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richard.goode(at)russiana
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 Posted: Fri Apr 23, 2010 9:53 pm Post subject: Power |
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There is only one way to measure power,and that is on a proper,callibrated dynonometer,corrected for temprature and pressure.
Our engine partner in Hungary has developed a clever system of a strain-gauge between engine and and prop which gives a continuous read-out of torque,so easily convertable to power while the engine is running-but only on the ground.
I'm happy to send photos to anyone interested in this.
We believe that it is accurate within 2%,when compared with dyno readings,but rather more scientific than a belief that some modification is worth 10%!!.
Thrust is fine to an extent,but can only give a relative figure since it depends on the efficiency of the prop.
Richard
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
[quote][b]
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cjpilot710(at)aol.com
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| Posted: Sat Apr 24, 2010 6:46 am Post subject: Power |
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Richard,
I do not disagree on a proper calibrated dynamometer test for engine power. To me however the final product is a measurable thrust. I agree that propeller efficiency would be the biggest factor on converting HP into thrust and you and I have seen a palfrey of props for the M-14 playing for just that aspect.
Once upon a time and far away, in the early days of the 707 power was measured in EPR (exhaust pressure ratio). As a co-pilot I had to sit (no crew concept back than) and listen to some captains expound that the engineers didn't know a hill of beans and that the EPR gage was obviously a poor design for figuring power. Their arguments were 'just look at the fuel flow gage' or ' line up the EGTs, that'll give you the same power across the wing'. Or my personal favorite ' adjust the throttle so that the fuel totalizers read the same'. I saw many a professional flight engineer in tears trying to over come those concepts.
The reason EPR were so important on the 707 was in trimming up the airplane which had a very real effect on fuel burn. Get the power squared out across the wing (yaw) than roll and rudder trim can be squared away with minima displacement. Next came the stabilizer adjustment which needed constant adjustment with fuel burn off.
In the end what we were only concern about was what thrust we were putting out. Some engine (low time ones) would have lower fuel flows and lower EGTs than an engine next to it on the same wing, that might be sucking a little more Kero and warmer, but they both had the same EPR setting. The over all trim of the airplane was more important gas wise.
Jim "Pappy" Goolsby
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mark.bitterlich(at)navy.m
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| Posted: Sat Apr 24, 2010 7:02 pm Post subject: Power |
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Pappy, I am going to weigh in on this one too and say that I agree with Richard. Engines are measured in horsepower and torque. Period. No matter what they hook to, whether it be a prop, or a driveshaft, they are measured with a dynamometer, or "dyno" for short. This includes most every engine ever developed including the WW-II radials you fly behind yourself.
Measuring thrust does indeed give relative performance indications. Relative, but not specific. If you are measuring horsepower, you need a dyno, and that is really all there is to that and I can't imagine how anyone could disagree.
Comparing thrust readings does give some indication of performance DIFFERENCES, but prop design has a MASSIVE influence on this kind of measurement.
Moving the discussion to jet engines is comparing apples to oranges. Piston engines have pretty much ALWAYS been rated in torque and horsepower. Jet engines have been measured in thrust.
Indeed the final answer in an airplane might be considered to be thrust, but typically a design engineer will match the prop to engine horsepower and torque and engine RPM, and sometimes even that fails and many attempts are made to get a good match between engine and prop. We've seen that ourselves with various props that have been bolted to the M-14!
By the way, EPR is still used. On the EA-6B using J-52P408's we still take N1 and N2 readings and do the math to display the raw data to the aircrew. And yes, all your statements about pilots equalizing fuel flow, EGT's, RPM, (you name it) are also true for our particular military members as well, which is why we computerized the EPR readout and made it more reliable. You again are also correct that different engines with different "numbers" (turbines) can put out the same EPR, mostly due to the way the engines were "trimmed" when in the engine test cell. Most of our engines are indeed trimmed to present the same EPR, even though fuel flow and EGT might be slightly different.
