Today's Message Index:
----------------------
1. 06:09 AM - Re: Rocket-List Digest: 1 Msgs - 01/26/05 (Lee Taylor)
2. 06:50 AM - Re: How to tame the Lycomisaur (James Baldwin)
3. 07:16 AM - turbine smooth? but what about performance? (Frazier, Vincent A)
4. 07:38 AM - Re: turbine smooth? but what about performance? (Morocketman@aol.com)
5. 07:48 AM - Re: turbine smooth? but what about performance? (Norman Younie)
6. 09:34 AM - Fw: F-18 Magic Carpet Ride (not Rocket, but almost as good) (Morocketman@aol.com)
7. 12:18 PM - Re: RV-List: Re: Headsets.....again... (JOHN STARN)
8. 09:17 PM - Re: How to tame the Lycomisaur (LesDrag@aol.com)
9. 09:40 PM - Re: turbine smooth? but what about performance? (LesDrag@aol.com)
10. 09:56 PM - Re: turbine smooth? but what about performance? (LesDrag@aol.com)
11. 10:08 PM - Re: turbine smooth? but what about performance? (LesDrag@aol.com)
Message 1
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| Subject: | RE: Rocket-List Digest: 1 Msgs - 01/26/05 |
--> Rocket-List message posted by: "Lee Taylor" <leetay@comcast.net>
Subject: Rocket-List: How to tame the Lycomisaur
--> Rocket-List message posted by: LesDrag@aol.com
Lycoming - tractor engine or turbine smooth?
This is the real question that needs to be asked when you are
considering
which propeller to buy. (Based on multiple cruise performance tests
using
several different propellers on the same aircraft with the same pilot.)
I had an opportunity to test four different constant speed propellers on
one
aircraft. There were three different 2 blade propellers and one 3
blade
propeller. This aircraft was owned by a friend who flew the aircraft.
I just
went along as the observer and data recorder.
The original 2 blade CS propeller on the aircraft had been dynamically
balanced on the engine. Since the plan was to leave the original
propeller on
the
aircraft when we were finished with the testing, we did not removed the
dynamic balance weights from the engine ring gear.
All three of the 2 blade propellers had about the same vibration level
during their flights.
Then we flew the 3 blade propeller. On the takeoff roll and initial
climb,
I noticed the pilot was highly stressed about something. About mid
field, as
we were climbing out, he finally said that something must be wrong with
the
engine. That the engine wasn't producing power.
We laughed about this later.
We seem to expect a certain vibration level which can be directly
related to
the engine power. We don't even think about this. And it's not
something
that any instructor I have had has ever talked about. It's just there.
I've been told that a 2 blade propeller has a 2nd order harmonic on the
Lycoming engine.
And the 3 blade propeller does not have the 2nd order harmonic on the
Lycoming engine.
What does this really mean?
On another test sequence, I had an opportunity to again ride in a
friends
aircraft. On this friends Harmon Rocket 2 with a stock Lycoming
IO-540-C4B5,
we removed a 2 blade propeller and installed a 3 blade propeller.
The 3 blade propeller made the Lycoming run like it was an electric
motor,
it was so vibration free.
When we installed a second 2 blade propeller, the same old vibration
came
right back. At the same level as the first 2 blade propeller.
So the question goes back to you, the builder/flyers. Do you want
"turbine
smooth" or "tractor engine"?
Regards,
Jim Ayers
JEEZUS, JIM!
WHAT A FANTASTIC test opportunity! And you shared it with the rest of
us.
THANK YOU!
So much stuff that we hear about, opinions, word-of-mouth, so
little of it is actual side-by-side comparisons of ACTUAL results in
non-debatable circumstances----- To test three different propellers,
on the same plane, on the same engine?????? I don't think I have
ever heard of such definitive results demonstrated in a manner so
conclusive.
Again, THANK YOU!
Message 2
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| Subject: | Re: How to tame the Lycomisaur |
--> Rocket-List message posted by: James Baldwin <rocket2man@isp.com>
Jim -
Yeah, great, but where's the data? I'm planning on using your MT 3
blade but being a data type guy I'd like to see what you've learned. JBB
LesDrag@aol.com wrote:
>--> Rocket-List message posted by: LesDrag@aol.com
>
>Lycoming - tractor engine or turbine smooth?
>
>This is the real question that needs to be asked when you are considering
>which propeller to buy. (Based on multiple cruise performance tests using
>several different propellers on the same aircraft with the same pilot.)
