Catto Prop Information

All, I wanted to start a thread where we can post our Catto propeller specs for future reference. When I recently talked to Catto about prop sizes, I was asked to provide the following information.
Static RPM, Max level RPM and what altitude the max level RPM was obtained. I also provided the specs for my engine.

o-360 narrow
9.5:1
Aero performance stage 3 cam
flowed cylinders
equal length exhaust 4-1 merge collector
Dual electronic PMAG ignition

Prop originally on our Cub
84/42 NON Metal Catto (original design)
Static 2410 rpm
Level 2910 rpm @125mph
29.90" @ 500 ft MSL
70* F

Catto recommended that I get an 86/36 for maximum takeoff performance. They said that the 84/42 was basically a cruise prop at this point and the switch would net me a loss of 6-9 mph at the same RPM. I was getting 90 at 2350. We were amazed to hear this as the performance was amazing and I cant wait for the 86/38 to show up. (six weeks lead time right now FYI) I am going to do some pull tests when I have both props available, I will post pics and the specs when that happens.


I asked DW about his prop choice in a PM and here is his response.

Hi Jay
i bought my 84X44 for cruise only with the idea of carrying my clime prop to my destination and then changing them out so I didn't check the static on it, for the most part I just pulled the power back and would cruise in the low 90s for better fuel use . Sounds like your engine is close to mine except I have 9.0:1 Pistons I'm running the 86X38 and very happy with it I think ether the 38 or 40 pitch would serve you well. My static is 2450.


-Jay

It's been a while sense I've done my pull test on the 86X38 but I think the static pull was 850 or so and with Nitrios it was 925 and climbing before I got off the button.

Stock O-360 C4P, Custom crossover no muffler exhaust

I tried the 86/38 Catto on my white cub on floats. Seem to be getting 2370 static rpm at 45* F @ 75' MSL.
The static was not easy to check loaded on floats....


Takeoff and climb was way better than with my sold McCauley 1A200FA8242. Lost maybe less than 5mph. About 90-95mph at 2450 @ 1000'msl

The Catto is much smoother, and spools alot faster.


Looking to buy a 86/40 Catto maybe. Will have to do some better test before choosing.

0360A4A ,Sutton exhaust shortened with the choke taken out of it. 9.5:1 pistons, pmag 86/38 catto 1200' asl 70f i get aprox 2470rpm, at 3500' 2500rpm 97mph cruise empty on floats with the 86/40 at 2500rpm i was about 108-110mph on skis(never flew that one on floats) it was 2400 static at 35f. it is an ext wing exp pa-12.

With the 86/40 vs 38, how would you rate the performance for take off? Does the 38 make a noticeable difference? I am on the fence over 38 vs 40.

I can't Imagine the takeoff roll difference will be much more than a couple feet. And maybe a couple MPH on the other end. I think if your not trying to do hardcore short work the 40 might be a good choice, ether one I think you'll be happy with the performance.

i like the 38 on floats but never ran the 40 on floats. i liked the 40 on wheels but never ran the 2 back to back to get a good feel for the diff. if i were on wheels more i would probably stick with the 40 but most of my flying is loaded heavy on floats and within a 70 mile radius so the 38 fits for me. the top end i got with the 40 was surprising, more then you think a 2" pitch diff would make. it was a demo prop and i sold it to a fellow with a supercub and he also picked up 8mph top end over his old prop,(an 82"mac of unknown pitch) the one he removed was not a catto 38 so kind of apples and oranges there. but he also picked up t/o and climb performance.

My engine was a moderately hopped up, narrow deck 0-320. 9 to 1 pistons, ported, flowed, matched, centercarb sump, etc.

