Prop Pull Testing Catto Props 0-375

[CaptAmerica]

I've been working with Craig Catto to find a prop design that is fine tuned for the O-375 from Aero Sport Power. We did some pull tests with the airplane attached to a dynamometer yesterday with three different props. The tests were all done at Flytek's shop on Lake Hood with Shawn Lidey. The dyno is the line pull type, with units in lbs, originally designed for applying proper tension to electrical lines, but is used in many applications. It has a scale of 0-1200lbs.

The engine is Bart's O-375, 9.6:1 pistons, port/polished, exhaust from Custom Aircraft Parts.

The airplane is a Steve Bryant Producer, it has straight skis on right now, so the tests were performed with dollies under the skis. As equipped, it has an empty weight around 1180ish lbs. (Mods have been happening and I don't have the exact weight tracking right now...)

Here are the test results, each prop was tested three times, for each test I'll give the data in this order...prop:test #:max static rpm:manifold pressure:OAT:Lbs Pull

Catto 84/43: 1: 2440: 27.9: 34: 730
Catto 84/43: 2: 2440: 27.9: 33: 750
Catto 84/43: 3: 2440: 27.9: 33: 745

Catto 84/44: 1: 2320: 28.0: 34: 770
Catto 84/44: 2: 2320: 28.0: 33: 800
Catto 84/44: 3: 2320: 28.1: 34: 775

McCauley: 90/37: 1: 2270: 28.0: 34: 820
McCauley: 90/37: 2: 2270: 28.0: 34: 820
McCauley: 90/37: 3: 2270: 28.0: 34: 820
(thx to Dave Calkins for the 90" prop)

It should be noted the mid-span blade area is quite different between the two Catto props, the 84/44 has larger blade area and longer chord at the mid-span as compared to the 84/43.

In discussions with Craig Catto yesterday, the next prop will likely be something in the range of an 84/42, but with the larger mid span chord similar to the current prop I have that is an 84/44.

Nitrous was tested with the 84/44 prop, when boosted, the #'s were as follows...84/44: 1: 2500: 30.0: 34: 895

That is it for now, curious to here the chatter...some things I wonder about is whether or not max pull at static rpm is indicative on a given set of props of which prop will perform the best from a short take-off point? Craig Catto is going to work up some thrust curves based on this data that should help illustrate this and look at the curve relating to the increase of thrust for each prop as rpm increases in t.o. roll...

Obviously, proof is in the pudding, and we didn't have time to test all the props and fly each of them...that will be for next time...

Comments...?

Josh Pepperd
Anchorage

[Bob Breeden]

Very Interesting.....

I see how you surmise that the next test with a larger blade area/chord and less pitch may help the power out....with a lighter prop than the 90 inch McCauley.

Bob Breeden

www.AlaskaAirpark.com

[palhal]

Josh----I also have an 0-375 from Bart with the same domed pistons that I just installed several weeks ago. I am running a McCauley 90X37 also.
I am on 35" tires and weight empty is 1175. With the brakes locked I can get 2425 RPM at 525 ft elev. @ 55f. My new Tach has been checked to see if it is correct and I also checked the pitch on the prop to see if it is correct.
Bart said I will get another 25 RPM when the rings get seated.
It is real important to see if the tach is correct. I had that problem one time thinking that I had other problems with the engine or the pitch of the prop.
Keep up the good work and info to us cubbers.

Harold K.

[gpepperd]

Harold,Check your mail as I sent you a PM re. further information. Greg Pepperd

[Fortysix12]

"Nitrous was tested with the 84/44 prop, when boosted, the #'s were as follows...84/44: 1: 2500: 30.0: 34: 895"

To me this mind boggling. Nearly 900 pounds of thrust. That's kicking butt.

[kase]

Interesting to me is that the 44 pulled harder than the 43 at less rpm.

[ksecub]

You need to pitch the 90" to 31-33 so it statics 2450+, then there will be no contest with the catto prop. You can do all you want but the bigger the diameter, the more the static thrust.

I find it interesting that people put big engines on their cub and then put little props on them. Its not HP that we want, its thrust. You can have a 5,000 HP dragster, but if you can't convert that HP into work (i.e. burning out the tires) it does not do much for you.

[aviationinfo]

Are the Catto props the ones that are designed to flex to a slightly steeper pitch as they unload? I would think that would give it a definite advantage over the McCauley in cruise speed.

