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Charles Heathco
Joined: 10 Jan 2006
Posts: 201
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 Posted: Thu Jan 10, 2008 7:17 am Post subject: Cato 3 blade vs sen 2 blade RV6a's |
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Shortly after I bought my 6a, I went on a trip with another 6a with almost ident paint job, with 3 blade and 160hp. I have 2 blade 150hp. He told me he had to max it out to stay with me as I was lead. On return he asked if I wanted to do form takeoff, and altho hadnt before, I said yes.( him in lead) I stayed with him thru long ground effect run and sharp pullup that we like to do (Rv builders on the ground watching), an then broke off with an instictive vert pull and hard rt turn when he pulled left in front of me. Other factors have a bearing of course, but that is my take on the 3 vs 2 blade comparison. I will add that he said his 6a performed better with the Cato than with his previous 2 blade. Charlie Heathco
[quote][b]
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steve(at)newtech.com
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| Posted: Thu Jan 10, 2008 9:49 am Post subject: Cato 3 blade vs sen 2 blade RV6a's |
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Charles Heathco wrote:
| Quote: | Shortly after I bought my 6a, I went on a trip with another 6a with
almost ident paint job, with 3 blade and 160hp. I have 2 blade 150hp.
He told me he had to max it out to stay with me as I was lead. On
return he asked if I wanted to do form takeoff, and altho hadnt
before, I said yes.( him in lead) I stayed with him thru long ground
effect run and sharp pullup that we like to do (Rv builders on the
ground watching), an then broke off with an instictive vert pull and
hard rt turn when he pulled left in front of me. Other factors have a
bearing of course, but that is my take on the 3 vs 2 blade comparison.
I will add that he said his 6a performed better with the Cato than
with his previous 2 blade. Charlie Heathco
Within about a month we will have a better comparison of 3 vs 2 blade
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propellers. My hangar mate and building buddy has an RV-7 with a
Mattituck O-360 180 HP engine and Sensenich fixed pitch metal prop. I
am putting a Catto 3 blade on my RV-7A O-360 180 HP that should be
flying sometime in April. My Catto prop is scheduled to ship in another
week. When it gets here we are going to put it on my hangar mates RV-7
and get comparison performance numbers for both props on the same
plane. Should be interesting.
Steve Eberhart
RV-7A - O-360-A1A, Catto 3 blade, Slider and a whole bunch of Kandy
Apple Red paint
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ronlee(at)pcisys.net
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| Posted: Thu Jan 10, 2008 10:16 am Post subject: Cato 3 blade vs sen 2 blade RV6a's |
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When I changed my Aymar-Demuth 2 blade for a catto three blade
(will need to provide prop specs on both) I saw a 3-3.5 knot improvement
in 75% power, full speed with the Catto prop.
Personally, a Hartzell blended airfoil 2 blade would be optimal.
I know of a guy using a MT 2 blade constat speed prop and has had prop
grease leaage issues on the original and a replacement prop.
Ron Lee
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carlosh(at)sec-engr.com
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| Posted: Thu Jan 10, 2008 10:21 am Post subject: Cato 3 blade vs sen 2 blade RV6a's |
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This is especially interesting to me. You have essentially the same
setup as I have planned for my 7A. I will be waiting for the follow up
info on this.
Carlos in AZ
Do not archive
Steven Eberhart wrote:
| Quote: |
Charles Heathco wrote:
> Shortly after I bought my 6a, I went on a trip with another 6a with
> almost ident paint job, with 3 blade and 160hp. I have 2 blade 150hp.
