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Standards for H.P. corr. factors ??



 
 
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  #1  
Old July 4th 07, 03:27 AM posted to rec.aviation.homebuilt
jerry wass
external usenet poster
 
Posts: 180
Default Standards for H.P. corr. factors ??

To what standards are today's(and/or yesterdays) A/C engines corrected to???

I find the older SAE J607--60F---29.92" Hg 0% humidity
SAE J1349--77F 29.234"Hg 0%
DIN 68F 29.92
JIS 77F 29.234 0%
?? J1995 77F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry
Ads
  #2  
Old July 4th 07, 02:33 PM posted to rec.aviation.homebuilt
Peter Dohm
external usenet poster
 
Posts: 1,754
Default Standards for H.P. corr. factors ??

"Jerry Wass" wrote in message
news
To what standards are today's(and/or yesterdays) A/C engines corrected

to???

I find the older SAE J607--60F---29.92" Hg 0% humidity
SAE J1349--77F 29.234"Hg 0%
DIN 68F 29.92
JIS 77F 29.234 0%
?? J1995 77F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry


To the best of my knowledge and recollection, they use International
Standard Atmosphere (ISA) and part of the definition, including 59F and
29.92"Hg, can be seen at: http://www.pilotsweb.com/wx/w_sense.htm#isa
However, little is stated in the article with regard to humidity except that
the atmosphere can contain a lot of water--which displaces the other gasses.
The figure of 5% was shown somewhere one the page, but was not tied to a
particular temperature.

I was also able to find a an article in Wikipedia:
http://en.wikipedia.org/wiki/Standar...e_and_pressure which
includes a table, about a third of the way down the page. The table
suggests that ISA is based upon 0% humidity--which would not be achieved in
real life.

I do know that the effect of humidity, especially at high temperatures, is
considerable on the takeoff roll and dramatic on climb performance. IIRC,
the reduction in horsepower due to humidity can be around 10%, while the
same amount of humidity would have only a 1% reduction in air density with
regard to the wings.

Considering that climb performance is entirely based on reserve power, above
that required to fly the aircraft, the result can be downright scary!

I have seen articles on the subject, including real numbers usefull for
pre-takeoff planning, but can not find any at the moment.

Peter


  #3  
Old July 4th 07, 03:34 PM posted to rec.aviation.homebuilt
jerry wass
external usenet poster
 
Posts: 180
Default Standards for H.P. corr. factors ??

Peter Dohm wrote:
"Jerry Wass" wrote in message
news
To what standards are today's(and/or yesterdays) A/C engines corrected

to???
I find the older SAE J607--60F---29.92" Hg 0% humidity
SAE J1349--77F 29.234"Hg 0%
DIN 68F 29.92
JIS 77F 29.234 0%
?? J1995 77F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry


To the best of my knowledge and recollection, they use International
Standard Atmosphere (ISA) and part of the definition, including 59F and
29.92"Hg, can be seen at: http://www.pilotsweb.com/wx/w_sense.htm#isa
However, little is stated in the article with regard to humidity except that
the atmosphere can contain a lot of water--which displaces the other gasses.
The figure of 5% was shown somewhere one the page, but was not tied to a
particular temperature.

I was also able to find a an article in Wikipedia:
http://en.wikipedia.org/wiki/Standar...e_and_pressure which
includes a table, about a third of the way down the page. The table
suggests that ISA is based upon 0% humidity--which would not be achieved in
real life.

I do know that the effect of humidity, especially at high temperatures, is
considerable on the takeoff roll and dramatic on climb performance. IIRC,
the reduction in horsepower due to humidity can be around 10%, while the
same amount of humidity would have only a 1% reduction in air density with
regard to the wings.

Considering that climb performance is entirely based on reserve power, above
that required to fly the aircraft, the result can be downright scary!

I have seen articles on the subject, including real numbers usefull for
pre-takeoff planning, but can not find any at the moment.

