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RobHickman(at)aol.com Guest
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Posted: Tue Sep 02, 2008 3:59 pm Post subject: Hartzell Composite Three blade RPM Test |
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On my trip to Moses Lake and back over the weekend I tried different propeller RPM's for speed. I was level at 8500 Ft and full throttle.� I started at 2600 RPM and then tried 2500, 2400, 2300, and 2200; for every 100 RPM drop I would see a couple of knots drop in airspeed.
Rob Hickman
N402RH RV-10
It's only a deal if it's where you want to go. Find your travel deal here.
[quote][b]
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patrick.pulis(at)seagas.c Guest
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Posted: Tue Sep 02, 2008 4:14 pm Post subject: Hartzell Composite Three blade RPM Test |
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pascal(at)rv10builder.net Guest
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Posted: Tue Sep 02, 2008 4:15 pm Post subject: Hartzell Composite Three blade RPM Test |
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Thanks Rob for the update. So 2600 produced the best speed at the price of higher fuel, and the loss of speed was consistent for every 100rpm? how did this effect fuel rate?
Pascal
From: RobHickman(at)aol.com (RobHickman(at)aol.com)
Sent: Tuesday, September 02, 2008 4:57 PM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Hartzell Composite Three blade RPM Test
On my trip to Moses Lake and back over the weekend I tried different propeller RPM's for speed. I was level at 8500 Ft and full throttle. I started at 2600 RPM and then tried 2500, 2400, 2300, and 2200; for every 100 RPM drop I would see a couple of knots drop in airspeed.
Rob Hickman
N402RH RV-10
It's only a deal if it's where you want to go. Find your travel deal here.
[quote]
href="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-List
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Lenny Iszak
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Joined: 23 Mar 2008 Posts: 270
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Posted: Wed Sep 03, 2008 7:17 am Post subject: Re: Hartzell Composite Three blade RPM Test |
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It would be pretty useful to make a surface chart using Rob's engine data.
rpm vs airspeed vs fuel flow...
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_________________ Lenny Iszak
Palm City, FL
2014 RV-10, N311LZ - 500 hrs |
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Tim Olson
Joined: 25 Jan 2007 Posts: 2879
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Posted: Wed Sep 03, 2008 8:32 am Post subject: Hartzell Composite Three blade RPM Test |
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Fuel flow will be one of the key data points, too.
It doesn't matter if I post that I've seen 183-4kts
with my RV10, because the times that I've seen
over 180kts I was burning 19+gph. It would be
insane to try to run the engine like that to go
on a trip. So really, to make any data valuable,
you'd want RPM, MP, Fuel Flow, Altitude, OAT, Loaded
weight (and distribution) and things like that so you
can get realistic comparisons. It's like saying "My
car gets 85mpg", but not stating that when it does
this, you're rolling down an mountain.
Almost all of my experience is with flying in a mode
that provides best economy. I have very little time
spent flying for max performance. I enjoy being
able to flight plan 160-165kts, and do it with
fuel flows generally being 10gph or less. Various
loadings produce vastly different cruise speeds,
so sometimes I cruise 157-160kts, and sometimes
I cruise 173-175kts, but I rarely cruise over 13.5gph,
and there is usually a few more kts available if
I'm willing to bump up the fuel flow.
Speaking of loadings being important, last year at
OSH while flying people around, I found that I was
easily 2 or 3kts slower than Scott. We weren't
loaded identically, but I remember being slower.
This year, on the way to OSH, I was easily outclimbing
and then out-cruising him...even though we were
both loaded up. But, I don't think his loading
was as light as mine. It was interesting to see
how a little added passenger load or distribution
of CG caused really different performance numbers.
Again, most of my experience and numbers I know,
are loaded up with the wife, kids, my portly
self, and maybe 10-125lbs of baggage. How it
performs with just one or two people in the
plane is much more foreign to me. We all remember
what we know best...for me, I know that if I
want to burn 8-10gph, I can count on 157-165kts
depending on altitude and loading, and if I
want to burn 12.5-14gph, I can plan to fly 164-175kts
..loaded with the family.
I would say that Rob's estimate of being 7kts slower
is probably in the ballpark. I would have guessed 8-12,
but, without fuel flow data included, it's hard to
tell how directly it compares. 2600 RPM is a speed
that almost nobody will ever cruise at. When the
numbers were first posted at 2450RPM, my first
question in my head was "hmmm, wonder what the fuel
flow was...", because 2450 is a little more aggressive
of a cruise RPM, and almost certainly is burning
more fuel than what people are used to hear reported
by the MT and Hartzell 2-blade folks. If it was
171kts at 13.5gph and 2450RPM at 8500', then
that's not really too bad at all. If it's 171kts at
18gph, then I'd say that kinda stinks. Most
people I've talked to find something between 2200
and 2360 that they cruise at. Most of my cruising
is at 2360, as I haven't found that I can keep the
speeds up when I go down towards 2200. I've just
found 2360 to be a sweet spot for smoothness and
economical performance. To me, it's all about
economy....it stands out in my head that on ONE trip
to Oregon alone, just cruising LOP saved me over
$200 in fuel. On this weekend's trip, with 2
hours to go to destination, I had to choose between
10-20 minutes of time savings, or 6 gallons of
fuel...I chose to save the fuel. So fuel flow
numbers are important parts of the data set.