[CaptAmerica]

aviationinfo, my cruise at 2450 is 98-100mph ground speed with the 84/44 catto prop...

[brooks18]

90/37 is way too much prop for that engine. If my memory serves me right i remember hearing about that very prop over boosting a lycon360 and burning it up. Proof was in the burnt pistons from what i heard thru the grape vine, i am sure leaning didnt help the situation. If katto wants a prop to compete he needs to build his prop in a 90" and have a nickel le. Even then most off airport guys wont run a composite just the contest and 100 mile hamburger guys. ksecub said it right. I like comment on " big engines little props" so true.

[Dave Calkins]

Hi Brooks.

I see you're a relatively new member of the website. Welcome. I agree with your comments about Katto doing a 90" prop. I like metal out front unless there's another wood or glass prop on hand. It is not acceptable to think a willow twig will explode these things. Captain America has gotten away with a few twigs, so I am encouraged on the Katto props.

I don't believe we have met, but I see you mentioned something about the 90 inch prop burning up an engine and the proof in the pistons.

My findings are that this prop runs cool and pretty good on a Lycon-modded IO-360 with 11-1 pistons. The engine simply likes alot of fuel/manifold pressure to cruise at decent speeds, yet made acceptable static RPM and pulls HARD out of the hole. Yes, less pitch would be even better out of the hole. To make the kind of horsepower required to turn that prop at 2500 RPM and get 96 MPH out of the airplane it's pulling, the engine needs 17.3 gallons per hour. That's a tough compromise to swallow. It aint' the props fault.

DAVE

[Mauleguy]

I have run the 90/32 for 1200 hours on my airplane with a Lycoming 0-360, 10-1 pistons. The engine now has almost 2800 TT smoh and is still going strong.

The engine turns 2500 rpm in cruise and I see 20"mp at sea level at that rpm. I burn 8.5 gph at this setting and ground speed is 95 mph which is about what you will see with this propeller on any airplane with a 32 pitch.

I had it on the Super Cub and had about the same numbers.

Many people have turned this propeller for years pitched flat and never burned up an engine.

Greg

[CaptAmerica]

Greg,

What static do you get at what density altitude with the 90/32? I remember from a thread some time ago that palhal started about his new O-375 ride that Mikeo said he had found that 90/34 was the best pitch for the O-375...I believe Mikeo and I have the same engine...

Anybody know of a 90/32-34 I could try in front of the dyno in Anchorage? My bird is down for a month getting cowling work done and other things, but back in the air in March...I will have the large blade area 84/42 Catto prop then to try. Catto will have the nickel le available this spring...

I'd also like to try a 3 blade composite as well...

I hear that Mikeo has another wood prop that is performing real well...I was hoping to find a prop that did close to the 90 without the weight penalty...maybe not...

Josh

[pa18guru]

I was wondering if the mauleguy has any numbers for the 90-32 O-360 10:1 on the thrust pull test the Capt. did?

Also, did Dave try the 90-38 IO-360 11:1 lycon in the test that the Capt. did?

Being from the east coast, I don't know any of you guys but it sounds like there is some good data.

I would have to agree with Brooks, that 90-38 could burn up an IO-360 11:1 rather quickly if it was leaned out.(<40hrs)

Mauleguy has it figured out, 90-32

That Catto guy needs to make a 20lb 90-32 by the sounds of it. No sence in re-inventing the wheel!!

[Mauleguy]

2450 is the static number to shoot for, with the cool dense air during winter I only see around 2375 static

At sea level on a cool day (50 deg. approx.) it pulled an average of 800 in 3 pulls.

[Speedo]

I would have to agree with Brooks, that 90-38 could burn up an IO-360 11:1 rather quickly if it was leaned out.(<40hrs)

OK, I'll put my ignorance on display: can you explain why this prop and piston combination would burn up the engine? This is an area (or should I say another area, about which I know nothing.

Eric

[willyb]

Eric ever have a car in high gear at low speed and try to accelerate and it pings(spark knock).Putting a heavy load on the engine, same as a prop taking a big bite.Good way to destroy an engine.

Bill

[pa18guru]

Eric, if you take a look at the numbers that Capt put up, he state that the 90-37 @ 2270 had 28.0 MP. This is way too high for rpm ratio. If you have ever flown a constant speed prop, you want these numbers a lot closer (2300 rpm - 23.5" MP in cruise). Add high compression piston to the equation ie. 11:1, a tight a** pilot leaning the mixture out to lower gph, that pressure and high temp has to go some where. Usually if an engine is over proped, the pistons will have groves burnt in the skirt from blow by.

