Today's Message Index:
----------------------
1. 07:06 AM - Re: Re: changing props (Dear Jim why MT?) ()
2. 08:28 AM - Re: Re: changing props (Dear Jim why MT?) (LessDragProd@aol.com)
3. 12:22 PM - Phantasm Facts (was: changing props (Dear Jim why MT?)) (LessDragProd@aol.com)
4. 12:48 PM - Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) (Rick Rammos)
5. 01:03 PM - Re: Phantasm Facts (was: changing props (Dear Jim why (flyer01@adelphia.net)
6. 01:10 PM - Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) (Imken)
7. 03:08 PM - Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) (Don Hall)
8. 03:14 PM - Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) (T Bryant)
9. 03:36 PM - Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) (Hinde, Frank George (Corvallis))
10. 05:16 PM - Re: Phantasm Facts (phantom MT props data) ()
11. 05:46 PM - Re: Re: changing props (Dear Jim why MT?) (Darrell Reiley)
12. 06:41 PM - Re: Re: changing props (Dear Jim why MT?) (LessDragProd@aol.com)
13. 09:47 PM - Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) (Dan Checkoway)
Message 1
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| Subject: | Re: changing props (Dear Jim why MT?) |
In all of this Jim you still have no response, or you are saying you have a
response but are not going to tell us because of my attitude. I apologize sincerely.
Please answers the questions, I would love to hear what you have to say.
Just show me. Your last response was
"The MTV-12-B/183-59d propeller is an improved model of the MTV-12-B/183-59
propeller. The MTV-12-B/183-59b propeller is a farther improvement over the MTV-12-B/183-59d."
Jim this has nothing to do with anything. I am talking about a 11 MPH difference
in performance. No dash number change will affect how absurd your data is.
YOU CAN'T GO FASTER ON LESS HP!
YOUR 7,500 FT DATA AT 2,500 RPM DOES NOT MATCH ANYONES DATA
NO SMALL CHANGE IN THE MT PROP WILL PRODUCE GAINS LIKE YOU SHOW
Last I am sorry if you think I am bashing your company Less Drag Products. One
guy I recall wrote that you went way out of your way to help him. Very nice
Jim. I also have said nice things about MT props, but realistic things not alleged
performance.
THE ONLY BASHING I AM DOING IS THE TABLE OF DATA ON YOUR WEB SITE.
>It amazes me, sometimes, on how much can be said
>just on an opinion, and a scattering of engine and
>propeller theory.
When I first talk to you you about your data almost a year ago, you where quite
rude, disrespectful and condescending. Sorry I am an engineer and you are not.
I also can tell you don't understand aerodynamics. Just because you buy Fluid
Dynamic Drag, by Hoerner, does not make you an engineer. BECAUSE OF YOUR ATTITUDE
I have to be a little more blunt and aggressive with you. I am done. Say
what you want; When your customer puts a MT on his RV-6a and looses speed
over the Hartzell they had on it, they are going to do all the BASHING and you
can take credit for it yourself.
Hey but like I said it is your business.
ON a related note, It took 6 post from others to convince you one Comm antenna
does not produce 1/3rd of the air-craft's drag (you where off by a factor of
66 times, it is 0.5%, or a 1/2 mph). I don't say this to embarrass you, but it
points to the fact that you can not recognize bad results. You believe any number
you come up with, especially if it supports the preconceived ideas you have
about the products you sell.
I'm not patient or diplomatic enough to convince you that your data is incorrect,
and by this last response you refuse to reply to any question because of
ME. OK; You have no response or can you defend your data. Got it. That is what
I thought.
George
A friendly suggestion, If you want to prove me wrong, get MT propeller company,
the maker of the product you sell, "validate" your data. I think it's a good
suggestion and devoid of "attitude". If MT can claim their props go 6 mph faster
on 40 less HP at 12,500 than 2,500 feet, than I want to buy one.
LessDragProd@aol.com wrote:
In a message dated 12/13/2005 10:52:43 AM Pacific Standard Time, gmcjetpilot@yahoo.com
writes:
Why did you get the results you did?
May be you did not re-lean after every RPM change?
May be you just messed up the calculations or made a recording error?
Did you install spinners on every prop?
What was the weather, vertical gust, turbulence?
Dear George,
Why are you now asking questions? By your attitude, I could have no credible
answers for any of your questions.
You have claiming repeatedly that my data is wrong and I should remove it from
my website.
