Today's Message Index:
----------------------
1. 05:12 AM - Re: Cowling: Percent power. How to calculate? (923te)
2. 07:18 AM - Re: Cowling: Percent power. How to calculate? (Gil Alexander)
3. 07:32 AM - Re: Cowling: Percent power. How to calculate? (flyv35b)
4. 08:39 AM - Re: Cowling: Percent power. How to calculate? (923te)
5. 09:01 AM - Re: Cowling: Percent power. How to calculate? (az_gila)
6. 09:04 AM - Re: Cowling: Percent power. How to calculate? (Phil Kelsey)
7. 09:09 AM - Re: Cowling: Percent power. How to calculate? (923te)
8. 10:06 AM - Re: Cowling: Percent power. How to calculate? (az_gila)
9. 12:28 PM - Percent power. How to calculate? . . . Survey says! (teamgrumman@AOL.COM)
10. 02:49 PM - Re: Percent power. How to calculate? . . . Survey says! (Phil Kelsey)
11. 07:51 PM - Percent power. How to calculate? (GOLDPILOT@AOL.COM)
12. 10:02 PM - Re: Percent power. How to calculate? (teamgrumman@AOL.COM)
13. 10:02 PM - Re: Percent power. How to calculate? . . . Survey says! (teamgrumman@AOL.COM)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cowling: Percent power. How to calculate? |
Hi Gary,
I didn't really understand what you needed when I first read your email.
I guess I'm a little slooow but after rereading it a few times I have
something for you that might help. The Lycoming Operators Handbook
gives Figure 3-34 for determining power in flight. It replaces the
Figure 3-2 in earlier manuals that I think you were referring to. Anyway
Figure 3-34 is Fuel Flow VS Percent Rated Power. From there you can
determine HP from your fuel flow.
Attached Figure 3-34
Best Regards,
ned
----- Original Message -----
From: teamgrumman@aol.com
To: teamgrumman-list@matronics.com ; bpoe@avspec.net
Sent: Friday, April 24, 2009 6:19 PM
Subject: TeamGrumman-List: Cowling: Percent power. How to calculate?
Please read and make comments and recommendations if you have any
additional information.
OK, so, the FAA has been working on the paperwork submitted by myself
and the DER for the last month or so. There seems to be a hitch in
the
giddy-up: I used the POH to compute percent power for a 30=C2=B0F
OAT, 5000
feet, and 10.8 gph for 75% power. (Note: altimeter setting was 29.84
at 120 MSL with an OAT on the ground of 52=C2=B0F)
Problem 1: The POH I used is not an FAA approved document.
Apparently, the FAA wants the equivalent computation
based on the charts in the Lycoming Engine handbook. They could not
tell me if the handbook was or was not FAA approved. It isn't marked
as such.
Problem 2: The Lycoming Engine handbook itself.
The problem is, based on feedback from LyCon Engine
Rebuilder's engine/performance specialist, that the charts in the
Lycoming handbook are built from full throttle operation with a
constant speed propeller used to limit RPM at a given manifold
pressure.
I've researched articles from the Lycoming website. Specifically,
"Lycoming Flyer." Case in point: From Lycoming Flyer, General
Operation, page 22-23 (Note: material in "quotes" is quoted from the
Lycoming Flyer article.)
"As an example, the standard fixed pitch propeller supplied with an
aircraft may allow the engine to dev
elop 180 horsepower at 2700 RPM at
full throttle, in flight at sea level, with a standard temperature.
The
Lycoming O-360-A Series normally aspirated engine illustrates this
example."
For the test plane used (65 inch pitch), we could easily exceed 2700
rpm in level flight at 5000 feet. Therefore, we had to reduce
manifold
pressure (throttle) just to maintain engine operation below the 2700
rpm redline. (Note: the 65 inch pitch propeller is the maximum pitch
certified for this engine/plane combination)
"Next, let us assume that this same engine/propeller combination is
operated at 75% power with a =9Cbest economy=9D fuel/air
mixture setting.
Again, assume sea level and standard temperature to simplify and
standardize the discussion.
75% power will require about 2450 RPM with a brake-specific fuel
consumption of .435 pounds per brake horsepower hour. Also, 75% of the
180 rated horsepower is equal to 135 horsepower. Fuel usage at this
power and mixture setting will be 58.7 pounds per hour or 9.8 gallons
per hour."
Again, this is based on sea level operation. At 5000 feet, more
throttle is required, i.e., fuel flow, to obtain 75% power. The only
tool available to the owner/operator of the plane is the POH. So, now
what?
