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  #1  
Old 09-30-2013, 08:15 PM
sirlegin's Avatar
sirlegin sirlegin is offline
 
Join Date: Feb 2006
Location: Keller, Texas
Posts: 312
Default Prop pitch

If you have a 9A with a 320 and a fixed pitch propeller, 2 or 3 blade, what pitch did you go with and why?
Any performance numbers would help
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Nigel
RV9A-N113SQ
52F
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  #2  
Old 09-30-2013, 08:33 PM
Rupester Rupester is offline
 
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,195
Default Catto 3-blade

I went with whatever pitch Craig recommended when I ordered it. He asked model RV, engine and HP, and then said he makes a LOT of props for that combination. Sorry I can't be more specific ... if I had the nameplate data here at home, I'd give you the pitch.
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Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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  #3  
Old 09-30-2013, 09:18 PM
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flyboy1963 flyboy1963 is offline
 
Join Date: Oct 2008
Location: Lake Country, B.C. Canada
Posts: 2,428
Default some rough numbers

I have an older 0-320, 7:1 compression, Sensenich metal 2 blade 70" x 77 pitch.
Turns up about 2150 static, so on the takeoff roll, my rough calculations say its making about 85 hp.....so climb of 750 to 1000 fpm is typical.
the prop seems to 'bite' better as you pass thru 85 kts, and it actually climbs better at this speed than at the theoretical 'best' r.o.c. speed of 78 kts.
cruise at 2450 is about 155 kts. at 6000'. ( not calibrated or percent power, just on a calm day the gps groundspeed is about the same).
On a full throttle descent you can nudge up to the 2600 rpm limit.

Overall I am ok with the prop....but wonder why the plane is not a little faster, if it's a bit overpitched, or if it's underpitched, why the low static revs.
If I were buying a new prop, it would likely be the Sensenich adjustable, so that one could dial it in better, or run more pitch in the winter vs summer.
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RV-9a - SOLD!....
Lake Country, BC
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  #4  
Old 10-01-2013, 04:53 AM
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pierre smith pierre smith is online now
 
Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,901
Default We need speed.

We decided early on, that we wanted the most cruise speed that we could get for our -6A. Craig asked if we minded turning the engine 2750 RPM's and I said that I didn't mind and we ended up with a prop that gave us 201 MPH TAS at 7,500'.

Some guys want better takeoff and climb so they give up some cruise speed for that.

Best,
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  #5  
Old 10-01-2013, 07:11 AM
bforsyth bforsyth is offline
 
Join Date: Jul 2011
Location: Thunder Bay, ON, Canada
Posts: 18
Default Prop pitch

We have two 9a's, 160hp fixed pitch. One is Sensenich 79" pitch, the other Catto I believe he calls it a 71" pitch, it is his recommended stock 2blade for the 160hp 9a. The Catto is superior in acceleration, climb, and deceleration, and virtually identical in cruise and top end. The Sensenich has 600+ hours and looks like it just came out of the box. The Catto 100+, so far so good (has metal leading edge option), needs more frequent inspection and torque check.
The most noticeable difference is being able to slow down more effectively on descent/landing with the Catto. Both great props, significantly different in operation.
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  #6  
Old 10-01-2013, 07:19 AM
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Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 11,034
Default

Quote:
Originally Posted by pierre smith View Post
We decided early on, that we wanted the most cruise speed that we could get for our -6A. Craig asked if we minded turning the engine 2750 RPM's and I said that I didn't mind and we ended up with a prop that gave us 201 MPH TAS at 7,500'.
Some guys want better takeoff and climb so they give up some cruise speed for that.
Best,
I've tested a few props for Craig and have found that in many cases, a lower pitched prop, pitched for take-off, will still cruise up there with a cruise prop if you are willing to do it at a higher RPM. Of course, this means a higher fuel burn.
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EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
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  #7  
Old 10-01-2013, 07:26 AM
bforsyth bforsyth is offline
 
Join Date: Jul 2011
Location: Thunder Bay, ON, Canada
Posts: 18
Default Prop pitch

Just to clarify, in cruise, side by side, our 79" Sensenich and 71" Catto are virtually identical in speed and rpm
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  #8  
Old 10-01-2013, 07:58 AM
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Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 11,034
Default

Quote:
Originally Posted by bforsyth View Post
Just to clarify, in cruise, side by side, our 79" Sensenich and 71" Catto are virtually identical in speed and rpm
Prop pitch is not comparable between different manufacturers. Besides the different methods of measuring pitch is the different planforms, airfoils, and many other parameters involved.
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Mel Asberry, DAR since the last century. Over 1,000 certifications accomplished. Discount for Veterans, Law Enforcement, Fire Fighters.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
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  #9  
Old 10-01-2013, 08:24 AM
Rupester Rupester is offline
 
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,195
Default Catto 3-blade performance #s ...

I'm seeing a static RPM of 2280; climb vs cruise seems to be a good combination. In warm weather, climbing at 1500+ is normal; in winter weather it'll do 2000fpm with no problem. Cruise numbers are 2450rpm LOP and 145ktas. To my surprise, full throttle and ROP will spin it to 2750rpm (sometimes 2800!) at any altitude up to 8500'.
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Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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  #10  
Old 10-01-2013, 08:55 AM
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Neal@F14 Neal@F14 is offline
 
Join Date: Aug 2007
Location: Wichita Falls, TX
Posts: 2,182
Default

Quote:
Originally Posted by flyboy1963 View Post
If I were buying a new prop, it would likely be the Sensenich adjustable, so that one could dial it in better, or run more pitch in the winter vs summer.
It's a great prop. It is very pricey however. The only regrets I have are each month when I make that credit card payment but whenever I pull out onto the runway and push the throttle in, those regrets all go away

BTW, my hangar mate just bought an RV-4 with 150hp O-320 and put his Whirlwind ground-adjustable GA-200 prop on it. It's a very good looking prop but kind of a pain to set the pitch of each blade with a prop protractor whereas the Sensenich has the pitch pins that make the task a breeze. He's still in the process of dialing in his optimum pitch, but we got to fly our planes together in a crude test of "Brand S" vs "Brand W" and the performance is roughly similar. I get better static rpm and initial takeoff climb rpm, and can outrun him pretty easily in level cruise (I've got 10 more horsepower), but in an extended climb up to 8000' he walked off and left me behind. He's got about 75-80 less pounds of weight to carry, though, so that is a factor there. Either way, both of these ground adjustable carbon fiber props are excellent performers and would be a good choice on an RV-9 too.
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