>
>I had an opportunity to test four different constant speed propellers on one
>aircraft. There were three different 2 blade propellers and one 3 blade
>propeller. This aircraft was owned by a friend who flew the aircraft. I just
>went along as the observer and data recorder.
>
>The original 2 blade CS propeller on the aircraft had been dynamically
>balanced on the engine. Since the plan was to leave the original propeller on
the
>aircraft when we were finished with the testing, we did not removed the
>dynamic balance weights from the engine ring gear.
>
>All three of the 2 blade propellers had about the same vibration level
>during their flights.
>
>Then we flew the 3 blade propeller. On the takeoff roll and initial climb,
>I noticed the pilot was highly stressed about something. About mid field, as
>we were climbing out, he finally said that something must be wrong with the
>engine. That the engine wasn't producing power.
>
>We laughed about this later.
>
>We seem to expect a certain vibration level which can be directly related to
>the engine power. We don't even think about this. And it's not something
>that any instructor I have had has ever talked about. It's just there.
>
>I've been told that a 2 blade propeller has a 2nd order harmonic on the
>Lycoming engine.
>And the 3 blade propeller does not have the 2nd order harmonic on the
>Lycoming engine.
>
>What does this really mean?
>
>On another test sequence, I had an opportunity to again ride in a friends
>aircraft. On this friends Harmon Rocket 2 with a stock Lycoming IO-540-C4B5,
>we removed a 2 blade propeller and installed a 3 blade propeller.
>The 3 blade propeller made the Lycoming run like it was an electric motor,
>it was so vibration free.
>When we installed a second 2 blade propeller, the same old vibration came
>right back. At the same level as the first 2 blade propeller.
>
>So the question goes back to you, the builder/flyers. Do you want "turbine
>smooth" or "tractor engine"?
>
>Regards,
>Jim Ayers
>
>
>
>
Message 3
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| Subject: | turbine smooth? but what about performance? |
--> Rocket-List message posted by: "Frazier, Vincent A" <VFrazier@usi.edu>
SNIP **********Time: 09:00:32 AM PST US
From: LesDrag@aol.com
Subject: Rocket-List: How to tame the Lycomisaur
--> Rocket-List message posted by: LesDrag@aol.com
Lycoming - tractor engine or turbine smooth?
This is the real question that needs to be asked when you are
considering which propeller to buy. (Based on multiple cruise
performance tests using several different propellers on the same
aircraft with the same pilot.)
I had an opportunity to test four different constant speed propellers on
one aircraft. There were three different 2 blade propellers and one 3
blade propeller. This aircraft was owned by a friend who flew the
aircraft. I just
went along as the observer and data recorder.
The original 2 blade CS propeller on the aircraft had been dynamically
balanced on the engine. Since the plan was to leave the original
propeller on the aircraft when we were finished with the testing, we
did not removed the dynamic balance weights from the engine ring gear.
All three of the 2 blade propellers had about the same vibration level
during their flights.
Then we flew the 3 blade propeller. On the takeoff roll and initial
climb,
I noticed the pilot was highly stressed about something. About mid
field, as
we were climbing out, he finally said that something must be wrong with
the engine. That the engine wasn't producing power.
We laughed about this later.
We seem to expect a certain vibration level which can be directly
related to the engine power. We don't even think about this. And it's
not something that any instructor I have had has ever talked about.
It's just there.
I've been told that a 2 blade propeller has a 2nd order harmonic on the
Lycoming engine.
And the 3 blade propeller does not have the 2nd order harmonic on the
Lycoming engine.
What does this really mean?
On another test sequence, I had an opportunity to again ride in a
friends aircraft. On this friends Harmon Rocket 2 with a stock Lycoming
IO-540-C4B5,
we removed a 2 blade propeller and installed a 3 blade propeller.
The 3 blade propeller made the Lycoming run like it was an electric
motor, it was so vibration free.
When we installed a second 2 blade propeller, the same old vibration
came right back. At the same level as the first 2 blade propeller.
So the question goes back to you, the builder/flyers. Do you want
"turbine smooth" or "tractor engine"?
Regards,
Jim Ayers SNIP ************
I'll be Devil's advocate here, simply because I like my 2-blade and
don't think that the vibes are objectionable at all. Three blades might
indeed be smoother, I cannot say, but I'd certainly want to know a lot
more than just how smooth it will be.
Vince
The following is presented as food for thought.....
