Don't know anything about the math, but will say that there's a significant increase in performance with the 88" vs 82" McCauley 2 blades at high altitude/DA like 8,000' and over. At sea level, the difference is marginal at best IMO, but the 88" always sounds damn good [emoji12]

I bought a brand new 88" C-203 a little over a year ago with a brand new spinner for $7500 out the door. I just saw them about a month ago for $9500 with spinner and governor on barnstormers. That might even be my old C-50 for sale. I sold it to a prop shop in Troutdale Oregon. My prop guy said it would cost around $5500 to overhaul it. He seemed pretty adamant about me ditching the C-50 in favor of the new C203. Said the C-50 was really outdated, and mine was over 40 years old. Other folks said the C-50 is tough as nails and it's a great prop. I am not a big fan of pumping lots of $ into old outdated stuff, so I went with the C-203. Sold my spinner for $450, so it cost about $1500 more to get a brand new prop.

hotrod180 wrote:Matt, thanks for bringing up the 180 TCDS. I see that the Hartzell props all seem to have a low setting of 12 degrees. Here's the mac breakdown from the C180 TCDS::
Cessna 180 (A J & K engines)
36C-- 82": 10.5 degrees low & 22 degrees high 88" : 8 & 22
34C-- 82" 10.5 & 22 88" 10.5 & 22
(BTW when I asked Dick Jacobs at NW Prop about the 2A34C50 prop, he told me it was considered a 2A34C as per the TCDS)
C66-- 82" 10.5 & 22 88" 8 & 22
Cessna 180G & H
C201 -- 82" 13 & 24.5 88" 10.5 & 24.5
C203-- 82" 12.5 & 25 88" 10 & 24.5

I agree with Rob that props are more a black art than science.

Keep in mind that the pitch settings will vary with prop length. These you've listed are for the 82" props which are OK, but not the same as the magical 88

Here a link to an old, but good resource;
http://www.mccauley.textron.com/MAG.pdf

49_sedan wrote:I am not a big fan of pumping lots of $ into old outdated stuff

Don't read too much into this, but I find that comment funny coming from someone with a handle like "49_sedan"

I get it about not pumping $$ into outdated stuff. Part of the reason that re-blading my 82" C203 was not cost-effective is that it would have to be upgraded to oil-filled per the McCauley SB ($$). A guy here on my airport just bought a new prop and his old 82" C66 is probably available cheap. It's already oil-filed, so I thought that maybe it would make a better candidate for re-blading. Prop shop told me no, unless I could scrounge up a set of blades, because new blades weren't even available for the C66 anymore. That's part of the reason I didn't buy the C50 on BS-- if I ever need to replace a blade, I'd be screwed. Might as well spend (hopefully not too much) more money & get the modern prop for which all the parts are still available.

hotrod180 wrote:As far as more performance vs just making more noise, check this page off Ponk's site.

http://www.pponk.com/HTML%20PAGES/propellers.html

It shows 940 lbs thrust for the 82" C58 prop at 2600 rpm vs 1016 for the 88" version, an increase of just over 8% -- a significant (but not huge) amount. It shows an even bigger difference between the 80" and 86 / 88" 3-bladers.

At take off, what will your tip speed be. At my ranch strip I will not let folks here with super sonic tip speed. I like happy neighbors.

Tim

"At take off, what will your tip speed be. "


Depends on where you set your prop.

55wagon wrote:"At take off, what will your tip speed be. "


Depends on where you set your prop.

Then what is your tip speed at take off at your prop setting. I usually have mine against the panel.

Tim

qmdv wrote:

hotrod180 wrote:As far as more performance vs just making more noise, check this page off Ponk's site.

http://www.pponk.com/HTML%20PAGES/propellers.html

It shows 940 lbs thrust for the 82" C58 prop at 2600 rpm vs 1016 for the 88" version, an increase of just over 8% -- a significant (but not huge) amount. It shows an even bigger difference between the 80" and 86 / 88" 3-bladers.

At take off, what will your tip speed be. At my ranch strip I will not let folks here with super sonic tip speed. I like happy neighbors.

Tim

You might need to factor in Temp as well. it affects the speed of sound.

Regardless of prop length you can make your prop not bark when necessary by just rolling it back a bit. Have to experiment w your setup a little. Usually around 2550 or so on my 88 is bearable. Will go more if need.
The U motor had some 90" props out there but weren't to loud due to the Rpms being dialed back a bit.
I can be quiet but then make some noise when I want with mine.
Guess I'm a little twisted. I love the bark where allowed.

qmdv wrote: At take off, what will your tip speed be. At my ranch strip I will not let folks here with super sonic tip speed. I like happy neighbors. Tim

Per Ponk's website:
prop diameter x 3.14 / 12 x rpm x 60 / 5280 = tip speed in mph
Mach is 760 on a standard 59 degree day.
Ponk says max thrust is achieved between .88 and .92 mach.
Over .92 mach and the airflow begins to detach from the blades.
88" prop at 2600rpm = 680 mph tip speed or .89 mach ....... right in the sweet spot!
But if that's too much for you I'll refrain from landing at your strip.