But this really comes back to the fact that we are not talking about turbines here, but in fact piston engines with a crankshaft, and engines of that type are rated by HP and torque and these numbers are developed by a dyno. But just to make things more complicated, just what is a "dyno" really?
With the prop connected to the output shaft of the M-14, we are putting a load on the engine and then trying to achieve thrust by moving air. We measure how hard we are "pulling" with a strain gage. This we call "thrust". But in reality, the engine is kept at a certain RPM by varying the pitch of the prop, so as to put exactly enough load on the engine to keep it from increasing in RPM. We all agree on this correct? We can also agree that the pitch of the prop is NOT under our control. It is under AUTOMATIC control. The only thing WE control is the engine RPM!
With a dyno, we really do almost exactly the same thing. We put a load on the engine. With a modern dyno, this load is variable and computer controlled. So is the throttle (as compared to older manually controlled models). Very accurate measurements are taken to determine air density. The computer runs the engine up to full power, and torque is measured as well as the load being applied. The engine is allowed to go to a pre-determined RPM, again controlled by a computer. The end result is accurate numbers across the whole RANGE that the engine operates in. Not just full power... but all the way across the whole RPM range! Every aspect of the engines performance is measured and recorded. I've been there and done this myself on a number of engines. This is not hear-say on my part ok?
But my point is simply... in EITHER case we are simply running an engine with a load on the crank. One is hooked to a prop and we use a strain gage. The other is hooked to a CALIBRATED load, and gives accurate measurements.
Remember, the statement was: "THIS ENGINE HAS 440 HORSEPOWER". The comment was not: "THIS ENGINE HAS 200 POUNDS MORE THRUST THAN WHEN WE STARTED".
If Bill Blackwell had an easy way to hook an M-14 to a Dyno, he'd do it. But that just is not easy. For anyone. Richard included. So we use what we can and make very rough estimates.
I again would like to ask just exactly what was done to this engine. If that exhaust system was just slapped on and a 10% increase in HP was claimed, I would look askance at that. But I think Bill PROBABLY tuned that engine and who knows what else was done.
Richard: Although I fully agree with you on the dyno issue, I also want to give a lot of credit to what Pappy is saying Not that I believe that pure prop thrust is the way to go, but the fact that prop thrust IS a measurement and it IS increasing. Americans are some of the best in the world at hot rodding an engine. The Australians are damn good too! Australians and Americans have always been big fans of drag racing. That said, I've seen ways to get more power out of piston engines, and Bill is applying these exact same techniques to what he is doing with the M-14. His valve selection types, his valve seal additions, gapless rings, piston designs, etc., all add up to a logical approach to coaxing more power out of the engine, rather than just applying more and more boost pressure from the supercharger. With a given cam design, equalizing cylinder power output, lowering and BALANCING exhaust gas flows, increasing timing, adding more fuel... all add to more power being produced. When fuel injection is fully realized, it's going to get REALLY interesting... and we all know everyone is trying their hand at getting THAT to work. In the end, is this engine putting out 440 HP or 400 HP? No one really knows for sure. But it sure looks really cool does it not? Regardless, I am just happy that Bill is working along these lines and we don't have to rely strictly on the Russians for coming out with higher powered M-14's. We're just very lucky we can do this under the Experimental rules that the FAA allows us.
Mark Bitterlich
________________________________
From: owner-yak-list-server(at)matronics.com on behalf of cjpilot710(at)aol.com
Sent: Sat 4/24/2010 10:44 AM
To: yak-list(at)matronics.com
Subject: Re: Power
Richard,
I do not disagree on a proper calibrated dynamometer test for engine power. To me however the final product is a measurable thrust. I agree that propeller efficiency would be the biggest factor on converting HP into thrust and you and I have seen a palfrey of props for the M-14 playing for just that aspect.
