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  #1  
Old 04-12-2013, 06:35 PM
Walt's Avatar
Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 6,117
Default Whirlwind Prop Balance

Whirlwind recommends dynamic prop balancing before first flight in their installation manual. Based on the this one and a few other whirlwinds I've done, I would definately agree that this is not something you should ignore!

This one started out quite high (a bit of an understatement) at 0.747 IPS (the little red circle represents the upper limit), 4 runs later I had it at 0.023 IPS after adding 61 grams of weight.

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EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
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  #2  
Old 04-12-2013, 07:33 PM
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Gash Gash is offline
 
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Location: Goodyear, Arizona
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Default

I'm getting mine done next week. I have about 55 hours on the prop, no balance yet. I hope I haven't damaged anything already.
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  #3  
Old 04-12-2013, 08:01 PM
brad walton brad walton is offline
 
Join Date: Jul 2007
Location: Cypress, TX
Posts: 531
Default

Walt can you tell by feel when balance is needed? I guess if is far out of balance but to what extent can you depend on your senses to tell if you need balancing. I have a Catto 3 blade that feels good at some rpms and less so at others but overall feels OK

Last edited by brad walton : 04-13-2013 at 07:00 AM.
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  #4  
Old 04-12-2013, 08:37 PM
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Walt Walt is offline
 
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Quote:
Originally Posted by brad walton View Post
Walt can you tell by feel when balanci is needed? I guess if is far out of balance but to what extent can you depend on your senses to tell if you need balancing. I have a Cargo 3 blade that feels good at some rpms and less so at others but overall feels OK
Most folks have no frame of reference to compare it to, so unless you know what "smooth" feels like in an RV, you'll have no way of knowing what excessive vibration is.

In something like the one above there was a very obvious and noticable reduction in vibration. If the vibration is around 0.2 IPS to start the decrease to lets say 0.03 will be much less noticeable by the average person and some folks may not feel it at all. However, even though you can't feel it, the airframe/engine/avionics 'feels' it, less vibration means less fatigue on these componets which equates to a longer life.
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EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1900+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154

Last edited by Walt : 04-13-2013 at 06:42 AM.
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  #5  
Old 04-12-2013, 10:14 PM
Michael Henning Michael Henning is offline
 
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Location: Nashua, NH
Posts: 544
Default Average cost?

What is the average cost for a two and a three blade?
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  #6  
Old 04-12-2013, 11:17 PM
GregM GregM is offline
 
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Boy, you'd think they could get a better static balance to start off with....
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  #7  
Old 04-13-2013, 06:33 AM
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Walt Walt is offline
 
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Quote:
Originally Posted by Michael Henning View Post
What is the average cost for a two and a three blade?
I still do experimental aircraft for $175 (owner RR's his upper cowl) and most certified AC for $225. Same price for 2 or 3 blades.

Quote:
Originally Posted by GregM View Post
Boy, you'd think they could get a better static balance to start off with....
My guess would be the prop itself is static balanced, but the spinner and associated attachments which on the whirlwind are quite substancial, may be more difficult to effectively balance.
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Walt Aronow, DFW, TX (52F)

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1900+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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  #8  
Old 04-13-2013, 07:40 AM
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ColoRv ColoRv is offline
 
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Hey Walt, what is the proper sequence on a newly overhauled (no test cell time) engine and a new Whirlwind? A new engine is supposed to get minimum ground run time so I ASSume the balance should take place after engine break in?
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  #9  
Old 04-13-2013, 08:02 AM
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Walt Walt is offline
 
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Quote:
Originally Posted by ColoRv View Post
Hey Walt, what is the proper sequence on a newly overhauled (no test cell time) engine and a new Whirlwind? A new engine is supposed to get minimum ground run time so I ASSume the balance should take place after engine break in?
The one above was done at 25 hrs (new engine/prop), for a whirlwind I would do it asap after break-in which for most engines probably could be done around 5-10 hrs (after you see the typical drop in CHT's during break-in).
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Walt Aronow, DFW, TX (52F)

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1900+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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  #10  
Old 04-13-2013, 09:56 AM
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jjconstant jjconstant is offline
 
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One note of caution for WW owners: the spinner and backplate are both marked with a "1" and a "2" so if the spinner comes off you can clock it the same way when it goes back on, however there is no indication of clocking the backplate to the actual blades. I have had my prop off and when reinstalling it didn't know how to clock the back plate to the prop blades. Once you have balanced your prop, mark the back plate with the blade number stamped at the base of the blades. That way, if the prop comes off, you can clock it correctly when it goes back on.

All that said, if it comes off for reseal or overhaul, you're going to be re-balancing anyway
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