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bignose

Active Member
Would like to hear opinions about the pro and cons of composite against aluminum propellers. Not to mention their price tag, off course...
 
Three blade composite.....SEX APPEAL, says "I had a lot of money but its tied up in my prop". Should climb a bit better, maybe better if ground clearance is important to you, but a bitch to get the cowls off compared to the two blade.

The two blade Alloy..........much better in all respects. The Hartzell Blended Airfoil is hard to go past.
 
Three blade MT for me. Besides the added clearance, the third blade really smooths the engine out. The cowl removal really isn't bad with some minor work on the lower cowl.

There's nothing wrong with either and I've flown behind both in the RV-10. The three blade is a much nicer ride and that's something I expect in a nice cross country plane.

Sure the 3 blade composites cost a bit more, but it's an RV-10 and (in Texas words) "They ain't cheap." If you can afford to finish the airplane then you can afford the extra $5,000 for the prop thats right for you. The prop isn't the right place to get cheap.

Phil
 
I'm going for the 3-blade MT for smoothness and ground clearance. By all accounts, you lose a couple of knots in the cruise over the Hartzell blended aerofoil.
 
Before you guys commit to a MT I seriously advise you to go fly with an owner with an 8068 blade Hartzell especially now they are configured from the factory oriented with the blades in line with the #1 crankpin. Over the years I have become unimpressed with MT's based on their service history and I haven't found them to be much smoother.
 
I'll state the obvious since no one else has:

Composite is significantly lighter. I suppose that could be a pro or a con depending on how your CG is shaping up.

Erich
 
Maintenance and service ?

The post is about the material used: Aluminum or composite. (not 2 or 3 blades)

What about maintenance and service?

I mean, aluminum props are around for long time, and there are lots of people knowing how to work on it. All they need from time to time is sand and paint. (talking about blades only)

Looks like these fancy compos need very specialised workmanship... I read some place that even the external paint is completely different...

Probably better to "keep it simple".

Would be nice to hear from the two blade blended airfoil Hartzell drivers how they feel. How big is the difference?

Probably more a question about two or tree blades... (and balance)
Read some 25 years ago that theoretically, the most efficient prop would be ONE BLADE...

Shure the new composite looks great and runs quiet and smooth, but is the difference really that great compared to the conventional aluminum???

The big question is: if there where a smoot running aluminum scimitar tree blade(or a 2 blade composite) avaiable, would some go composite or aluminum???

Thanks.
 
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Do you plan to fly in rain?

I've seen some composit props pretty chewed up from a couple of hours in moderate rain. Some use tape on the leading edge. Also understand some of the manufacturers are even adding metal to the LE. If you're a VFR pilot, no issue. If you plan to fly instruments, you'll need to be fully aware of the props limitations-you may have to turn lower RPMs in precipitation. I'm sure someone will respond that they fly instruments with no problem-the question is water droplets. How many and what size.
Still, composite three blade look really cool.
Terry, CFI
RV9A N323TP
 
Whirlwind composite prop

I have flown 287 hours behind a Whirlwind 151H on my RV-6, the prop blades have about 330 hours on them, they look like they just came out of the box. The blades have an inset nickel leading edge which protects them, I have flown off of grass and through rain with no damage to the blades. The prop was statically balanced at the factory and dynamically balanced after mounting using a Dynavibe and is a very smooth combo. You will find the engine turns over at start up faster than with a heavier metal prop, but be careful if you need the weight up front due to cg considerations. I am now flying behind a Whirlwind 200 RV and notice the acceleration on takeoff and climb have suffered a bit, but I have gained a few on the top end.
 
In Randy Lervold's prop comparison a few years ago weight was one of the biggest differences. The WW prop was measurably quieter and there were small performance differences. The measureable performance differences will be very slight between well designed props of aluminum vs. composite IF their design goals are similar. Weight not only affects W & B but it also has an effect on flywheel characteristics. A light prop stops instantly when the engine is stopping, starts quickly and has less mass to damp vibrations when running. These vibrations may not be noticeable...Lots of people with wood or Catto props that feel very smooth. My WW200RV (carbon fiber) has RPM restricted bands, but that was in response to previous Hartzel restrictions. I asked if they had done any vibration analysis and they said no.

For me, quiet was a priority and the considerably weight reduction was a bonus. For others the priority may be top speed, or C.G or climb or clearance or smoothness or...

Jeremy Constant
 
terrykohler said:
I've seen some composit props pretty chewed up from a couple of hours in moderate rain. Some use tape on the leading edge. Also understand some of the manufacturers are even adding metal to the LE. If you're a VFR pilot, no issue. If you plan to fly instruments, you'll need to be fully aware of the props limitations-you may have to turn lower RPMs in precipitation. I'm sure someone will respond that they fly instruments with no problem-the question is water droplets. How many and what size.
Still, composite three blade look really cool.
Terry, CFI
RV9A N323TP
Click to expand...

It is unneccessary to put the tape on the leading edge of a MT Propeller.

The stainless steel leading edge on the MT Propeller is three times more resistant to rain and sand erosion than the aluninum blade.

What Terry is saying about composite (and wood) propellers, when flying in the rain without leading edge protection, is very true.
Been there. Done that. Using a fixed pitch wood propeller without stainless steel leading edge protection.
However, it doesn't apply to the those blades that have stainless steel leading edge protection.

Regards,
Jim Ayers
 
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