Catto Props - Speedy? Safe? Other Benefits?

This post is based on a request from 1 or 2 folks and I will do my best to relate my experience. My experience is based on operation of my aircraft and I do not have a load of data except "time in the saddle".

First, I want to thank Bob Axsom for all the information he shares with everyone on this list on almost a daily basis. I wish I had the talent and the inquiring mind he possesses.

My RV-8 started its career in 1999 with an Irlbeck 2 blade wooden prop. After several years outside being tied down, the wood prop (and some of the paint on my airplane) began to show wear and tear. It was time for a change (2003ish). (The 2 blade prop was pretty fast on my airplane.)

I contacted Craig Catto. Craig did not have a 3 blade on an RV-8 at the time. He had one (or more) on an RV-4. He first sent me an RV-4 prop and it oversped. He made up one for my plane and it worked well, but was not faster than my 'old' 2 blade prop. It was MUCH smoother in operation (even after I had balanced my 2 blade prop).

I had a landing mishap with this prop. I believe that the mishap would have been worse except for Craig's prop acting as a support for my nose (an upside down "Y"). [A tail dragger standing on its nose is not a pretty picture.] Craig's props are very STRONG.

You can likely guess that I replaced the broken prop with another of Craig's props (and will always buy Craig's props for the safety factor). An interesting side note is that Craig's props are considered wood for prop strike purposes. I complied with all inspection requirements after the prop strike and did not have to "tear down" my engine.

I have since put 10 additional hp in my engine (hi compression pistons) and run my current prop in the rain ruining the finish on the leading edge. So, time for a new one. With a new one, I hope to get more speed (have asked Craig for "cruise" prop pulling 190hp), but I'm guaranteed a metal leading edge for rain issues.

I'm sending the removed prop to Craig for overhaul and refinish. It will be like new and I will sell it to the first one sending me a reasonable offer.

Bottom line benefits of Craig's props: (1) Structurally strong props; (2) Treated as wood props for prop strike purposes (don't try this at home); (3) Weather better than wood props; (4) Better in rain than wood (but must protect leading edge finish with tape or purchase prop with metal edge); (5) Smooth operation; (6) Can be torqued to 40 ft. lbs.; (7) Appealing appearance.

I am hoping for speed improvement with this next prop and will report any speed improvement if noted. (I will work with Craig to get speed, but Craig has said speed comes at 2700 rpm (+) and I don't usually go there for obvious reasons.)

Thanks for sharing. My experience with Craig has been that he has built sufficient numbers of RV propellers that he really knows the parameters. I gave him the data collected on my wood Aymar Demuth propeller and he said he'd design for a top RPM of 2750 and hoped for 4kts over my current propeller. His hit the RPM perfectly and managed 3.75 kts improvement. My reason for the new propeller was the nickel leading edges for rain tollerance. Even though Craig had not previously built a propeller for a 150hp RV-8, his extrapolation was nearly exact. I never run at WOT so those 3.75 kts are just for the books.

Oh yeah - ditto with my appreciation for all that Bob Axsom has shared with the community!

humptybump said:

...... I never run at WOT so those 3.75 kts are just for the books.

Oh yeah - ditto with my appreciation for all that Bob Axsom has shared with the community!

Click to expand...

Aaaargh! I can hear Racer Bob right now. "WOT is the only place to run..." I even had some guys tell me there is no Vne in racing.

Catto prop torque interval

Are Catto props also like wood--check and retorque w/seasonal humidity changes expanding/contracting the wood core? Or is the core effectively sealed off from the weather--barring WOT thru the rain, sans nickel?

DrillBit said:

Are Catto props also like wood--check and retorque w/seasonal humidity changes expanding/contracting the wood core? Or is the core effectively sealed off from the weather--barring WOT thru the rain, sans nickel?

Click to expand...

I've been running Craig's props since 2003 and wouldn't have anything else. I check the torque twice a year just as I did on my wood props. However, I have never found it to be off on a Catto prop.
He's working on me a "new & improved" 3-blade right now. I can hardly wait.

Catto Prop's repair

Hi Guys

I got a little nick on one of my blades on my 3 bladded Catto that will have to be fix and was wondering how you guys who have done repairs on Catto's have done it.

It is nothing major but I will have to address it and repaint the worked area after..What kind of paint did you guys used?

Thanks for your imputs

Bruno
[email protected]

RV-4 said:

Hi Guys

I got a little nick on one of my blades on my 3 bladded Catto that will have to be fix and was wondering how you guys who have done repairs on Catto's have done it.

It is nothing major but I will have to address it and repaint the worked area after..What kind of paint did you guys used?

Thanks for your imputs

Bruno
[email protected]

Click to expand...

Craig uses PPG Concept to paint his props. I would check with Craig about the 'nick' because one man's nick is another man's crack. I had am issue where my spinner "gap seals" put a shallow line in the back of one prop blade root. Craig said fill it (micro balloons, filler, whatever), paint it and carry on. BUT, IT WAS A SHALLOW LINE. NOT A NICK OR A CRACK. Bottom line is to call Craig with the details of the nick.