WHICH PROP IS BETTER
Mike Penketh IAC #3213
Sean DeRosier IAC#187992
"I dunno," that's probably an honest answer. I know we've all tried or
flown behind different propellers but its not often we have the same
airframe/engine combination and several composite constant speed
propellers available for evaluations. Several years ago the Hoffman
propeller off my Zlin 50 made an extended visit to the prop shop, a
borrowed a MT propeller gave me a rare chance to compare two aerobatic
composite constant speed propellers on the same aircraft, the Zlin 50
powered by an AEIO-540/260hp.
So...what did I find out?
In this early comparison the take-off, climb and cruise were all
about the same, no marked difference. Slow speed pushes and pulls
revealed a noticeable difference. The Zlin 50 is a remarkable aerobat;
it flies well at slow speeds such as found in the vertical S described
below.
Using the original equipment Hoffman propeller starting at about
160mph in level flight using full power and no more than a 3 G pull the
1st half of an inside loop was completed. Hanging upside down I would
hesitate a moment looking for a minimum of 85 mph, then with no more
than -3G I could push over the top and the 1st half of an outside loop
was completed; all this with a very solid feel to the aircraft. I then
switched to the MT propeller, using the same technique; all was the same
until I reached the vertical phase of the half outside loop? Shutter,
shutter, shake, shake and the maneuver was all over. Even an evaluation
as simple as this is uncommon. Below we've tried to go a step further
and expand the comparison paramaters.
For the ya-buts, what-ifs and nit-pickers...
We have tried to be as consistent as possible in our comparative
evaluations. The same pilot, same aircraft and same procedures have been
used in comparing five different composite aerobatic propellers.
a. The same pilot, Sean DeRosier;
b. the same aircraft, G202 with a Monte Barrett AEIO-360, 180 hp;
c. temperatures varied +- 5 degrees for all evaluations;
d. all power readings were read directly from an electronic VM 1000
;
e. All speeds are indicated mph with the exception of the GPS mph
ground speed.
The following composite aerobatic propellers were compared:
1. Hartzell 2 blade,
2. Whirlwind 2 blade,
3. Whirlwind 200C 2 blade,
4. Whirlwind 3 blade and
5. MT 3 blade.
The following comparisons are offered for information only. They
represent real numbers,
hanger flying, dreaming or salesmanship is not a factor.
We are not in the business of selling propellers, the final decision in
yours.
Page one
GSPD R/C VMAX VMAX
VERT PENETRATION
(Notes) (1) (2) (3)
(4) (5)
HARTZELL 210 1957 fpm 210 mph 195 mph
1800 feet
2 BLADE
52 lbs. - 78 inch diameter
A/C EW 1037 lbs.
WHIRLWIND 207 1836 fpm 205 mph 195 mph
1500 feet
2 BLADE - standard
45 lbs. - 78 inch diameter
A/C EW 1030 lbs.
WHIRLWIND 210 2000 fpm 210 mph 193 mph
1800 feet
2 BLADE - 200C
46 lbs.- 77 inch diameter.
A/C EW 1031 lbs.
WHIRLWIND 204 1682 fpm 202 mph 190 mph
1500 feet
3 BLADE
65 lbs. - 74 inch diameter
A/C EW 1050 lbs.
MT 202 1764 fpm 202 mph
193 mph 1400 feet
3 BLADE
59 lbs. - 76 inch diameter
A/C EW 1044 lbs.
(notes)
(1) GPS ground speed 4 way average, full power - 1500 MSL - 31.5mp /
2680 rpm
(2) 2000-5000' - full power - speed stabilized at 100mph, 1-G
flight prior to beginning timing.
(3) 3500 MSL - 29 mp / 2680 rpm - level flight
(4) 3500 MSL - 25 mp / 2500 rpm - level flight
(5) Vertical penetration is initiated from level flight at 1500'
MSL, VMAX (3) using a 3.5G pull and full power (31.5 mp / 2680 rpm.)
The vertical is held till the aircraft begins to slide backwards.
There are numerous distributors for Hartzell and MT propellers, these
can be found in publications such as SPORT AEROBATICS, SPORT AVIATION or
TRADE -A-PLANE. Whirl Wind products are only available from the
manufacturer at:
Whirl Wind Propellers Corp.
1860 Joe Crosson Drive, suite J
El Cajon, CA 92070
619-562-3725
Page two
Message 4
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| Subject: | Re: turbine smooth? but what about performance? |
--> Rocket-List message posted by: Morocketman@aol.com
DO NOT ARCHIVE I flew many compostite propellers in the 1990's (IVO,
Whirlwind, etc.) and they were smooth. However, if you plan on any IFR flying
be
very careful about rain eroding the leading edge. Same applies to a wooden
prop. I realize my info is quite dated, but I don't believe you can fly "in
the rain" (even a little) without damaging those props. Tell me if I am wrong,
please. And by the by, what were your cruise and climb performance numbers?