Until now, you didn't seem to care in the least what I did to establish a repeatable
test program.
Maybe we need to establish some ground rules.
Payments due from discussions are not made by purchasing MT Propellers. They
are paid in Strawberry shakes at Sun'N'Fun.
A perspective:
Empirical data is always subject to measurement errors.
Engineering theory is based on empirical data.
(An opportunity for continual learning by reducing error in obtaining empirical
data and improving theory.)
I spent yesterday working with two different friends on their aircraft, and working
on my RV-6A.
I spent today working on my RV-6A.
I have 6 different propellers that need to have test data gathered, and I need
to get my RV-6A completed to do this.
You can expect much more empirical data on my website in the near future.
You have spent an inordinate amount of time bashing my company. Quite frankly,
as a lobbyist, you have failed.
Regards,
Jim Ayers
---------------------------------
Message 2
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| Subject: | Re: changing props (Dear Jim why MT?) |
Good Morning George,
I received your email to the RV-7 list this morning. I really enjoy reading
your phantasm facts.
In your mind, I did not know how to collect accurate cruise performance data.
Perhaps you can provide me with the appropriate procedure to collect
accurate cruise performance data.
From the following quote, I believe your are now starting to bring out the
real issues. If I might quote your most recent email.
"When I first talk to you you about your data almost a year ago, you where
quite rude, disrespectful and condescending. Sorry I am an engineer and you
are not. I also can tell you don't understand aerodynamics."
Now you have finally started to state your assumptions.
I have a strong tendency to believe other people follow the Golden Rule. If
I was quite rude, disrespectful and condescending of you, it is very likely
that was how I was being treated by you.
It's really very simple: if you don't want to be treated in that manner,
don't treat me in that manner.
I have a BSME degree from California State University at Long Beach.
I don't know where you graduated. Although you didn't actually say you are
a graduate engineer.
Try sticking to one subject. Speculating on my knowledge of aerodynamics is
off your topic of proper cruise performance data gathering.
I use one aircraft for all of the flight tests. There are no modifications
or changes to this aircraft during the flight test period for all of the
propellers flown.
I do not have any instrumentation on the aircraft to measure winds aloft.
Any reference to ground speed by GPS would introduce an unknown, and therefore
unacceptable, error into the data.
My flight test area is 20 to 80 miles off the coast.
You have chosen a public forum, instead of a direct email, to vent your
spleen. Now it is your turn to toe the mark.
Please provide an appropriate cruise performance procedure.
This is in no way a contract, direct or implied, for payment or use on the
part of Less Drag Products, Inc.
Regards,
Jim Ayers
President
Less Drag Products, Inc.
PS I suspect the RV-7 cowl for the Sensenich propeller has already been
fitted by now. Less we forget were this all started. :-)
Message 3
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| Subject: | Phantasm Facts (was: changing props (Dear Jim why MT?)) |
Good Morning Again George,
You said, "YOU CAN'T GO FASTER ON LESS HP!"
Using the data point you choose, and I quote:
SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
mph, but at 12,500 you are going 191mph????? Impossible! Why? You have
156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
According to the Lycoming data for the O-360 engine used and the actual
flight conditions, the engine was producing 134 hp at 2,500 feet and 103 hp at
12,500 feet.
As might be expected, the indicated airspeed at 2,500 feet was higher than
the indicated airspeed at 12,500 feet.
Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
When corrected for the density altitude, the True Indicated Airspeed was 187
mph at 2,500 feet and 191 mph at 12,500 feet. (These are the summary
numbers shown in the website data.)
And that's how you go faster on less power.
And theatrically, on 2.6 gph less fuel. (With a greater fuel savings at
altitude, if the aircraft owner is unwilling to lean to 30 degrees C ROP at the
lower altitudes and higher power settings achievable 3.3 gph decrease shown
in the website data.)
Regards,
Jim Ayers
_www.lessdrag.com_ (http://www.lessdrag.com)
The website data being discussed is on the "Lycoming O-360 propeller" page.
Just open the page and scroll down to it.
Message 4
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| Subject: | Phantasm Facts (was: changing props (Dear Jim why MT?)) |
You can't pay for this kind of entertainment. Hell, I might even learn
something.
_____
From: owner-rv7-list-server@matronics.com
[mailto:owner-rv7-list-server@matronics.com] On Behalf Of
LessDragProd@aol.com
Subject: RV7-List: Phantasm Facts (was: changing props (Dear Jim why MT?))
