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  #1  
Old 01-20-2019, 09:32 AM
walker172 walker172 is offline
 
Join Date: Aug 2018
Location: Cold Lake, AB Canada
Posts: 8
Default Hartzell 3 blade Aluminum Prop

Hey guys/gals,

First time builder on the RV-10 and I’m just about at the tailcone attach phase of the build. A question for all of you about weight and balance and propellers. I bought a recently overhauled IO-540 C4B5 for my project and it came with a brand new Hartzell 3 bladed aluminum scimitar prop. I haven’t weighed it just yet, but does anyone know what kind of weight difference it would have compared to the 2 blade option Vans sells? And would anyone be willing to plug that weight difference into their W and B numbers to see if the forward c of g limit would become a pain to manage?

I’ve been doing a fair bit of reading about the issues removing the lower cowl with a 3 blades prop, and some of the heavy nose concerns in the 10 with only front seats occupied. Do you think this prop would practically usable in my 10, or am I better off selling and going with the standard Vans 2 blade option?

Thanks in advance for your wisdom,

Mike
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CF-18/F-16 Fighter Pilot
1st Time Builder - RV-10 #41779
Cold Lake, AB Canada

Last edited by walker172 : 01-20-2019 at 09:33 AM. Reason: Spelling
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  #2  
Old 01-20-2019, 10:46 AM
AviatorJ AviatorJ is offline
 
Join Date: Feb 2015
Location: Oklahoma City
Posts: 735
Default

I'm biased to the 3-blade props so I would keep that. There's solutions to make it easier to take the cowl off such as using a RamAir unit, or you could easily make the stock scoop removable as well.
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RV-10, N10JW
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  #3  
Old 01-20-2019, 01:04 PM
CDN CDN is offline
 
Join Date: Nov 2011
Location: Calgary, AB
Posts: 90
Default Removable scoop

Hi former hangar neighbour,
If I had to do it over again I would have modified my cowling to make the intake scoop removable on my stock cowling. A friend here in Calgary has done it with his and it works well.
Taking the lower cowling off even with a 2 blade prop is not particularly easy, especially by yourself.

As for the weight, I wanted all the useful load I could get with mine. Every extra pound steals from it and I didn't want to go without the nice Aerosport interior and other amenities that make this a jaw dropping airplane. However, I wanted to keep it in a range to still carry 4 adults and full fuel. You can easily turn the rv-10 into a 3 person airplane if not weight conscious. I, apparently, am still a growing boy and it is (shamefully) easier to remove weight from the airplane than it is from me. I went with the lightest CS prop I could find (2 blade whirlwind RV-10) and put an EarthX battery on the firewall (instead of a lead acid battery behind the baggage bay) to keep the CG around what it would have been with the factory recommended configuration. These 2 changes saved nearly 50 pounds IIRC. Lots of ways of building it, everything is a compromise.

Have you weighed the prop to see how heavy it really is compared to the 2 blade? It may not be as bad as you expect...or maybe it's worse.
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  #4  
Old 01-24-2019, 11:45 PM
walker172 walker172 is offline
 
Join Date: Aug 2018
Location: Cold Lake, AB Canada
Posts: 8
Default

I havenít weighed the prop just yet. I guess thatís the next step. Iím just concerned about a heavier prop up front, with a lighter (earth x) battery in the back. Iím worried about forward c of g when itís just me, or me and one of the kids flying in it. I know some fly with ballast in the trunk for those types of flights, but Iíd like to avoid it if at all possible.
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CF-18/F-16 Fighter Pilot
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Cold Lake, AB Canada
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  #5  
Old 01-25-2019, 01:59 AM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,503
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I built as light as I could (1607 lbs bew) and ended up with a slightly forward cg when solo. For solo flying, I carry a 2.5 gal plastic water jug in the back. When carrying a heavy load, I just pour the water out. I think you’ll find most -10’s are limited by cg, not weight. So having to carry a bit of ballast when solo is a plus.
But, back to your question: the three blade has some nice things (smoother, more ground clearance) but will most likely cost you a few knots in cruise.

