McCauley Prop Info Needed

[rv8bldr]

Hey all

I'm considering putting a McCauley CS prop on my 4pl Bearhawk but am completely baffled by the (seemingly) hundreds of hub and blade part numbers. Do any of you happen to know which hubs and blades would be applicable to a Lycoming O-540-A1C5 (out of an Aztec) ? I'm still thinking about a Hartzell as well, but I was able to figure out the appropriate part numbers there.

I'm trying to do a cost/weight/life cycle analysis...

Thanks in advance

Mark

[Battson]

The blade and hub numbers are simple enough once you have the key to their code.

You'll need to read the 500 page applicability guide, or contact MacCauley Propeller for applicability. They were a complete PITA for me, my first prop was a Mac which I put 500 hours on. They wouldn't help me replace it after it was damaged, because of the uncertified nature of the Bearhawk and it's engine. Hartzell is a lot more experimental friendly.

__________________________________________________ _________

McCauley Aircaft Propeller Model Designations

McCauley Constant Speed aircraft propeller model numbers have two important constants - one at the beginning that designates the number of blades and one at the end that specifically identifies the propeller model.

A numerical value at the beginning of the model number in either the first or second position (i.e. B2 or 2A) indicates the number of blades. (This first constant will be followed by a two digit number value between 31 and 37 which reflects a particular McCauley design.)

The most important designator in a McCauley Constant Speed Aircraft Propeller Model will be the two or three digits following the "C" at the end of the model number. If there is only two digits following the “C" the propeller will be a threaded propeller and an obsolete design. If there are three digits following the "C" the propeller will be a threadless blade design and is current production. A Propeller Technician may refer to a McCauley Propeller as a C66 (threaded) or a C203 (threadless) - names which in "propeller speak" accurately identifies a McCauley Constant Speed Propeller Model.

The C200 series - two-bladed constant speed threadless non-feathering aircraft propellers

The C300 series - two-bladed constant speed feathering aircraft propellers

The C400 series - three-bladed constant speed non-feathering aircraft propellers

The C500 series - three-bladed constant speed feathering aircraft propellers

The C600 series - Garrett Turbine Engine aircraft propellers - either three or four bladed

The C700 series - Pratt Whitney Turbine Engine Propellers - either three or four bladed

The C1000 series - Pratt and Whitney Turbine Engine Propellers - five bladed

The C1100 series - Garrett engine propellers - five bladed aircraft propellers

In addition to the Propeller Model number there is a blade model number for all McCauley Aircraft Propellers. The propeller diameter is a result of the difference between the first two digits and the dash number at the end of the blade model number. For example in the blade model 90DA-2 the propeller will have an 88 inch diameter (90 inches minus 2 equals 88 inches). The "DA" indicates the blade design.

__________________________________________________ __________

By the by, I believe MacCauley have a better designed propeller hub and spinner for reliability and it's a more ideal engineering solution too. However, the Hartzell props seem to be designed for lower cost manufacturing.

[whee]

A quick look at the MAG show that the only props for that model are a 74" two blade and a 77" three blade. I didn't have time to find it but there is a 84 or 86" two blade applicable for use on the 540 and maybe your engine has the same counterweight arrangement.

Battson, Out if curiosity what did McCauley say they wouldn't do? Why didn't you send your Mac hub to Whirlwind and get a set of their blades installed?

[bergy]

There is probably a better thread in which to post this question, but I have not been able to find one in the forum-jungle.

Whether one uses a ground-adjustable prop, or a fancy constant-speed prop, it seems to me that one still needs to select a design-speed for their aircraft. In other words, any variable-pitch prop works best at just one airspeed, the airspeed for which the twist of each individual propeller blade was initially designed; flying the aircraft at any other speed involves compromising efficiency

Here are some calculation upon which I base my conclusions:

I will try leave as much engineering mathematics to those who write textbooks and use mostly simple arithmetic in my examples. I will put the various airfoil designs aside as well and design my examples using simple flat fan-blades, much as a household fan uses. I will round-off the value of Pi=3.14159265+ to simply 3.