When I have checked my prop bolts at annual, I have never had to re-torque. The wood is sealed within composite, so the moisture and temperature issues are reduced to nil.

Catto' s Prop repairs

Hi Jay

Thank you for your imputs.

I took pictures of the nick on my blades and will send them to Craig to get his advises on what is required to fix it properly..

Cheers

Bruno

Yep...Love Catto! Mines been back to him twice (re-pitch and for a uh...prop issue...uh...hit a runway marker) Craig, goes way beyond what is reasonably expected for a manufacturer. I wouldn't consider another fixed pitch option.

I Agree

apkp777 said:

I wouldn't consider another fixed pitch option.

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I 100% agree

Received my Catto prop about 2 weeks ago and my OSH trip was real true X/C test flight. Lost about 2-3 mph compared to my older Aymar Demuth prop, but flew thru rain several times and did not throttle back. Catto prop took a lickin' and kept on tickin'.....rain had no affect on finish.


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Jim, have (or will) you fabricate new aluminum gap seals for between the backside of the Catto and the spinner back plate?

I ask because there is a noticeable difference between my Aymar Demuth's airfoil near the hub compared to the Catto. I'm not sure how big an issue this is beyond esthetics.

The shape and size of the blade roots on the A-D and the Catto props, where they exit the spinner, is vastly different. I wouldn't be surprised if a whole new spinner plus the backplate filler inserts are needed. I've been contemplating the Catto props too (for the metal leading edges for rain protection), and am pretty much convinced that I'd need a new spinner assembly specifically cut to fit a Catto prop. That way I could sell my Aymar-Demuth and its matching spinner assembly together, so that whoever buys it would have a ready-to-bolt-on complete setup.

I got such good airspeeds to/from Oshkosh with my A-D prop (195-200 mph TAS @ 7500 MSL, no kidding) that I'd hate to lose any airspeed at the top end... but then I'd really like to have some more climb power too. My A-D prop has rather ho-hum climb performance, it's definitely a cruise prop.

humptybump said:

Jim, have (or will) you fabricate new aluminum gap seals for between the backside of the Catto and the spinner back plate?

I ask because there is a noticeable difference between my Aymar Demuth's airfoil near the hub compared to the Catto. I'm not sure how big an issue this is beyond esthetics.

Click to expand...

I haven't, as of yet. The spinner fit took a little adjusting, but is fine. There is a gap on backside, but not too bad. It's definitely not a snug, tight fit. I'm sure I'll get around to fabricating new ones eventually. I don't know how much difference it makes in performance.

Neal - what Craig and I planned out the Aymar Demuth to Catto switch, he correctly said it was a direct swap - but he did guess the back side of the airfoil would be different.

On the spinner, I had to sand about 1/32" over a 2" span with 1/16" for about 3/4" of the 2" span. That was it. I will fly like this for a while until such time as I want to tinker in the shop. But that could be a while. As you said, the Aymar Demuth is such a well matched prop that if it were not for the rain tolerance of the nickel edges on the Catto, I'd have no real good reason for the switch.

FYI - for the new gap on the back side of the Catto, I will need to do is drill out the 5 rivets for each of the existing fillers and fit and rivet new onces. The existing spinner, front plate, and backer plate are reused without other mods.



BTW Neal, what is the pitch of your Aymar Demuth ? Mine is 68-71

My A-D prop is 68-74.

My hangar mate has a Catto prop on his Glasair-I and his blade root are much smaller than my A-D. Just eyeballing the difference, there would be a pretty large gap there if I used my existing spinner on such a prop. Maybe the props Catto makes for the RVs these days have thicker blade roots and there wouldn't be as large of a gap?

Anyway, my prop does have the epoxy-filled leading edges (J-B Weld?) supposedly to help give a little better rain tolerance, but nothing like metal leading edges would.
It's a gray epoxy, from where a bit of the paint has come off. I flew into a little bit of very light rain/virga on my way to Oshkosh, and I throttled back to 2000 rpm, but a small bit of paint did erode off anyway, that was intact before the flight, and you can see the gray epoxy showing in one tiny spot. It'll be very easy to touch up the paint there.

Went out to the hangar tonight and measured my prop/spinner cutout and also my hangar mate's Catto / spinner cutout. His blade root is much more square-shaped than yours, yours looks a lot more like my Aymar-Demuth at the blade root. My spinner is cut about 1/4" - 3/8" deeper than his, measuring from the front of the rear bulkhead to the foremost apex cut into the fiberglass. So the gap on my spinner with a blade profile like his, wouldn't be as dramatic as I originally thought, but would still be at least a 1/4" in front of the blade. So maybe a new Catto prop, with blade roots like yours would be able to be made to fit my existing spinner after all.

First in, last out...

I installed Craig Catto's first RV 2 blade prop on my RV4 in 1997 and would end up putting over 1000 hours on it. It replaced an Ed Sterba wood prop that had been eroded by flight through light rain (standard ops in the SE USA). Since Craig hadn't made an RV prop before, the first prop was a Glasair prop blade design. Later he built me a unique blade for the RV which I installed and tested as well. Overall, I tested nine different props on my RV4 over the years and the Catto was the overall best compromise, Gary Hertzler's "Silver Bullet" a close second.