You alluded to their importance and then ommitted any info. My two blade
Hartzell is very, very smooth. Les Featherston HRII w IO-540 C4B5 N206KT
"Airgasm" has just over 150 wonderfull hrs. DO NOT ARCHIVE
Message 5
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| Subject: | Re: turbine smooth? but what about performance? |
--> Rocket-List message posted by: Norman Younie <rv6capt@pacificcoast.net>
According to theory 2 blades are more efficient than 3 or more. One
blade would be the most efficient but the vibration would be overwhelming.
Frazier, Vincent A wrote:
>--> Rocket-List message posted by: "Frazier, Vincent A" <VFrazier@usi.edu>
>
>
>SNIP **********Time: 09:00:32 AM PST US
>From: LesDrag@aol.com
>Subject: Rocket-List: How to tame the Lycomisaur
>
>--> Rocket-List message posted by: LesDrag@aol.com
>
>Lycoming - tractor engine or turbine smooth?
>
>This is the real question that needs to be asked when you are
>considering which propeller to buy. (Based on multiple cruise
>performance tests using several different propellers on the same
>aircraft with the same pilot.)
>
>I had an opportunity to test four different constant speed propellers on
>one aircraft. There were three different 2 blade propellers and one 3
>blade propeller. This aircraft was owned by a friend who flew the
>aircraft. I just
>
>went along as the observer and data recorder.
>
>The original 2 blade CS propeller on the aircraft had been dynamically
>balanced on the engine. Since the plan was to leave the original
>propeller on the aircraft when we were finished with the testing, we
>did not removed the dynamic balance weights from the engine ring gear.
>
>All three of the 2 blade propellers had about the same vibration level
>during their flights.
>
>Then we flew the 3 blade propeller. On the takeoff roll and initial
>climb,
>I noticed the pilot was highly stressed about something. About mid
>field, as
>
>we were climbing out, he finally said that something must be wrong with
>the engine. That the engine wasn't producing power.
>
>We laughed about this later.
>
>We seem to expect a certain vibration level which can be directly
>related to the engine power. We don't even think about this. And it's
>not something that any instructor I have had has ever talked about.
>It's just there.
>
>I've been told that a 2 blade propeller has a 2nd order harmonic on the
>Lycoming engine.
>And the 3 blade propeller does not have the 2nd order harmonic on the
>Lycoming engine.
>
>What does this really mean?
>
>On another test sequence, I had an opportunity to again ride in a
>friends aircraft. On this friends Harmon Rocket 2 with a stock Lycoming
>IO-540-C4B5,
>
>we removed a 2 blade propeller and installed a 3 blade propeller.
>The 3 blade propeller made the Lycoming run like it was an electric
>motor, it was so vibration free.
>When we installed a second 2 blade propeller, the same old vibration
>came right back. At the same level as the first 2 blade propeller.
>
>So the question goes back to you, the builder/flyers. Do you want
>"turbine smooth" or "tractor engine"?
>
>Regards,
>Jim Ayers SNIP ************
>
>
>I'll be Devil's advocate here, simply because I like my 2-blade and
>don't think that the vibes are objectionable at all. Three blades might
>indeed be smoother, I cannot say, but I'd certainly want to know a lot
>more than just how smooth it will be.
>
>Vince
>
>The following is presented as food for thought.....
>
>WHICH PROP IS BETTER
>
>Mike Penketh IAC #3213
>Sean DeRosier IAC#187992
>
>"I dunno," that's probably an honest answer. I know we've all tried or
>flown behind different propellers but its not often we have the same
>airframe/engine combination and several composite constant speed
>propellers available for evaluations. Several years ago the Hoffman
>propeller off my Zlin 50 made an extended visit to the prop shop, a
>borrowed a MT propeller gave me a rare chance to compare two aerobatic
>composite constant speed propellers on the same aircraft, the Zlin 50
>powered by an AEIO-540/260hp.
>
>So...what did I find out?
>
> In this early comparison the take-off, climb and cruise were all
>about the same, no marked difference. Slow speed pushes and pulls
>revealed a noticeable difference. The Zlin 50 is a remarkable aerobat;
>it flies well at slow speeds such as found in the vertical S described
>below.
