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Hartzell Composite Clocking

Richard Connell

Well Known Member
I have the 3bladed Hartzell composite on my RV10.
I’m up to about 50h TT so far and It doesn't seem as smooth as I was expecting. Definitely no better than my RV7 with a metal one.
I haven’t dynamically balanced it as yet. It’s on the list to do.

Is it possible the clocking is wrong? From my research it seems like the indexing pins will likely allow me to install it 180° Around from where I have it. The crank flange has 4 dowels (2 flush at 0-180) and the prop hub has 1 hole with no counterbore - which could go at 0 or 180.
Anyone got any insight?

Thanks

Richard.
 
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I would definitely balance it first, I just had my Whirlwind 3 blade prop balance about 2 weeks ago it made a huge difference.
 
It is generally preferable, for cabin vibration, to have a blade aligned with the #1 crankpin. Lycoming Service Instruction No. 1098 identifies the #1 crankpin with respect to the bushings. With the configuration using 4 long and 2 flush bushings and the standard HC index of the Hartzell three blade compact hub, having the non-counterbored hub bolt hole aligned with bushing C will result in a blade aligned with the #1 crankpin. It can also be installed aligned with bushing F, which will result in a blade being 60 degrees off from the #1 crankpin.

The prop is statically balanced at the factory, and it is possible that this static balance is in conflict with what is necessary to achieve dynamic balance. In other words, if during dynamic balance, weight is need at the opposite side of the static balance weights (if any) on the hub, it would likely benefit from being installed 180 degrees differently.
 
Thanks Trevor, that is very helpful.
I went and revisited some photos and SI1098 and it would appear I have the counterbore aligned with bushing F.
I’ll spin it around, balance and report back.
Thanks again!
Richard.
 
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The prop is statically balanced at the factory, and it is possible that this static balance is in conflict with what is necessary to achieve dynamic balance. In other words, if during dynamic balance, weight is need at the opposite side of the static balance weights (if any) on the hub, it would likely benefit from being installed 180 degrees differently.

If you flipped it 180 based on static balance weight location then the blade won’t align with #1 crank pin?
 
If you flipped it 180 based on static balance weight location then the blade won’t align with #1 crank pin?

Yep. It's generally preferable to have the blade aligned with the #1 crank pin for cabin vibration, but it's not an absolute. The best dynamic balance solution for that particular airframe/engine/propeller might or might not be achieved with a blade aligned with the #1 pin because in the case where the dynamic balance requires weight opposite the static balance weights it's a tradeoff between the alignment and the extra mass; it just depends on which is a stronger function for that application. Service experience seems to indicate that 3 blade composite props on Lycoming 6 cylinder engines are not especially sensitive to alignment with the #1 pin. So, for this application, some may be better balanced with more mass and aligned while some may be better balanced with less balance mass and 60 degrees off.
 
I reindexed the prop and took it for a spin today.
Chalk and cheese. A large improvement. So good that I suspect the dynamic balance may not require much at all.
Thanks again Trevor.
 
Late to to the party....
Good to hear it all worked out for you. Sounds like you'll still get it dynamically balanced. Rivets to radios, just a good idea.
Yup, "K" flange can be installed 180° as you see fit. Owners manual 115N, page 3-49:

Grease the prop too, Per 115N, before you do the dynamic... Its all in 115N
 

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Late to to the party....
Good to hear it all worked out for you. Sounds like you'll still get it dynamically balanced. Rivets to radios, just a good idea.
Yup, "K" flange can be installed 180° as you see fit. Owners manual 115N, page 3-49:

Grease the prop too, Per 115N, before you do the dynamic... Its all in 115N

Thanks Joe,
Its an "R" flange and It shipped with manual 145. Interestingly the equivalent manual page though dosent have those instructions/options for combinations of R prop flange on a K engine flange. Maybe its somewhere else in 145 but I can't find it. I had a close read of that at install.

Im satisfied its probably still the case for this combination given everyones feedback though - and the fact its noticeably smoother.

Noted on the greasing, balancing is next on the list.

Cheers
 
Thanks Joe,
Its an "R" flange and It shipped with manual 145. Interestingly the equivalent manual page though dosent have those instructions/options for combinations of R prop flange on a K engine flange. Maybe its somewhere else in 145 but I can't find it. I had a close read of that at install.

Im satisfied its probably still the case for this combination given everyones feedback though - and the fact its noticeably smoother.

Noted on the greasing, balancing is next on the list.

Cheers

Richard,

Did you happen to record the actual location of the propeller in relation to the 0 marked on the crank? (see picture)

I seem to be going down the same path as you did.

Thanks!

Matt
 

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