My first impressions of Craig's props were of smoothness and durability as mentioned above. I also noted Craig's props performance are optimized for higher RPM's as his background is Reno racing where running at WOT is SOP. I am currently running a Catto 2 blade on my RVX with equally excellent performance albeit above 2700 RPM which if you really know Lycomings, isn't a huge deal. I have surprised several higher horse-powered RV's with only 150HP under my hood. Throttled back the Catto is within 5 knots of most of the competitors.

If you want light weight, reasonable economy, durability and value, Craig's props (now certified on Carbon Cubs) are an excellent choice. Craig also offers RV spinners custom cut to fit or the template to "roll your own".

Highly recommended.

V/R
Smokey

PS:"There are no new threads, just new users" http://www.vansairforce.com/community/search.php?searchid=15893665

Same observation

I had a metal sensenich fp 70dia 81 pitch for 400 hrs and have a catto 2 blade for the last three hundred hrs. I also find the catto does not perform well until at least 2600 rpm. As an all around performer I liked my metal prop more but the 2600 rpm limit was an issue. At 2600 rpm my sensi was 5kts faster.

160 hp 0-320
Chris m -4

Neal@F14 said:

My A-D prop is 68-74.

My hangar mate has a Catto prop on his Glasair-I and his blade root are much smaller than my A-D. Just eyeballing the difference, there would be a pretty large gap there if I used my existing spinner on such a prop. Maybe the props Catto makes for the RVs these days have thicker blade roots and there wouldn't be as large of a gap?

Anyway, my prop does have the epoxy-filled leading edges (J-B Weld?) supposedly to help give a little better rain tolerance, but nothing like metal leading edges would.
It's a gray epoxy, from where a bit of the paint has come off. I flew into a little bit of very light rain/virga on my way to Oshkosh, and I throttled back to 2000 rpm, but a small bit of paint did erode off anyway, that was intact before the flight, and you can see the gray epoxy showing in one tiny spot. It'll be very easy to touch up the paint there.

Click to expand...

You may want to try adding prop-guard tape from Aircraft Spruce.
Mine has held up quite well.

Close the gaps

According to the late Paul Lippse, a big gap around the prop shank is a huge drag generator and the gap should be as small as practical for best speed/thrust.

Best,

Pierre, I had heard something along these lines. Once My Catto comes back, I will run another set of performance tests before and after the gap filler aluminum work.

(Blame it on Bob - he's got me addicted to testing mods for speed)

Got This Email from Craig Last Evening...

"Jay,

Just waiting on the Nickel edges. We got 20 in last week and they were gone. Getting 20 more in on Thursday and your prop will get them.

I am sending you our latest in prop designs, so will be curious to get your feedback on it. So far all has been great."

I'm getting excited!

The Air up There...

pierre smith said:

According to the late Paul Lippse, a big gap around the prop shank is a huge drag generator and the gap should be as small as practical for best speed/thrust.

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Hi Pierre,
Very astute sir! I had many discussions with Paul and that was a biggie. I used RTV to fill the small gap in my spinner/prop gap. The Nickel Leading edge works very well. I used prop tape on previous Catto props with excellent results but a 1% performance penalty.

One thing Paul was insistent was rated RPM at max cruise altitude. I have found to get this requires a higher low altitude max RPM in excess of 115%
I Like getting rated up high, for what it's worth.

My 150HP numbers:
Sea Level WOT 2850 177 KIAS.
13,500' WOT 2700/132 KIAS/172 KTAS
Paul was right...

Both of them.
V/R
Smokey

Speaking of which...how do you seal the gap completely on a blended airfoil Hartzell CS prop? Guys have mentioned using leather INSIDE the spinner but it has to rotate some as the blades change pitch.

Best

Smokey, is there any chance you have a picture (or could take one) of your propeller / spinner gaps ... similar to to the detail I depict back here in this thread ?

I'd like a reference for what an optimal fit looks like.

Standing in the Gap...

humptybump said:

Smokey, is there any chance you have a picture (or could take one) of your propeller / spinner gaps ... similar to to the detail I depict back here in this thread ?

I'd like a reference for what an optimal fit looks like.

Click to expand...

Glen.
I have tried several iterations, first was RTV, then tape. The best though is innertube rubber, cut to fit. First I used solder, rolled out with enough to wrap around the prop blade at the hub where it meets the spinner. I then wrapped the solder around the blade forming a airfoil template, then you slide it off the end of the blade. On workbench lay template over a piece of bicycle innertube rubber, mark and cut. Remove Spinner and contact cement the rubber "prop fairings" in place, let dry and reinstall spinner. Might work well on a Hartzell if cut correctly.

Here's a photo of my Catto-pre-cut spinner/prop gap, seal not installed, I will take a better photo of completed spinner.

V/R
Smokey



Not now Catto!