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Propeller orientation

Rich Pulman

Well Known Member
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Does it matter how a propeller is oriented when installed? I.E. with #1 cylinder at TDC, should the propeller be installed in the vertical, horizontal, or somewhere in between? I’m just wondering if there’s a “best practice” or recommended procedure out there. FWIW, I’m installing a WhirlWind GA200L on a Lycoming O290D2.

Any suggestions and/or anecdotes are much appreciated.
 
In general, prop clocking matters; possible harmonics, torsional vibrations, etc.

The only opinion here that really matters is the prop OEMs. PP OEMs tend to be silent on said applications and I can't blame them.

Stay within your prop manufacturers recommendations. They may not have a restriction. Any anecdotal evidence by anyone else, "trouble free for xxx hours", should be ignored IMO. Potentially serious problems associated with the aforementioned probably won't give any indications of pending issues; i.e. it will probably reveal itself in very dramatic fashion. If you do consult the prop OEM, let us know what they say.
 
A two blade Hartzell should be aligned with the crank throws, at TDC it would be basically horizontal. The engine won't stop at TDC, but in-between anyway.

There are no hard rules, though, different props, # cylinders and measured vibration with mounts all have an influence on airframe vibration. The basic reason for the 4 cylinder is torsional and blade dynamics. A 6 is a different animal. Sometimes prop vibration is traded for airframe, but not without data.

An airplane in a 4-5 G arc will have the 2-blade alternate from a maximum and minimum mass inertia compared to the arc axis. Index with prop aligned with throws has the minimum inertia aligned with the firing pulse. Remember what happens when you try to rotate the axis of a spinning bicycle wheel? A composite like the WW will be minimal effects on the engine compared to aluminum or wood.

Top prop manufacturers work with engine manufacturers for their index recommendations. It appears WW has a locating lug per their instructions.
 
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As others have said, yes it does (or may) matter, find out what the manufacturer suggests.

Having said that, and more to your point...

The convention is to clock the prop at Ten / Two o'clock. 2 o'clock when viewed from the pilot seat and 10 o'clock if you are the guy "hand propping". Since you have a 2 bladed prop on an O-290, having it clocked properly for hand propping may come in really handy one day.
 
Clarification...

As others have said, yes it does (or may) matter, find out what the manufacturer suggests.
Having said that, and more to your point...
The convention is to clock the prop at Ten / Two o'clock. 2 o'clock when viewed from the pilot seat and 10 o'clock if you are the guy "hand propping". Since you have a 2 bladed prop on an O-290, having it clocked properly for hand propping may come in really handy one day.

This orientation would be for the engine coming up on compression. Not TDC.
 
Whirlwind

You installation manual for Whirlwind should say Cyl#1 TDC, prop as close to 10 o'clock. That what my 74HRT says. Won't necessarily shut down at this position.
 
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Your prop manufacturers instructions would be your first source for this.

It may or may not conflict with Lycoming SI 1098G. Caution- when reading this Lycoming document, note that they are not referring to a TDC position, but to the position of the #1 connecting rod bearing when describing prop bushings & clocking position.
 
Another source of info -
I found that the Cessna 172 manuals describe how the prop is supposed to be clocked to the engine.
 
Prop Orientation 0-290 D2

Rich Pulman,
Page 7-1 of the Lycoming Manual for the 0-290 says this about prop orientation:
"Propeller Installation – Consult the airframe manufacturer for information relative to propeller installation."
 
Thanks

Thanks for all the replies.

I contacted WW and they said it didn't matter how the propeller was oriented but suggested it be attached for ease of hand propping as some of you have mentioned.
 
If you research this more you will find out the the orientation for Hand Propping is NOT the best orientation for vibration minimization. A Whirlwind is very light, so it is not a big deal. Props have been oriented that way for 50 years; however, with my metal Sensenich I decided to forgo hand propping and orient it the best for vibration. If you have electronic ignition, you won't be able to hand prop anyway.
 
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