> Using the original equipment Hoffman propeller starting at about
>160mph in level flight using full power and no more than a 3 G pull the
>1st half of an inside loop was completed. Hanging upside down I would
>hesitate a moment looking for a minimum of 85 mph, then with no more
>than -3G I could push over the top and the 1st half of an outside loop
>was completed; all this with a very solid feel to the aircraft. I then
>switched to the MT propeller, using the same technique; all was the same
>until I reached the vertical phase of the half outside loop? Shutter,
>shutter, shake, shake and the maneuver was all over. Even an evaluation
>as simple as this is uncommon. Below we've tried to go a step further
>and expand the comparison paramaters.
>
>For the ya-buts, what-ifs and nit-pickers...
>
> We have tried to be as consistent as possible in our comparative
>evaluations. The same pilot, same aircraft and same procedures have been
>used in comparing five different composite aerobatic propellers.
>a. The same pilot, Sean DeRosier;
>b. the same aircraft, G202 with a Monte Barrett AEIO-360, 180 hp;
>c. temperatures varied +- 5 degrees for all evaluations;
>d. all power readings were read directly from an electronic VM 1000
>;
>e. All speeds are indicated mph with the exception of the GPS mph
>ground speed.
>
>The following composite aerobatic propellers were compared:
>
>1. Hartzell 2 blade,
>2. Whirlwind 2 blade,
>3. Whirlwind 200C 2 blade,
>4. Whirlwind 3 blade and
> 5. MT 3 blade.
>
>
>The following comparisons are offered for information only. They
>represent real numbers,
>hanger flying, dreaming or salesmanship is not a factor.
>We are not in the business of selling propellers, the final decision in
>yours.
>
>
> Page one
>
>
> GSPD R/C VMAX VMAX
>VERT PENETRATION
> (Notes) (1) (2) (3)
>(4) (5)
>
>HARTZELL 210 1957 fpm 210 mph 195 mph
>1800 feet
>2 BLADE
>52 lbs. - 78 inch diameter
>A/C EW 1037 lbs.
>
>WHIRLWIND 207 1836 fpm 205 mph 195 mph
>1500 feet
>2 BLADE - standard
>
>45 lbs. - 78 inch diameter
>A/C EW 1030 lbs.
>
>WHIRLWIND 210 2000 fpm 210 mph 193 mph
>1800 feet
> 2 BLADE - 200C
>46 lbs.- 77 inch diameter.
>A/C EW 1031 lbs.
>
>WHIRLWIND 204 1682 fpm 202 mph 190 mph
>1500 feet
>3 BLADE
>
>65 lbs. - 74 inch diameter
>A/C EW 1050 lbs.
>
>MT 202 1764 fpm 202 mph
>193 mph 1400 feet
>3 BLADE
>59 lbs. - 76 inch diameter
>A/C EW 1044 lbs.
>
>(notes)
>(1) GPS ground speed 4 way average, full power - 1500 MSL - 31.5mp /
>2680 rpm
>(2) 2000-5000' - full power - speed stabilized at 100mph, 1-G
>flight prior to beginning timing.
>(3) 3500 MSL - 29 mp / 2680 rpm - level flight
>(4) 3500 MSL - 25 mp / 2500 rpm - level flight
>(5) Vertical penetration is initiated from level flight at 1500'
>MSL, VMAX (3) using a 3.5G pull and full power (31.5 mp / 2680 rpm.)
>The vertical is held till the aircraft begins to slide backwards.
>
>There are numerous distributors for Hartzell and MT propellers, these
>can be found in publications such as SPORT AEROBATICS, SPORT AVIATION or
>TRADE -A-PLANE. Whirl Wind products are only available from the
>manufacturer at:
> Whirl Wind Propellers Corp.
> 1860 Joe Crosson Drive, suite J
> El Cajon, CA 92070
> 619-562-3725
>
>
>Page two
>
>
>
>
Message 6
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| Subject: | Fwd: F-18 Magic Carpet Ride (not Rocket, but almost as good) |
--> Rocket-List message posted by: Morocketman@aol.com
Do not archive! Got this from a friend! It is the way it was in the old
days--F-100--for me. This is the real reason we build Rockets! i.e. Civilian
Fighter Airplanes. Enjoy this Gummy Bear. Or as Jackie would have said,
"Away we go!" Les Featherston N206KT This is why I call her "Airgasm" Do Not
Archive!
ockets
Subject: F-18 Magic Carpet Ride
From: "Frazier, Vincent A" <VFrazier@usi.edu>
This is one of the better downloads I've seen lately. There's nothing
quite like zooming thru the clouds. Vince
Lots of fun
Just another day at the office.
http://raf.union.rpi.edu/downloads/f18_ride.wmv
- Poker One
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This is one of the better downloads I've seen
lately. There's nothing quite like zooming thru the clouds.