After running airboats here in south Florida for 35 yrs, unfortunatly, I am speeking from experience. I have burnt up a few engines myself.

I'm sure that Mr Calkins knows what he is doing but I would be interested to know how many hours has on that IO-360 11:1 running that 90-37 club.

Mauleguy

The engine turns 2500 rpm in cruise and I see 20"mp at sea level at that rpm.

[Icarus]

Greg the Maule Guy, What are you getting for full throttle rpm in cruise with this prop / engine setup? I was always told on the fixed pitch cubs like you said to get 2450 rpm static, do a takeoff & climb out at 60 -65 mph IAS No Flaps and you should be about 2520 rpm and be able to break redline 2700 rpm in level cruise flight. Like stated above changing the prop pitch is like the gearing in a car. Every pitch on the prop changes speed approx. 3 -4 mph & 40 rpm. Just curious to see what numbers you are running. Thats great with that kind of time on the engine with 10:1 pistons. Again the hotrod engine guys always say DON'T lean these hard unless you want to burn holes in the pistons or toast the engine. Change your Oil often. And use 100 LL, car gas is hard on the 10:1's. We carry & have used Octane Booster in the planes in case of Bad Village Gas this is with 8.5 :1 pistons. Thanks Guys Good Flying & Be Safe

[Mauleguy]

Greg the Maule Guy, What are you getting for full throttle rpm in cruise with this prop / engine setup? I was always told on the fixed pitch cubs like you said to get 2450 rpm static, do a takeoff & climb out at 60 -65 mph IAS No Flaps and you should be about 2520 rpm and be able to break redline 2700 rpm in level cruise flight. Like stated above changing the prop pitch is like the gearing in a car. Every pitch on the prop changes speed approx. 3 -4 mph & 40 rpm.

At full throttle rpm in cruise (which I would never do) it turns 2750 +depending on the density of the air.

On take off climb 2500rpm+, depends on speed and how steep you climb.

I found that on this big prop 1 degree of pitch change = 25 rpm

Greg

[palhal]

I have been running a 90" McCauley on my 0-375 with 8.5/1 pistons for 108 hrs and was only getting 2350 rpm static so I was working the engine real hard and leaning aggressively. Instead of repitching the prop I decided to up the compression.
I pulled the cyls to install the 9.6/1 pistons and the old pistons looked like new on the skirts with the usual crust on tops.
I now get 2425 rpm static (another 25 rpm will come when rings seat) and I get 2700 rpm red line at full throttle at level flight with the 90" prop.
I think it will be real hard to beat a 90" prop out of the hole but it really sucks in cruise.
I plan on using the 90" locally and using a cruise prop for the long hauls.
Some day it might become possible to get the best of both worlds with the composite props that are being radically designed and built with the metal leading edges to cut thru some of the brush I land in.

[pa18guru]

Palhal, this stands to reason with 8.5:1. What pitch is your 90"?

[palhal]

pa18guru-----My 90" is a 37 pitch measured on the flat.
I was talking to Catto and he said there were 3 different ways to check pitch.
Some check pitch on the flat and some check pitch spliting the cord line which comes to 3 pitches less than on the flat. He said about another way and he lost me on that one.
So, depending on who twist your prop to your desired pitch would be different from all prop repair stations.
I know of one who uses a prop protracter on the flat side with a degree reading out of a book and uses a long bar and manualy twist the blade.
I know another who uses an expensive digital pitch checking machine and hydraulic twist the blades to pitch.
What I have found is they all can twist your existing prop to get the rpm you need.
Remember that one pitch is only around .030 movement in the middle of the blade. I would think this is why pitch numbers vary among users.
The same holds true on boat props. Everyone has their own way of checking pitch. Take care----Palhal

[pa18guru]

Palhal, actually there's only one way to measure pitch. I don't know where you got that info.

The pitch of any prop, boat or airplane is measured by inches of travel through a solid in one complete revolution. So a 90-37 is 90" long 37" of forward travel in one revolutin.

There is a formula to figure out all the numbers posted. Hp is the only variable. The number of revolutions per min is relevant to the inches of travel (pitch) of the prop. As the length of the prop increases at a constant rmp, the greater the thrust. So calculation of # of thrust in relationship to a given prop is easily calculated.

The only info need is the static run up of the same prop on different engines, ie hp variable.


