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Catto Prop Information

Your engine produces full horsepower at a certain RPM (2700 ??). For STOL performance, you want high power (RPM) on take off and climb.

86 (inches in length) X 44 (inches traveled forward in 1 full revolution)
The bigger the "bite" (inches traveled forward) the more load on the engine - it will not allow the engine to turn a higher RPM when moving slowly at the beginning of the takeoff run.
A fixed pitch prop requires you to choose between takeoff performance (low "bite", high RPM on take off, but too much RPM in cruise) or cruise performance ( big "bite", lower RPM on takeoff, but full RPM in cruise flight).

For STOL performance you want lower bite for higher RPM and horsepower.

Hope this helps.

John Scott
Yes,I understand.Thank you very much,I learned more knowledge from your post.
 
Are you instructor of tailwheel fly?I am going to America learn tailwheel or bushfly,what's your suggestion?Thank you.

No, lm just a poor slob who can only afford to buy a Catto prop once, hopefully someday. What part of USA are you planning to visit?

Glenn
 
No, lm just a poor slob who can only afford to buy a Catto prop once, hopefully someday. What part of USA are you planning to visit?

Glenn
I like this kind of ridicule,but hard to understand why are you say you are a poor slob?"slob" in culture of America is a commendatory term?
 
The larger the diameter the more thrust you will get out of the prop Craig has computer-generated the maximum length of the propeller to peak horsepower....as the diameter increases beyond the 86 inches the blade tips begin to go supersonic and begin to pull horsepower from the engine. To get the stump pulling power out of the 86" Craig has worked on the cord and airfoil of the prop....this keeps you in the sweet spot for making horsepower.
 
Sageelite if your purpose is STOL as you say then go with 86X38 I also think the 86X40 would be a good choice you will only lose a few feet on take off with the 40" literally just a couple of feet and you will pick up a couple miles an hour maybe more on the other end both good choices but the 44 inch is just too much bite.
I had make a call to Nicole reduce 44 to 40 this morning,good sevice Catto.
 
I doubt if you're going to find anyone that will field approve an experimental prop on a certified plane ......the STC process is still in the works at Catto but as usual it with the FAA it takes time.
 
Hey Kirby yes it is but like anyone that has a successful product he's up to his ass in alligators but chipping away at it.
 
No way!! Me and DW go way back and he will pull some strings to bump you off #1 on the list.


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After he hauled that junk frame of yours home thinking he actually got something... welcome to last in line.
 
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If you both send me all your money I'll see what I can do....Right after I get back from the Caribbean...
 
This is an old thread but I have a question. I have an 86*38 and I’m looking for a 84*42. If I can find one I have mine for sale
 
I have a 84x41 available


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I’m on floats all the time and would like to get a little more speed out of it. I can afford to give up some on takeoff for it jumps off the water fairly fast and my runway is now longer. Talked to Nicole at Catto and they can twist my prop 3 degrees so I’m thinking I’ll go that route. To bad Arizona wasn’t a little closer to try gdafoes prop out.
correction she told me inches not degrees
 
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they can twist my prop 3 degrees

Degrees or inches? It's odd that she'd give you a number in degrees when the prop is rated in inches. Also I think it's a re-contour/re-finish process. That's a wood core prop, and not twistable like aluminum.
 
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Anyone running a CATTO on an 0-200? If so what are you seeing for numbers?

Larry.

I have a CATTO 76X42 on my Sport Cub S2HP. Love the performance. 1,000 FPM+ when heavy at sea level and will do almost 120mph at 2750 rpm flat out With 26” tires. Normal cruise is 105-110 tas at 2450-2500. The engine was done by Lycon and is 10:1 compression ratio with port and polish and I think it has a C90 cam. If you’re stock I think CATTO makes a few others with a little less pitch. I just flew the new sensenich ground adjustable 76” on a similar cub and the way it was pitched it definitely climbed better but was not as fast. I think the CATTO was also smoother but waiting to balance the sensenich before I fully commit to that.
 
I have a 78x37 Catto on my cub with a 0-200 that has c85 pistons and a after market cam ( close to the old c90 cam )
I like it works great. I put it on the stock 0-200 to see how it would preform and it couldn’t turn it very good. Not enough hp.


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Similar to Dougs experience.

I tried what was labeled a 7638, but actually signed off in sharpie on the inside bore as a 7637. It worked okay on the Sport Cub O-200 with 10:1 pistons, but my C90 with the 988 cam would just not spin it enough. Just not enough horsepower.

Interesting phenomenon with this prop on the c90. Consistently after 40-45 seconds of level flight (and trimming to get least drag) it would surge forward just a touch and run 5 mph faster. Almost like the wing finally got on step and the prop shifted up a gear. After noticing this I repeated it multiple times and every time it did the same thing.

But still performed poorly on the 90. Climb and overall was obviously the wrong prop for the power.

Pb

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Side note, before trying the above 7638/7, Nicole had spec’d me a 7640, and then shipped me a 7642. Prop turned 2000 rpm WFO.

Huge waste of time and money.

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I have a Mac 74-38 that on the modified 0-200 gets me off the ground a little faster but my airspeed isn’t very good. The Catto is 10mph faster and I get off almost as short. I thought about having them repitch it to a 36 but decided to keep it the same. Hard to go anywhere at 65 to 70 mph
 
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