I will create two propellers, one a 48" 'borer-prop' of sorts, That is .... with each revolution it will advance 4' through calm air. We will also look at a 60" 'speed-prop' that will advance 5 feet through calm air with each revolution. We will look at the slope/pitch of flat-surface fan-blades at distances of 12", 24", and 36" from the prop-shaft required to meet each propeller's specs. The math comes out easiest if we start with a 48" prop and radius of 24" from the prop-shaft.

At 24" from the prop-shaft the diameter is 4 feet, and a point on the propeller at that radius will travel in a circle of circumference ~12
feet. The slope of the prop-blade at 100% efficiency would then be 4/12 or 1/3 (which comes out to be about 18 degrees).

At 12" and 36" from the shaft the blades will still need to advance through the same 4 feet of air but the circumference of the circle
through which they swing will be 6 feet and 18 feet and the slope of the prop blades will be 4/6 and 4/18.

So in summary: A 48" prop at radial distances of 12, 24, and 36 inches from the shaft will have blade-slopes of 4/6, 4/12, and 4/18 for blade-angles of 34, 18, and 12.5 degrees

Doing similar calculations for a 60" speed-prop gives blade-slopes at radial distances of 12, 24, and 36 inches of 5/6, 5/12, and 5/18 for blade-angles of 40, 23, and 16 degrees

We see from the above calculations that the blade-angle differences between the 48" and 60" props vary at radial distances of 12, 24, and 36" by 6 degrees, 5 degrees, and 3.5 degrees

Now let's take an extreme case of an aircraft owner that has a ground-adjustable propeller with blades designed to give similar performance to the fixed-pitch 60" speed-prop. You then decide to put the aircraft on floats and desire a 48" prop. What does the owner do?

Well he could flatted the prop-blades by 3.5 degrees to get a propeller-bite at a radius of 36" similar to the borer-prop, but that would not match the optimal slope at other radial
distances. The best we can do is flatten the blade-slope to some average amount, but no matter what we do we can never keep the propeller happy at all times

Bergy

[zkelley2]

I'm not sure you understood what he wrote. The constant speed prop has the same problem as the ground adjustable prop, the pitch at different stations can only be optimized for one profile. 48", 60", etc. If you take that math to the extreme, and a lot of guys do with their ground adjustable rotax props, you actually get reverse thrust at the tips(even if the pitch while stationary isn't negative) while inboard it's just very fine, or if you go too coarse, the tips are doing all the work while the inboard section of the prop is stalled. On top of that, unless you are at the designed blade pitch, some part of the prop is at optimal, but the other parts are creating excessive drag.
Every prop, including constant speed props have a design speed in mind. Outside that one range, there's rather large inefficiencies.

[Bdflies]

Oh, I think I understood Bergy's post. Any given blade profile will describe a theoretical helix on rotation. Optimizing every station, for a given helix, will render those stations less efficient when rotated (re-pitched) in the hub, producing a different helix. Until 'shape shifting' propellor blades are developed, we're kinda stuck with that phenomenon, don't you think?
That 'inefficiency' is built into helicopter MR blades as well. The inboard section displays less pitch than the outboard portion. It's why autorotations are possible. Undoubtedly, copters could fly more efficiently if the blade angles, at each station were more optimized for lift, but it would take a special pilot to fly the thing, having no possibility of surviving a power failure. It's a compromise.
I assume propellor manufacturers optimize station angles of fixed pitch props. I'm less sure about how CS blade twists are determined. I would guess that they're compromised for the middle of the pitch limit stops. Don't know for sure.
So yes, I acknowledge and agree that all propellors (including CS) represent a compromise, much the way automotive transmissions also represent compromises. Any given gear will be most efficient at a given speed and load, but less efficient outside of that specific set of parameters. Thus the ability to select a different gear. No gear being perfect, but working together, the best compromise available. Constant speed props represent similar compromises. Now, about those 'shape shifting ' blades....

Bill

[JimParker256]

Um... Former Army helicopter instructor pilot here... Every helicopter I've ever seen or flown is designed with the outboard blade pitch lower than the inboard (washout), just like airplane wings. This was especially noticeable on the two-bladed rotor systems, where you could sight down one blade and see the other (albeit drooped) blade. It is exactly that washed-out blade portion that allows for autorotation at "flat" pitch (bottom collective position), because the lift-vector at the outer end of the blade is inclined forward of the axis of rotation, which counters the drag produced by the rest of the blade. Without that washout, there would be no stable-state autorotation.

