Catto Propeller Users

[Steve Daudelin]

I'm researching building an RV-7A and I'm trying to make the engine/propeller decision. Looks like I'll probably go with a 180 hp Lycoming (but I'm open to opinions on the 200 hp version) and I'm looking at using a 3-blade Catto fixed pitch prop. Anyone have any experience with a Catto prop and/or other issues to consider? Any input would be appreciated. Thanks in advance for your help.

 

[David-aviator]

The 3 blade Catto gives excellent service and looks cool but if I had to do it again, I would go with the 2 blade prop with the 7A. It is a bear to remove the bottom cowl.

 

[MartinPred]

Catto!

I can't say enough good things about the Catto. I've got about 150 hours on my O-360/three-blade combo and it's head-and-shoulders above my old Sensenich two-blade wood. Just as smooth, plus I can run it at a higher RPM and get ALL the horsepower out of the engine.

I fly mostly low level so I like to carry a fair amount of speed but still have some throttle left. I can cruise with the Catto at 2700 RPM and push it up to 2900 if needed to climb away from the terrain. Plus the Catto is so light that it spins up instantly vs. the lag of a constant speed.

BL: I highly recommend it.

-Matt
402BD

 

[roadrunner20]

I've been flying a catto 3-blade prop for 4 1/2 years, 577 hobb hours.
Nice looking and a smooth ride.
I believe I'm a bit over pitched at 66x76. My wot is ~2680. Compare with Dave Dormier he gets more rpm.
I'm very satisfied except for the issue of weight impacting my cg.
Low fuel, near gross weight puts me into an aft cg which I must compensate with reduced baggage(60lbs) especially on cross country. I compensate by adding scuba bean bags weights in the forward cabin when I'm on a long cross country which may impact my landing configuration when low fuel & wife onboard.

 

[cjensen]

I've got 27 hours behind mine now, and I've loved every minute of it! I can't enough good about the prop and performance. Craig's service is great (he is VERY backordered tho), and it just looks drop dead gorgeous!! Yeah, removing the cowl can be a bit cumbersome, but it's not enough to make a difference to me.

Two thumbs up!!

 

[newtech]

I'm very satisfied except for the issue of weight impacting my cg.
Low fuel, near gross weight puts me into an aft cg which I must compensate with reduced baggage(60lbs) especially on cross country. I compensate by adding scuba bean bags weights in the forward cabin when I'm on a long cross country which may impact my landing configuration when low fuel & wife onboard.

I added a 22 pound Saber crush plate to mine after the plane went down on its tail because of the aft CG issue. With the new crush plate I have access to about 75 pounds in the baggage area.

Love the prop and wouldn't consider anything else. I might consider using the longer O-320 mount to get my angle valve O-360-A1A farther out in front. The RV-7 was designed for a heavy parallel valve engine and constant speed prop.

 

[Mel]

Since December of 2003!

Installed Catto 3-blade on my RV-6 12/30/03. Just getting ready to send it in for refinish.
If I had it to do over again, I wouldn't change a thing!
Did I mention that I like it?
No problem pulling the lower cowling. My tail wheel doesn't interfere at all.

 

[uk_figs]

Landoll ring

I've been flying a catto 3-blade prop for 4 1/2 years, 577 hobb hours.
Nice looking and a smooth ride.
I believe I'm a bit over pitched at 66x76. My wot is ~2680. Compare with Dave Dormier he gets more rpm.
I'm very satisfied except for the issue of weight impacting my cg.
Low fuel, near gross weight puts me into an aft cg which I must compensate with reduced baggage(60lbs) especially on cross country. I compensate by adding scuba bean bags weights in the forward cabin when I'm on a long cross country which may impact my landing configuration when low fuel & wife onboard.

I had the same issue with the FP sensenich and added the landoll harmonic balancer which brought everything back into the CG range (100 lbs baggage and low fuel). I am about to switch from the Sensenich to a Catto 3 blade which I believe weights less than the Sensenich so I will have to recheck the numbers. I am also about to paint which I think has the potential to move the CG aft also. Definitely something you have to consider on the -7.

