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larywil(at)comcast.net
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 Posted: Mon Sep 20, 2010 6:08 pm Post subject: What is best RPM? |
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| Quote: | I've been flying behind an IO-360 with a constant speed Hartzell
HC-C2YK for 10 years. For most of these years, I have flown at 18-20
inches and 2400 RPM. A very experienced DFE felt there was a sweet
spot at 2400. I have recently been trying explore a lower RPM
alternative. Since there is a restriction between 2000 and 2250 RPM,
I am limited. What have some of you found to be best( besides buying
the new "unlimited" prop)?
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Louis I Willig
1640 Oakwood Dr.
Penn Valley, PA 19072
610 668-4964
RV-4, N180PF
190HP IO-360, C/S prop
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jhnstniii(at)aol.com
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| Posted: Mon Sep 20, 2010 6:36 pm Post subject: What is best RPM? |
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Louis--We had our Hartzell CS blended airfoil prop dynamically balanced at Hartzell's factory in Piqua OH and they asked us what rpm we wanted it balanced at. We selected 2400. We run it at 2400 all the time except for takeoff and it's pretty smooth. It seems rougher to me at other rpms.
LeRoy Johnston RV-6A "Esperanza" 390 hours Ohio
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Vanremog(at)aol.com
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| Posted: Mon Sep 20, 2010 6:36 pm Post subject: What is best RPM? |
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Louis-
I normally cruise all day at 2300 rpm at 23 inHg (around 68% power) burning 8.6 gph and truing out at 180 mph. This setting gives about a 700 sm no-wind range with a daytime reserve. In practice I usually only push for 540 sm because my "wet sump" is only good for 3 hrs and I like carrying extra to cope with weather diversions.
-GV (RV-6A N1GV 955hrs)
In a message dated 9/20/2010 7:09:14 P.M. Pacific Daylight Time, larywil(at)comcast.net writes:
| Quote: | --> RV-List message posted by: Louis Willig <larywil(at)comcast.net>
| Quote: | I've been flying behind an IO-360 with a constant speed Hartzell
HC-C2YK for 10 years. For most of these years, I have flown at 18-20
inches and 2400 RPM. A very experienced DFE felt there was a sweet
spot at 2400. I have recently been trying explore a lower RPM
alternative. Since there is a restriction between 2000 and 2250 RPM,
I am limited. What have some of you found to be best( besides buying
the new "unlimited" prop)?
|
Louis I Willig
1640 Oakwood Dr.
Penn Valley, PA 19072
610 668-4964
RV-4, N180PF
190HP IO-360, C/S ========================; ties Day ================================================ - MATRONICS WEB FORUMS ================================================ - List Contribution Web Site sp; ===================================================
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[quote][b]
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Mon Sep 20, 2010 7:27 pm Post subject: What is best RPM? |
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Why are you looking to go slower? I have IO-360-A1A with similar prop,
which has restriction from 2000-2350. I had it balanced for 2500 and
that is where I fly it until I get above 8000 ft, where I need more rpm
to keep the power up anywhere near 75%. The lower rpm you run, the less
potential power you can produce. I could understand if you cruised down
in the 3-4000 ft range, but unless you are looking for a fuel economy
champ and don't care about going slow, I'd use more MP and more rpm.
Somewhere around 2400/24" or 2500/24" will be close to 75%.
On 9/20/2010 7:00 PM, Louis Willig wrote:
| Quote: |
> I've been flying behind an IO-360 with a constant speed Hartzell
> HC-C2YK for 10 years. For most of these years, I have flown at 18-20
> inches and 2400 RPM. A very experienced DFE felt there was a sweet
> spot at 2400. I have recently been trying explore a lower RPM
> alternative. Since there is a restriction between 2000 and 2250 RPM,
> I am limited. What have some of you found to be best( besides buying
> the new "unlimited" prop)?
Louis I Willig
1640 Oakwood Dr.
Penn Valley, PA 19072
610 668-4964
RV-4, N180PF
190HP IO-360, C/S prop
|
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
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Matt Dralle
Site Admin
Joined: 08 Nov 2005
Posts: 25781
Location: Livermore CA USA
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| Posted: Mon Sep 20, 2010 7:39 pm Post subject: What is best RPM? |
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Louis,
I have an IO-390 with a 72" Hartzell on the RV-8 and just this weekend was experimenting with slightly higher RPM settings than I've been running. At 23/2300 (at) 7500ft I was seeing 10 GPH / 20.3 MPG / 201 MPH True. See attached photos of the EFIS displays.
