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Monday, May 12, 2008, 06:18 PM - FOR PEOPLE FLYING BEHIND 0-235, 0-290 AND 4 CYLINDER CONTINENTALS
Posted by Administrator

I am tooling up and starting production of blades and hubs for the above listed engines. The alert just below does not effect these small 4 cylinder engines. They are certified on Pipers, Cessnas, Aeroncas, Swifts and others using these engines. This focus is directed at the Experimental/Homebuild market. But this is not to say that I am excluding the certified market. If you are really interested in one of these propellers then send your deposit and we will do serious business.

A little discussion about this effort. For those of you that are not familiar with the Aeromatic prop I am making the following comments.

Some of these comments are at least partially mentioned in other places on this web site. But briefly here is what you can expect from and Aeromatic propeller.

1. It give you virtually everything, with certain limits, that you get from a constant speed propeller. That is 100% horse power for whatever that means at the given density altitude.

2. It is 100% automatic. That means there is no pilot input to the propeller. It is virtually transparent to the pilot excepting of course you will feel the seat back pushing on you during takeoff whereas you don't have that nice warm feeling with a fixed pitch prop.

3. It works on any engine, that means that you do not need a hollow crank shaft in your engine. It used no oil pressure for it's function. A-U-T-O-M-A-T-I-C.

4. It is lighter than a constant speed prop and of course needs no governor or controls to the cockpit. Typically this prop weighs in at around 30 to 32.5 pounds.

5. It has a steel hub with wood core blades covered with fiberglass. The wood laminations are 1/16" thick as opposed to those clubs that are made from 1/2" to 1" planks. This blade design was used on early Spitfires and Hurricanes which were equipped with those great and wonderful Rolls Royce Merlin engines, during the Battle of Britton. Call it old technology if you wish but read the next item first.

6. These props have been around for civilian airplanes since 1946. They were certified on over 100 different models of airplane here and abroad. There were more than 12,000 of them built.

7. And here is one of the nicest facts about the Aeromatic propeller. There have been only 3 AD notes against them in all of these years since 1946. One of the 3 applies to the blades of older production. It does not apply to my PMA production blades.

8. One AD applies to an internal hub part change. It is not repetitive.

9. The other AD note requires that the balance bands be loosened and inspect for cracks under it. About a 15 minute effort. However, I asked a prop shop, Aero Propellers, of Hemet, CA., how many cracked hubs he has seen in his, perhaps, 45 years of overhauling Aeromtics and he said "none". This problem was traced to a faulty machining of the hub. The AD will not go away because there could be one or more of those old hubs still in service.

10. Last but not least, if you are making a landing and have to power up for some reason, the prop immediately changes into low (high rpm) pitch. Ain't that cool?

One more comment. You can't take an Aeromatic off one airplane/engine combination and bolt it on a different one unless the airspeed and horsepower and rpm is the same, because it has to be set up for a particular airplane/engine combination. There is at least one Swift expert that found that out but he curses the propeller instead of his ignorance. So, the reason for these comments is as follows:

a) I have the setup data for all the production airplanes that these props were certified on. This data was developed by the original manufacturers of the Aeromatic, namely the Koppers Co. So, we will have to work together a little until we get the right combination of angles for your airplane/engine combination. I have the engineering data needed to set up the propeller to get the maximum expected performance. There are a few Experimental airplanes out there using the Aeromatic successfully. My latest home built customer is using it on his RV-9 with an 0-290. The first feedback from him is very positive. But his thinks he has a spinner vibration problem the last time I talked with him. He was here when we balanced his prop so he knows we got it right with static balance.

b) As I gain more data on various experimental airplanes I will have this data to use which will save test time for follow on applications.

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