Good Morning Again George,
You said, "YOU CAN'T GO FASTER ON LESS HP!"
Using the data point you choose, and I quote:
SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
mph, but at 12,500 you are going 191mph????? Impossible! Why? You have
156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
According to the Lycoming data for the O-360 engine used and the actual
flight conditions, the engine was producing 134 hp at 2,500 feet and 103 hp
at 12,500 feet.
As might be expected, the indicated airspeed at 2,500 feet was higher than
the indicated airspeed at 12,500 feet.
Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
When corrected for the density altitude, the True Indicated Airspeed was 187
mph at 2,500 feet and 191 mph at 12,500 feet. (These are the summary
numbers shown in the website data.)
And that's how you go faster on less power.
And theatrically, on 2.6 gph less fuel. (With a greater fuel savings at
altitude, if the aircraft owner is unwilling to lean to 30 degrees C ROP at
the lower altitudes and higher power settings achievable 3.3 gph decrease
shown in the website data.)
Regards,
Jim Ayers
www.lessdrag.com
The website data being discussed is on the "Lycoming O-360 propeller" page.
Just open the page and scroll down to it.
Message 5
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MT?))
| Subject: | Phantasm Facts (was: changing props (Dear Jim why |
MT?))
--> RV7-List message posted by: flyer01@adelphia.net
---- Rick Rammos <rrammos@bonvivantc.com> wrote:
> You can't pay for this kind of entertainment. Hell, I might even learn
> something.
>
> No wonder you guys cant get your airplanes finished,but it is entertaining!
>
> _____
>
> From: owner-rv7-list-server@matronics.com
> [mailto:owner-rv7-list-server@matronics.com] On Behalf Of
> LessDragProd@aol.com
> Sent: Wednesday, December 14, 2005 3:21 PM
> To: rv7-list@matronics.com
> Subject: RV7-List: Phantasm Facts (was: changing props (Dear Jim why MT?))
>
>
>
> Good Morning Again George,
>
>
>
> You said, "YOU CAN'T GO FASTER ON LESS HP!"
>
>
>
> Using the data point you choose, and I quote:
>
>
>
> SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
> mph, but at 12,500 you are going 191mph????? Impossible! Why? You have
> 156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
> 115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
>
> According to the Lycoming data for the O-360 engine used and the actual
> flight conditions, the engine was producing 134 hp at 2,500 feet and 103 hp
> at 12,500 feet.
>
>
>
> As might be expected, the indicated airspeed at 2,500 feet was higher than
> the indicated airspeed at 12,500 feet.
>
> Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
>
>
>
> When corrected for the density altitude, the True Indicated Airspeed was 187
> mph at 2,500 feet and 191 mph at 12,500 feet. (These are the summary
> numbers shown in the website data.)
>
>
>
> And that's how you go faster on less power.
>
>
>
> And theatrically, on 2.6 gph less fuel. (With a greater fuel savings at
> altitude, if the aircraft owner is unwilling to lean to 30 degrees C ROP at
> the lower altitudes and higher power settings achievable 3.3 gph decrease
> shown in the website data.)
>
>
>
> Regards,
>
> Jim Ayers
>
> www.lessdrag.com
>
> The website data being discussed is on the "Lycoming O-360 propeller" page.
> Just open the page and scroll down to it.
>
>
>
Message 6
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| Subject: | Phantasm Facts (was: changing props (Dear Jim why MT?)) |
I really dont know whose side to take on all this. We may need to read
about 200 more of these back and forth between George and Jim before
deciding.
Chuck I.
-----Original Message-----
From: owner-rv7-list-server@matronics.com
[mailto:owner-rv7-list-server@matronics.com]On Behalf Of
LessDragProd@aol.com
Subject: RV7-List: Phantasm Facts (was: changing props (Dear Jim why MT?))
Good Morning Again George,
You said, "YOU CAN'T GO FASTER ON LESS HP!"
Using the data point you choose, and I quote:
SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
mph, but at 12,500 you are going 191mph????? Impossible! Why? You have
156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
According to the Lycoming data for the O-360 engine used and the actual
flight conditions, the engine was producing 134 hp at 2,500 feet and 103 hp
at 12,500 feet.
As might be expected, the indicated airspeed at 2,500 feet was higher than
the indicated airspeed at 12,500 feet.
Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
When corrected for the density altitude, the True Indicated Airspeed was 187
mph at 2,500 feet and 191 mph at 12,500 feet. (These are the summary
numbers shown in the website data.)
And that's how you go faster on less power.
And theatrically, on 2.6 gph less fuel. (With a greater fuel savings at
altitude, if the aircraft owner is unwilling to lean to 30 degrees C ROP at
the lower altitudes and higher power settings achievable 3.3 gph decrease
shown in the website data.)
Regards,
Jim Ayers
www.lessdrag.com <http://www.lessdrag.com>
The website data being discussed is on the "Lycoming O-360 propeller" page.
Just open the page and scroll down to it.
Message 7
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| Subject: | Phantasm Facts (was: changing props (Dear Jim why MT?)) |
They are both completely wrong. I am embarassed for both of these fine
fellows to be posting such combined poppycock. I have all the facts, and
they are not disputable, and you will all revel in the accuracy of my data.
I will forward these obvious facts to the list when the voice in my head
instructs me to do so.
Don
_____
From: owner-rv7-list-server@matronics.com
[mailto:owner-rv7-list-server@matronics.com] On Behalf Of Imken
Subject: RE: RV7-List: Phantasm Facts (was: changing props (Dear Jim why
MT?))
I really don't know whose side to take on all this. We may need to read
about 200 more of these back and forth between George and Jim before
deciding.
Chuck I.
-----Original Message-----
From: owner-rv7-list-server@matronics.com
[mailto:owner-rv7-list-server@matronics.com]On Behalf Of
LessDragProd@aol.com
Subject: RV7-List: Phantasm Facts (was: changing props (Dear Jim why MT?))
Good Morning Again George,
You said, "YOU CAN'T GO FASTER ON LESS HP!"
Using the data point you choose, and I quote:
SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
mph, but at 12,500 you are going 191mph????? Impossible! Why? You have
156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
According to the Lycoming data for the O-360 engine used and the actual
flight conditions, the engine was producing 134 hp at 2,500 feet and 103 hp
at 12,500 feet.
As might be expected, the indicated airspeed at 2,500 feet was higher than
the indicated airspeed at 12,500 feet.
Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
When corrected for the density altitude, the True Indicated Airspeed was 187
mph at 2,500 feet and 191 mph at 12,500 feet. (These are the summary
numbers shown in the website data.)
And that's how you go faster on less power.
And theatrically, on 2.6 gph less fuel. (With a greater fuel savings at
altitude, if the aircraft owner is unwilling to lean to 30 degrees C ROP at
the lower altitudes and higher power settings achievable 3.3 gph decrease
shown in the website data.)
Regards,
Jim Ayers
www.lessdrag.com
The website data being discussed is on the "Lycoming O-360 propeller" page.
Just open the page and scroll down to it.
Message 8
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| Subject: | Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) |
Gecko/20040804 Netscape/7.2 (ax)
Yep that it is... entertaining! AFA props and engines etc. What I know
is that the 72 inch CS Hartzell Blended airfoil prop on a AeroSport
IO360/180 will drive a RV7A past Vne TAS at 7000 ft. What else matters?
Tyler B N442TM
Rick Rammos wrote:
> You can't pay for this kind of entertainment. Hell, I might even
> learn something.
>
>
>
>
> From: owner-rv7-list-server@matronics.com
> [mailto:owner-rv7-list-server@matronics.com] On Behalf Of
> LessDragProd@aol.com
> Sent: Wednesday, December 14, 2005 3:21 PM
> To: rv7-list@matronics.com
> Subject: RV7-List: Phantasm Facts (was: changing props (Dear Jim why MT?))
>
>
>
> Good Morning Again George,
>
>
>
> You said, "YOU CAN'T GO FASTER ON LESS HP!"
>
>
>
> Using the data point you choose, and I quote:
>
>
>
> SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
> mph, but at 12,500 you are going 191mph????? Impossible! Why? You
> have
> 156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
> 115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
>
> According to the Lycoming data for the O-360 engine used and the
> actual flight conditions, the engine was producing 134 hp at 2,500
> feet and 103 hp at 12,500 feet.
>
>
>
> As might be expected, the indicated airspeed at 2,500 feet was higher
> than the indicated airspeed at 12,500 feet.
>
> Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
>
>
>
> When corrected for the density altitude, the True Indicated Airspeed
> was 187 mph at 2,500 feet and 191 mph at 12,500 feet. (These are the
> summary numbers shown in the website data.)