With a 74-56 prop I was getting 2600 static RPM. I am at 850' MSL and the temp was about 60 degrees. At 60 mph climb I was getting 2600 RPM and at 80MPH climb I was seeing 2700 RPM. Max speed and RPM in level flight was 2820 RPM and 124 MPH(I am sure of the RPM but not really sure of the speed I can't find my notes)

Then I tried a 82-42 Borer. I got 2500 static and 2600 RPM gave me 50MPH climb and 2700RPM gave me 70MPH climb. Much smoother prop than the 74-56

I then got a Catto 82-41 and I got 2450 Static. At 80 MPH in the climb I was seeing 2700RPM. It was quite bumpy during my test so I am not real confident of the climb number. Max RPM in level flight was over 3000. The prop was much smoother than the 74-56. The 74-56 weighed 27.2 pounds. The Catto weighed 14.2 pounds. A savings of 13 pounds even.
I was very pleased with the Catto

Bill

I recently switched from the McCauley "Pawnee" prop @ 84/43 to a Catto 2nd generation 84/44. After several evaluation flights with full fuel, half fuel, and with passenger, I have to say I am quite delighted with this change.

First the weight savings is significant. The Pawnee weighs in at 35.8 lbs. The Catto is 14 lbs + 2.4lbs for crush plate assembly. So a net savings of about 19 lbs. This was appreciated because my Cub was a little nose heavy.

One thing I didn't want to loose in the switch is the great climb performance the Pawnee prop. It always served me well there.

The following numbers are for O-360-A1A wide deck, stock except 1 E-Mag, Custom Aircraft exhaust. 50*F between 3500 and 5500 MSL, 44 gals of fuel, 1 pilot.

Pawnee 84/43:
Ground static: 2400 rpm
Cruise: 94 mph IAS @ 2450 rpm
Time to climb average (3500-5500) @ 60 mph IAS: 1100 fpm

Catto: 84/44 2nd Gen
Ground static: 2300 rpm (-100)
Cruise 101 mph IAS @ 2450 rpm (+7)
Time to climb average (3500-5500) @ 60 mph IAS: 1050 fpm

My impressions so far of flying the Catto over Pawnee:
The prop spins up almost instantly and develops full thrust earlier. Despite the -100 in static, I still get off the ground just as short, if not slightly shorter that before. I would call it a draw on climb performance. I have gained at least 7mph in cruise. This is a nice benny if you want to X/C your Cub a little. Today (~25*F OAT) I was a little less than half fuel and was showing a 105 IAS in cruise. VSI frequently showing 1300-1500 FPM. I love the weight loss on the nose especially for landing. Can do more aggressive flare and nose doesn't want to drop out on me, result is land shorter. Prop feels smooth, but so does the Pawnee, not a noticeable change there. On shut down, the prop stops quick.

I am still getting familiar with the Catto, but I can say without doubt this is a keeper.

I order a 86X44 from Catto,I can feel that is a poweful propeller as I seen this thread,but my PA18 still in process of building.Thanks bug66 again,your website is my "manual instuction",lots of useful information,I visit that everyday,again and again.

86 X 44 that's a lot of pitch on a 86" prop.

DW said:

86 X 44 that's a lot of pitch on a 86" prop.

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That's what I was thinking.

Sageelite what engine are you going to use?

86x38

That's what I run the 86X38 very happy with it......cruises in the very low 90s I usually throttle back and cruise in the high 80s.

Bugs66 and I have the same prop. We also had the same Pawnee prop. Pitch was the same on both. Per Craig's advise I have reduced the RPM for cruise from 2480 (Pawnee prop) to 2350 for 2nd Gen Catto. Before I was seeing 97 mph TAS @2480. I know see 100 light and 98 heavy @2350. My FF is 1.1 gph less at the new setting for the same speed as before. If I run 2480 now I see 108 mph TAS. This is on 31's, square tips, and a pod. I have a warmed over O-360. I static at 2350.


I notice Bugs uses 60 mph IAS for a climb speed. I have bumped mine up to 75 IAS and see another 125 rpm and my climb rate is 250 fpm more than at 60 IAS (1200-1350).

