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Anybody using a 2 blade Catto?

N333M

Active Member
I am wondering if anyone has any info on the 2 blade Catto, vs the standard 2 blade metal Sensenich prop on a 9A? I have the 79 pitch metal sensi, placarded for 2600 rpms max, and it seems a little ..well..just not optimal. My indicated airspeed is about 175 or so at 2600, and I do have to pull the throttle back a tad as it will exceed 2600 (160 hp). Climb performance seems a little sluggish, ( from the engine rpm standpoint ) And it takes a long time for the engine to bring it up to speed when leveling out..could be just my perception, as I have not had experience with an airframe with such a wide performance envelope before, admittedly.
Anyway, would like to hear of others experience.
One thing I am awfully happy about however, is the 2350 rpm cruise, at 155 to 160 mph indicated, and 6.7 gph! Not sure I would want to change anything if I had to give that up!
 
I have quantitative and qualitative data for the props on a -4. if you are interested, I can post some of the results. I did not want to derail this by posting for a different airframe although it should be similar enough.
 
I am wondering if anyone has any info on the 2 blade Catto, vs the standard 2 blade metal Sensenich prop on a 9A? I have the 79 pitch metal sensi, placarded for 2600 rpms max, and it seems a little ..well..just not optimal. My indicated airspeed is about 175 or so at 2600, and I do have to pull the throttle back a tad as it will exceed 2600 (160 hp). Climb performance seems a little sluggish, ( from the engine rpm standpoint ) And it takes a long time for the engine to bring it up to speed when leveling out..could be just my perception, as I have not had experience with an airframe with such a wide performance envelope before, admittedly.
Anyway, would like to hear of others experience.
One thing I am awfully happy about however, is the 2350 rpm cruise, at 155 to 160 mph indicated, and 6.7 gph! Not sure I would want to change anything if I had to give that up!

Indicated airspeed is a poor indicator to use as a comparison of performance.
I suggest you first start using true airspeed (best to do some testing first to confirm calibration of you ASI). Particularly when you are mentioning at what altitude that is at. At 10,500 my RV-6A indicates only 160 MPH but the true airspeed is over 190.
 
Top end could certainly be impacted, from what you've said. Having to hold that horse back to avoid > 2600 RPM. Not a big deal in cruise flt above 8000 ft where you likely can't make it turn that fast.

Are you progressively leaning during WOT climb to maintain peak EGT minus 250 degrees ROP? Once below 65% or so (~8000 ft), you can lean for best power (RPMs) to improve a bit more.

John Deakin has a great article on this topic.

Hopefully I haven't misrepresented his information :D
 
I've got a -9A (160-hp IO-320-D1A) with a 70x70 two-blade Catto. Going back to Oshkosh I achieved 145 KTAS at around 7.0-7.2 gph, and 155 KTAS at 8.0 gph, with DA ranging from 10,500 to 12,000 feet. It was spinning pretty fast at 155 kts, between 2600 and 2650 rpm IIRC. Very smooth at those engine speeds. At 8000' DA, it'll top out about 170 KTAS...just what Van's promised.
 
I use a Catto 2-Blade. Here is some performance data. This is at 8,000 DA

KTAS 154
RPM 2600
MP 23.7
GPH 7.8
%Power 74
NM/G 19.74

"WOT"
KTAS 162
RPM 2740
MP 24.3
GPH 9.0
%Power 82
NM/G 18.00
 
AX-o, Yes, Id love to see some stats on props info for your -4!

Scott, I understand, I just installed a new ASI..actually a Garmin G-5, and had it calibrated, along with the old ASI which I left in the panel. The avionics guy used a manometer. I was present, and will do it myself next time! The speeds I quoted are all at or below 3500 ft. An no, it wont turn that fast a 10k
 
Raymo,
Thanks for the reply!
unfortunately, I dont have EGT monitoring yet, (which is killing me) so I am leaning the old fashioned way..pull till it coughs..then turn it back in a bit. And I have read Johns Pelican perch on leaning ..several times, trying to get it all to stick. At OSh this year I spent alot of time looking at several EIS methods..as when I bought the craft a few months ago, the avionics were a little buggy, (all steam gages) so its getting a panel upgrade..and after going back and forth between Dynon, GRT, MGL, and Garmin about 3 times each in two days..(till my wife just rolled her eyes and went back to the campgrounds) , I was trying to decide which way to proceed with the upgrade, I finally gave up, just bought a G-5 to get me by , and came home to digest all the choices..wow things are changing so fast I cant keep up, and it kind of , overwhelmed me..Had the money to buy..but couldnt decide.
 
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Doug, and Tony Thanks for those numbers!
Doug, What is the engine turning at WOT..170 kts at 8000 DA?

Tony, What engine do you have in that beautiful Taildragger? And do you remember what pitch Catto you are running?
 
Scott, I understand, I just installed a new ASI..actually a Garmin G-5, and had it calibrated, along with the old ASI which I left in the panel. The avionics guy used a manometer. I was present, and will do it myself next time!
You still need to do an airborne GPS TAS check. A manometer will not show a static source installation location error. That can only be done while actually flying.

:cool:
 
Doug, and Tony Thanks for those numbers!
Doug, What is the engine turning at WOT..170 kts at 8000 DA?

I did this during my Phase 1 testing back in mid-2016, so the memory's a little fuzzy, but I think it was in the 2850-rpm range. I'm uncomfortable spinning the engine that high for any length of time, but I just wanted to "see what she'd do." Highest TAS on the way back from OSH was 161 kts at about 2700 rpm.

I'm extremely happy with the mix of economy/speed the -9 delivers. :)

The prop itself has a redline of 3200 rpm.
 
I have had two different engines on my -9, both with Catto two bladed props.

There is nothing else out there that combines the smoothness and performance of the Catto.

My first engine was a 135 hp O-290D2 and I now fly behind an O-360.

My numbers don?t compare to an O-320 other than I can go faster while burning more fuel.

75% power for me is right at 175 knots / 200 mph but my typical flight is in the 155 to 160 knot range burning 7 GPH.

Climb rates depend on OAT and GW but it is not uncommon to see 1600 FPM when heavy.
 
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