Catto 2 vs 3 Blade - Smoothness

[db1yg]

Howdy Brandon,

I had the opportunity to test fly a 2 blade Catto and a 3 blade Catto back to back on the same airplane.

Back in 2014-2017 I tested propellors for Craig on side by side RV aircraft--used my IO360 powered RV9a as the test bed. Lost count as to the number of props on that plane but on one occasion, out of my own curiosity, I tested my personal 3rd gen 3 blade 74.5 inch pitch Catto against a buddy's 3rd gen 2 blade 74.5 inch pitch Catto. Got some base line info on day 1 with the 3 blade then switched to the 2 blade in the afternoon and tested it on the same card as the 3 blade on day 2.

The 3 blade was smoother and noticeably quieter as well given the shorter blades and slower prop tip speeds. I used a phone app to check aircraft vibration in flight to confirm the difference in perceived smoothness.

Ref performance, as expected the 3 blade got off the runway quicker, climbed slightly better, but was 1.5 to 2 knots slower in cruise.

I would have to say both props were smooth but the nod went to the 3 blade.

Craig has since gone to newer generational designs and I do not know if my results still hold but I would say you really can't go wrong with a Catto Propellor--and they are so **** pretty!!!

Hope this helps,

Cheers,

db

[PilotjohnS]

I think the 3 vs 2 debate can be settled by saying to me smoothness is not most important. I think a prop dynamically balanced would be best, 3 or 2 blade.

I chose the 3 blade because Catto said cruising up high, the 3 blade would preform slightly better. Also, there is an inherent benefit with a 3 blade and its moment of inertia not varying through one revolution when there is a axis offset to the direction of flight. Why do you think Hughes helicopters used 3 blades for their Hughes 300C, they knew something Bell did not?

[Mel]

Originally Posted by db1yg

Howdy Brandon,
I had the opportunity to test fly a 2 blade Catto and a 3 blade Catto back to back on the same airplane.
Back in 2014-2017 I tested propellors for Craig on side by side RV aircraft--used my IO360 powered RV9a as the test bed. Lost count as to the number of props on that plane but on one occasion, out of my own curiosity, I tested my personal 3rd gen 3 blade 74.5 inch pitch Catto against a buddy's 3rd gen 2 blade 74.5 inch pitch Catto. Got some base line info on day 1 with the 3 blade then switched to the 2 blade in the afternoon and tested it on the same card as the 3 blade on day 2.The 3 blade was smoother and noticeably quieter as well given the shorter blades and slower prop tip speeds. I used a phone app to check aircraft vibration in flight to confirm the difference in perceived smoothness.
Ref performance, as expected the 3 blade got off the runway quicker, climbed slightly better, but was 1.5 to 2 knots slower in cruise.
I would have to say both props were smooth but the nod went to the 3 blade.
Craig has since gone to newer generational designs and I do not know if my results still hold but I would say you really can't go wrong with a Catto Propellor--and they are so **** pretty!!!
Hope this helps,
Cheers,
db

YEP; I was an early adopter of Craig's props on my RV-6. 3-Blade, fiberglas, December of 2003. I think I sold a few for him.

[scarlson]

I have been flying with a Catto 3-blade on my RV 9A for the last 2 years and recently tested a Catto 2-blade on the same plane (Titan IO-370, 185 HP). Both props are 68 inches diameter, but different pitches (3-blade 71 in, 2-blade 78 in). Both props were dynamically balance to 0.06 IPS or less. The 3-blade is noticeably smoother at the same RPM. I would suspect that the newer 3-blade prop model with a diameter of 66 inches is even better.
Because the prop pitches are different, it's not a direct comparison. Also, the 2-blade Catto is smoother than 2-blade Sensenich props that I have flown behind. The cowl issue wouldn't be a deciding factor for me, both are a pain. My choice would be a 3-blade prop.