Once upon a time and far away, in the early days of the 707 power was measured in EPR (exhaust pressure ratio). As a co-pilot I had to sit (no crew concept back than) and listen to some captains expound that the engineers didn't know a hill of beans and that the EPR gage was obviously a poor design for figuring power. Their arguments were 'just look at the fuel flow gage' or ' line up the EGTs, that'll give you the same power across the wing'. Or my personal favorite ' adjust the throttle so that the fuel totalizers read the same'. I saw many a professional flight engineer in tears trying to over come those concepts.
The reason EPR were so important on the 707 was in trimming up the airplane which had a very real effect on fuel burn. Get the power squared out across the wing (yaw) than roll and rudder trim can be squared away with minima displacement. Next came the stabilizer adjustment which needed constant adjustment with fuel burn off.
In the end what we were only concern about was what thrust we were putting out. Some engine (low time ones) would have lower fuel flows and lower EGTs than an engine next to it on the same wing, that might be sucking a little more Kero and warmer, but they both had the same EPR setting. The over all trim of the airplane was more important gas wise.
Jim "Pappy" Goolsby
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kjkimball(at)aol.com
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| Posted: Sat Apr 24, 2010 7:36 pm Post subject: Power |
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FYI, Barrett precision engines will have their m14 test cell up and
running thus summer. At that time, there will actually be an accurate
test device in the USA for these engines. Thus device will Allow true
comparing tests of the claims made. It will be easy to test volt on
items to see the actual differences in performance.
Sent from my iPhone
Kevin
On Apr 24, 2010, at 11:01 PM, "Bitterlich, Mark G CIV Det Cherry
Point, MALS-14 64E" <mark.bitterlich(at)navy.mil> wrote:
[quote]
Point, MALS-14 64E" <mark.bitterlich(at)navy.mil>
Pappy, I am going to weigh in on this one too and say that I agree
with Richard. Engines are measured in horsepower and torque.
Period. No matter what they hook to, whether it be a prop, or a
driveshaft, they are measured with a dynamometer, or "dyno" for
short. This includes most every engine ever developed including the
WW-II radials you fly behind yourself.
Measuring thrust does indeed give relative performance indications.
Relative, but not specific. If you are measuring horsepower, you
need a dyno, and that is really all there is to that and I can't
imagine how anyone could disagree.
Comparing thrust readings does give some indication of performance
DIFFERENCES, but prop design has a MASSIVE influence on this kind of
measurement.
Moving the discussion to jet engines is comparing apples to
oranges. Piston engines have pretty much ALWAYS been rated in
torque and horsepower. Jet engines have been measured in thrust.
Indeed the final answer in an airplane might be considered to be
thrust, but typically a design engineer will match the prop to
engine horsepower and torque and engine RPM, and sometimes even that
fails and many attempts are made to get a good match between engine
and prop. We've seen that ourselves with various props that have
been bolted to the M-14!
By the way, EPR is still used. On the EA-6B using J-52P408's we
still take N1 and N2 readings and do the math to display the raw
data to the aircrew. And yes, all your statements about pilots
equalizing fuel flow, EGT's, RPM, (you name it) are also true for
our particular military members as well, which is why we
computerized the EPR readout and made it more reliable. You again
are also correct that different engines with different
"numbers" (turbines) can put out the same EPR, mostly due to the way
the engines were "trimmed" when in the engine test cell. Most of
our engines are indeed trimmed to present the same EPR, even though
fuel flow and EGT might be slightly different.
But this really comes back to the fact that we are not talking about
turbines here, but in fact piston engines with a crankshaft, and
engines of that type are rated by HP and torque and these numbers
are developed by a dyno. But just to make things more complicated,
just what is a "dyno" really?
With the prop connected to the output shaft of the M-14, we are
putting a load on the engine and then trying to achieve thrust by
moving air. We measure how hard we are "pulling" with a strain
gage. This we call "thrust". But in reality, the engine is kept
at a certain RPM by varying the pitch of the prop, so as to put
exactly enough load on the engine to keep it from increasing in
RPM. We all agree on this correct? We can also agree that the
pitch of the prop is NOT under our control. It is under AUTOMATIC
control. The only thing WE control is the engine RPM!