 

[db1yg]

I have 310+ hrs on my Catto 3 blade (first flown 3-06). It is light (17.5 lbs), incredibly smooth, outstanding performer, and looks GREAT!! The bottom cowl removal is more difficult than a two blade but not really hard. You will have a longer slot cut under the bottom cowl for the nose gear leg but can easily deal with that via a longer intersection fairing.

My personal advice--go for the Catto 3 blade!!!

Cheers,

db

 

[cropdusterdave]

Anyone know if craig can re pitch his props? I've got an engine I'm going to hop up 10HP at overhaul (a few hundred hrs hopefully)

I'm definately planning on a Catto...just can't decide between 2 or 3 blades!

 

[sbarger24]

Re Pitching

He re pitched my hangar neigbors Catto Prop on his 6, so the answer is yes.

I too really like my Catto Prop, just installed all of the fairings and am now able to run it up to 2800 to 2850 rpm at 8000 density altitude in cruise. Wondering if I don't need a little more pitch, but then again hate to loose any climb performance. Bottom line need to run it some more, and get a better feel for it. Extremely smooth and nice looking

 

[a8301]

Sam James told me to try tying the tail down (take the weight off the nose wheel) when I remove the lower cowl, should make it easier.


Bruce 9A
Catto 3 blade

 

[elippse]

Anyone know if craig can re pitch his props? I've got an engine I'm going to hop up 10HP at overhaul (a few hundred hrs hopefully)

I'm definately planning on a Catto...just can't decide between 2 or 3 blades!

Three blades will give you better static thrust and its effect in decreasing take-off run, plus more rate-of-climb, and it is smoother running, and if you do a good job of sealing the prop hub to the spinner you should see no loss of speed with a three-blade than with a two-blade. As far as re-pitching is concerned, when you go from 150hp to 160hp or from 160hp to 170hp you will only see a 2% speed increase This will increase rpm 2% also, as from 2700 rpm to 2755 rpm.

 

[Mel]

Just to add...

It's pretty easy to decrease pitch on a wood/composite prop. It's much more difficult to increase pitch.
So if you are unsure of required pitch, it's always better to start out with a slightly coarser pitch than desired.

 

[hevansrv7a]

The question of pitch..

The question of pitch is really the question of required HP vs. available HP and what RPM you want at what altitude for a given speed. We specify props with a geometric pitch measurement, usually at the 75% radius station, but that's a very rough way to get at the real/effective pitch which some also call "advance".

If, for example, you want a given airplane to use 2700 rpm at 8000 density altitude, WOT, you must know something about the power and drag. If you don't, then you will get the pitch correct only by accident or luck. Craig had to re-pitch mine (more pitch). He got it right where I wanted it on the second try, but it costs him $$ to do that and it takes a lot of the builder's time, too.

The required HP is the THP that your airplane needs for a given speed at a given density altitude. This can be closely estimated with the methods I developed and which are explained on the pages linked below.

The available BHP is a little harder because it's tied into your (unknown) propulsive efficiency which is part propeller efficiency and part propwash-airplane interactions. That said, if you know what the airplane can do with an existing prop and can estimate the THP as above, the right answer can be narrowed down considerably. It is nice to say that for a given RPM and MP a Lyc-type engine produces X BHP, but it really isn't all that accurate. If it were, there would not be so much variation between charts. In reality, the manufacturers are not consistent about how they measure BHP in the test cell, so they may be exaggerating for effect. Or not. For example, it is not very accurate, especially with RV's, to use 75% of rated power at 8000 feet.

If your new prop is more or less efficient than the old one, then for a given speed and altitude, assuming to can reach that point, the rev's will vary accordingly.