Peter

Thanks, Peter I found the above at -- wahiduddin.net/calc/cf.htm -


-But it seemed to be race car engine oriented--I recently rebuilt my
airplane engine & can measure all the parameters, but didn't know what
system of specs to use in order to compare it with the A/C engines in
use today--Jerry
  #4  
Old July 4th 07, 06:26 PM posted to rec.aviation.homebuilt
Charles Vincent
external usenet poster
 
Posts: 170
Default Standards for H.P. corr. factors ??

Jerry Wass wrote:
To what standards are today's(and/or yesterdays) A/C engines corrected
to???

I find the older SAE J607--60F---29.92" Hg 0% humidity
SAE J1349--77F 29.234"Hg 0%
DIN 68F 29.92
JIS 77F 29.234 0%
?? J1995 77F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry


I sincerely doubt it was the J607 standard used to rate the engines
since if you actually read the J607 standard you will see that it
clearly states that it was developed for basically lawnmower engines(
50 ci displacement and 20hp) You will also see that it allows for only
a ten percent correction to be applied. A real hoot when you see it
applied to a 500hp supercharged engine. However your question seems to
be what is the standard day used for calculations, rather than the
calculations applied, so I will say I believe the FAA uses standard day,
standard atmosphere at sea level with zero humidity calculated by the
formulas defined in the US Standard Atmosphere 1976 standard(Temperature
= 15C, specific humidity = 0.00 kg H2O/kg dry air, and pressure =
101325 Pa). I also believe that this standard is largely in agreement
with the international standard at near sea level altitudes that you are
concerned with.

As far as what standard was in effect at the time a particular engine
was certified, I can't tell you. There are versions of the US Standard
Atmosphere going back to 1958, and I do not know what correction factors
were applied.

The FAA engine certification tests are more rigorous than the typical
dyno run and require an endurance test that includes the following regimes:

(1) A 30-hour run consisting of alternate periods of five minutes at
takeoff power and speed, and five minutes at maximum best economy
cruising power or maximum recommended cruising power.

(2) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 75 percent maximum continuous
power and 91 percent maximum continuous speed.

(3) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 70 percent maximum continuous
power and 89 percent maximum continuous speed.

(4) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 65 percent maximum continuous
power and 87 percent maximum continuous speed.

(5) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 60 percent maximum continuous
power and 84.5 percent maximum continuous speed.

(6) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 50 percent maximum continuous
power and 79.5 percent maximum continuous speed.

(7) A 20-hour run consisting of alternate periods of 2 hours at maximum
continuous power and speed, and 2 hours at maximum best economy
cruising power or at maximum recommended cruising power

I will bet that many of the un-certified engines being marketed out
there couldn't finish the endurance test without swallowing an exhaust
valve.


Charles
  #5  
Old July 4th 07, 08:35 PM posted to rec.aviation.homebuilt
jerry wass
external usenet poster
 
Posts: 180
Default Standards for H.P. corr. factors ??

Charles Vincent wrote:
Jerry Wass wrote:
To what standards are today's(and/or yesterdays) A/C engines corrected
to???

I find the older SAE J607--60F---29.92" Hg 0% humidity
SAE J1349--77F 29.234"Hg 0%
DIN 68F 29.92
JIS 77F 29.234 0%
?? J1995 77F 29.53 0%
(29.53"Hg = 100KPa )


My guess is that it is the older J607--,but I'd like a 2nd opinion.

Thanks a Whole bunch--Jerry


I sincerely doubt it was the J607 standard used to rate the engines
since if you actually read the J607 standard you will see that it
clearly states that it was developed for basically lawnmower engines(
50 ci displacement and 20hp) You will also see that it allows for only
a ten percent correction to be applied. A real hoot when you see it
applied to a 500hp supercharged engine. However your question seems to
be what is the standard day used for calculations, rather than the
calculations applied, so I will say I believe the FAA uses standard day,
standard atmosphere at sea level with zero humidity calculated by the
formulas defined in the US Standard Atmosphere 1976 standard(Temperature
= 15C, specific humidity = 0.00 kg H2O/kg dry air, and pressure =
101325 Pa). I also believe that this standard is largely in agreement
with the international standard at near sea level altitudes that you are
concerned with.

