to be there Thu - Fri - Sat.
Galin
Message 3
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Since I now live 2 hours drive from Lakeville, I will definitely be there
one of those days. If you give me your cell #, I'll get in touch when I'm
there.
Al Rosa
On Sat, Feb 19, 2011 at 8:56 AM, Galin Hernandez <galinhdz@gmail.com> wrote:
> Anyone going to Sun-N-Fun this year? I hope to be there Thu - Fri - Sat.
>
> Galin
>
> *
>
> *
>
>
Message 4
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| Subject: | Re: CATTO 3 bladed prop |
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 sam
e time.- Anyhow, just trivia..
-
Scott
--- On Fri, 2/18/11, Robert Reed <robertr237@att.net> wrote:
From: Robert Reed <robertr237@att.net>
Subject: Re: KIS-List: Re: CATTO 3 bladed prop
Well, there is one thing you won't have to worry about with the Catto 3 bla
ded is any significant weight increase. -It is a very light prop. -I kn
ow all the issues of 2 vs. 3 but my main reason for the Catto 3 blade was t
he 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 se
xiest looking props around.
Bob
Sent from my iPhone
On Feb 18, 2011, at 5:25 PM, Scott Stearns <sstearns2@yahoo.com> wrote:
I remember when the 'new' cessna 182 came out.- The 3 bladed propeller wa
s an option.- The POH showed no difference in performance between the two
and three bladed propellers, except the 3 bladed propeller was 40 pounds h
eavier and a $10,000+ option.- I've never seen a new 182 with a two blade
d 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@teledynamix.com> wrote:
From: BlueSkyFlier <bleuskyfly@teledynamix.com>
Subject: KIS-List: Re: CATTO 3 bladed prop
Hi Galin,
As part of making a decision about my new propeller (and also because I wan
ted to do it) I created an performance model for the KIS which integrates p
ropleller 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 negat
es 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 diame
ter which maximises residual engine power across the speed range.
The diameter determines the prop blade power loading which in turn determin
es the prop drag losses. Therefore, optimising diameter is equivalent to op
timising prop drag losses across the speed range for chosen RPM and altitud
e.
These non-linear characteristics of the propulsion system only become appar
ent when the airframe and propeller are integrated together.
Regards,
- - - - - - Alfred
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