dan carley
Well Known Member
just purchased slightly used catto 3 bladed prop, was wondering what pitch is the best. this one is diameter 66 inch,pitch 72".ment for rv-4 160 hp
thanks
dan carley
'
thanks
dan carley
'
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Catto 3 bladed prop
- Thread starter dan carley
- Start date
It may be useful to most of use transcribe Mr. Catto's answer to my similar request. I added that I will use my -4 on slightly short runways (450 meters).
"Hello,
We produce both two and three bladed propellers for this aircraft. These
propellers have NO rpm restrictions.
If your gear legs are short ones, then you may really want to consider the
three bladed for ground clearance. This propeller is 67 inches in diameter.
The two bladed is 70 inches in diameter.
As for pitch, you probably want to run just a bit on the climb side, as you
are operating out of the short grass strip. This will help you with getting
in and also getting out of the strip.
I fly a 160hp RV-6 and can safely takeoff and land in less than 1000ft. I
fly with the three bladed 67x70 and I top out at 198mph at 2740rpm.
For you, I would recommend dropping down one inch of pitch, down to a 69
pitch. This will give you a higher static rpm for takeoff, about 2300 and
depending on how fast your plane is, The RV-4 is spec'd at 194mph so your
rpm would be about 2750~.
If we drop down to a 68 pitch , then the top end rpm will come up to 2800rpm
and your static rpm up to about 2350.
The two bladed propeller would be the same pitch ranges for the rpm."
Even if I opted for a 67X70 three-blade propeller and sent two more emails, I received no answer from Mr. Catto. So I am looking for a used Catto propeller, in order to jump the long production cue. I found a 68X74 three blade made for a 180HP RV7. This friend goes over 2700 well before full throttle. So I was wondering if that propeller may fit my plane. In addition, I was wondering if also the Craig suggested 67X70 may be underpitched for the -4.
"Hello,
We produce both two and three bladed propellers for this aircraft. These
propellers have NO rpm restrictions.
If your gear legs are short ones, then you may really want to consider the
three bladed for ground clearance. This propeller is 67 inches in diameter.
The two bladed is 70 inches in diameter.
As for pitch, you probably want to run just a bit on the climb side, as you
are operating out of the short grass strip. This will help you with getting
in and also getting out of the strip.
I fly a 160hp RV-6 and can safely takeoff and land in less than 1000ft. I
fly with the three bladed 67x70 and I top out at 198mph at 2740rpm.
For you, I would recommend dropping down one inch of pitch, down to a 69
pitch. This will give you a higher static rpm for takeoff, about 2300 and
depending on how fast your plane is, The RV-4 is spec'd at 194mph so your
rpm would be about 2750~.
If we drop down to a 68 pitch , then the top end rpm will come up to 2800rpm
and your static rpm up to about 2350.
The two bladed propeller would be the same pitch ranges for the rpm."
Even if I opted for a 67X70 three-blade propeller and sent two more emails, I received no answer from Mr. Catto. So I am looking for a used Catto propeller, in order to jump the long production cue. I found a 68X74 three blade made for a 180HP RV7. This friend goes over 2700 well before full throttle. So I was wondering if that propeller may fit my plane. In addition, I was wondering if also the Craig suggested 67X70 may be underpitched for the -4.
brad walton
Well Known Member
I think the O-320 has 7/16 inch prop bolts and the O-360 uses 1/2 inch prop bolts. For pitch questions, best to talk to Craig Catto. If he doesn't answer your email, call him. He seems to stay very busy.
dan carley
Well Known Member
catto prop
i was wondering if anyone with an rv-4 has a 3 bladed prop and what pitch and diameter they are using
dan carley
i was wondering if anyone with an rv-4 has a 3 bladed prop and what pitch and diameter they are using
dan carley
dan carley
Well Known Member
3 bladed prop
no one has any input on a 3 bladed prop on a rv4? with 0-320 160 hp engine
dan carley
no one has any input on a 3 bladed prop on a rv4? with 0-320 160 hp engine
dan carley
AX-O
Well Known Member
Dan,
There is a lot of information out there regarding this configuration (check out the search function). But here is the issue, what works well for me does not mean it will work well for you. You did not say where you wanted to perform best (at cruise, in climb). You also did not mention your particular aircraft configuration (short gear, old wheel pants, old gear leg fairings, fastback, etc).
Everything that changes the drag polar on the aircraft also causes changes to the RPM in flight. A slick rv-4 will have the capability to spin the prop faster than an rv-4 with a lot of drag; everything else remaining constant. i.e. If Work (the Physics? definition) remains constant; you can pedal a bike much faster if you don?t have a parachute (drag) slowing you down.
In addition to that, I have had conversations with Craig Catto and he measures the pitch of the blade differently on different designs. A 67 pitch in the old style blade does not necessarily mean the same pitch on a 67 pitch new blade. He also told me that the way he measures the pitch is different than most other prop manufactures. I have mentioned this a few times on the forum. The request from Craig was to fly the set up, collect data, call him with the data and he can go into his clipboard and find out what pitch you will need in a particular blade design. Then he can change the pitch by changing the airfoil (adding carbon fiber/epoxy)
When you a buy a new prop, he gives you the prop set up that works best depending on what you want the airplane to do (climb/cruise). If your plane is cleaner than the standard, you may need a pitch change.
I hope that helps. I have done some comparison and it is documented in the archives. Others have done a great job here doing the same. Check those posts out. At the end of the day I am sure that you will love your prop. And if it needs some extra love (repitch), Craig will take care of you.
There is a lot of information out there regarding this configuration (check out the search function). But here is the issue, what works well for me does not mean it will work well for you. You did not say where you wanted to perform best (at cruise, in climb). You also did not mention your particular aircraft configuration (short gear, old wheel pants, old gear leg fairings, fastback, etc).