Vince
Lots of
fun
Just another=20day at the
office.
http://raf.union.rpi.edu/downloads/f18_ride.wmv
- Poker
One
Message 7
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|
"rv-list" <rv-list@matronics.com>, <vansairforce@yahoogroups.com>
| Subject: | Re: RV-List: Re: Headsets.....again... |
--> Rocket-List message posted by: "JOHN STARN" <jhstarn@verizon.net>
Sorry but I must humbly disagree. While gathering data or asking questions
on any RV subject I want as many opinions / observations as possible. If you
want to limit the number of messages received, pick your "favorite ONE". By
the way you forgot the Rocket list, 'cause we're RV's too. We're just on
steroids. 8*)
Keep up the posts Bill, I have a delete button. Do Not Archive. KABONG
SoCalRV, HRII
---- Original Message -----
From: "Larry Bowen" <Larry@bowenaero.com>
Subject: Re: RV-List: Re: Headsets.....again...
> --> RV-List message posted by: "Larry Bowen" <Larry@BowenAero.com>
>
>
> Good discussion....But posting across multiple lists is poor netiquette.
> Pick your favorite ONE. None of us needs four copies of this topic.
>
>
> -
> Larry Bowen
> Larry@BowenAero.com
> http://BowenAero.com
> do not archive
>
>> ----- Original Message -----
>> From: "Bill VonDane" <bill@vondane.com>
Message 8
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| Subject: | Re: How to tame the Lycomisaur |
--> Rocket-List message posted by: LesDrag@aol.com
The performance data was taken for the 2 blade Hartzell "D" blade and "J"
blade propellers and the MTV-9-B/198-52 three blade Rocket propeller.
The data I have on the HR2 was not taken at typical cruise power settings
and altitudes. The data was taken in preparation for the Reno 2003 races at
5,000' and 6,000' pressure altitudes with 88+ degree f OAT. This was single
point data collection without even a second data flight for correlation. Just
a "how do we go faster" flight test.
The results of the data we collected indicated that the best performance was
obtained with the 2 blade Hartzell "J" propeller at full throttle and 2,800
RPM.
For the performance numbers below 2,700 RPM, the numbers were the same.
I am still trying to get my HR2 finished so I have an opportunity to get a
reasonable amount of test data under normal cruise conditions.
BTW, John Harmon said the smoothest propeller he has flown was the four
blade MTV-14-B/190-119a on his Harmon Rocket 3.
I am planning to try the MTV-14-B-C/C190-59b on my HR2. This
counterweighted 4 blade propeller and spinner will be about 2 to 4 pounds heavier
than the
Hartzell 2 blade propeller and spinner. :-)
Regards,
Jim Ayers
In a message dated 01/27/2005 6:51:31 AM Pacific Standard Time,
rocket2man@isp.com writes:
Jim -
Yeah, great, but where's the data? I'm planning on using your MT 3
blade but being a data type guy I'd like to see what you've learned. JBB
Message 9
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| Subject: | Re: turbine smooth? but what about performance? |
--> Rocket-List message posted by: LesDrag@aol.com
MT Propeller custom designs the propeller blades. Their propeller numbering
system can be used to determine the aircraft for which the propeller was
designed. Saying an MT propeller was used for testing, without the MTV part
number being identified, is meaningless.
For example, the Hartzell 72" diameter 2 blade propeller will bolt very
nicely on a Lycoming IO-540-C4B5 260 hp engine. SAE2 bolt pattern with 1/2"
diameter bolts.
I think we can all agree that this propeller for the 180 to 200 hp Lycoming
would not have the same performance as a Hartzell 80" dia. 2 blade propeller
on the Lycoming IO-540.
What I'm trying to say is that no valid conclusion can be made regarding the
performance of an undefined MT Propeller. I don't disagree with the data
provided. But what was the "loaner" MT propeller?
Regards,
Jim Ayers
In a message dated 01/27/2005 7:18:04 AM Pacific Standard Time,
VFrazier@usi.edu writes:
--> Rocket-List message posted by: "Frazier, Vincent A" <VFrazier@usi.edu>
SNIP **********Time: 09:00:32 AM PST US
From: LesDrag@aol.com
Subject: Rocket-List: How to tame the Lycomisaur
--> Rocket-List message posted by: LesDrag@aol.com
Lycoming - tractor engine or turbine smooth?