Back to the line of this thread, think of your prop as moving through a solid. This will help in your decision making process of how much stress you want to put on your engine, ie piston compression and prop configuration.

[Dave Calkins]

The pitch of any prop, boat or airplane is measured by inches of travel through a solid in one complete revolution. So a 90-37 is 90" long 37" of forward travel in one revolutin.

.

Airplane prop 'pitch' is actually an 'average' pitch. There is a 'helical' pitch to our blades (think 'twist', or steeper pitch at the hub and flatter at the tips). This is obvious to most of us, yes?

I have only seen one way of measuring pitch (marking stations from hub to tip and measuring at each station line).

The IO-360 in question is a Lycon done with 11:1 pistons that turned the 90/37 (I did not verify pitch) at 2350 RPM with them. We have learned through Marc Englerth and Wayne Mackey and others that 10:1 pistons are a better compromise on fuel burn/horsepower and that is what is in it now.

With 10:1's the 90/37 would make only 2250 static , so we have a 84/45 on it now and that is a good compromise.

But, with the 11:1's and the 90/37, that sucker pulled HARD. The prop is one that Mikeo had.

I am curious that Greg(Mauleguy) is able to fly as fast as us with less pitch/same rpm. (he mentioned "groundspeed"?) We have a draggy airplane apparently, and it is flown at gross (2350) most of the time. It is also flown as a float plane, so that may be a speed factor. It was around 100 hours when presumably the red knob was pulled out agressively. The thing purred before that day. I and a friend changed the cylinders with the airplane on a sandbar, high and dry on floats after the tide went out. There was a beluga and a seal chasing salmon as a team when the tide came in and the a/c went back in the river

[Mauleguy]

The Maule is a little faster then the Supercub with the same pitch. The Maule 95mph and the Supercub was 90 mph @2500 rpm.

[gander]

pa18guru it seems you have alot of knowledge with engines on aircraft and airboats. We have a older gentleman in our neighborhood which is the same. Unlike aircraft guys the airboats guys try alot more modifications to these engines and find out what works and why, This is one area more guys need to look for engine info as alot goes on. The old timer in our neighborhood is a wealth of knowledge that stumps most engine builders because he has actually tried it. Yes you can put 10:1s in a narrowdeck 320 with out the base plates boat guys have been doing it for years.
18guru i have pmd you, hope to talk to you more on engine mods.
Hang in there Dave.

[palhal]

pa18guru----You are dead wrong on checking pitch only one way. Some of them get into airfoil design and split the cord like I said earlier. I check my own pitch on aluminum props on the flat side ONLY and found the McCauleys from the factory are dead on. At least the ones that I have checked.
I Mfg highspeed boat props for 44 years now and I know all about pitch and I can show you how to make pitch patterns Mathamatically in case you are interested.
Everytime I visit a prop shop, I have seen their home made gadgets for checking pitch and no one knows mathamatically to prove their pitch because most of the time they copyied another prop.
Also, you can widen the blade and shorten the dia. and still pull the same as the longer dia. with the narrow blade. This is controlling slippage or cavitation. All the composite props are into this experimenting these days which I think is a good thing.
If you want to know about progressive pitch and variable pitch and true pitch let me know and I will try to anwser your question.---Take care

[pa18guru]

Dave, Palhal, how one determines the pitch, is a series of measurement taking at different stations. That is a given. My point was, that if you determine that you have a "37" pitch prop, this is not a degree of measurement. It is 37 inches. I don't think that many people in aviation or on this web site know that. This is true with any prop, boat or plane.

Palhal, if you are prop manufacturer and don't know that the PITCH of a prop refers to inches of forward travel in one revolution, I understand your confusion with this thread. This info is free. Just call your local ACO and ask any of the aero space engineers on staff or just go to the NASA web site. Thanks for the offer on the math formulas but I allready have them. Actually I have written a software program that runs the algorithm.

I am sure that your 90-37 PULLED hard. It should. I was just wondering how many hours you have on that IO-360 11:1 running that prop? Did you burn that engine up?

I would find it interesting to know some static rpm numbers.

O-360 10:1
O-375 9.6:1 same prop. It doesn't matter which one.

I just can't see spending that kind of money for an exp engine that may only give you 20-40 rpms more.

Thanks Gander. I have avoided getting involved with this web site for years, just for this reason. Most people on here are just assemblers following someone elses advice and don't think for themselves.

Are you that guy that is on the cutting edge, with carbon fiber?