Everything that changes the drag polar on the aircraft also causes changes to the RPM in flight. A slick rv-4 will have the capability to spin the prop faster than an rv-4 with a lot of drag; everything else remaining constant. i.e. If Work (the Physics? definition) remains constant; you can pedal a bike much faster if you don?t have a parachute (drag) slowing you down.
In addition to that, I have had conversations with Craig Catto and he measures the pitch of the blade differently on different designs. A 67 pitch in the old style blade does not necessarily mean the same pitch on a 67 pitch new blade. He also told me that the way he measures the pitch is different than most other prop manufactures. I have mentioned this a few times on the forum. The request from Craig was to fly the set up, collect data, call him with the data and he can go into his clipboard and find out what pitch you will need in a particular blade design. Then he can change the pitch by changing the airfoil (adding carbon fiber/epoxy)
When you a buy a new prop, he gives you the prop set up that works best depending on what you want the airplane to do (climb/cruise). If your plane is cleaner than the standard, you may need a pitch change.
I hope that helps. I have done some comparison and it is documented in the archives. Others have done a great job here doing the same. Check those posts out. At the end of the day I am sure that you will love your prop. And if it needs some extra love (repitch), Craig will take care of you.
My SS leading edge 3 blade Catto is 68" dia x 71 pitch on an RV-4 with an O320 and PR wheel pants and one Lightspeed Plasma II ignition.
WOT at 8K DA, I get 142 KIAS OR 160 KTAS (per D10-A) at 2800 RPM.
The prop is super smooth and good looking but sometimes wish I had a little more pitch.
WOT at 8K DA, I get 142 KIAS OR 160 KTAS (per D10-A) at 2800 RPM.
The prop is super smooth and good looking but sometimes wish I had a little more pitch.
dan carley
Well Known Member
catto prop
the one i got is a 66x72 wonder how that will work?it's 160hp
dan carley
the one i got is a 66x72 wonder how that will work?it's 160hp
dan carley
Last edited:
Hi Dan,
That is what I have on mine. (O-320 160 hp) Works great & I love it. I got 207 mph, WOT @ 10,000' DA and 2,700 rpm. I told Craig I wanted best cruise properties as I usually fly alone and use it for commuting. This was what he fixed me up with.
I have a 2 blade Aymar-Demuth that gave slightly better performance in both climb & cruise. Climb was better and emphasize slightly better cruise. The Catto is super smooth though. The climb performance is still outstanding though even if it's primarily a cruise prop.
For doing aerobatics I'd prefer the 2 blade A-D. However, I fly my -4 like a C-172 these days and this prop is wonderful for me. I've got 24 years of -4s under my belt now and just do a roll now & then for grins & giggles. It does that no problem. Sweet!!
So for smooth and quick, this prop is giving me yeoman's service.These days, and with a Dynon D-180 and Pmags, I'm fascinated by the fuel economy I'm getting. So I usually fly X-country about 50-55% power and around 150 mph. However, if I want to do 3 miles/minute, just shove the throttle forward and it'll do it. Just watch the fuel burn go up. Mucho fun and interesting.
Hope this helps you. Happy flying.
Cheers,
dan carley
Well Known Member
catto prop
thanks deal,
sounds like i got the right prop. we should be putting it on Saturday. what are you getting on climb out at what speed? is it all that hard to get the bottom cowl off with the 3 bladed prop? are you running a balancer?
regards
dan carley
thanks deal,
sounds like i got the right prop. we should be putting it on Saturday. what are you getting on climb out at what speed? is it all that hard to get the bottom cowl off with the 3 bladed prop? are you running a balancer?
regards
dan carley
Dan my home base is only 130' ASL. My takeoff routine is to concentrate on a possible engine out and scramble for 1,000' AGL. Then I notice numbers better. Climb varies of course with density altitude; but I'm always at least 1,500'/min. Light & cool temps give it around 2,000 +/-. Then I ease into a climb/cruise of 500 to 800 fpm and "about" 120 mph. I like cool smooth air and try to get above 6,000' quickly in hot months. I'm giving approximate numbers because they sure vary depending on conditions & locations. Suffice to say you have wonderful performance in a -4 though. A heavy passenger robs some performance of course and does affect the handling. There are numerous threads available here regarding that. Oh, the WnB Pro app is a great tool for you to use when you're loading up the rear seat. Use it for your safety.
Removal/installation of the bottom cowl takes patience & finesse. It's not "hard"; but get in a hurry and you risk scratching paint. I use a good cardboard box from U-Haul to assist me. The box provides a backup & rest if needed. Two more arms would be nice. I will not remove if it I'm in any agitated state of mind. Calm, patient easy movements gets it on & off ok. No question the 2 blade definitely makes lower cowl removal easier
No balancer but have a beautiful Saber extension and the spinner Craig provides.
Wish you safe & fun flying Dan!! I think you're going to love your -4.
precession
Well Known Member
Question for Deal Fair
Hi Deal,
Since you have both the 2 blade and 3 blade props, I'd be interested to know if you've noticed any significant difference in noise level between the two(??).
I'm pretty set on ordering a 2 blade, pitched for best cruise, but I'm also interested in preserving my hearing, and if the 3 blade is noticeably quieter I might consider changing my mind.
Any thoughts?
Thanks.
Hi Deal,
Since you have both the 2 blade and 3 blade props, I'd be interested to know if you've noticed any significant difference in noise level between the two(??).
I'm pretty set on ordering a 2 blade, pitched for best cruise, but I'm also interested in preserving my hearing, and if the 3 blade is noticeably quieter I might consider changing my mind.
Any thoughts?
Thanks.
