EAAAirVenture OshkoshShopJoin

aeromatic prop

Posted By:
Ray Toews
Homebuilder or Craftsman
16
Posts
4
#1 Posted: 8/22/2009 18:45:09

Does any one own or have experience with an Aeromatic Prop.

 

I didn't realize they were still in production.

Seems like a good idea.

What's the downside?

 

Ray



Reggie Smalls
Homebuilder or Craftsman
126
Posts
49
#2 Posted: 8/23/2009 20:28:29

This web page promotes the benefits:   http://www.aeromatic.com/ 

and the SAIB linked at the bottom of the page is the downside, there's at least one accident where there was a blade separation.  Flying behind an old aeromatic, there will always be the little question in the back of your mind "will it pitch a blade on me"?



David Darnell
61
Posts
18
#3 Posted: 8/23/2009 21:21:01

  For me, the downside would be $6000.  Also appears to be a bit of a pain to set up



Larry Sciortino
1
Post
2
#4 Posted: 8/27/2009 21:43:29

Hi Ray,

 

I agree, it does seem a good idea.  I owned and operated one that came with a GC1-B Swift I bought many years ago, in the mid'70s. It was properly set up when I got it, it would attain takeoff RPM just about flying speed on takeoff, and modulate the RPM in a reasonable way through climb and cruise.  The precision of RPM control did not equal that of a manually variable pitch prop, or a constant speed prop like a hydraulic or electrically controlled unit, but it was quite an improvement over a fixed pitch prop, and it seemed vibrationally very smooth.  Here's how I learned of a weak point of the design:  The engine in the Swift, a C-125, was getting to be high time so I arranged to have it swapped out for a freshly overhauled C-145, by Vince Fette Aviation, Venice, FL.  I flew the airplane from northern Virginia to Venice, arriving at dusk.  Mr. Fette, then in his 70s, watched as I shut down on his ramp. He looked at the airplane from maybe 20' off the side, and walked up as I was climbing onto the wing.  His first words were "you've got a propeller about ready to come apart".  I was a little taken aback by this welcome to Florida, and wondering if he was quite all there, to be making such a statement without even closely inspecting the propeller. But, Mr. Fette was more than all there. His practiced eye could spot discrepancies on Swifts from long distance, and he knew exactly what he was looking at.  I asked what he meant, so he showed me that the leading edge of one of the two blades was canted a few degrees, sort of like a drooped wing leading edge cuff.  He explained that the back of the blade should be flat - no camber, and indeed the other blade was so.  The culprit is the line of rivets that attaches the segmented sheetmetal leading edge to the wood core.  The rivets run along the grain direction, weakening the blade integrity, which over time can result in the forward inch or so of the prop to split off, which could result in such a gross imbalance as to sling an entire blade - and you know how undesirable that can be. They swapped the engine, and loaned me a fixed metal blade to fly the airplane home with, and I shipped the sick Aeromatic home.  There may have been improvements in the way the leading edge sheetmetal is fastened since then, but if they still rivet it on along the grain direction of the wooden blade, I would be leery. If they have switched to a composite blade with a synthetic leading edge gaurd like so many modern props are made, I think that would be great, but given that the FAA would probably necessitate a whole new certification program, I doubt they have.



Bill Barker
20
Posts
1
#5 Posted: 8/31/2009 15:25:05

   A few years ago, they were showing this prop at OSH, STC'd for the Cessna 172.

   It looked like a good idea to me until I looked at the added weight and the price $$.  It claimed to improve climb, but no improvement on cruise speed.

   Losing useful load in a C-172, without any increase in cruise seemed too expensive to me, at any price.

Bill



Ray Toews
Homebuilder or Craftsman
16
Posts
4
#6 Posted: 9/5/2009 23:58:31

Thanks all, I appreciate the input.

 

Ray