[gander]

Theres is nothing cutting edge about what i am doing as it all has been done before just not on a cub. As you know general Aviation moves slow. I would sure like to hear some airboat/lycoming stories. I think the catto props are good thing to the cub world it is nice to see something move forward in this stale world. I think you need to compare the catto to the pawnee that would be more apples to apples like. Aspect ratio will be more efficeint length wise vs width. 90 will win every time. Thats why gliders have long wings not wide wings.

[Mauleguy]

I am pretty sure that 37" or whatever you have pitched your prop to in inches is a theoretical number and that through the air movement is going to vary on each make of airplane based on it's own drag profile.

I have watched them re-pitch my prop several times and it is not a pretty thing, it's a guy that knows what he is doing with a big cheater bar, this is the best way to describe it. I think there is some room for error, how much I am not sure!

Greg

[palhal]

pa18guru----Where do you get that I don't know that pitch refers to forward travel! I don't appreciate your insults on this forum.

If you would read in the above post I ran 8 1/2 to 1 compression with the 90" for 108 hours and the pistons looked like new. I went to the domed pistons 9.6 to 1 and got my static rpm now at 2450.

90X37 prop 8.5-1= 2350 RPM.
90X37 prop 9.6-1= 2450 RPM.


I don't care what pitch anyone is running. If you get 2450 static you should be happy.

Greg--I think you are right that the air movement will vary on make of aircraft due to drag profile. I believe the slats in front of my wing is not helping my cruise speed.

Harold K.

[gander]

Pal, What kind of MP were you seeing with 8.5 and 9.6???
This is all good data, seems maulguys numbers look the best for MP rpm fuel burn cruise. Maybe the 375 is just such a torque monster it can swing a 90-37. I would like to see the same prop on a 375 and 360 10:1.

[palhal]

gander----I don't have a manifold pressure guage to give you the numbers. I did everything possible to keep this aircraft as light as possible.

Bart said that the 0- 375 made better torque than expected. The 9.6-1 pistons helped the hp mainly we guess by the flame pattern rather than the compression rise. There is a dome on top of the piston and the piston pins must be offset in the pistons because the piston has to go in the cylinder with the arrow pointing forward.

Have you finished the new pod yet?

Take care,
Harold K.

[Dave Calkins]

Boys, miscommunication is no reason to get snippy or get offended.

let's communicate so we can get on the same page.

I did not realize that Mauleguy was talking about the 90/32 on the Maule. I thought that was on the Cub.

I was not flying the day the hotrod motor got sick. I think it was a problem on that day only, as it never acted funny to me, then I got this call to fly out to where it was.

As far as CaptAmerica's rig, I think that our thrust numbers will go up here in a couple of weeks.

[dougsappllc]

The long awaited Rhinometric Calibrometer has finally arrived, now we can pull test the 4 blade Warp drive against the Borer, same day same temp same aircraft. Anyone close to Omak WA who wants to take advantage of it while it's here, please give me a call, 509-826-4610. It's borrowed, so it will only be here for about 3 weeks. Plan to give it a go next Sat and Sunday. Will post what we discover.

[gander]

Pal, I have gotten side tracked on my helio project when the wings are finished i will be making some new style pods and few other new additions.

[av8ron]

My, my, my where have I been during all this discusion?

Although Ol' 18guru has ruffled a few feathers, he raises some good points. But pa18guru, you might want to lighten up on these guys. I've figured out from years on this site, they don't like it when you start questioning their ability

Josh called me the day they were testing and I couldn't make it. It will be interesting to try that Catto on my O-360. I don't have 10:1 though. It would be interesting to see the diff between an O-360 w/10:1 vs O-375

Ron.

[brooks18]

Dave, You sound like my teenage kids every time i find a dent in the car." It didnt happen when i was driving"

[JimC]

.....I found that on this big prop 1 degree of pitch change = 25 rpm

Greg, did you mean 1 degree, or 1 inch?

Re other posts about pitch measurements, most manufacturers measure pitch at about 70% to 70.7% (square root of 2 over 2) of semispan -- but not all do that, so it's not appropriate to compare pitch measurements directly between different manufacturers, and different choices for semispan variations in angle of attack, airfoil distribution, and chord make the comparison even more tedious. Personally, I like Hartzell's propmaps as an easy way to compare prop changes, and wish more prop manufacturer's would emulate their techniques (not their props, just their calculation and presentation methods).
JimC