Catto 3-blade RV-4 O-320

A big thanks to Craig Catto for an excellent prop. I replaced my Aymar-Demuth (68 diameter, 75 pitch) two-blade prop with a Catto (67 diameter, 70 pitch) three-blade with nickel leading edges.

Along with that swap at Craig's recommendation came new bolts for both sides of the hub, a Saber Manufacturing 4" Extension (3/8" bolts on engine, 7/16" bolts on prop side) and a Van's 13" spinner cut, painted and balanced for the three-blade prop.

I was fortunate to have the opportunity to fly down to Amador-Westover Airport (KJAQ) to visit Craig and his team where he manufactures these props. I learned that it is best to measure everything, twice, and pass along as much information as possible. By visiting I was able to learn a ton about prop bolts vs. AN bolts, prop hub specifics and the hub diameter requirements for Catto props and how to torque and service my new prop.

Craig is busy building and repairing props, as well as helping "new to the scene" customers like me who are still on the steep learning curve. Ashley and Nicole responded back when I left messages and put up with me rescheduling several times for different issues including this week's crazy weather.

Flight reports to follow.

Some specific differences - Catto and Aymar-Demuth

Big picture differences included low RPM thrust, static RPM, top end RPM at altitude, vibration and sound. Some of the differences are between the two-blade and three-blade configuration of the props.

Quieter. The three-blade Catto prop was quieter than the Aymar-Demuth wood, two-blade prop.

Less Vibration. Smooth power was one of the most immediate differences I felt as I powered up for the inital take-off with my new prop.

Pitched for rated power. The AD prop would easily spin above 2850 RPM at 8500 feet. The Catto was steady at 2700 RPM.

Traffic pattern. The RV-4 is a light weight aircraft for 160 hp. With the AD I was at idle power from abeam the numbers to touchdown on a normal VFR pattern. With the Catto I require a little power to maintain the same approach path and airspeed, which transitions to a less "floaty" flare and touchdown, little use of the brakes when I turn off the runway and a slower taxi speed. This helps save my brakes and has shortened my landing distance, especially on runways with a downslope here in the foothills of NorCal.

Climb. Through 5000' MSL both the AD and Catto were at 1500 fpm using 100 mph indicated airspeed. I was solo with full fuel on takeoff.

The timing triangle for average true airspeed won't have been done on the same day and conditions are changing this Winter quite regularly, so I may not end up getting that info. Craig nailed the prop design for a 160hp RV-4 and I am very happy so far! Back in Phase I for another few hours!

Sharp & mean looking prop!

I've been eyeballing/considering the Cato 3-blade and am looking forward to reading your performance stats in the future.

Looks like a good sales pitch, never knew Craig to provide Paint to match spinners on an install.

So what is the difference between prop bolts and an bolts?

Bolts

Length of the threads vs shank for a given bolt size. The prop bolts have more threads to prevent any posibility of bottoming out against the shank.

As far as the spinner goes...I had no presumptions...just asked.

Bottom line, if you can visit Catto Props it is worth the trip.

Very nice report thanks Al. I am flying behind a three blade Catto since 2011. This prop has been some places. Over 1,500 hours couldn't be happier.

Al, I also bought a 67x70 there blade nickel edge Catto propeller for my -4. But airplane is still in the building phase.
Could you please tell me what is the static rpm?
And how much of the runway is needed for take off?
Thanks.
Camillo

You've come a long way....

FlyinTiger said:

Length of the threads vs shank for a given bolt size. The prop bolts have more threads to prevent any posibility of bottoming out against the shank.

As far as the spinner goes...I had no presumptions...just asked.

Bottom line, if you can visit Catto Props it is worth the trip.

Click to expand...

Al,
Craig has certainly come a long way since he made the first one for my RV4 in 98'" in his front yard, wow! 3000 Catto hours on 2 different airplanes is a testimonial in itself. Congrats!

V/R
Smokey

Flying with the Catto three blade

I need to check my aircraft tach for accuracy before I post any more numbers...I'm told they can be off a couple hundred RPM. I'll try a hand held tachometer. If that doesn't work I'll resort to running nearby some flourescent lights until the prop appears to stop and check to see if I'm at a multiple of 60 (i.e. 1200 RPM) since the lights are 60 hertz.

I took a break from cockpit updates to fly...it was good to get some air under the wings. Formation last Saturday with a Citabria was fun. At 100mph cruise speed we explored what I would describe as the bottom end of RV-4 formation flight. The prop braking at idle was adequate to stay in position during turns as two on the inside.

All the non-numbers oriented benefits of a composite three bladed prop continue to be pleasing.

With a panel renovation almost done and radio swap there should be less wrenching and more flying in the near future.

Ok, Al. Thank-you.
Camillo

I like what you say about the prop-braking effect when landing. I never heard anyone make that point before. Although a 2 blade is more efficient (results may vary), I am liking this observed benefit of the 3 blade. Gives me more reason to want a 3 blade other than it looking so d*mn good.

Question for Catto prop users out there,

I have a 3 blade NLE on my RV7, 68"dia. 75" pitch.

On initial power application on takeoff I get about 2050 RPM, then about 2200 initial climb at around 100 kias. Another RV flyer (who has a CS prop) that flew with me was concerned that the RPM should be higher...

Any opinions on this?

Thanks

Those numbers are right. I get 2080 on the ground on the 2 bladed and 3 bladed prop.

I have an O-360 on my RV-8. I have a CATTO 68x75 3 blade. I get about 2088 RPM on initial take off roll, and climb at 2200 RPM @ about 100 KIAS also.
Perhaps this is low for aerobatics, but for a cross country cruiser I think it's about right.
I was flying in some light rain a few days ago, I don't have the nickel leading edges. I steadily reduced RPM after climb out and settled at about 2050 RPM @ about 134 KIAS. I think that's pretty fast for such a low RPM.
My son Peter just received his CATTO 3 blade for PITTS S1 O-360. It has a much flatter pitch. We were noticing the rear face airfoil of the blade is concave for a portion of the span, whereas the wood Sensenich was convex through the whole of the back of the blades. Interesting. Can't give a flight report on Peter's new CATTO, the spinner has not been delivered yet.

Craig's Three blade NLE 67x70 on the RV-4/160hp is the perfect match...if you want such a set up. I'm very pleased with this combination having tried a 67x72.
Static 2200 WOT 2800 at sea level. Well matched for form flight with an RV-4 160hp with constant speed prop. On takeoff we are identical and I walk away from CS prop on top end.
Catto mfg date: 8/2014. Having patiently gone through such trial test, I believe we are there. Craig... you are right on now.
Three blade NLE 67x70 on the RV-4/160hp is it.

Dave, how can your -4 take off in the same lenght as a c/s -4 does? Maybe your -4 is lighter. I am impressed from this report!