As far as what standard was in effect at the time a particular engine
was certified, I can't tell you. There are versions of the US Standard
Atmosphere going back to 1958, and I do not know what correction factors
were applied.

The FAA engine certification tests are more rigorous than the typical
dyno run and require an endurance test that includes the following regimes:

(1) A 30-hour run consisting of alternate periods of five minutes at
takeoff power and speed, and five minutes at maximum best economy
cruising power or maximum recommended cruising power.

(2) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 75 percent maximum continuous
power and 91 percent maximum continuous speed.

(3) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 70 percent maximum continuous
power and 89 percent maximum continuous speed.

(4) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 65 percent maximum continuous
power and 87 percent maximum continuous speed.

(5) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 60 percent maximum continuous
power and 84.5 percent maximum continuous speed.

(6) A 20-hour run consisting of alternate periods of 1 hours at maximum
continuous power and speed, and hour at 50 percent maximum continuous
power and 79.5 percent maximum continuous speed.

(7) A 20-hour run consisting of alternate periods of 2 hours at maximum
continuous power and speed, and 2 hours at maximum best economy
cruising power or at maximum recommended cruising power

I will bet that many of the un-certified engines being marketed out
there couldn't finish the endurance test without swallowing an exhaust
valve.


Charles


Thanks, Charles, I'm inclined to agree with you--the 59F temp rings a
bell in my memory.
  #6  
Old July 5th 07, 01:26 AM posted to rec.aviation.homebuilt
Morgans[_2_]
external usenet poster
 
Posts: 3,924
Default Standards for H.P. corr. factors ??


"Charles Vincent" wrote

I will bet that many of the un-certified engines being marketed out there
couldn't finish the endurance test without swallowing an exhaust valve.


Time for someone to trot out the GM stress test for new engines.

It makes the FAA tests look like a walk in the park.

Anyone got a copy of that handy?
--
Jim in NC


  #7  
Old July 5th 07, 02:52 AM posted to rec.aviation.homebuilt
Charles Vincent
external usenet poster
 
Posts: 170
Default Standards for H.P. corr. factors ??

Morgans wrote:
"Charles Vincent" wrote

I will bet that many of the un-certified engines being marketed out there
couldn't finish the endurance test without swallowing an exhaust valve.


Time for someone to trot out the GM stress test for new engines.

It makes the FAA tests look like a walk in the park.

Anyone got a copy of that handy?


I have the GM Automotive Test Code for 1967 (the FAA test regime was
codified in 1964). It specifies a two hundred hour durability test,
whereas the FAA is one hundred and fifty hour endurance test for
reciprocating non supercharged engines or reciprocating single speed
supercharged engines. Two speed supercharged and helicopter engines are
longer as I recall. The GM test code requires the engine to complete a
200 hour test schedule "without major failure". The engine is cycled
between peak torque rpm and peak hp rpm +200 rpm (max rpm not to exceed
4600)on five minute intervals. Every five and a half cycles, speed to
be reduced to idle from max test speed by closing throttle for two
minutes, after which engine speed is brought up to maximum upshift speed
within 10 seconds +/- 5 seconds, the speed is then reduced again to the
peak torque rpm and the normal cycle is continued again. The engine is
inspected every twenty five hours for cranking compression, blowby, belt
tension and ignition timing. I don't have the current testing codes for
GM, and since GM isn't selling an uncertified engine for aircraft use, I
don't know the relevance and doesn't effect my belief that many of the
un-certified engines being marketed out there couldn't finish the
endurance test without swallowing an exhaust valve.

Charles


  #8  
Old July 5th 07, 03:47 AM posted to rec.aviation.homebuilt
Rich S.[_1_]
external usenet poster
 
Posts: 227
Default Standards for H.P. corr. factors ??

"Morgans" wrote in message
...


Time for someone to trot out the GM stress test for new engines.

It makes the FAA tests look like a walk in the park.

Anyone got a copy of that handy?


No, but I remember one test for the Chevy 350 V-8. They were trying to run
the test in the greater Los Angeles area and couldn't pass. It turned out
the intake air was more polluted than the specs for the exhaust emissions.

They had to move the laboratory out to some dry lake east of L.A. to run the
test. It passed. The exhaust was more pollution-free than the air in L.A.