Rob wrote:....It's my purely uneducated opinion that the reason the 88" C58/66 perform so much better than the other 88" props is due to the increased cord of the 90AT blades ......
The earlier hubs (C1, C18, C29, C50, C58, and C66) all have low blade angles in the 8.5° to 10°.5. The longer the blades, the lower the angle. The later hubs (C201/203/204) all have low blade angles at 10.5° to 13°. ....

I stopped in at NW Prop today & talked with Dick Jacobs. I mentioned this low blade angle business and he told me that yes it is true that different angles are spec'd out, but what the TCDS doesn't tell you is that they measure that blade angle at different stations on the different model props. So the 8 degree low setting on the 88" C66 is not necessarily any flatter than the 10 degree low setting on the 88" C203. I asked him if there was any one of these props that was better than the others as far as takeoff power (or whatever you wanna call it) and he said not really. FWIW he flies a souped-up 182 with a big engine so he has a pilot's perspective as well as a prop technician's.

I'm not gonna argue with Rob's comment about the C58/66 having better performance due to it's wider blades. Sure seems to make sense but then again prop design is a black art so who knows?

Its for sure a strange thing these props. Flown behind several different ones. Ill catch a lot flack on this one but probably one of my favorites was a 3 blade fat paddle Hartzell. Can't recall the model off hand. Pulled like a truck. Great air brake. Easily adjusted right on the plane. Only around 80"s give or take a couple, so tons of ground clearance.
3 draw backs
Heavier. (Which my plane could use a diet anyway)
quiet.
And its a Hartzell.

Fyi I had the same prop on my 182 as u do hotrod180. Was told the same thing about not being worth modifying to oil filled. Sold it for 1200 in the end to a Mule driver with an io 360. I guess it's the bad A prop for that machine.
I got a good deal on a shrinking c66. Rumored to be an 88. Called the guy who said it was an 86 in the log book. Asked him to measure it and said it was an 84. Bought it for 25 with nice spinner. Got home and it measures 82" DOH!!
Still a good prop and it's a legal length for what it's worth.

No matter what you end up doing it will come down to how much $ it is worth for the difference it will make. Dick has done all my props and just did my 203 88". I bought it used and had it shipped direct to him for a inspection. It is well worth the cost before you just bolt it on. As I mentioned earlier I had no prop and went with a 88 so I can wake up all the cry babies that forgot about our golden age of aviation with round engines with fat butter blades over 100" making beautiful music to kids that became pilots from that one moment.

mountainwagon wrote: As I mentioned earlier I had no prop and went with a 88 so I can wake up all the cry babies that forgot about our golden age of aviation with round engines with fat butter blades over 100" making beautiful music to kids that became pilots from that one moment.

Constellation Super G taking off from Lockheed Air Terminal in early fifties about 500 AGL over my house in Burbank, I was 7 and loved the sound. Dad did not like that the window glazing would come loose and my mom did not like the skillet rattling on the stove.

tim

McCauley Seaplane Prop 88" Black Mac prop.Model 2A34C203-C. New in 2005. Low time. Excellent condition. US$ • Contact Larry , Owner - located Headingley, MB Canada • Telephone: 204-771-3997

TOOLGUY134 wrote:McCauley Seaplane Prop 88" Black Mac prop.Model 2A34C203-C. New in 2005. Low time. Excellent condition. US$ • Contact Larry , Owner - located Headingley, MB Canada • Telephone: 204-771-3997

I will be calling you this afternoon.

David

55wagon wrote:Its for sure a strange thing these props. Flown behind several different ones. Ill catch a lot flack on this one but probably one of my favorites was a 3 blade fat paddle Hartzell. Can't recall the model off hand. Pulled like a truck. Great air brake. Easily adjusted right on the plane. Only around 80"s give or take a couple, so tons of ground clearance.
3 draw backs
Heavier. (Which my plane could use a diet anyway)
quiet. [emoji14]
And its a Hartzell.

I have this prop on my 180. Never flown a different one so nothing to compare it with. But the 85 lb weight of it makes me want a different prop badly...

Thought I'd re-open this prop discussion. Still looking for a good used seaplane prop. Made a tentative deal for that C50 on BS last month, then found a C203 for sale locally and backed away from the C50. The C203 owner ended up selling it to his buddy, so I called the C50 guy back....only to find he'd just sold it the day before. Shame on me for fizzling out, I guess.
Now I've found an 88" C201. The STC covering the current C203 installation on my 180 includes both 82" & 88" versions of both the C201 & C203, so no problem with applicability or approval. These are both modern threadless hubs, main difference seems to be that the C201 uses 90DA blades & the C203 uses 90DCA's. I'm guessing that the old threaded hub designs are all pretty much the same as each other too, with the blades being the primary difference.
From the C180 TCDS:
2A36C ....90M-8 or -2
2A34C.....90A-8 or -2
2A34C66....90AT-8 or -2
2A34C201.....90DA-8 or -2
2A34C203.....90DCA-8 or -2
C2A34C204....90DCB-8 or -0
I thought I'd seen something online that explained these blade designations but I can't find it now. Anyone?

This topic has been covered pretty well, but I thought I would add that the cruise speed difference between a old 82" McCauley and a newer 88" McCauley is about 2-3 mph (approx 8500 elev). YMMV