With a dyno, we really do almost exactly the same thing. We put a
load on the engine. With a modern dyno, this load is variable and
computer controlled. So is the throttle (as compared to older
manually controlled models). Very accurate measurements are taken
to determine air density. The computer runs the engine up to full
power, and torque is measured as well as the load being applied.
The engine is allowed to go to a pre-determined RPM, again
controlled by a computer. The end result is accurate numbers across
the whole RANGE that the engine operates in. Not just full power...
but all the way across the whole RPM range! Every aspect of the
engines performance is measured and recorded. I've been there and
done this myself on a number of engines. This is not hear-say on my
part ok?
But my point is simply... in EITHER case we are simply running an
engine with a load on the crank. One is hooked to a prop and we use
a strain gage. The other is hooked to a CALIBRATED load, and gives
accurate measurements.
Remember, the statement was: "THIS ENGINE HAS 440 HORSEPOWER".
The comment was not: "THIS ENGINE HAS 200 POUNDS MORE THRUST THAN
WHEN WE STARTED".
If Bill Blackwell had an easy way to hook an M-14 to a Dyno, he'd do
it. But that just is not easy. For anyone. Richard included. So
we use what we can and make very rough estimates.
I again would like to ask just exactly what was done to this
engine. If that exhaust system was just slapped on and a 10%
increase in HP was claimed, I would look askance at that. But I
think Bill PROBABLY tuned that engine and who knows what else was
done.
Richard: Although I fully agree with you on the dyno issue, I also
want to give a lot of credit to what Pappy is saying Not that I
believe that pure prop thrust is the way to go, but the fact that
prop thrust IS a measurement and it IS increasing. Americans are
some of the best in the world at hot rodding an engine. The
Australians are damn good too! Australians and Americans have
always been big fans of drag racing. That said, I've seen ways to
get more power out of piston engines, and Bill is applying these
exact same techniques to what he is doing with the M-14. His valve
selection types, his valve seal additions, gapless rings, piston
designs, etc., all add up to a logical approach to coaxing more
power out of the engine, rather than just applying more and more
boost pressure from the supercharger. With a given cam design,
equalizing cylinder power output, lowering and BALANCING exhaust gas
flows, increasing timing, adding more fuel... all add to more power
be!
ing produced. When fuel injection is fully realized, it's going to
get REALLY interesting... and we all know everyone is trying their
hand at getting THAT to work. In the end, is this engine putting
out 440 HP or 400 HP? No one really knows for sure. But it sure
looks really cool does it not? Regardless, I am just happy that
Bill is working along these lines and we don't have to rely strictly
on the Russians for coming out with higher powered M-14's. We're
just very lucky we can do this under the Experimental rules that the
FAA allows us.
Mark Bitterlich
________________________________
From: owner-yak-list-server(at)matronics.com on behalf of cjpilot710(at)aol.com
Sent: Sat 4/24/2010 10:44 AM
To: yak-list(at)matronics.com
Subject: Re: Power
Richard,
I do not disagree on a proper calibrated dynamometer test for engine
power. To me however the final product is a measurable thrust. I
agree that propeller efficiency would be the biggest factor on
converting HP into thrust and you and I have seen a palfrey of props
for the M-14 playing for just that aspect.
Once upon a time and far away, in the early days of the 707 power
was measured in EPR (exhaust pressure ratio). As a co-pilot I had
to sit (no crew concept back than) and listen to some captains
expound that the engineers didn't know a hill of beans and that the
EPR gage was obviously a poor design for figuring power. Their
arguments were 'just look at the fuel flow gage' or ' line up the
EGTs, that'll give you the same power across the wing'. Or my
personal favorite ' adjust the throttle so that the fuel totalizers
read the same'. I saw many a professional flight engineer in tears
trying to over come those concepts.
The reason EPR were so important on the 707 was in trimming up the
airplane which had a very real effect on fuel burn. Get the power
squared out across the wing (yaw) than roll and rudder trim can be
squared away with minima displacement. Next came the stabilizer
adjustment which needed constant adjustment with fuel burn off.