Tim Olson - RV-10 N104CD - Flying
do not archive
Lenny Iszak wrote:
Quote: |
It would be pretty useful to make a surface chart using Rob's engine data.
rpm vs airspeed vs fuel flow...
--------
Regards,
Lenny
#40803
Fuel System...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 2327#202327
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rickbarnes(at)highlandden Guest
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Posted: Wed Sep 03, 2008 9:18 am Post subject: Hartzell Composite Three blade RPM Test |
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Thanks Tim.
It's nice to have someone put it all in perspective. If you want pure speed
an F1 rocket with a three blade MT is the way to go. If you want a good
four place plane that cruises at a good TAS then an RV10 is ideal. It would
be nice to see all values compared, for both economy (reality) and
performance (bragging rights).
Rick Barnes
Still building
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wcurtis(at)nerv10.com Guest
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Posted: Wed Sep 03, 2008 9:24 am Post subject: Hartzell Composite Three blade RPM Test |
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This is one of the reasons I shake my head when some report the best speeds at some low ~2200-2400 RPM. I discovered when I was breaking in a new engine on the Cardinal that my best power and speeds was at 2700 RPM. Anything less than 2700 would produce a slower speed. Now I primarily use two settings for my prop--2700 for takeoff, 2500 for climb and cruise with occasional reduction during letdown.
All things being equal, you will achieve the best power and speed from a prop at 2700 RPM. At 2700 RPM, and 50 degree ambient temperature, an 84" prop will have a tip speed of Mach 0.895. To produce maximum thrust at full power your tip speed should fall between .88 and .92 mach. The primary benefit of reducing RPM is for increased passenger comfort (less noise) and reduced engine wear an tear.
What is the diameter of the Hartzell Composite Three blade?
William
http://nerv10.com/wcurtis/
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flysrv10(at)gmail.com Guest
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Posted: Wed Sep 03, 2008 2:29 pm Post subject: Hartzell Composite Three blade RPM Test |
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I have been reporting best speeds at 2250 RPM. Perhaps with your
theory I can do better. I am curious and will test it and report back.
I consistently get 172 kts at 12,500 with 10 gal/hr burn. Perhaps I
really mean best speed/fuel economy combination and don't realize it.
I do know that being in absolute smooth air and giving the plane a
chance to accelerate for a few long minutes makes a big difference.
The speed goes all over the place with the slightest turbulence.
It will be a while before I can do the test but I WILL report back. I
also need to qualify that I do not have three blades so, who knows!
Thank for making me think.
On Sep 3, 2008, at 1:40 PM, William Curtis wrote:
[quote]
This is one of the reasons I shake my head when some report the best
speeds at some low ~2200-2400 RPM. I discovered when I was breaking
in a new engine on the Cardinal that my best power and speeds was at
2700 RPM. Anything less than 2700 would produce a slower speed.
Now I primarily use two settings for my prop--2700 for takeoff, 2500
for climb and cruise with occasional reduction during letdown.
All things being equal, you will achieve the best power and speed
from a prop at 2700 RPM. At 2700 RPM, and 50 degree ambient
temperature, an 84" prop will have a tip speed of Mach 0.895. To
produce maximum thrust at full power your tip speed should fall
between .88 and .92 mach. The primary benefit of reducing RPM is
for increased passenger comfort (less noise) and reduced engine wear
an tear.
What is the diameter of the Hartzell Composite Three blade?
William
http://nerv10.com/wcurtis/
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rene(at)felker.com Guest
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Posted: Wed Sep 03, 2008 3:05 pm Post subject: Hartzell Composite Three blade RPM Test |
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Boy, I really feel slow now......
12,500
12.2 GPH Rich of peak
2480 RPM
161 knots (TAS from GRT)
My speed test at 8000 feet and 75% power showed about 171......but I have
not seen speeds like that in cruise at 12500.
Rene' Felker
RV-10 N423CF Flying
801-721-6080
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pitts_pilot(at)bellsouth. Guest
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Posted: Wed Sep 03, 2008 4:02 pm Post subject: Hartzell Composite Three blade RPM Test |
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I think that all the 'data' needs to be taken at a certain manifold
pressure ...... that being an indicator of horsepower that we can
measure. That also should yield a fairly constant fuel flow. The data
then, could be plotted to find the 'most efficient' and 'best cruise'
etc. I want y'all to get all this data so I can use it when I fly!!!
Linn
do not archive
Rob Kermanj wrote:
[quote]
I have been reporting best speeds at 2250 RPM. Perhaps with your
theory I can do better. I am curious and will test it and report back.
I consistently get 172 kts at 12,500 with 10 gal/hr burn. Perhaps I
really mean best speed/fuel economy combination and don't realize it.
I do know that being in absolute smooth air and giving the plane a
chance to accelerate for a few long minutes makes a big difference.
The speed goes all over the place with the slightest turbulence.