>
>
>
> And that's how you go faster on less power.
>
>
>
> And theatrically, on 2.6 gph less fuel. (With a greater fuel savings
> at altitude, if the aircraft owner is unwilling to lean to 30 degrees
> C ROP at the lower altitudes and higher power settings achievable 3.3
> gph decrease shown in the website data.)
>
>
>
> Regards,
>
> Jim Ayers
>
> www.lessdrag.com <http://www.lessdrag.com>
>
> The website data being discussed is on the "Lycoming O-360 propeller"
> page. Just open the page and scroll down to it.
>
>
>
Message 9
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| Subject: | Phantasm Facts (was: changing props (Dear Jim why MT?)) |
Eh?...230mph on 180HP???...Sounds way fast...how come?
Frank
________________________________
From: owner-rv7-list-server@matronics.com
[mailto:owner-rv7-list-server@matronics.com] On Behalf Of T Bryant
Subject: Re: RV7-List: Phantasm Facts (was: changing props (Dear Jim why
MT?))
Yep that it is... entertaining! AFA props and engines etc. What I know
is that the 72 inch CS Hartzell Blended airfoil prop on a AeroSport
IO360/180 will drive a RV7A past Vne TAS at 7000 ft. What else matters?
Tyler B N442TM
Rick Rammos wrote:
You can't pay for this kind of entertainment. Hell, I might
even learn something.
=09
=09
________________________________
From: owner-rv7-list-server@matronics.com
[mailto:owner-rv7-list-server@matronics.com] On Behalf Of
LessDragProd@aol.com
Sent: Wednesday, December 14, 2005 3:21 PM
To: rv7-list@matronics.com
Subject: RV7-List: Phantasm Facts (was: changing props (Dear Jim
why MT?))
=09
Good Morning Again George,
=09
You said, "YOU CAN'T GO FASTER ON LESS HP!"
=09
Using the data point you choose, and I quote:
=09
SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500
going 186
mph, but at 12,500 you are going 191mph????? Impossible!
Why? You have
156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you
could do is
115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
According to the Lycoming data for the O-360 engine used and the
actual flight conditions, the engine was producing 134 hp at 2,500 feet
and 103 hp at 12,500 feet.
=09
As might be expected, the indicated airspeed at 2,500 feet was
higher than the indicated airspeed at 12,500 feet.
Specifically, 176 mph ias at 2,500 feet and 150 mph ias at
12,500 feet.
=09
When corrected for the density altitude, the True Indicated
Airspeed was 187 mph at 2,500 feet and 191 mph at 12,500 feet. (These
are the summary numbers shown in the website data.)
=09
And that's how you go faster on less power.
=09
And theatrically, on 2.6 gph less fuel. (With a greater fuel
savings at altitude, if the aircraft owner is unwilling to lean to 30
degrees C ROP at the lower altitudes and higher power settings
achievable 3.3 gph decrease shown in the website data.)
=09
Regards,
Jim Ayers
www.lessdrag.com
The website data being discussed is on the "Lycoming O-360
propeller" page. Just open the page and scroll down to it.
=09
Message 10
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| Subject: | Re: Phantasm Facts (phantom MT props data) |
Phantasm: That is the perfect word for your data.
You are right I am wrong OK, I just don't get it. The MT prop is the greatest
thing I have ever seen and every prop maker should just fold up shop and go home.
I hear if you climb up to 18,000 feet you can shut the engine down and the
MT prop will keep turning, making thrust forever, because it is so efficient,
it does not even need an engine. FANTASTIC!
Der-Vonder-prop dos Fliege
Jim every time you bring up something new and not relevant. Compare IAS to
IAS or TAS to TAS, that's that.
HP who cares. So what. You avoiding the FACTS and grasping, but stop. You win
I give up. I asked a few questions and you can't answer them so you divert and
confuse the issue with a non sequitur. Great have a nice day.
I get the concept of true airspeed and indicated airspeed, but this is not an
issue.
HP numbers you have mean nothing and are also way off anyway. You say 31 HP difference,
OK. Fine. I say 40HP. It still does not matter.
LOOK Van's aircraft data (180hp RV-6 solo), shows TRUE airspeed, WOT at sea level
is 210mph. This is called TOP SPEED for a reason. OK
At WOT at 8,000 feet, which is about 75% power (at 2400 rpm) is 199 mph.