In the end what we were only concern about was what thrust we were
putting out. Some engine (low time ones) would have lower fuel
flows and lower EGTs than an engine next to it on the same wing,
that might be sucking a little more Kero and warmer, but they both
had the same EPR setting. The over all trim of the airplane was
more important gas wise.
Jim "Pappy" Goolsby
--
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cjpilot710(at)aol.com
Guest
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| Posted: Sat Apr 24, 2010 9:35 pm Post subject: Power |
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With a test cell, will be a great asset, practically if it has something that can accurately measure power.
Here is a question. I do not have the answer to this and I'm sure I may be simplifying this big time.
What if we took (say ) a CJ-6 with a straight M-14p (dymo tested at 360hp) engine and paddle prop.
We (figuratively) tie it to a tree. Than we run the engine full power and full rpm.
In the tie down line we have a gage that can measure the pull in pounds and that pull measured (say) 1,000 lbs.
We than tear down the engine and insert dome pistons.
We than put the engine back on the same airplane and again make a full power run.
This time the gage in the line reads 1,110 pounds in pull. An increase of 110 lbs pull.
If we have 1110/1000, I believe we have a 11.1% increase.
If original engine equaled 360hp, would the new configuration equal 399.96 hp (360+11.1%)?
BTW I was never known as being particularly astute in math.
Jim "Pappy" Goolsby
[quote][b]
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kjkimball(at)aol.com
Guest
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| Posted: Sun Apr 25, 2010 2:53 am Post subject: Power |
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Jim,
The short answer to your question is no. A 10% increase in thrust does not directly pair with the same % increase in horsepower. Thrust is a product of torque and it is possible to increase torque without increasing hp the same % as seen in auto engines. A dyno measures torque not horsepower. The hp numbers are derived from the torque readings and then corrected for the conditions at the moment of the run to a standard day.
Hp claims should be viewed as advertising and given just such value. For example, there are engine builders who claim 400+ hp from 540 lycomings when in fact, when tested show less hp than engines claiming 330hp.
So far with BPE m14p engines, we see about 300# increase in thrust compared to the stock engines. We have a pull test rig here to use for this. This is about 18% increase in thrust from stock while at the same time getting a decrease in head and oil temps, decrease in fuel burn at cruise etc.
Sent from my iPhoneKevin
On Apr 25, 2010, at 1:34 AM, cjpilot710(at)aol.com (cjpilot710(at)aol.com) wrote:
[quote]
With a test cell, will be a great asset, practically if it has something that can accurately measure power.
Here is a question. I do not have the answer to this and I'm sure I may be simplifying this big time.
What if we took (say ) a CJ-6 with a straight M-14p (dymo tested at 360hp) engine and paddle prop.
We (figuratively) tie it to a tree. Than we run the engine full power and full rpm.
In the tie down line we have a gage that can measure the pull in pounds and that pull measured (say) 1,000 lbs.
We than tear down the engine and insert dome pistons.
We than put the engine back on the same airplane and again make a full power run.
This time the gage in the line reads 1,110 pounds in pull. An increase of 110 lbs pull.
If we have 1110/1000, I believe we have a 11.1% increase.
If original engine equaled 360hp, would the new configuration equal 399.96 hp (360+11.1%)?
BTW I was never known as being particularly astute in math.
Jim "Pappy" Goolsby
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richard.goode(at)russiana
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| Posted: Sun Apr 25, 2010 4:34 am Post subject: Power |
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A 10% increase in thrust is a good indicator of 10% more power ,but no more than that.
Firstly,a prop will work more or less efficiently at certain powers-for example the V-530 props on Yaks has a problem to transmit more than 350 HP.
Seccondly temp.and air pressure are likely to change,and finally,a spring-type of gauge is not very accurate.
I go back to my original tennant,and that is,if someone makes any claim about power,or performance [or whatever] it should have been properly measured!
