Propeller Fences

Geico266

Geico266

Touchdown! Greaser!
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Geico
Catto Propellers are used on many RV's, racers, and other experimentals due to performance, weight , and price. They really are amazing propellers and look good too! Catto Props are literally works of art. Craig Catto is an amazing prop builder and is constantly experimenting and refining the profile of the blades to get the absolute maximum out of each inch of the blade.

Catto_Prop_Fences.jpg


The latest innovation is continued research into "Propeller Fences". If you look closely at this picture you can see the little black "fences" near the hub. These little fences add 6-7 knots over a stock Catto blade and are molded into the wood / composite covered blades. The little "tell tales" are indicators of airflow over the blade. The aluminum extension appears to be holding a GoPro so the airflow of the blade can be recorded and studied as indicated in the website clip below.

"In 2013 Catto Propellers began to develop a method to record the dynamic air flow of a propeller in flight. With a custom mount made by Saber Manufacturing and a vacuum formed carbon fiber case to house the GoPro, we were able to maintain a live feed on the propeller aerodynamics. The GoPro Hero 3+ with 60 frames per second, 1080p, provided a real time visual throughout the flight profile that allowed Craig Catto to improve the propeller efficiency by actively notating where it is possible to reattach flow and modify the airfoils accordingly, ultimately improving the performance of the blade, in all aspects."

Got to love the experimental spirit of aviation. Pretty amazing stuff.
 
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Interesting concept, without thinking too much this seems like a logical idea. 6-7 knots sounds like a lot, but impressive if it proves accurate.
 
WingNut42 said:
Interesting concept, without thinking too much this seems like a logical idea. 6-7 knots sounds like a lot, but impressive if it proves accurate.
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Craig is known for being precise. His knowledge of airframes / HP /prop pitch, and real world attainable speeds is legendary. If he said it, I believe it.
 
Geico266 said:
Craig is known for being precise. His knowledge of airframes / HP /prop pitch, and real world attainable speeds is legendary. If he said it, I believe it.
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Not that every website is true, but the more I have read since I read your post the more I am coming to that conclusion.
 
WingNut42 said:
Not that every website is true, but the more I have read since I read your post the more I am coming to that conclusion.
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He is not the first to come up with this idea. A couple of other prop builders tried it years ago with limited success. He is just refining it with the latest technology and innovation. Truly an amazing guy.

His props truly are works of art. Home builders cherish their "Catto props". :yes:
 
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I've emailed Craig several times about my prop. The guy gets back to you within hours. Never seen anything like it. CEO of a company already back logged because of demand and he has time to send out a polite, well thought out response to my email. When the time comes to get a new prop in the Velocity, it'll be a Catto.

As far as fences. I've seen guys use vortilon tape along the span to keep airflow attached as well. Not sure which method is better.
 
Velocity173 said:
I've emailed Craig several times about my prop. The guy gets back to you within hours. Never seen anything like it. CEO of a company already back logged because of demand and he has time to send out a polite, well thought out response to my email. When the time comes to get a new prop in the Velocity, it'll be a Catto.

As far as fences. I've seen guys use vortilon tape along the span to keep airflow attached as well. Not sure which method is better.
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What is the current lead time on a 3 blade? A couple of years ago it was 18 months.
 
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So that camera is on the hub and rotating w/ the prop?
I want to see that GoPro video.
 
Geico266 said:
What is the current lead time on a 3 blade? A couple of years ago it was 18 months.
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In 2011 I remember it being around 4 months...at best. Not sure what it's up to now. I've been thinking of trading mine out for one of the newer props with the metal leading edge. Rain / debris have been harsh on my current one.

I will say that in 2011 they repaired, re-pitched and refurbished my prop in only 30 days.
 
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My Pusher gyroplane powered by a Lycoming IO-320 has a three blade Catto propeller on it.
I was very pleased with the first on and it appeared to work better in every way I could measure.
Unfortunately both the alternator brackets broke and the alternator hit the prop damaging the propeller beyond repair.
I was even more pleased with the second one.
Craig has been very good to work with and in my opinion his propellers are a lovely combination of art and science.
The maneuvers I do in an air show are very hard on a propeller so he made the hub extra strong.
I questioned the way he statically balanced my propeller and he showed me that a short piece of masking tape about two thirds out was enough to show with his balancing method.
My computer crashed so I could not find better pictures of the propeller.
These are from the Hollister air show 2014.
 

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I could see the fences improving airflow through the cowl, too.
 
Can someone explain the theory on how this improves efficiency?

Is it due to the cowling right behind the prop?