Other than that, I agree with your discussion about propellers (and helicopter rotors, which are just adjustable-pitch propellers) being optimized at each station for a specific set of conditions. That's why a prop designed for an RV-10 with the IO-540 would be "less-than-optimal" for a Bearhawk with the same IO-540 – the speed envelope is just too different between the two aircraft. That RV-10 prop would be producing very little thrust at Bearhawk takeoff and landing speeds...

[Battson]

A quick look at the MAC show that the only props for that model are a 74" two blade and a 77" three blade. I didn't have time to find it but there is a 84 or 86" two blade applicable for use on the 540 and maybe your engine has the same counterweight arrangement.

Battson, Out if curiosity what did McCauley say they wouldn't do? Why didn't you send your Mac hub to Whirlwind and get a set of their blades installed?

They wouldn't recommend a compatible prop for Bob's IO-540-A4EXP (which is essentially a -D4A1) engine.
They said they had done no vibration analysis so they couldn't sell me a prop for that engine, due to liability reasons I presume.

My hub was an no longer airworthy and insurance paid up, so I could choose whatever prop I liked for the money.
Whirlwind's CS carbon STOL series props are nice products and have more history than Hartzell's carbon STOL prop (Trailblazer).
However they openly say their props are aimed at smaller engines. I guess they don't make long enough blades or big enough paddles to get all the benefits from 260hp. That's the unscientific view I reached anyway.

By the way, the Mac prop I had been using was a B2D34C235-B hub with C-90DKB-8E blades. The 90 is the original length -8 inches cut off the tips, all per that model number (so 82" blades). That hub is the reason why my nose is a bit longer than most Bearhawks, roughly a 3 to 4" longer hub. It was originally used on a new model Cessna 182, pitched for max RPM 2450.

[rv8bldr]

Hey guys, thanks for the great info.

Jono, you are a wealth of knowledge!

[MitchG]

82" McCauley CS prop, Hub: B2D34C219, Blades: 90 HDB-8, Originally found on T-182 Skylane equipped with an O-540-L3C5D.

If I'm correct, the 5 before the D in the engine model is the counterweights, which is the same on your engine and mine (C4B5 also of an Aztec).

They are plentiful and relatively economical used and inspected.

[rv8bldr]

Thanks, Mitch! I will start my search....

Cheers

Mark

[whee]

The 86" two blade Mac I was looking for is the B2D37C224-B/G-90RA-9 and was certified for use on O540J and IO540W engine installed on Maules. They used O-540-J1A5D, O-540-J3A5, IO-540-W1A5D, IO-540-W1A5 engines on those airplanes which have the same counterweight designation as your engine. The guys that developed the STC said they couldn't do it on the other engines because the higher max rpm exceeded noise restrictions.

Another option is the 82" B2D34C214/90DHB-8 that was used on Cessna 182RGs. They too had the "5" counterweight designation.

[Scott]

Ok, I’m at a point in my 4 place build where I need to get select a propeller. I have very limited knowledge hopefully I can validate my thoughts and get som good advice from those who have gone before me. My mission is Alaska bush flying, wheels, skis, floats. I have ordered a Bob. Barrows 260HP O-540.

I have decided to use the McCauley hub, I believe it to be the better design plus I have the option to use catto’s New CS blades which are in the test phase now and should go into production early next year (well before my completion date). I’d like to focus on the McCauley hubs.
1. What is the real world advantage of a 3 blade prop?
I’d go about 80” so quieter than an 84” two blade? More ground clearance? Quicker deceleration? What are the performance advantages/disadvantages? My understanding is slightly better static pull but slower cruise. Obviously 2 blades are less expensive, weigh less and are not as smooth.

2. I’m very confused on which hub to look for. It needs to be threadless so C2XX (2 blades)or C4XX (3 blades). I can’t seem to find a guide for the numbers and letters that precede and follow the “C” designation. Has anyone cracked the code”.

[AZBearhawk272]

The code is cracked at the website
propellerman.com

then a visit to then McCauley website to view the different Blade / Shape designs. The unknown letters.