Last edited by BobTurner : 01-25-2019 at 02:03 AM.
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  #6  
Old 01-25-2019, 05:25 AM
paul330 paul330 is offline
 
Join Date: Feb 2007
Location: Mpumalanga, South Africa
Posts: 1,015
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Second the comments on weight and CofG. I don't know if it is actually possible to exceed the front limit. I guess if you had a very forward empty datum, one light pilot and full fuel, you might just do it. However, everything else you put in and fuel you burn takes the CofG aft.

There is also no doubt that it handles better with the CofG back, especially on approach where you can start to run out of trim. But any of these problems are only going to manifest themselves lightweight so there is absolutely no issue with carrying a few pounds of ballast in the baggage compartment.

So my advice would be - build as light as possible and get the empty CofG to the forward end.

As for the 3 blade argument, a "few" knots slow in the cruise is, I think a myth put around by the 2-blade fraternity I was air-racing last year following a 2-blade -10 for about an hour. We tried everything to overtake him but we were just too well matched. In the end, he JUST crept away from us - maybe 1/2kt...........
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Mercy Air, White River FAWV
RV-10 ZU-IIZ - "Zeus"
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  #7  
Old 01-25-2019, 09:12 AM
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9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 1,561
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I think that the 3 blade in aluminum is going to make you a little nose heavy. My RV-10 had the two blade Hartzell and had dual PC680's in the per plans tail location. Since I have short legs and had the seat full forward when I flew, that did not help either. I flew mostly alone and had ballast in the baggage compartment to lighten up on the nose. A removable scoop is a no-brainer for removal/installation of the lower cowling with a three blade prop,,,especially by yourself. MY W&B:

N959RV Weight & Balance Data
Empty Weight: 1703 lbs. (8 qts oil & Wheel Fairings @ #3.75 lbs. each
Gross Weight: 2700 lbs.
Datum: 99.44" forward of wing leading edge
CG Range Limits: 107.84" - 116.24" aft of Datum
Fuel: 108.90" Aft of Datum
Pilot/Front Passenger: 114.58" Aft of Datum
Rear Seat Passengers: 151.26" Aft of Datum
Baggage: 173.50" Aft of Datum
Right Wheel: 688 lbs., arm 123.85", moment 85209
Left Wheel: 685 lbs., arm 124.15", moment 85043
Nose Wheel: 330 lbs., arm 49.90", moment 16467
Total Weight: 1703 lbs., moment 186719
Empty CG: 109.64" (moment divided by weight)
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RV-9A: Under Construction.
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  #8  
Old 01-25-2019, 01:07 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 5,503
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Quote:
Originally Posted by paul330 View Post

and fuel you burn takes the CofG aft.

.....
Actually, if you start out close to the forward cg limit, burning fuel moves the cg more forward. With the 10 you must always check cg at the expected landing configuration.
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  #9  
Old 01-25-2019, 03:20 PM
walker172 walker172 is offline
 
Join Date: Aug 2018
Location: Cold Lake, AB Canada
Posts: 8
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Appreciate the feedback and information from everyone. Iíll weigh the prop and compare to the 50-55 pounds quoted by vans for the 2 bladed alternatives and see where I am at.
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Mike Walker
CF-18/F-16 Fighter Pilot
1st Time Builder - RV-10 #41779
Cold Lake, AB Canada
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  #10  
Old 01-25-2019, 09:57 PM
F1Boss's Avatar
F1Boss F1Boss is offline
 
Join Date: Aug 2006
Location: Taylor Texas
Posts: 718
Default Weights:

About 75lbs for the 3 blade; about 62lbs for the two blade (same as the MT 3 blade).

Make sure the prop is designed for the RV-10. Other props wonít be set up for that airframe.
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You know who you are."
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