Does it "hold" or "force" the air through the prop instead of sliding down the blade? I'm having a tuff time verbalizing the concept.

Would a pusher enjoy the same benefit?
 
Geico266 said:
Can someone explain the theory on how this improves efficiency?

Is it due to the cowling right behind the prop?

Does it "hold" or "force" the air through the prop instead of sliding down the blade? I'm having a tuff time verbalizing the concept.

Would a pusher enjoy the same benefit?
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Well fences prevent spanwise flow of air. Just like the Vortilons on my Velocity, they prevent spanwise flow at slow airspeeds. If you can keep the airflow or wind vector perpendicular to the cord, you have greater lift.

What I'm curious is to why some guys in the homebuilt race community experiment with vortex tape on their props. Seen it on top of a Tango wing as well. Basically zig zag tape that excites the boundary layer and allows for a slower stall speed. Not sure how on a prop it would benefit unless the inboard portion is stalled.
 
Geico266 said:
Can someone explain the theory on how this improves efficiency?

Is it due to the cowling right behind the prop?

Does it "hold" or "force" the air through the prop instead of sliding down the blade? I'm having a tuff time verbalizing the concept.

Would a pusher enjoy the same benefit?
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Actually there's a guy in Tennessee trying it right now on a Long Ez.
 
I guess he only makes fixed pitch? I wonder how the fences would work on a CS prop?
 
Geico266 said:
What is the current lead time on a 3 blade? A couple of years ago it was 18 months.
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My hangar mate just put a 3 blade on his RV-6 last week... I " think" it took less then a month from order to delivery...:dunno:..

It is a SWEET lookin prop too.... The old 2 blade Sensenich was 42 lbs complete.. The Catto is 22 lbs Complete.....
 
N801BH said:
My hangar mate just put a 3 blade on his RV-6 last week... I " think" it took less then a month from order to delivery...:dunno:..

It is a SWEET lookin prop too.... The old 2 blade Sensenich was 42 lbs complete.. The Catto is 22 lbs Complete.....
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Wow! Catto did announce he built a huge new facility. He was working out of a shop at his house. Very cool to see lead times come down. It was hurting his business for a while. Home builders are impatient. ;)
 
The fence would stop or slow the lateral flow of air down the prop blade forcing it over the blade creating more lift.


I see a problem being those things flying off and killing someone on the ramp. But I suppose if they're going to let loose they'd do it at high RPM when the plane is presumably away from people.
 
Captain said:
The fence would stop or slow the lateral flow of air down the prop blade forcing it over the blade creating more lift.


I see a problem being those things flying off and killing someone on the ramp. But I suppose if they're going to let loose they'd do it at high RPM when the plane is presumably away from people.
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If one flew off.. The shaking would probably rip the motor from the engine mount...... Game OVER.....:redface:.....:sad::sad::sad::sad::sad::sad:
 
How do these things do in precip / ice? Not rated for it at all, or what?
 
denverpilot said:
How do these things do in precip / ice? Not rated for it at all, or what?
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His new props like the one in the pic have a metal leading edge so rain shouldn't be a problem. His older props (mine) without the metal leading edge don't do so well in rain. I flew down to Velocity a few years ago IFR with moderate rain almost the entire way. I was running 2,500 rpm. On landing, I couldn't believe what I saw. The last 1/3 of the leading edge of each of the blades was shredded about 1/4 inch into the blade. Fiberglass was bristling in every direction like mice had been eating on it. Rumor is, no more than 2,000 rpm should be used with a Catto prop in rain. I'd agree with that. Since the erosion didn't reach the wood core, Catto told Velocity just fill it it with epoxy / flox or even JB weld. Same procedure that used for damage from rocks or screws. That's what they did and it's held up fine ever since. Can't even tell there was any damage.
 
N801BH said:
If one flew off.. The shaking would probably rip the motor from the engine mount...... Game OVER.....:redface:.....:sad::sad::sad::sad::sad::sad:
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Depending on what he's using (carbon fiber?) those fences could be pretty light. They might give you a nice shaking, but I doubt you'd lose the engine. Might shake a few fillings loose, thought. ;-)
 
Captain said:
The fence would stop or slow the lateral flow of air down the prop blade forcing it over the blade creating more lift.


I see a problem being those things flying off and killing someone on the ramp. But I suppose if they're going to let loose they'd do it at high RPM when the plane is presumably away from people.
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Killing someone on the ramp? :rofl::rofl::rofl:

If they stayed on in flight I doubt they would come off taxiing. :rolleyes:
 
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