I am willing to assist VAFers with the use of the spreadsheets, linked below, in order to assist with telling Craig (or any other prop maker) what the requirements are. Online or offline. It can't hurt and it might help.

 

[sbarger24]

You did lots of work!

I looked over your work and spreadsheet on your RV-7A, and that is really interesting information. We have similar airplanes, though I'm sure mine is slightly different in one way or another. I may try to gather the data on my plane and enter it into your spreadsheet. Just knowing where the drag curves meet and where the airplane is the most efficent (fuel, power off etc) would be nice to know.

Thanks,

 

[Jaknjoan]

What pitch and length is your Catto

On behalf of my neighbor who owns a new RV-4 equipped with an 0-360 engine, he would like to know the pitch and length of Catto's prop you are using. Your response, Matt, would be appreciated.

I can't say enough good things about the Catto. I've got about 150 hours on my O-360/three-blade combo and it's head-and-shoulders above my old Sensenich two-blade wood. Just as smooth, plus I can run it at a higher RPM and get ALL the horsepower out of the engine.

I fly mostly low level so I like to carry a fair amount of speed but still have some throttle left. I can cruise with the Catto at 2700 RPM and push it up to 2900 if needed to climb away from the terrain. Plus the Catto is so light that it spins up instantly vs. the lag of a constant speed.

BL: I highly recommend it.

-Matt
402BD

 

[RV-4]

Catto Re-Pitched

Hi Dave
I've been flying with a Catto 3 Bladded since 2001 on my RV-4 and got it re-pitched in 2007 by Craig.It is still a little under-pitched but much better than the first time.

He told me at the time that he will do a first re-pitched for free and he did a beautiful job.

Go for it, you gonna love every minute of it.

Bruno Dionne
[email protected]

 

[MartinPred]

On behalf of my neighbor who owns a new RV-4 equipped with an 0-360 engine, he would like to know the pitch and length of Catto's prop you are using. Your response, Matt, would be appreciated.

Mine is 66 inch diameter, 74 pitch.

The 2900 RPM is what I can get with WOT at about 4,000 feet and leaned for best power. Of course, once you pitch up, the RPM starts to decay a bit.

-Matt
402BD

 

[Ron Lee]

My Aymar Demuth 2 blade ran at 2700 RPM at full throttle and 8000' DA. My Catto three blade will do over 2700 RMP (probably as designed) at much higher than 8000' DA.

I had considered going high at getting IAS and RPM at full throttle from 15,500' SA or so on down to try to determine if I need more pitch. and hopefully provide data to determine the new pitch.

Then the other issue is whether it has any value in terms of improved cruise speed.

Any ideas?

 

[elippse]

My Aymar Demuth 2 blade ran at 2700 RPM at full throttle and 8000' DA. My Catto three blade will do over 2700 RMP (probably as designed) at much higher than 8000' DA.

I had considered going high at getting IAS and RPM at full throttle from 15,500' SA or so on down to try to determine if I need more pitch. and hopefully provide data to determine the new pitch.

Then the other issue is whether it has any value in terms of improved cruise speed.

Any ideas?

I've always recommended that a fixed-pitch prop be designed to give at least rated rpm at 14,500' density altitude. That will allow the engine to give higher static rpm for initial takeoff acceleration, higher rpm in climb, and the highest airspeed at the highest density altitude you will fly at on cross-country flights. If you have a plane it is usually because you like speed, right? If you are more concerned about fuel mileage, then fly your plane at either the Carson speed, 1.316 times best L/D speed, or at best L/D, and have the prop designed for very high pitch and very poor take-off and climb. Typically, you will use 2% more fuel to fly 1% faster. If your prop is designed to give rated rpm at 8000'-9000' density altitude, on a low aspect ratio RV such as the -3 to -8, your airspeed and rpm will drop off about 1%/1000' dalt, so if you get 190 mph and 2700 rpm at 8500' dalt, you will now be down to about 6% less speed and rpm at 14,500' dalt, 179 mph and 2550 rpm.