It will be a while before I can do the test but I WILL report back. I
also need to qualify that I do not have three blades so, who knows!
Thank for making me think.
On Sep 3, 2008, at 1:40 PM, William Curtis wrote:
>
>
> This is one of the reasons I shake my head when some report the best
> speeds at some low ~2200-2400 RPM. I discovered when I was breaking
> in a new engine on the Cardinal that my best power and speeds was at
> 2700 RPM. Anything less than 2700 would produce a slower speed. Now
> I primarily use two settings for my prop--2700 for takeoff, 2500 for
> climb and cruise with occasional reduction during letdown.
>
> All things being equal, you will achieve the best power and speed
> from a prop at 2700 RPM. At 2700 RPM, and 50 degree ambient
> temperature, an 84" prop will have a tip speed of Mach 0.895. To
> produce maximum thrust at full power your tip speed should fall
> between .88 and .92 mach. The primary benefit of reducing RPM is for
> increased passenger comfort (less noise) and reduced engine wear an
> tear.
>
> What is the diameter of the Hartzell Composite Three blade?
>
> William
> http://nerv10.com/wcurtis/
>
> ------
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chuck(at)chuckdirect.com Guest
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Posted: Wed Sep 03, 2008 5:01 pm Post subject: Hartzell Composite Three blade RPM Test |
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Lots of good info here Tim. Thanks!
Chuck
do not archive
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Tim Olson
Joined: 25 Jan 2007 Posts: 2879
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Posted: Wed Sep 03, 2008 7:08 pm Post subject: Hartzell Composite Three blade RPM Test |
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Have you done a 4-way GPS course to make sure your true airspeed
is reading right? (also depends on your OAT reading right)
I originally found that I was something like 6-7kts low in my
readings, until I changed static ports. These days with the
new ports, I'm 1.8kts low...so I always have to try to add
1 or 2 to give accurate numbers. If you were even just a couple
kts low, that might make all of the difference up.
Tim Olson - RV-10 N104CD - Flying
do not archive
Rene Felker wrote:
[quote]
Boy, I really feel slow now......
12,500
12.2 GPH Rich of peak
2480 RPM
161 knots (TAS from GRT)
My speed test at 8000 feet and 75% power showed about 171......but I have
not seen speeds like that in cruise at 12500.
Rene' Felker
RV-10 N423CF Flying
801-721-6080
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rene(at)felker.com Guest
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Posted: Wed Sep 03, 2008 7:41 pm Post subject: Hartzell Composite Three blade RPM Test |
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I have not done a 4-way GPS course, but the TAS readings seem to correlate
with the GPS ground speed......but you know how that goes, if you don't use
a scientific method than you never really know. I am hoping to be able to
do some more testing this fall. The actual speed is really not that
important to me, it is what it is, but it would be nice to know.
I have been using 161 knots in the flight planning and on the last trip I
arrived early (I had a good forecasted tail wind)....but the return trip I
was a little late but I had to deviate around a storm and thus really can't
use that as a measurement.......
Rene'
801-721-6080
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flysrv10(at)gmail.com Guest
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Posted: Thu Sep 04, 2008 4:27 pm Post subject: Hartzell Composite Three blade RPM Test |
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I was thinking about this....may be I mean to say that at a given
manifold pressure (19.0 in my case), 2250 RPM, 10 gal and 12,500 (65%
as stated in lycoming HP chart) I will lose speed if I increase RPM
and keep everything else, including fuel, constant.
Now guys, don't jump all over me for being wishy-washy!
Rene, you should always be able to go faster at a higher altitude!
Right?
At the end, I believe that we are very close to each other since it is
hard to make a major rigging error on the 10. We are just measuring
with different instruments and comparing speeds at different parameters.
I have enclose two photos of my panel from a trip. They are both
taken on the same trip at different altitudes. I have done the GRT
speed correction but will try the GPS speed calibration for the next
one. Now, if my outside temp sensor is really out of wack and my
numbers are off, it is not my fault!
I took these shots with the AP engaged and the plane level in smooth
air, with everything settled. Notice no vertical speed, TAS on the
right bottom and OAT.
You might think that I am a real liar, but if I wiggle my rudder just
right, I get a couple of more knots.
On Sep 3, 2008, at 7:04 PM, Rene Felker wrote:
[quote]
Boy, I really feel slow now......
12,500
12.2 GPH Rich of peak
2480 RPM
161 knots (TAS from GRT)
My speed test at 8000 feet and 75% power showed about 171......but I
have
not seen speeds like that in cruise at 12500.
Rene' Felker
RV-10 N423CF Flying
801-721-6080
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wcurtis(at)nerv10.com Guest
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Posted: Sat Sep 06, 2008 11:30 am Post subject: Hartzell Composite Three blade RPM Test |
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Consider that the Cirrus SR-20 and SR-22 with both 2 and 3 blade props don't have any direct prop control. They have only two prop speeds--2500 and 2700 RPM. 2700 RPM when the throttle is pushed in all the way and 2500 when the throttle is anywhere but full power.
William
http://nerv10.com/wcurtis/
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