The International Cessna^® 170 Association

Even still, it's a $14,000 prop without the STC

I'd buy an Aromatic and get field approval long before I'd pay that much.
If only we could fit MT blades to an Aeromatic hub and make it legal.

I think Ron Massicot ran one of those Aeromatic's on his 170 25 or so years ago. He could probably fill you in on the benefits which were probably few since it has not been on his plane for a number of years. As long as these engines have been around, someone would have come up with a reasonable option by now if it had been feasible. Who would want to now for an engine you can't even hardly find a crackshaft for? There is no perfect airplane out there, ya just need to select one that meets your mission profile 90 % of the time. For the other 10% just live with it or get another plane for that portion (if your wife will let you) .

If you look at the selling prices and uses of the older Continental powered C-172s, I really doubt that many owners would be willing to come up with that kind of money. The C-172 owners are not a "Cult" of loving aviators as are the C-170 bunch.
When you talk about the Aeromatic Propeller, keep in mind that it was not the aviation answer to sliced bread. If it had been that great, it would still be with us. It isn't! They were a great selling point on the Stinson 108 series and on the Bellanca Cruisairs. A helluva lot of people took them off to be replaced with fixed pitch props, particularly if their flying was to airports with seriously different elevations, such as we are concerned with here out west.

The MAIN reason they were removed....was to install an ALL METAL MCCAULEY!
These things sat outside most of the time.

If anyone was into bicycle racing in the mid 80's you might remember a non-round chain ring called Bio-Pace. It was specifically designed to provide the average rider, with a 90RPM cadence and non perfect power transfer, a little more efficiency in their stroke. For the average rider, it WAS a good improvement.

Why did it fail to sell??

Because none of the professional riders of the day never used them. Why? Because the Pro's would pedal at 120RPM cadence and had years of training on rollers to apply uniform pressure on the pedals. Bio-Pace was not needed for them and could actually diminish their efficiency.
So, word on the street went out that Bio-Pace is a piece of crap because the Pro's wont use them (and we are all as good as the pros, no?)

I still think the idea of a self regulating prop is a good idea and I think the Aeromatic has gotten a bad rap over the years because it doesn't satisfy the last 10% of flying folks might do. Its the Bio-Pace chain ring of the Aviation industry.

If only we could get an Aeromatic prop with all metal blades

That aeromatic prop control system might work better out there in Maryland where no airports are any higher than the one you departed from. But come out here where I live at about 200 ft. MSL and fly for an hour up to Lake Tahoe for lunch at an elevation just over 6,000 ft. MSL. Be sure to bring the tools you need to readjust the prop to go home.
I reiterate, if they were any good, they would still be using them. I havent even seen one for about fifty years.

The manager of our airport just put a new one on his Fairchild 24R. He likes it but he has not flown it any in the mountains yet. He thinks its a little better than the original prop but nothing spectacular. I thought of trying to get one but since I go to the Rockys occasionally I decided it was not a good choice for me. Bill K

bagarre wrote:...If only we could get an Aeromatic prop with all metal blades

McCauley also made a hydraulically, adjustable prop which did approximately the same thing as the Aeromatic. One of our Members, Dave Bengston, has one, and he let a couple of us have a demo of it at Benton Harbor. it provides slightly better than ordinary takeoff and climb, and allows similar-to-normal cruise speeds at slightly lower RPM (less noise and slightly less fuel consumption) ...but nothing to write home about. Certainly not enough difference to warrant changing to the C-145-2H/O-300-B engine if you didn't already have the hydraulic-provisions on your engine.

Another problem is: McCauley will not support that prop if it develops a problem, and...it weighs more than a fixed-pitch with the added complication of possible oil-leaks.

Despite the number of us who think this would be a "cool" mod to have,...from a business standpoint, there's no money in it for the mfr's. They couldn't sell enough of them to warrant the product-support. That's why McCauley discontinued offering it.

And Aeromatic is wooden blades with plastic covering (for rain erosion control and to reduce permeability in rain) but useless against rocks and with difficult renewal processes. Balancing is a problem with repairs and the the blades are held in the hub with ordinary lag-screws. Not something particularly confidence-inspiring, and which carries an AD note.

It might be simpler to unbolt your cruise prop and install your climb prop for trips to the hills, and return to the cruise prop for trips across the prairie, thereby dispensing with the maintenance troubles of moveable blades. It'd certainly be cheaper than a prop and/or engine change.

The MT is a composite blade, no? You're not gonna fix that with a file and emery paper.

Does prop swapping and installation fall within the maintenance functions allowed the owner/pilot?

Nope

blueldr wrote:Does prop swapping and installation fall within the maintenance functions allowed the owner/pilot?

Sorry, bluEldr. This suggestion is not for "sticklers" such as yourself.

while we were on the subject of aeromatic props.....

If nothing else, they sure are pretty.

Do you know the guy that owns that one?
If you know the owner, can we talk him into giving us a review compared to what he had before? Better yet, could he swap it with a metal one and compare?

quick note on prop swap, I bought 09V with a a em53 (6 bolt) pitched it to a 50. from time to time i would try to borrow a 53 if i was to to a long trip, my speeds were at 2500rpm were 108 mph vs 122 mph. while seeing higher numbers on the speedo was cool, the time it took to swap install and track ect two propellors twice really didnt same me much time. some day ill tellt he story leaving medina OH on a 115 degree day at gross weight on the way to kosh...

bagarre wrote:If nothing else, they sure are pretty.

Do you know the guy that owns that one?
If you know the owner, can we talk him into giving us a review compared to what he had before? Better yet, could he swap it with a metal one and compare?

I was there for the test flights, I knowthe the guy who flew it while they were working on the set up of the wieghts. I could ask him but from what I could get from his converstion back then was that take of was alittle quicker it climbed well but cruise was marginal at best, the test pilot is a little bit of a curmudgeon so it tends to be tought to impress him sometimes, so ill try to get a better answer then "ehh its okay" out of him. What I do know was that i saw the airplane this summer and it had a metal fixed pitch prop on it. Ill try to find out why that came about also.