John,

 

Like everything else about airplanes, the prop is a compromise. I wouldn’t recommend a composite (or wood) prop for operation off gravel/dirt strips, but the early folks used wooden props for years…the best material they had that would endure the significant flex and strain loads placed on the blades. Today’s metal props will take more abuse from foreign objects/debris, but are not invulnerable, and will eventually be damaged/destroyed if used as leaf-blowers. This happens much faster with the wood/composite props—if you operate them in that kind of environment. The MT’s replaceable nickel leading edges help, but a big hit that cuts through the nickel will cost you a prop blade at the minimum, and Lancairs are not known for their prop/ground clearance under the best of circumstances.

 

Given my operation only off hard surfaces (except the occasional taxi on grass at OSH/airshows---which I’ve learned does more damage to my prop than years of “normal” operation), I really like the MT’s smoothness and relative quite. I suspect other composite props provide the same/similar qualities, but I don’t have any personal experience with them. I chose the MT for weight, noise and smoothness, and have been very pleased with the result. Were I operating in a different environment, the choice would be different.

Personal operating techniques, especially on the ground, makes a big difference. I thought I took very good care of my prop with regard to where and how I taxi, but I see props with hundreds of hours on them and nary a nick. This is a trick I have not yet perfected!

 

I have not addressed the engineering aspects, and am not knowledgeable enough to do so. I suspect, however, that a lot of the “engineering excellence” of one design over the other is so much advertising hoopla. Good designs have a tendency to rise to the top in the aircraft/flight world, and insufficient/deficient ones drop away rather quickly. The free market place works well in this regard. So, in summary, there are definitely better choices based on prop application/use; there may be better choices with regard to design and engineering (certainly the new scimitar shapes increase efficiency), but I’d be reluctant to trade out a good functional unit for a “better engineered” one unless you’re engaged in competitive racing and are prepared to spend the significant money required to seek out and evaluate the alternatives.

My two cents,

 

Bob

 

 

 

John wrote:

It has seemed obvious to me that the ACI graphite prop is a much better choice for any application where you don’t absolutely need the extra weight of metal at the pointy end of the airplane.  I originally put a deposit on an MT prop when they became available, but then changed to the ACI prop after that for reasons in my mind that related to structural integrity and durability.

 

I am aware of one IV driver who had to change the MT prop out after flying fewer than 100 hours off a grass strip.  The dirt and gravel munched the thing.

 

Have only a few hours on my  airplane ( and ACI prop)  now and am wondering if my logic is wrong in some way.  Any thoughts?  Is the MT better in some way?

 

Thanks,

John Barrett

 

 

At 4 years and about 750 hours, I have almost the identical experience with a 4-blade MT prop on my IV-P. The prop is smooth, quiet, and has been maintenance free except for a small grease leak at about 300 hours. This was fixed by the MT prop shop in Deland, FL, and I’ve had no issues since. My prop has been painted once, and needs repainting again…which I consider good service. I don’t think I ever had any noticeable paint erosion in rain…and have flown in rain quite a bit…but sleet or ice crystals are a different matter! This is not something I do intentionally, but even the slightest encounter with sleet will do a sandpaper number to the prop.  Even knowing this, I’ll be sticking with the MT, and would chose it again.

 

Bob