Kevin D # 272

[whee]

Ok, I’m at a point in my 4 place build where I need to get select a propeller. I have very limited knowledge hopefully I can validate my thoughts and get som good advice from those who have gone before me. My mission is Alaska bush flying, wheels, skis, floats. I have ordered a Bob. Barrows 260HP O-540.

I have decided to use the McCauley hub, I believe it to be the better design plus I have the option to use catto’s New CS blades which are in the test phase now and should go into production early next year (well before my completion date). I’d like to focus on the McCauley hubs.
1. What is the real world advantage of a 3 blade prop?
I’d go about 80” so quieter than an 84” two blade? More ground clearance? Quicker deceleration? What are the performance advantages/disadvantages? My understanding is slightly better static pull but slower cruise. Obviously 2 blades are less expensive, weigh less and are not as smooth.

2. I’m very confused on which hub to look for. It needs to be threadless so C2XX (2 blades)or C4XX (3 blades). I can’t seem to find a guide for the numbers and letters that precede and follow the “C” designation. Has anyone cracked the code”.

I assume you are on Cattos email list for the CS prop. The number of blades will depend on the engine and airframe. The hub will be determined by the angle of travel required. So Catto will tell you which hub you need and that info in not yet available. IMO you don't need a prop till you are really close to done. Sure, having one makes placing the spinner easier but it isn't required. I would wait till Catto can tell you which hub you need.

I'm super excited about this and really hope I can put one on my BH.

[svyolo]

I have never heard of the Catto CS, just checked their website and googled it. Nothing. How did you hear about it? Sounds interesting. I was looking into used props as well. The McCauley info here really helps. I had no idea how to decipher it.

[Mark Moyle]

Mounting a 3 blade square tip McCauley on my IO520. The prop is off a Cessna 207 with a TSIO 310 hp Continental. The key to making that prop fit my engine was the counterweight arrangement. Took a bit of research to find the information in Alaska Aircraft Engines library. The arrangement now has no RPM limitations...can run at any RPM up to 2700 continuous. 5 minutes at 2850rpm.

[Scott]

Whee, you are correct. I don’t need to rush my order for a prop but Bob is building my engine soon so it’s best to know my prop so I can get the proper weights if required. To tell you he truth I’m struggling with all the models out there, trying to break the code is time consuming and I don’t seem to be getting anywhere.

Question, Are the counterweights dependent on the engine/prop combination or the engine/hub combo or all three? I know in the certified world it’s an airframe STC as well but that discussion doesn’t get too far with experimental. My understanding is that counterweights are not required with composit propellers but I can’t find that in writing.

FYI. here is the letter on Catto CS props that wWee is talking about. I was told to expect pricing around $2500/blade. They will do custom blades for your application.

Hello!!

We wanted to update everyone on the progress of our constant speed propeller. As of 11/8 we have a flying constant speed! The initial tests were to make sure we were hitting our targeted static RPM range. Flight test went well, the propeller will stay on this particular aircraft for further performance and endurance testing. It outperformed the constant speed propeller that was on it previously by 4 to 5%. We will do a full tear down once we reach 50 hours of flight time.
I do not have an accurate estimated time of when the blades will be available. It will depend on how the tear town goes and insure that aren’t any issues we need to fix. We are not expecting any issues as we have spent the last two years in development with static tests, pull tests and FEA modeling.

We will be using the McCauley hub. The C200 series for a two bladed and a C400 series for a three bladed. The number of blades will depend on the engine and airframe combination. We will require a minimum distance of travel on the blades depending on the aircraft. This will determine the model of the hub needed. I do not have a list with this information yet. As soon as I have more information for you I will drop everyone an email.

You can use any governor. That is engine specific.

We will just be selling blades. You can purchase a new hub from any McCauley dealer or best to find a used one that is rebuilt. Any prop shop should be able to assemble them for you.

As far as a TBO, that is a question that will be answered over time. We cannot answer that at this time.

All blades will have nickel leading edges.

Pricing has not been established.

If you have any questions please don’t hesitate to ask.

Happy Thanksgiving. We appreciate your continued patience and support!

Kind Regards,

Nicole Klith
Catto Propellers
12370 Airport Rd. #156
Jackson, CA 95642
209-754-3553