This is the real question that needs to be asked when you are
considering which propeller to buy. (Based on multiple cruise
performance tests using several different propellers on the same
aircraft with the same pilot.)
I had an opportunity to test four different constant speed propellers on
one aircraft. There were three different 2 blade propellers and one 3
blade propeller. This aircraft was owned by a friend who flew the
aircraft. I just
went along as the observer and data recorder.
The original 2 blade CS propeller on the aircraft had been dynamically
balanced on the engine. Since the plan was to leave the original
propeller on the aircraft when we were finished with the testing, we
did not removed the dynamic balance weights from the engine ring gear.
All three of the 2 blade propellers had about the same vibration level
during their flights.
Then we flew the 3 blade propeller. On the takeoff roll and initial
climb,
I noticed the pilot was highly stressed about something. About mid
field, as
we were climbing out, he finally said that something must be wrong with
the engine. That the engine wasn't producing power.
We laughed about this later.
We seem to expect a certain vibration level which can be directly
related to the engine power. We don't even think about this. And it's
not something that any instructor I have had has ever talked about.
It's just there.
I've been told that a 2 blade propeller has a 2nd order harmonic on the
Lycoming engine.
And the 3 blade propeller does not have the 2nd order harmonic on the
Lycoming engine.
What does this really mean?
On another test sequence, I had an opportunity to again ride in a
friends aircraft. On this friends Harmon Rocket 2 with a stock Lycoming
IO-540-C4B5,
we removed a 2 blade propeller and installed a 3 blade propeller.
The 3 blade propeller made the Lycoming run like it was an electric
motor, it was so vibration free.
When we installed a second 2 blade propeller, the same old vibration
came right back. At the same level as the first 2 blade propeller.
So the question goes back to you, the builder/flyers. Do you want
"turbine smooth" or "tractor engine"?
Regards,
Jim Ayers SNIP ************
I'll be Devil's advocate here, simply because I like my 2-blade and
don't think that the vibes are objectionable at all. Three blades might
indeed be smoother, I cannot say, but I'd certainly want to know a lot
more than just how smooth it will be.
Vince
The following is presented as food for thought.....
WHICH PROP IS BETTER
Mike Penketh IAC #3213
Sean DeRosier IAC#187992
"I dunno," that's probably an honest answer. I know we've all tried or
flown behind different propellers but its not often we have the same
airframe/engine combination and several composite constant speed
propellers available for evaluations. Several years ago the Hoffman
propeller off my Zlin 50 made an extended visit to the prop shop, a
borrowed a MT propeller gave me a rare chance to compare two aerobatic
composite constant speed propellers on the same aircraft, the Zlin 50
powered by an AEIO-540/260hp.
So...what did I find out?
In this early comparison the take-off, climb and cruise were all
about the same, no marked difference. Slow speed pushes and pulls
revealed a noticeable difference. The Zlin 50 is a remarkable aerobat;
it flies well at slow speeds such as found in the vertical S described
below.
Using the original equipment Hoffman propeller starting at about
160mph in level flight using full power and no more than a 3 G pull the
1st half of an inside loop was completed. Hanging upside down I would
hesitate a moment looking for a minimum of 85 mph, then with no more
than -3G I could push over the top and the 1st half of an outside loop
was completed; all this with a very solid feel to the aircraft. I then
switched to the MT propeller, using the same technique; all was the same
until I reached the vertical phase of the half outside loop? Shutter,
shutter, shake, shake and the maneuver was all over. Even an evaluation
as simple as this is uncommon. Below we've tried to go a step further
and expand the comparison paramaters.
For the ya-buts, what-ifs and nit-pickers...
We have tried to be as consistent as possible in our comparative
evaluations. The same pilot, same aircraft and same procedures have been
used in comparing five different composite aerobatic propellers.
a. The same pilot, Sean DeRosier;
b. the same aircraft, G202 with a Monte Barrett AEIO-360, 180 hp;
c. temperatures varied +- 5 degrees for all evaluations;
d. all power readings were read directly from an electronic VM 1000
;
e. All speeds are indicated mph with the exception of the GPS mph
ground speed.
The following composite aerobatic propellers were compared:
1. Hartzell 2 blade,
2. Whirlwind 2 blade,
3. Whirlwind 200C 2 blade,
4. Whirlwind 3 blade and
5. MT 3 blade.
The following comparisons are offered for information only. They
represent real numbers,
hanger flying, dreaming or salesmanship is not a factor.
