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  #1  
Old 02-03-2020, 06:34 PM
greghughespdx's Avatar
greghughespdx greghughespdx is offline
 
Join Date: Nov 2011
Location: Aurora, OR
Posts: 874
Default 3-Blade Sensenich Prop - Now available for RV-12is/RV-12

Van's has published updated RV-12/12iS powerplant kit order forms, a new plans section (47AiS/U) and a service letter (SL 19-12-31), all of which are related to the now-available optional 3-blade Sensenich propeller kit.

We displayed this prop on a stand in our booth at Oshkosh last year and flew it to the show on one of our factory aircraft. It garnered quite a bit of interest. Now that the engineering has been completed and testing of the final install package is all wrapped up, the three-blade prop and spinner kit is available to order as an option on new powerplant kit orders (you'll get to choose either a two-blade or three-blade prop when you order). You can also place a stand-alone order for the prop without the rest of the Powerplant kit (just use the powerplant kit order form and select only the 3-blade prop option in that case).

Note that when building your airplane, in order to register ELSA the parts - including the propeller - must be bought directly from Van's and tracked in our records under that aircraft serial number. Once an aircraft has been licensed and registered ELSA you may, of course, make any changes as you wish.

People will, of course, want to know what's different between the two-blade and three-blade prop. Our testing experience showed that:
  • Cruise performance was the same (at lower altitudes)
  • Climb performance was greater
  • Propeller braking action was slightly greater, which allowed a slightly steeper descent angle in the pattern
  • The sound/pitch is different, although the measured noise level is about the same (they are the same diameter).

And, of course, there's the aesthetics: The blades are wider on the two-blade prop. Some folks prefer the look of three blades, while others prefer two. Some people like a thinner blade, while others prefer the "beefier" look.



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Last edited by greghughespdx : 02-03-2020 at 06:50 PM.
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  #2  
Old 02-03-2020, 08:24 PM
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Dvalcik Dvalcik is offline
 
Join Date: Jul 2011
Location: Royersford, PA
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Default new prop

Installed the new Sensenich 3 blade replacing my 6 year old 3 blade Sensenich a few months ago. Longer blades and thinner than the original 3 blade I had.

.

Still dialing in the pitch, but performance is much improved from the older 3 blade. I picked up a few knots but still have the climb. Since I never had a 2 blade I can?t compare it since I started with a 3 blade. Performance seam very close when flying next to my buddies. Sound a little different on the ground, but smooth.
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  #3  
Old 02-03-2020, 10:55 PM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Default

David,
I am glad to hear that your experience parallels what we discovered.

That the original 3 blade with wide cord blades did not perform up to the level of the two blade. We just didn’t feel that we could promote it as a viable option with the only virtue being cool factor, at the expense of slightly reduced performance.

Though to some, the skinny blades don’t have the same wow factor, but it at least does provide a slight performance boost over the two blade (as mentioned.... a modest increase in climb rate while maintaining the same cruise performance).

Because of some refinement that Sensenich was able to do to the hub while changing the blade design (likely allowable because the blades were lighter as well) the overall weight of the 3 blade install is lighter than the two blade which is good for helping to maximize useful load. The weight reduction is at a less than ideal location as far as baggage payload goes, but it doesn’t seem to be a factor on RV-12’s that have a standard build configuration.

Once dynamically balanced well, it is very smooth. The simplification and weight reduction do come at a price (besides just the higher cost)......... there is now 3 blades that need to be adjusted to have closely matching pitch angles, and there is no indexing methods incorporated into the propeller. Not a big loss in my mind because they don’t work well enough to set the blade pitch close enough to each other to get it running real smooth anyway. Just something to be aware of though.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

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RV-6A (aka "Junkyard Special ")

Last edited by rvbuilder2002 : 02-06-2020 at 09:37 AM. Reason: typo
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  #4  
Old 02-04-2020, 03:43 AM
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Piper J3 Piper J3 is offline
 
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Does Sensenich require prop disassembly/visual exam at Annual Condition Inspection? Putting three blades back together correctly every twelve months doesn't sound like fun...
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Last edited by Piper J3 : 02-04-2020 at 05:13 AM.
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  #5  
Old 02-04-2020, 09:56 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Piper J3 View Post
Does Sensenich require prop disassembly/visual exam at Annual Condition Inspection? Putting three blades back together correctly every twelve months doesn't sound like fun...
I think the specified inspection procedure is the same for the 3 blade as for the 2 blade. It is not that big of a deal after getting a little experience doing the blade adjustment.

One benefit over the two blade is that the hub design is different in such a way that the propeller can be removed from the engine as a complete assembly without disturbing the blade pitch adjustment. This also allows for disassembly or assembly of the propeller with it laying on a work table.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #6  
Old 02-04-2020, 10:31 PM
dpemmons dpemmons is offline
 
Join Date: Apr 2017
Location: San Francisco, CA (KDVO)
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Quote:
Originally Posted by rvbuilder2002 View Post
One benefit over the two blade is that the hub design is different in such a way that the propeller can be removed from the engine as a complete assembly without disturbing the blade pitch adjustment. This also allows for disassembly or assembly of the propeller with it laying on a work table.
Oh this is super interesting - it means one could build a jig that would let you dial in all the blades precisely and hold everything fast while you tighten the bolts.
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  #7  
Old 02-05-2020, 08:32 PM
Wolf Wolf is offline
 
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How much lighter is this prop as opposed to the two blade option?
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  #8  
Old 02-05-2020, 11:19 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Wolf View Post
How much lighter is this prop as opposed to the two blade option?
I may be off a bit (memory is going bad) but I think it is just shy of 6 lbs lighter.
Seemed hard to believe when we first weighed it but each blade is quite a bit lighter than the what a 2 blade blade is, plus the lower hub mass. It all adds up......
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #9  
Old 02-06-2020, 09:20 AM
steveb steveb is offline
 
Join Date: Mar 2015
Location: FL
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steve from Sensenich here.

Yes, the disassembly time for the new 3 blade is every 2000 hours.
We bobbled our initial release of prop instructions and had annual disassembly on there by mistake, but the current revision instructions on our website have the correct inspection interval.
3Y0-Installation-Instructions-rev-C-20200204-1.pdf
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  #10  
Old 02-06-2020, 10:17 AM
NinerBikes NinerBikes is offline
 
Join Date: Dec 2018
Location: Granada Hills
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Interesting that when landing it has increased braking action.

Will the POH be revised for the 3 blade prop to reflect this change, in terms of glide ratio /glide slope when dead stick landing, in the event of an emergency?

I believe with the 2 blade prop currently it's 13:1, or about 2.47 miles per 1000 ft elevation loss?
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