One note of caution for those contemplating a Catto. If you have high comp (9.5-1) and dual P-mags you can expect the prop to kick back on occasion. This really messes with the starter spline gear (chipped teeth). The perfect setup for this to happen is a weak battery and too much fuel in the intake. There is a solution. Per Brad Dement at E-mag, I retarded my timing 2 degrees. So now at start up instead of firing at TDC, it starts smoother every time at 2 deg BTDC. I find that my starts are quicker also, rarely more than 1 blade and it's running. Less strain on the starter. I run the full advance (up to 37Deg) so haven't noticed any drop in performance. One benefit is my hottest CHT is now 5 deg cooler.

Overall, I highly recommend a Catto for anyone EX. I think of it as an "almost constant speed."
One last thought....I took 18.1# off the nose with my Catto and another 11.9# (15.4-3.5) by replacing my Odyssey P680 with a EarthX 36D. Total weight loss of 30#....and I didn't have to give up beer or ice cream.

Lou

tcraft128 said:

That's what I was thinking.

Sageelite what engine are you going to use?

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Actually I havn't more knowledge about propeller,I told Nicole Catto my engine model is IO360,she suggest me choose their's 86X44 for my purpose of STOL.

Hey Lou, how about 2 deg. ATDC ?

My limited experience with Catto is they tend to recommend on the heavy side when it comes to pitch. Sageelite, I would call them and get that pitch reduced to 40 " otherwise I think you will be disappointed in your rpm and climb performance.

PerryB said:

My limited experience with Catto is they tend to recommend on the heavy side when it comes to pitch. Sageelite, I would call them and get that pitch reduced to 40 " otherwise I think you will be disappointed in your rpm and climb performance.

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Tell me why？pls

Good information Lou! I will play around more with the climb speeds. Interesting.

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.

DW said:

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.

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I have no idea about propeller,Craig suggest me 86X44 too,and forward my email to Nicole,I should listen to the opinions of those who?

DW said:

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.

Click to expand...

DW,could you tell me the 86X44 design for?I am a beginner,and maybe you know,you cann't fly from here to anohter in China,my PA18 just for STOL show,and I ordered 35" Alaska bushwheel,is my choice right?

If you have a stock 180hp.O-360 (or IO-360 ) you are going to have a low static RPM and sluggish climb performance with 44 inches of pitch. If you want STOL performance you should keep your prop pitch on the shallow side. When I got my Catto prop I went with Craigs recommendation and was over pitched.
Just curious as to why you're going with an injected engine. It seems like extra weight and complexity.

PerryB said:

If you have a stock 180hp.O-360 (or IO-360 ) you are going to have a low static RPM and sluggish climb performance with 44 inches of pitch. If you want STOL performance you should keep your prop pitch on the shallow side. When I got my Catto prop I went with Craigs recommendation and was over pitched.
Just curious as to why you're going with an injected engine. It seems like extra weight and complexity.

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Ok,thank you all.I understand,I will discuss this question with Craigs.My IO360 is bought form an air show in China,they only bring this to here from America.

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

sageelite said:

Tell me why？pls

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Your stopped going up on a big hill In your 5 speed Toyota. 8438 is like starting off in first gear. 8440 is second gear. 8444 is fourth gear. What gear is going to get you moving the best

Glenn

I inquired about the weight of inject and carburteter 360 a moment ago,they are same in weight but the inject eninge more complex than carburteter one and inject engine is more economical.

cubdriver2 said:

Your stopped going up on a big hill In your 5 speed Toyota. 8438 is like starting off in first gear. 8440 is second gear. 8444 is fourth gear. What gear is going to get you moving the best

Glenn

Click to expand...

Yes,an good analogy.thanks.

cubdriver2 said:

Your stopped going up on a big hill In your 5 speed Toyota. 8438 is like starting off in first gear. 8440 is second gear. 8444 is fourth gear. What gear is going to get you moving the best

Glenn

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Are you instructor of tailwheel fly?I am going to America learn tailwheel or bushfly,what's your suggestion?Thank you.