Three blades for o-320

[Dennis Madden]

Folks,
I have an RV-4 with a Warnke "almost constant speed" F/P prop. (O-320) I love the prop, but am open to improvments. My question is, if I switched to a three blade Catto, will it add drag when throttled back to help decelerate in the patten? (I know C/S would be best for this, but it's not an option) Just wondering if anyone noticed any difference.
Also, do these hold up in the rain? Lastly, how much top end (speed) would I be giving up with three blades?
Thanks,

[Mel]

The 3-blade will actually REDUCE drag because it is a smaller diameter. The reduced disc "area" provides less drag.
As far as top speed goes, I went from a Sensenich wood cruise prop to a climb Catto and didn't loose any top speed.

[pierre smith]

Hi Dennis,
Yep, less drag on approaches but nothing you won't adapt to. It will more than likely be faster than your Warnke......Catto's props do what he says they will. We have almost 300 hours on ours and I'd definitely buy one again.We beat Van's numbers by 4 MPH at 75%/7500'. It's also very smooth.......and quieter inside and outside the airplane.

Regards,

[Avenger V]

I have a Catto three blade on my RV-9A with a 0-320. The only problem I have is removing the lower cowl. I even extended the slot on the bottom of the cowl and it still is a major pain.
Ron Russ, Canton, GA

[videobobk]

I gotta agree, taking off the bottom cowl is a real pain. But you can do it. As far as drag on final, I have the rpm set WAY low, and it works just fine. I rarely pull the throttle all the way back except on final, but when I do, my 320 idles at 380-400 rpm on the ground. That give much more drag on final than when I have the throttle set to where it would give 6-700 if it were setting still. I haven't found any need to clear the engine, but it would probably be a good idea. I try for pretty tight patterns and short finals. I have an E-Mag on the right, and when I switch to that alone (left mag off) it even idles smoothly at 400rpm. I love my three blade Catto and don't think I am giving up much in any area except takeoff run, compared to a CS. I see 2200 rpm on initial takeoff.

Bob Kelly

[E. D. Eliot]

Please give us the diameter and pitch of the Cattos listed above. Also, How well do Cattos work with an IO-320 on an RV-9. Thanks in advance

[videobobk]

Sorry, don't remember. Will check next time I'm at the airport. Sounds like a good excuse to go... I do know that I asked Craig for one biased toward cruise and that I had an E-Mag. Rely on what he says and you'll be okay. IMHO, you shouldn't try to pick your own pitch.

Bob Kelly

[glenn654]

E.D.,
I've been flying a Catto 3-blade on my -4 for 4 yrs now and I can confirm everything Pierre wrote. The dia/pitch is 66x72 used on an O-320-D1A, 160 hp. If you buy it you will like it.

Glenn Wilkinson
N654RV @ MLJ

[N941WR]

Originally Posted by E. D. Eliot

Please give us the diameter and pitch of the Cattos listed above. Also, How well do Cattos work with an IO-320 on an RV-9. Thanks in advance

E.D.,

I don't know about the three bladed prop in an O-320 powered -9A but my two bladed Catto works great on my O-290 powered -9.

I fully expect to exceed Van's number for this engine airframe combination (I'm working on the gear leg fairings right now.) but my climb numbers on 95 degree days and GW of around 1,400 ft-min just blow me away. Cruise w/o the fairings is right at 160 mph and I suspect I'm under pitched but will know more once those fairings are on. This is for a 990 lb -9 with a 135 hp O-290-D2 and duel P-mags.

What I'm trying to say is, "Trust Craig Catto and go with what he recommends. He really knows how to size props."

Oh, and I originally wanted a three bladed prop for my engine because I think they look so cool. He talked me out of it because he felt I didn't have enough power. I'm very happy with the results. (Besides, putting the cowling on and off with a three bladed prop must be a pain.)