"With this information as background, it is easy to see that setting a
desired power with a fixed-pitch propeller can only be accomplished if
the pilot has a chart tha
t applies to the specific
aircraft/engine/propeller combination. Although the power chart for a
new aircraft may come from data obtained by test flying with a
calibrated torque meter, a fairly accurate chart can be derived for
any
fixed-pitch propeller and engine combination. Briefly, this is done by
finding the maximum available RPM at any particular altitude and
applying data from the propeller load curve.
To conclude, the purpose of this article is to make readers more aware
of some operational aspects of the fixed-pitch propeller. Usually, it
is only necessary to accept the material provided by the airframe
manufacturer and to use the engine/propeller as directed."
As quoted by Lycoming in their own reference, "the airframe
manufactures data should be used. "
=======================
Gary
PS, any feedback is welcome.
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cowling: Percent power. How to calculate? |
Ned... I'm not sure you can base instrumentation off this chart.
It assumes that you have leaned for "Peak Economy" hence the note on
the chart "Minimum Fuel Flow"
The experimental EMS systems don't seem to use fuel flow for % HP
calculations. I believe they base it on temp - manifold pressure - rpms.
gil A
>Hi Gary,
>
>I didn't really understand what you needed when I first read your
>email. I guess I'm a little slooow but after rereading it a few
>times I have something for you that might help. The Lycoming
>Operators Handbook gives Figure 3-34 for determining power in
>flight. It replaces the Figure 3-2 in earlier manuals that I think
>you were referring to. Anyway Figure 3-34 is Fuel Flow VS Percent
>Rated Power. From there you can determine HP from your fuel flow.
>....
>
>Best Regards,
>ned
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cowling: Percent power. How to calculate? |
The full throttle curve in Fig 3-2 is for engines with CS props and the pro
peller load curve is for a prop that is pitched to result in full throttle
at 2700 rpm. Any other situation would be a different curve. Fig. 3-34 is
for O-360-A4D, -F engines (don't know what the difference is but they shou
ld be very similar. Notice on this curve that the fuel flow makes a jog be
tween 75 and 80% power. The upper portion is a rich mixture, probably best
power, and the lower portion is a lean mixture, or best economy. If you a
re at peak on LOP the fuel flow will be relative and a fixed % or power but
on the rich side the fuel flow can be all over the place depending on wher
e you are on the curve, i.e., how rich.
Of course you (Gary) have a special situation that changes the relevance of
either of these curves! Probably the best curve to use (for FAA purposes)
would be Fig. 3-17 provided you have a MP gauge and use that along with RP
M, pressure alt. and OAT to determine % power. It is with an MA4-5 carb bu
t there should not be any significant difference with the HA-6.
I don't know where you came up with .435 BSFC. Fig. 3-2 shows the best BSF
C to be about .46 lb/hp-hr at 2350 rpm on the propeller load curve. I don'
t think you can get that low on any 8.5:1 CR Lycoming engine unless you hav
e FI or a pressure carb under the most ideal conditions.
Cliff
----- Original Message -----
From: 923te
To: teamgrumman-list@matronics.com
Sent: Tuesday, April 28, 2009 5:11 AM
Subject: Re: TeamGrumman-List: Cowling: Percent power. How to calculate=3F
Hi Gary,
I didn't really understand what you needed when I first read your email.
I guess I'm a little slooow but after rereading it a few times I have somet
hing for you that might help. The Lycoming Operators Handbook gives Figure
3-34 for determining power in flight. It replaces the Figure 3-2 in earlie
r manuals that I think you were referring to. Anyway Figure 3-34 is Fuel Fl
ow VS Percent Rated Power. From there you can determine HP from your fuel f
low.
Attached Figure 3-34
Best Regards,
ned
----- Original Message -----
From: teamgrumman@aol.com
To: teamgrumman-list@matronics.com ; bpoe@avspec.net
Sent: Friday, April 24, 2009 6:19 PM
Subject: TeamGrumman-List: Cowling: Percent power. How to calculate=3F
Please read and make comments and recommendations if you have any
additional information.
OK, so, the FAA has been working on the paperwork submitted by myself
and the DER for the last month or so. There seems to be a hitch in the
giddy-up: I used the POH to compute percent power for a 30=C2=B0F OAT, 500
0
feet, and 10.8 gph for 75% power. (Note: altimeter setting was 29.84
at 120 MSL with an OAT on the ground of 52=C2=B0F)
Problem 1: The POH I used is not an FAA approved document.