Notice the speed drop 11 mph. WHY? A loss of about 45 HP. You can expect the
same +10 MPH true airspeed loss from 2,500 to 12,500 ft.
No prop can overcome 31, 40 or 45 HP loss and maintain thrust (and TAS), no matter
how efficient. Even with lower airframe drag, the loss of HP is too great
to be overcome by a prop, no matter how efficient. Don't believe me CALL MT
in Germany and ask. Oh they speak German. OH yea Hartzell engineers speak English,
it helps.
YOUR MT prop would need to be say need to gain about 30% more efficiency, least
110% efficient. JIM there is no such thing. 100% is perfect and that is not
physically in the history of aviation; 110% is ridiculous. RV's don't go faster
with altitude. You show a 4 mph increase climbing 10,000 feet, when a 10-14
mph decrease would be realistic. OK what you say is right I am wring I guess,
I give.
Strange enough you also show a humongous 20 MPH drop for the HARTZELL, BULL.
That is not true from Van's data, my experience or the analytical Hartzell data,
but I explained that before. You choose to ignore it and not address it. OK
So I don't know what you are driving at? What part of "your data is wrong" don't
you get?
OK you say you go 4 mph faster with a 10,000 foot climb, but funny thing is the
SAME PROP at 2700 RPM looses 10 mph for the 10,000' climb. Since it's the
same prop, speed vs. altitude change for a given RPM should be about the same,
with in a few MPH. One RPM goes +4, another RPM goes -10 mph? OK makes no sense
to me, but you are the expert. I give up, I'll let my Hartzell do the talking
when I pass you.
Folks find their Hartzell's are about 5-8 mph faster at 8000feet, 2500rpm. That
is a good indicator of overall performance advantage at all altitudes and RPMs.
Regardless of the your dash number, MTV-12-59a/b/c/d, or what ever, which may
be better than the original MTV-12(?), but you will never see huge large scale
changes in relative performance. Things are measured in fractions of a percent
or a few percent not 30%.
When Hartzell re-designed a new prop for the RV over the traditional C2YK/F7666
they got about 1.5% more efficiency. THAT IS FANTASTIC. Prop improvements are
measured in small increments. The C2YK was already an efficient prop (still
is). It is the gold standard, but the new "blended" did it one better, or 1.5%
better to be exact. That is really a fantastic achievement. Go USA.
Good Luck. I am out, done. ope you sell lots of MT props. George
LessDragProd@aol.com wrote:
Good Morning Again George,
You said, "YOU CAN'T GO FASTER ON LESS HP!"
Using the data point you choose, and I quote:
SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
mph, but at 12,500 you are going 191mph????? Impossible! Why? You have
156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
According to the Lycoming data for the O-360 engine used and the actual flight
conditions, the engine was producing 134 hp at 2,500 feet and 103 hp at 12,500
feet.
As might be expected, the indicated airspeed at 2,500 feet was higher than the
indicated airspeed at 12,500 feet.
Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
When corrected for the density altitude, the True Indicated Airspeed was 187
mph at 2,500 feet and 191 mph at 12,500 feet. (These are the summary numbers
shown in the website data.)
And that's how you go faster on less power.
And theatrically, on 2.6 gph less fuel. (With a greater fuel savings at altitude,
if the aircraft owner is unwilling to lean to 30 degrees C ROP at the lower
altitudes and higher power settings achievable 3.3 gph decrease shown in the
website data.)
Regards,
Jim Ayers
www.lessdrag.com
The website data being discussed is on the "Lycoming O-360 propeller" page.
Just open the page and scroll down to it.
---------------------------------
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| Subject: | Re: changing props (Dear Jim why MT?) |
There has to be a prop forum somewhere... To argue like this is ridiculous on the
RV List!! Please........
LessDragProd@aol.com wrote: Good Morning George,
I received your email to the RV-7 list this morning. I really enjoy reading
your phantasm facts.
In your mind, I did not know how to collect accurate cruise performance data.
Perhaps you can provide me with the appropriate procedure to collect accurate
cruise performance data.
From the following quote, I believe your are now starting to bring out the real
issues. If I might quote your most recent email.
"When I first talk to you you about your data almost a year ago, you where quite
rude, disrespectful and condescending. Sorry I am an engineer and you are
not. I also can tell you don't understand aerodynamics."
Now you have finally started to state your assumptions.
I have a strong tendency to believe other people follow the Golden Rule. If
I was quite rude, disrespectful and condescending of you, it is very likely that
was how I was being treated by you.