We are not in the business of selling propellers, the final decision in
yours.
Page one
GSPD R/C VMAX VMAX
VERT PENETRATION
(Notes) (1) (2) (3)
(4) (5)
HARTZELL 210 1957 fpm 210 mph 195 mph
1800 feet
2 BLADE
52 lbs. - 78 inch diameter
A/C EW 1037 lbs.
WHIRLWIND 207 1836 fpm 205 mph 195 mph
1500 feet
2 BLADE - standard
45 lbs. - 78 inch diameter
A/C EW 1030 lbs.
WHIRLWIND 210 2000 fpm 210 mph 193 mph
1800 feet
2 BLADE - 200C
46 lbs.- 77 inch diameter.
A/C EW 1031 lbs.
WHIRLWIND 204 1682 fpm 202 mph 190 mph
1500 feet
3 BLADE
65 lbs. - 74 inch diameter
A/C EW 1050 lbs.
MT 202 1764 fpm 202 mph
193 mph 1400 feet
3 BLADE
59 lbs. - 76 inch diameter
A/C EW 1044 lbs.
(notes)
(1) GPS ground speed 4 way average, full power - 1500 MSL - 31.5mp /
2680 rpm
(2) 2000-5000' - full power - speed stabilized at 100mph, 1-G
flight prior to beginning timing.
(3) 3500 MSL - 29 mp / 2680 rpm - level flight
(4) 3500 MSL - 25 mp / 2500 rpm - level flight
(5) Vertical penetration is initiated from level flight at 1500'
MSL, VMAX (3) using a 3.5G pull and full power (31.5 mp / 2680 rpm.)
The vertical is held till the aircraft begins to slide backwards.
There are numerous distributors for Hartzell and MT propellers, these
can be found in publications such as SPORT AEROBATICS, SPORT AVIATION or
TRADE -A-PLANE. Whirl Wind products are only available from the
manufacturer at:
Whirl Wind Propellers Corp.
1860 Joe Crosson Drive, suite J
El Cajon, CA 92070
619-562-3725
Message 10
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| Subject: | Re: turbine smooth? but what about performance? |
--> Rocket-List message posted by: LesDrag@aol.com
I heard that stainless steel is 3 times more resistant to water erosion than
aluminum.
The MT propeller blades have a stainless steel leading edge.
This would mean that the MT propeller blades are three times better than
Hartzell's aluminum blades in the rain.
Where is the materials expert that can authoritatively dispute, or support,
stainless steel being 3 times more resistant to water erosion than aluminum?
Regards,
Jim Ayers
In a message dated 01/27/2005 7:40:10 AM Pacific Standard Time,
Morocketman@aol.com writes:
--> Rocket-List message posted by: Morocketman@aol.com
DO NOT ARCHIVE I flew many compostite propellers in the 1990's (IVO,
Whirlwind, etc.) and they were smooth. However, if you plan on any IFR
flying be
very careful about rain eroding the leading edge. Same applies to a wooden
prop. I realize my info is quite dated, but I don't believe you can fly
"in
the rain" (even a little) without damaging those props. Tell me if I am
wrong,
please. And by the by, what were your cruise and climb performance
numbers?
You alluded to their importance and then ommitted any info. My two blade
Hartzell is very, very smooth. Les Featherston HRII w IO-540 C4B5 N206KT
"Airgasm" has just over 150 wonderfull hrs. DO NOT ARCHIVE
Message 11
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| Subject: | Re: turbine smooth? but what about performance? |
--> Rocket-List message posted by: LesDrag@aol.com
Part of the equation is missing.
There is a formula for power coefficient (Cp) and "J" factor that identify
the number of blades for the greatest efficiency.
For a very low Cp, what you said is correct.
The RV-6A with a Lycoming O-360 of 180 hp apparently has a Cp high enough to
have a 3 blade propeller developing a slightly better efficiency at cruise
altitudes than all three of the 2 blade propellers used.
MT Propeller has determined (by analysis only) that the HR2 with the
Lycoming IO-540 engine has a Cp high enough to allow a 4 blade propeller to be
in
the same efficiency range as the 3 blade propeller.
Regards,
Jim Ayers
In a message dated 01/27/2005 7:49:14 AM Pacific Standard Time,
rv6capt@pacificcoast.net writes:
--> Rocket-List message posted by: Norman Younie <rv6capt@pacificcoast.net>
According to theory 2 blades are more efficient than 3 or more. One
blade would be the most efficient but the vibration would be overwhelming.
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