Richard
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
United Kingdom
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
[quote] ---
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Fly4fude
Joined: 24 Jan 2010
Posts: 12
Location: USA
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psb777
Joined: 12 Aug 2009
Posts: 34
Location: UK
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| Posted: Sun Apr 25, 2010 7:48 am Post subject: Re: Power |
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I'm frustrated by repeated attempts here by some to use
the terms torque, power and thrust as if they're
interchangeable terms, but I'll leave that alone, for the time
being at least.
Who needs any equipment to measure a power difference?
There is a much easier, cheaper, better and much more
reliable way of measuring the change in the power produced
by an aircraft engine. It doesn't tell you the absolute
level of power produced - but it does tell you very
accurately the difference in power caused by any
engine mod.
Accurately measure the rate of climb at a
nominated set speed in the aircraft before the mod.
Don't use the VSI - there is no reason for these
to be calibrated correctly - use the altimeter and
a stopwatch.
Then do the engine mod and repeat the experiment.
We want to keep drag the same so fly the modded a/c
at the same speed as before. Assure the a/c has
the same weight. Any power difference then goes
entirely into providing a different rate of climb.
The formula for the power difference is,
Pd = m * g * (v2 - v1)
where
g is acceleration due to gravity,
m is the aircraft mass in kg,
v1 and v2 are the original and new climb rate in m/s,
Pd is the power difference caused by the mod in Watts.
Knowing
g = 9.81 m/s/s
1 Horsepower is 747 W.
1 m/s = 197 ft/min
1 kg = 2.20 lb
then, in old units,
m is now the aircraft mass in lb,
v1 and v2 are the original and new climb rate but now in feet/min, and
Pd is the power difference caused by the mod but now in hp.
Pd*747 = m/2.2 * 9.81 * (v2 - v1)/197
or, simplifying,
Pd = m * (v2 - v1) / 33100
E.g.
An M14P mod is claimed to increase power from 360
to 440hp. Before the mod I climb my 3000lb Yak-18T
at 1200ft/min full throttle max-RPM at an exact set
speed. After the mod, same atmospheric conditions,
*same* speed I can climb at 1400ft/min all levers
forward.
The power increase is
3000 * (1400 - 1200) / 33100 = 18 hp
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Paul Beardsell
G-PYAK http://beardsell.com/flying/g-pyak
Yak-18T http://beardsell.com/flying/yak18t |
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viperdoc(at)mindspring.co
Guest
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| Posted: Sun Apr 25, 2010 8:44 am Post subject: Power |
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Yes and also by using the 18th century medical device known as the medicinal
smoke bellows for rectal lavage...aka blowing smoke up ones ass.
Doc
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viperdoc(at)mindspring.co
Guest
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| Posted: Sun Apr 25, 2010 8:49 am Post subject: Power |
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I knew an aeronautical engineer would climb out of the lurking woodwork
eventually. Where have you been so long?
Thanks for the info.
Doc
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kjkimball(at)AOL.COM
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| Posted: Sun Apr 25, 2010 12:50 pm Post subject: Power |
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Paul,
Cool. So if i understand your example, your aiplane would
Need to see 400 fpm increase in roc to 1600 fpm to realize a 10%
increase in hp.
Likewise, to go from 360 hp to 440 hp as in your example, your
airplane would need to see a roc increase of 882 fpm to 2082fpm.
That's huge at 73% increase in roc with a 22% increase in hp.
Hope my math is ok here Maybe I missed something on these calcs as I
am walking through lowes after a day on the lakes.
Sent from my iPhone
Kevin
On Apr 25, 2010, at 11:48 AM, "psb777" <matronics.com(at)beardsell.com>
wrote:
| Quote: |
I'm frustrated by repeated attempts here by some to use
the terms torque, power and thrust as if they're
interchangeable terms, but I'll leave that alone, for the time
being at least.
Who needs any equipment to measure a power difference?
There is a much easier, cheaper, better and much more
reliable way of measuring the change in the power produced
by an aircraft engine. It doesn't tell you the absolute
level of power produced - but it does tell you very
accurately the difference in power caused by any
engine mod.