It's really very simple: if you don't want to be treated in that manner, don't
treat me in that manner.
I have a BSME degree from California State University at Long Beach.
I don't know where you graduated. Although you didn't actually say you are a
graduate engineer.
Try sticking to one subject. Speculating on my knowledge of aerodynamics is
off your topic of proper cruise performance data gathering.
I use one aircraft for all of the flight tests. There are no modifications or
changes to this aircraft during the flight test period for all of the propellers
flown.
I do not have any instrumentation on the aircraft to measure winds aloft. Any
reference to ground speed by GPS would introduce an unknown, and therefore unacceptable,
error into the data.
My flight test area is 20 to 80 miles off the coast.
You have chosen a public forum, instead of a direct email, to vent your spleen.
Now it is your turn to toe the mark.
Please provide an appropriate cruise performance procedure.
This is in no way a contract, direct or implied, for payment or use on the part
of Less Drag Products, Inc.
Regards,
Jim Ayers
President
Less Drag Products, Inc.
PS I suspect the RV-7 cowl for the Sensenich propeller has already been fitted
by now. Less we forget were this all started. :-)
Darrell Reiley
RV7A "Reiley Rocket"
N622DR Reserved
---------------------------------
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| Subject: | Re: changing props (Dear Jim why MT?) |
Finally. A reasonable statement.
Thanks.
Jim Ayers
In a message dated 12/14/2005 5:51:18 PM Pacific Standard Time,
lifeofreiley2003@yahoo.com writes:
There has to be a prop forum somewhere... To argue like this is ridiculous
on the RV List!! Please........
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| Subject: | Re: Phantasm Facts (was: changing props (Dear Jim why MT?)) |
Huh?!
Vne on the RV-7[A] is 230mph or 200knots. You mean to tell us you're getting 200
knots true? Sorry, I don't buy it. I assume you're kidding, in the spirit
of this silly thread & made-up data?
)_( Dan
RV-7 N714D (724 hours)
http://www.rvproject.com
----- Original Message -----
From: T Bryant
To: rv7-list@matronics.com
Sent: Wednesday, December 14, 2005 3:09 PM
Subject: Re: RV7-List: Phantasm Facts (was: changing props (Dear Jim why MT?))
Yep that it is... entertaining! AFA props and engines etc. What I know is that
the 72 inch CS Hartzell Blended airfoil prop on a AeroSport IO360/180 will drive
a RV7A past Vne TAS at 7000 ft. What else matters?
Tyler B N442TM
Rick Rammos wrote:
You can't pay for this kind of entertainment. Hell, I might even learn something.
From: owner-rv7-list-server@matronics.com [mailto:owner-rv7-list-server@matronics.com] On Behalf Of LessDragProd@aol.com
Sent: Wednesday, December 14, 2005 3:21 PM
To: rv7-list@matronics.com
Subject: RV7-List: Phantasm Facts (was: changing props (Dear Jim why MT?))
Good Morning Again George,
You said, "YOU CAN'T GO FASTER ON LESS HP!"
Using the data point you choose, and I quote:
SWEET SPOT? You show the MTV-12 at 2300 RPM at 2500 going 186
mph, but at 12,500 you are going 191mph????? Impossible! Why? You have
156HP @ 2300 RPM at 2,500 ft. At 12,500 ft the best you could do is
115HP (@ 2300 RPM). 6 MPH faster on 40HP less power!
According to the Lycoming data for the O-360 engine used and the actual flight
conditions, the engine was producing 134 hp at 2,500 feet and 103 hp at 12,500
feet.
As might be expected, the indicated airspeed at 2,500 feet was higher than
the indicated airspeed at 12,500 feet.
Specifically, 176 mph ias at 2,500 feet and 150 mph ias at 12,500 feet.
When corrected for the density altitude, the True Indicated Airspeed was 187
mph at 2,500 feet and 191 mph at 12,500 feet. (These are the summary numbers
shown in the website data.)
And that's how you go faster on less power.
And theatrically, on 2.6 gph less fuel. (With a greater fuel savings at altitude,
if the aircraft owner is unwilling to lean to 30 degrees C ROP at the
lower altitudes and higher power settings achievable 3.3 gph decrease shown in
the website data.)
Regards,
Jim Ayers
www.lessdrag.com
The website data being discussed is on the "Lycoming O-360 propeller" page.
Just open the page and scroll down to it.
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