Urban legend? I dunno, but I flew over L.A. in the 60's and had less than a
mile visibility on a clear day.

Rich S.


  #9  
Old July 5th 07, 03:50 AM posted to rec.aviation.homebuilt
Peter Dohm
external usenet poster
 
Posts: 1,754
Default Standards for H.P. corr. factors ??


"Charles Vincent" wrote in message
. ..
Morgans wrote:
"Charles Vincent" wrote

I will bet that many of the un-certified engines being marketed out

there
couldn't finish the endurance test without swallowing an exhaust valve.


Time for someone to trot out the GM stress test for new engines.

It makes the FAA tests look like a walk in the park.

Anyone got a copy of that handy?


I have the GM Automotive Test Code for 1967 (the FAA test regime was
codified in 1964). It specifies a two hundred hour durability test,
whereas the FAA is one hundred and fifty hour endurance test for
reciprocating non supercharged engines or reciprocating single speed
supercharged engines. Two speed supercharged and helicopter engines are
longer as I recall. The GM test code requires the engine to complete a
200 hour test schedule "without major failure". The engine is cycled
between peak torque rpm and peak hp rpm +200 rpm (max rpm not to exceed
4600)on five minute intervals. Every five and a half cycles, speed to
be reduced to idle from max test speed by closing throttle for two
minutes, after which engine speed is brought up to maximum upshift speed
within 10 seconds +/- 5 seconds, the speed is then reduced again to the
peak torque rpm and the normal cycle is continued again. The engine is
inspected every twenty five hours for cranking compression, blowby, belt
tension and ignition timing. I don't have the current testing codes for
GM, and since GM isn't selling an uncertified engine for aircraft use, I
don't know the relevance and doesn't effect my belief that many of the
un-certified engines being marketed out there couldn't finish the
endurance test without swallowing an exhaust valve.

Charles


I don't know of anything that is necessarily specific to any one automotive
brand, but a test procedure from some time in the 1990s has been posted to
this NG a couple of times. As of this time, I can't find it; either because
I can't remember the file name or because it died with an older computer.

To the best of my recollection, the more recent engine testing includes a
rather long run, possibly 100 total hours, at 100% power. Interestingly,
the actual purpose is to verify the effectiveness and durability of the
torsion dampener. Failure of the torsion dampener will cause a failure of
the crankshaft and/or drive train--as will its absence or incorrect
calibration--which should be of considerable interest on this NG.

I suspect that the cycling test between maximum torque and maximum power is
also primarily a verification of harmonic dampening; but that is only a
presumption on my part--with the discalimer that I am not an automotive
engineer.

In addition, there was mention of a temperature cycling test in which the
engine is repeatedly run at full throttle until normal temperature is
reached, shut down and chilled to below freezing, then started and run
immediately at full throttle until normal temperature is reached, etc. The
purpose was stated to be verification of the head gaskets and related
clamping force--especially on engines that were all or partly aluminum.

There is also a cycling test including an automatic transmission, in which
the engine repeatedly runs up through the gears and then back down--as
though a driver accelerated through the gears in drive with the accelerator
to the floor, then pulled the lever into low and coasted back
down--repeating the process over and over. According to the account which
was given, an engine will usually outlast multiple transmissions. Obvoiusly
the test has value in predicting warranty costs, but the exact purpose is a
mystery to me.

Further disclaimer: All of this is from memory and the true original source
is unknown, as is the brand of engine(s) involved.

Peter


  #10  
Old July 5th 07, 04:25 AM posted to rec.aviation.homebuilt
Dave S
external usenet poster
 
Posts: 406
Default Standards for H.P. corr. factors ??

Charles Vincent wrote:


I will bet that many of the un-certified engines being marketed out
there couldn't finish the endurance test without swallowing an exhaust
valve.


Charles


Mine could. Simply because it doesn't have valves.

On a side note that IS interesting about the certification requirements
and the endurance required.

I wonder how many "certified engines" are requiring rebuild at the
completion of a full regime used during the certification process.

Dave
Mazda rotary goin in a velocity SE
 




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