aeromatic

The aeromatics are not suitable for aircraft with the speed range of the RV's. They worked ok on a Stinson or the Swift with 125 hp. Very expensive to buy and maintain.
 
If you go Aeromatic, you better buy three............one on the way to the shop, one on the way back from the shop and one to fly until it breaks.
 
Antiques, not very reliable, uncommon, sure. But what about an updated Aeromatic? Seems like the premise is good, can it be brought back with new technology? Carbon fibre? Sure seems like a neat idea, suppose all it takes is money.:rolleyes:
 
There have been many attempts at something like this. For a while, the composite gurus were touting that they could cause a prop to twist in such a way as to act like a C/S prop based on propeller load, but further testing determined that the effect was minimal or non-existent.

The trouble with the Aeromatic was that it has all of the complexity of a C/S prop without the utility. If you are going to go to the trouble to put in a pitch-adjusting mechanism, it's much easier and nicer to go full C/S - because then the pilot gets to choose what RPM he wants to let the prop turn at based on flight conditions.
 
breister said:
There have been many attempts at something like this. For a while, the composite gurus were touting that they could cause a prop to twist in such a way as to act like a C/S prop based on propeller load, but further testing determined that the effect was minimal or non-existent.
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Really, breister, are you implying that these so-called "almost constant speed" props really weren't? Reassure me that while posting this you're not sitting on your veranda sucking on too many mint juleps.
And here I was giving these people kudos, at least in my mind, for being able to match the compliance of the wood core and the composite laminate and the CM of the airfoil to achieve this change of pitch with load or rpm and now you tell me that they really couldn't? I'm so disappointed that I'm going to have to sign myself into a mental health clinic!
Bummer!
 
Interesting thread. I have a buddy who has one of these still in the box and was going to go pick it up and consider whether it might work on an RV. There is a fellow near here (Kent Tarver - Fallon, NV - has posted here on the forum occasionally) who now owns the rights to these and I have been meaning to get over to talk with him.

Why don't they work on faster airplanes? Can't get enough pitch? Forgive the silly questions, but I don't consider myself very knowledgeable about props.

Cheers,
greg
 
I've read the web site completely and think there to be no reason why it would not. I would be very interested in the details if you happen to go by and ask about it.
 
I have flown behind an early version of this prop on a friend's F24W and it performed really well.

I too looked at one for my rebuild but with so few out there, I elected to stick with Catto as the prop is one place I really don't want to experiment too much.
 
SHIPCHIEF said:
Paul, Paul!! Don't sign up yet!
I'd hoped this would have gone the other way.
AVIA has an automatic propeller, many Zlin acro planes have them.
http://www.aviapropeller.com/v503ap.htm
The link describes one for an O-320 equipped Cessna 172.
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What I was referring to is a fixed pitch prop that under load or rpm or both torsionally flexes in such a way that it changes pitch to maintain an almost constant speed. I've seen the Avia before and it's really a CS with a unique pitch change mechanism.
 
The Aeromatic is an "antique" just like the Lycoming engine is an antique - it's an ancient design that is still available brand new today. I doubt you will find anyone who has seen a brand new Aeromatic and would not agree it is a work of art. As to reliability, I think the Aeromatic has a much better record than the Hartzell compact, which despite design change after design change seems to generate a new hub AD every few years.

I have several friends who swear by them - light weight, simple, and perform well. That said, I've only flown behind one - in a 145HP Swift, and despite spending two solid days of tweaking at the hands of the master himself - Kent Tarver- it does not perform well at all on this airplane.

That said, if you're interested in one, the Vans Cult is not likely the place to find "out of the box" thinking.. . I'd go do some digging on your own.
 
elippse said:
Really, breister, are you implying that these so-called "almost constant speed" props really weren't? Reassure me that while posting this you're not sitting on your veranda sucking on too many mint juleps.
And here I was giving these people kudos, at least in my mind, for being able to match the compliance of the wood core and the composite laminate and the CM of the airfoil to achieve this change of pitch with load or rpm and now you tell me that they really couldn't? I'm so disappointed that I'm going to have to sign myself into a mental health clinic!
Bummer!
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Paul, don't get your tail feathers in a knot - what I said was that they (the Aeromatics) don't have the UTILITY of a C/S prop. That's TRUE no matter how many mint juleps I might have had (and BTW I don't drink those girlie drinks!). :D

They (the old Aeromatic) DON'T have the utility of a modern C/S prop, because you cannot choose the rpm you want to turn in flight. And, as many others have pointed out these props were known to have a high failure rate.

Nice idea, no cookie. Maybe someone will do it better some day, but both of my (now deceased) WW II pilot friends who had experience with them said, "Just say no to those things." Elgin flew aerobatics until the last week of his life, and let's just say I think he was a pretty reliable source.

As for the "auto-adjusting composite props" - I read several articles over the years about this because I hoped to put one on my (something with an O-235 engine in it). All of the evaluations said that they could not discern the alleged "flex factor" providing any of the claimed material advantage over props not claiming that advantage. Is it theoretically possible? It certainly sounds reasonable. However, at least one manufacturer stopped touting that quality after the reports.

Now - when electric becomes all the fashion the Aeromatic type of solution would be absolutely optimal (provided they make it reliable). With electric there is no downside to turning one "optimum rpm," because RPM doesn't materially effect TBO and they typically will generate full hp across a range of rpms - so you can pick the rpm that is "most efficient" for your prop. For that matter, YOUR props will be much better with electric, too - because of the very fact that electric motors CAN make full hp over a wide range of rpms.

Blue skies,

Bill
 
Rather than start a thread, I figured I'd search and see if anyone has talked about these before.

Whoever said these are for antiques only is sadly mistaken, yesterday alone I saw Aeromatics on their Geronimo, a Long-eze, a Var-eze, and a Bonanza.


Walked through their shop in Fallon Nevada. I'm flat out sold. 90% of the benefits of a C/S prop (7% loss in effeciency above about 14K feet according to Tarver over a C/S)... however no oil lines, no prop gov, about 30 #'s lighter, and it's 2/3 the cost of a c/s.

They took me through from start to finish how they're made, how they work, the history of the aeromatic, everything. It was facinating. I'm completely sold. The guy that owned the Vari-eze was there, and showed me his written data comparing the Aeromatic over his old f/p. 500' reduction in takeoff, and a 15 knot increase in top speed flat out.

Oh and there has NEVER been an AD on an aeromatic prop, and they showed me several that were in for servicing, still flying, manufactured in the 30's.
 
If you decide to go with the Aeromatic, why not use a modern blade design? Like purchasing the hub and lag bolts from Tarver while having Catto make a set of blades for it.
 
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Sig600 said:
...Oh and there has NEVER been an AD on an aeromatic prop, and they showed me several that were in for servicing, still flying, manufactured in the 30's...
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I heard this too. NO AD'S EVER!

...A record Hartzel could only dream about.
 
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