Accurately measure the rate of climb at a
nominated set speed in the aircraft before the mod.
Don't use the VSI - there is no reason for these
to be calibrated correctly - use the altimeter and
a stopwatch.
Then do the engine mod and repeat the experiment.
We want to keep drag the same so fly the modded a/c
at the same speed as before. Assure the a/c has
the same weight. Any power difference then goes
entirely into providing a different rate of climb.
The formula for the power difference is,
Pd = m * g * (v2 - v1)
where
g is acceleration due to gravity,
m is the aircraft mass in kg,
v1 and v2 are the original and new climb rate in m/s,
Pd is the power difference caused by the mod in Watts.
Knowing
g = 9.81 m/s/s
1 Horsepower is 747 W.
1 m/s = 197 ft/min
1 kg = 2.20 lb
then, in old units,
m is now the aircraft mass in lb,
v1 and v2 are the original and new climb rate but now in feet/min, and
Pd is the power difference caused by the mod but now in hp.
Pd*747 = m/2.2 * 9.81 * (v2 - v1)/197
or, simplifying,
Pd = m * (v2 - v1) / 33100
E.g.
An M14P mod is claimed to increase power from 360
to 440hp. Before the mod I climb my 3000lb Yak-18T
at 1200ft/min full throttle max-RPM at an exact set
speed. After the mod, same atmospheric conditions,
*same* speed I can climb at 1400ft/min all levers
forward.
The power increase is
3000 * (1400 - 1200) / 33100 = 18 hp
--------
Paul Beardsell
HA-YAB http://beardsell.com/flying/ha-yab
Yak-18T http://beardsell.com/flying/yak18t
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=295635#295635
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psb777
Joined: 12 Aug 2009
Posts: 34
Location: UK
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| Posted: Sun Apr 25, 2010 1:04 pm Post subject: Re: Power |
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All correct except of course my 18T is rarely lighter than 3300 lb or 10% more than I said so its another 10% i.e. not 18hp but 20hp for an extra 200fpm
That's the point of course: For any 3300lb plane, with any engine, another 10hp is needed to add another 100fpm to the climb.
| kjkimball(at)AOL.COM wrote: | Paul,
Cool. So if i understand your example, your aiplane would
Need to see 400 fpm increase in roc to 1600 fpm to realize a 10%
increase in hp.
Likewise, to go from 360 hp to 440 hp as in your example, your
airplane would need to see a roc increase of 882 fpm to 2082fpm.
That's huge at 73% increase in roc with a 22% increase in hp.
Hope my math is ok here Maybe I missed something on these calcs as I
am walking through lowes after a day on the lakes.
Sent from my iPhone
Kevin
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_________________
Paul Beardsell
G-PYAK http://beardsell.com/flying/g-pyak
Yak-18T http://beardsell.com/flying/yak18t |
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N642K
Joined: 23 Jul 2008
Posts: 84
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| Posted: Sun Apr 25, 2010 6:50 pm Post subject: Re: Power |
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My two rules:
1. Money spent on the airplane always makes them faster and sexier.
2. Never do math in public.
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radiopicture
Joined: 23 Jun 2008
Posts: 263
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| Posted: Mon Apr 26, 2010 2:43 am Post subject: Power |
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I'll remember #1 when I'm relining my brakes.
On Apr 25, 2010, at 10:50 PM, N642K wrote:
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duncan1574(at)sbcglobal.n
Guest
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| Posted: Mon Apr 26, 2010 4:34 am Post subject: Power |
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Search the archives: Brian L. has had this discussion several times.
Russ
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N642K
Joined: 23 Jul 2008
Posts: 84
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MarkWDavis
Joined: 03 Jan 2007
Posts: 104
Location: Syracuse, KS
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| Posted: Mon Apr 26, 2010 6:52 am Post subject: Power |
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It also helps the airplane retain its snazzy appearance by not running off
the end of the runway into a ditch or taxiing into a gas pump.
Mark Davis
N44YK
---
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