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  #1  
Old 04-07-2018, 09:51 AM
Av8torTom's Avatar
Av8torTom Av8torTom is offline
 
Join Date: Nov 2009
Location: Yardley, PA
Posts: 1,334
Default Need Advice

Now that I have my engine I'm thinking about fixed pitch propellers. My plan was to go with the extended Sam James cowl on my 9A. Knowing that the 9A is a bit tail heavy, what are your recommendations for propeller?

My initial thinking was a 3 blade Catto cruise prop with nickel leading edges, but I'm wondering if the weight of a standard aluminum Sensenich prop might be welcomed.

Thanks again everyone.

T.
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RV-9A (empennage completed, both wings completed, fuselage and finish kit completed, engine hung, working on panel and wiring)
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Superior XP O-320, 160HP
Picture log: http://s271.photobucket.com/albums/j...8tor215/RV-9A/
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  #2  
Old 04-07-2018, 10:56 AM
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TJCF16 TJCF16 is offline
 
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Location: Greenville SC
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I recommend a constant speed prop on the RV-9A. It will help with center of gravity and will also make for much better performance and cruising! I have one on my 9A and would never go to a fixed pitch on a cruising airplane. IMHO
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"Merlin"
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  #3  
Old 04-07-2018, 11:32 AM
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airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
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Second on the constant speed prop - I'll never go back.

With an IO360 and constant speed up front I was fighting a NOSE heavy tendency, and ended up moving several remote-mounted avionics and the battery aft of the baggage compartment to compensate. I also have extended range fuel tanks though, which required a bit more aft empty-CG so I would still be in limits with 67 gallons in the wing leading edge.
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N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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  #4  
Old 04-07-2018, 11:49 AM
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Av8torTom Av8torTom is offline
 
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Location: Yardley, PA
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Default Thanks guys

Constant speed prop is not an option at this point (maybe in the future).
So given that fact, any advice for a fixed pitch prop? Catto? Sensenich? Composite? Metal? Ground adjustable? Weight? Extensions?
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RV-9A (empennage completed, both wings completed, fuselage and finish kit completed, engine hung, working on panel and wiring)
N677AT reserved
Superior XP O-320, 160HP
Picture log: http://s271.photobucket.com/albums/j...8tor215/RV-9A/
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  #5  
Old 04-07-2018, 11:56 AM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,219
Default

Quote:
Originally Posted by Av8torTom View Post
Constant speed prop is not an option at this point (maybe in the future).
So given that fact, any advice for a fixed pitch prop? Catto? Sensenich? Composite? Metal? Ground adjustable? Weight? Extensions?
There's plenty of data in the archives about the relative CG's of airplanes with metal and wood props. I have a composite/wood prop and a 10 pound prop spacer to get the CG on the -6 to what I consider a good compromise.

Personally, with a -9 (i.e. a non-acro aircraft), I'd go with the metal prop. They are efficient, don't suffer in the rain, and will help your CG. No, you won't be able to spin the engine all the way up to 2700 RPM, but I'm not sure that's as important in the RV-9 "mission".
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Marietta, GA
2001 RV-6 N46KB
2019(?) RV-10

Last edited by Kyle Boatright : 04-07-2018 at 01:00 PM.
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  #6  
Old 04-07-2018, 12:39 PM
rightrudder rightrudder is offline
 
Join Date: Mar 2014
Location: Laguna Hills, CA
Posts: 1,805
Default

Love the Catto on my -9A. I've got the two-blade 70x70 with nickel leading edges. Super smooth operation, and hits the Van's speed numbers nicely.

Minimal issues with W&B on my plane, even with a lightweight SkyTec starter. If I get down to 5 gallons of fuel in worst-case W&B scenario, I'd have to reduce baggage from 100 lb to 90 lb to stay within range, so no big deal....I've never landed with less than an hour's reserve. Went to Oshkosh with the cg pretty far aft (195 lb pilot, 250 lb copilot and approx. 90 lb baggage) and the the aircraft handled beautifully. You could always fit a boat-anchor standard starter up front, or weighted crush ring.

I'm a big proponent of FP props....less complexity, workload, cost and maintenance. I might consider a CS if I were based at a high altitude airport, but I'm very pleased with a solo-weight climb rate of 1300-1400 fpm.

And the less weight you put on that nose gear, the better (while staying within cg range, of course).
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RV-9A "slider"
Flew to Osh in 2017, 2018 & 2019!
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You haven't seen a tree until you've seen its shadow from the sky -- Amelia Earhart

Last edited by rightrudder : 04-07-2018 at 12:50 PM.
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  #7  
Old 04-07-2018, 12:53 PM
Michael Burbidge Michael Burbidge is offline
 
Join Date: May 2006
Location: Sammamish, WA
Posts: 654
Default Cargo 3 Blade

I have a Catto 3 Blade on my 9A and I have no issues with W&B. I?d have to have two +200 lbs. people and near empty tanks to be too far aft.

I was worried about it before I finished. But it has not been an issue.

Michael
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RV-14A Empennage
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  #8  
Old 04-07-2018, 03:01 PM
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agirard7a agirard7a is offline
 
Join Date: Aug 2009
Location: Newport, RI
Posts: 705
Default Wood prop

I really like my Sterba cruise prop. Light, runs smooth and inexpensive. No issues
with the CG. I can send you my W&B spreadsheet.
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  #9  
Old 04-07-2018, 04:01 PM
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Zuldarin Zuldarin is offline
 
Join Date: Mar 2013
Location: Snoqualmie, wa
Posts: 393
Default

I've got a 9A with an IO-360 so my numbers will be slightly different than yours but...

I started with a 3 bladed Catto prop just as you described. I loved that prop and it performed better than any certified airplane I ever flew (granted thats not a long list). However last year I got the bug to go constant speed so I installed a Whirlwind 200RV prop. You can read all about my thoughts on the process on my blog.

Here are the high points.

1. Cruise is no better with the constant speed..in fact its slower but only by a knot or two. To be fair to the Whirlwind, it is limited to 2700 rpm so I have my governor set so that I can't get above 2650 in cruise. The Catto would turn at 2750 which means I was getting more HP out of the engine.

2. Climb...holy **** the climb! The constant speed out-climbs the fixed pitch by a large margin...and thats saying something because the Catto would climb at 1500+ fpm.

3. The constant speed prop is quieter in cruise because I can pull the engine rpm back.

4. The ability to slow down with the constant speed prop is great but the con to that is my glide ratio really sucks now. In my informal testing I could glide at >10/1 with the Catto at idle but with the constant speed at idle that number drops to about 8/1.

5. The constant speed prop is has much more vibration than the 3 blade Catto. I even dynamically balanced my prop to 0.0 IPS and still have much more vibration. I've gotten used to it but that took a bit of time.

Was the conversion worth the money I paid? In my opinion the answer is no. The Catto is that good.
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Snoqualmie WA
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  #10  
Old 04-07-2018, 05:31 PM
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Ed_Wischmeyer Ed_Wischmeyer is online now
 
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Location: Savannah, GA
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Default

Not that it matters as you're already committed to a fixed pitch prop, but another advantage of the constant speed prop is drag on approach and rollout. And if you're in frisky up and downdrafts, like west Texas in the summer, you won't be constantly adjusting your power to keep the RPMs under control when the autopilot is holding altitude.

I've got a Sensenich fixed pitch on my -9A, but I'd much rather have a constant speed.

Along those lines, any thoughts on three blade vs two blade props in terms of getting the cowling on and off? The cowling on my -9A is moderately uncooperative, and that's with a two blade prop...
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