Matt Dralle
RV-8 #82880 N998RV
http://www.mattsrv8.com - Matt's RV-8 Construction Log
http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel
Status: 99+ Hours TTSN - Enjoying Every Minute...
At 07:29 PM 9/20/2010 Monday, you wrote:
| Quote: | Louis-
I normally cruise all day at 2300 rpm at 23 inHg (around 68% power) burning 8.6 gph and truing out at 180 mph. This setting gives about a 700 sm no-wind range with a daytime reserve. In practice I usually only push for 540 sm because my "wet sump" is only good for 3 hrs and I like carrying extra to cope with weather diversions.
-GV (RV-6A N1GV 955hrs)
In a message dated 9/20/2010 7:09:14 P.M. Pacific Daylight Time, larywil(at)comcast.net writes:
>I've been flying behind an IO-360 with a constant speed Hartzell
>HC-C2YK for 10 years. For most of these years, I have flown at 18-20
>inches and 2400 RPM. A very experienced DFE felt there was a sweet
>spot at 2400. I have recently been trying explore a lower RPM
>alternative. Since there is a restriction between 2000 and 2250 RPM,
>I am limited. What have some of you found to be best( besides buying
>the new "unlimited" prop)?
|
-
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Matt Dralle
Matronics Email List Administrator |
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lessdragprod(at)aol.com
Guest
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| Posted: Mon Sep 20, 2010 7:46 pm Post subject: What is best RPM? |
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For a 180 hp O-360 engine a full throttle in a RV-6A with a Hartzell 7666-4 propeller, the maximum airspeed was obtained at:
2700 RPM at 2,500' density altitude.
2550 RPM at 7,500' density altitude.
2400 RPM at 12,500' density altitude.
More horsepower isn't always faster.
I also found there was a different characteristic for each of the propellers I tested. Different propeller, different optimum RPM with altitude.
You might try this for yourself.
--
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Mon Sep 20, 2010 8:41 pm Post subject: What is best RPM? |
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Well, my install is on one of those clunky certified airframes that
has published data from 2500 ft up to 15000 ft, and in no circumstance
was any slower rpm faster than 2700 rpm. Maybe it is the extra drag of
all the FAA paperwork. 
On 9/20/2010 8:42 PM, Jim Ayers wrote:
[quote] For a 180 hp O-360 engine a full throttle in a RV-6A with a Hartzell
7666-4 propeller, the maximum airspeed was obtained at:
2700 RPM at 2,500' density altitude.
2550 RPM at 7,500' density altitude.
2400 RPM at 12,500' density altitude.
More horsepower isn't always faster.
I also found there was a different characteristic for each of the
propellers I tested. Different propeller, different optimum RPM with
altitude.
You might try this for yourself.
--
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
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martinaerodrome(at)gmail.
Guest
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| Posted: Tue Sep 21, 2010 5:01 am Post subject: What is best RPM? |
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Louis,
I have approximately 3000 hours on my RV8 over 10 years. I have also flown other Lyc airplanes. I have always used 2300 x 23 inches and average 9 gallons per hour fuel consumption with no problems and good performance.
Good Luck.
Dick Martin
RV8 N233M
the fast one
On Mon, Sep 20, 2010 at 9:00 PM, Louis Willig <larywil(at)comcast.net (larywil(at)comcast.net)> wrote:
[quote]--> RV-List message posted by: Louis Willig <larywil(at)comcast.net (larywil(at)comcast.net)>
| Quote: | I've been flying behind an IO-360 with a constant speed Hartzell HC-C2YK for 10 years. For most of these years, I have flown at 18-20 inches and 2400 RPM. A very experienced DFE felt there was a sweet spot at 2400. I have recently been trying explore a lower RPM alternative. Since there is a restriction between 2000 and 2250 RPM, I am limited. What have some of you found to be best( besides buying the new "unlimited" prop)?
|
Louis I Willig
1640 Oakwood Dr.
Penn Valley, PA 19072
610 668-4964
RV-4, N180PF
190HP IO-360, C/S ==================
owse, Chat, FAQ,
="http://www.matronics.com/Navigator?RV-List" target="_blank">http://ww===
http://forums.mle, List Admin.
=====
[b]
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