> He told me he had to max it out to stay with me as I was lead. On
> return he asked if I wanted to do form takeoff, and altho hadnt
> before, I said yes.( him in lead) I stayed with him thru long ground
> effect run and sharp pullup that we like to do (Rv builders on the
> ground watching), an then broke off with an instictive vert pull and
> hard rt turn when he pulled left in front of me. Other factors have a
> bearing of course, but that is my take on the 3 vs 2 blade
> comparison. I will add that he said his 6a performed better with the
> Cato than with his previous 2 blade. Charlie Heathco
Within about a month we will have a better comparison of 3 vs 2 blade
propellers. My hangar mate and building buddy has an RV-7 with a
Mattituck O-360 180 HP engine and Sensenich fixed pitch metal prop. I
am putting a Catto 3 blade on my RV-7A O-360 180 HP that should be
flying sometime in April. My Catto prop is scheduled to ship in
another week. When it gets here we are going to put it on my hangar
mates RV-7 and get comparison performance numbers for both props on
the same plane. Should be interesting.
Steve Eberhart
RV-7A - O-360-A1A, Catto 3 blade, Slider and a whole bunch of Kandy
Apple Red paint
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--
Carlos Hernandez <carlosh(at)sec-engr.com>
Structural Engineers Company
2963 W. Elliot Rd. - Suite 3
Chandler, AZ 85224
Phone: 480.968.8600
Fax: 480.968.8608
www.sec-engr.com
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from your system.
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wdleonard(at)gmail.com
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| Posted: Thu Jan 10, 2008 8:33 pm Post subject: Cato 3 blade vs sen 2 blade RV6a's |
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I also had an Aymar Demuth 2-blade that I swaped out for a Catto 3-blade. And I'll tell you - performance schmormance!
Look, it is an essentially undisputed fact that the fewer the blades, the more efficient the transference of h.p. Some RC models use even use a ONE bladed prop with a counter weight. That is, props that are optimum.
For me, now that I know the difference, give me the slightly less efficient 3 blade any day. The smoothness of the 3-blade makes all the difference in the world. Who cares if you get there 5 minutes later if the entire 3 hour trip was more pleasant?
I know, you really still want to know about the performance change. Performance for me is difficult to judge because the props are so different. I was under pitched with my 2-blade so the 3 blade has a lot more pitch in addition to the extra blade, though it is shorter. The extra pitch solidly increased my high altitude top speed, but take off roll and climb are marginally diminished. The Catto seems to have a slimmer and better blade, but the Aymar Demuth has a good reputation for efficiency.
The point is that the the other properties of the prop are going to usually make more difference than the 3-blade vs 2-blade issue. But the smoothness of the 3-blade makes a big difference.
--
David Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net
On Jan 10, 2008 10:12 AM, Ron Lee < ronlee(at)pcisys.net (ronlee(at)pcisys.net)> wrote:
| Quote: | --> RV-List message posted by: "Ron Lee" < ronlee(at)pcisys.net (ronlee(at)pcisys.net)>
When I changed my Aymar-Demuth 2 blade for a catto three blade
(will need to provide prop specs on both) I saw a 3-3.5 knot improvement
in 75% power, full speed with the Catto prop.
Personally, a Hartzell blended airfoil 2 blade would be optimal.
I know of a guy using a MT 2 blade constat speed prop and has had prop
grease leaage issues on the original and a replacement prop.
|
[quote][b]
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sarg314(at)comcast.net
Guest
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| Posted: Thu Jan 10, 2008 11:16 pm Post subject: Cato 3 blade vs sen 2 blade RV6a's |
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FWIW, Catto himself told me that for the O-320 RV's his 2 blade is about
the same as the 3 blade in terms of performance. For the O-360's he
prefers the 3-blade because it has better harmonics. I bought a
3-blade, as I have an IO-360 on my RV-6A. Not flying yet (give me a few
more months).
I talked to many people about props before I made this choice. The
stories about performance were pretty much all over the map. One thing
they all agreed on was that the 3-blade is very smooth. That's enough
for me right there. The prop is beautiful and Craig tells a pretty good
story (which I obviously bought in to), so I'm hoping for good cruise
performance. But, there's more art than science in the marriage of a
particular plane and a particular propeller. I hope I got a good
combination, but there's definitely an element of luck involved. We'll see.
--
Tom S.
RV-6A
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