Apparently, the FAA wants the equivalent computation
based on the charts in the Lycoming Engine handbook. They could not
tell me if the handbook was or was not FAA approved. It isn't marked
as such.
Problem 2: The Lycoming Engine handbook itself.
The problem is, based on feedback from LyCon Engine
Rebuilder's engine/performance specialist, that the charts in the
Lycoming handbook are built from full throttle operation with a
constant speed propeller used to limit RPM at a given manifold
pressure.
I've researched articles from the Lycoming website. Specifically,
=22Lycoming Flyer.=22 Case in point: From Lycoming Flyer, General
Operation, page 22-23 (Note: material in =22quotes=22 is quoted from the
Lycoming Flyer article.)
=22As an example, the standard fixed pitch propeller supplied with an
aircraft may allow the engine to dev
elop 180 horsepower at 2700 RPM at
full throttle, in flight at sea level, with a standard temperature. The
Lycoming O-360-A Series normally aspirated engine illustrates this
example.=22
For the test plane used (65 inch pitch), we could easily exceed 2700
rpm in level flight at 5000 feet. Therefore, we had to reduce manifold
pressure (throttle) just to maintain engine operation below the 2700
rpm redline. (Note: the 65 inch pitch propeller is the maximum pitch
certified for this engine/plane combination)
=22Next, let us assume that this same engine/propeller combination is
operated at 75% power with a =9Cbest economy=9D fuel/air mixture settin
g.
Again, assume sea level and standard temperature to simplify and
standardize the discussion.
75% power will require about 2450 RPM with a brake-specific fuel
consumption of .435 pounds per brake horsepower hour. Also, 75% of the
180 rated horsepower is equal to 135 horsepower. Fuel usage at this
power and mixture setting will be 58.7 pounds per hour or 9.8 gallons
per hour.=22
Again, this is based on sea level operation. At 5000 feet, more
throttle is required, i.e., fuel flow, to obtain 75% power. The only
tool available to the owner/operator of the plane is the POH. So, now
what=3F
=22With this information as background, it is easy to see that setting a
desired power with a fixed-pitch propeller can only be accomplished if
the pilot has a chart tha
t applies to the specific
aircraft/engine/propeller combination. Although the power chart for a
new aircraft may come from data obtained by test flying with a
calibrated torque meter, a fairly accurate chart can be derived for any
fixed-pitch propeller and engine combination. Briefly, this is done by
finding the maximum available RPM at any particular altitude and
applying data from the propeller load curve.
To conclude, the purpose of this article is to make readers more aware
of some operational aspects of the fixed-pitch propeller. Usually, it
is only necessary to accept the material provided by the airframe
manufacturer and to use the engine/propeller as directed.=22
As quoted by Lycoming in their own reference, =22the airframe
manufactures data should be used. =22
=======================
Gary
PS, any feedback is nbsp; Features Chat, http://www.mnbsp;
via the Web href==22http://forums.matronics.com=22>http://forums.matronics.com
=5Fp; generous bsp; href==22http://www.matronics
.com/contribution=22>http://www.matronics.com/c================
--
We are a community of 6 million users fighting spam.
The Professional version does not have this message
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cowling: Percent power. How to calculate? |
Gil and Cliff,
I must be missing some paperwork. I just don't see what you guys are
basing your assumption upon. If you have more data I sure wuold like to
see it. Could you send it to me?
The Fig3-34 in my copy of the manual clearly states it is for O-360-A
series engines along with several other series. Why are you limitining
it to the O-360-A4D, -F?
The Lycoming Engine Operators manual says
Page 3-7
1) "maintain mixture control in "Full Rich" position for rated
....maximum cruise powers (above approximately 75%)."
2) "Operate the engine at maximum power mixture for performance cruise
powers and at best economy mixture for economy cruise power, unless
otherwise specified in the airplane owners manual."
Page 3-9:
3) 2. LEANING TO FLOWMETER "Lean to applicable fuel-flow tables or lean
to indicator marked for correct fuel flow for each power setting."
Page 3-50 Figure 3-34 Fuel Flow VS. Percent Rated Power for the O-360-A
Series (which by my assumption must include the A4K in the Tiger)
The logic of the manual seems clear:
A) Figure 3-34 is based on the above specified leaning practices and is
meant to be used in conjunction with Leaning based on Page 3-9 LEANING
TO FLOWMETER.
B) Figure 3-34 takes into account whether you are at best economy or
power and it is based on the leaning instructions given on page 3-7.
Notice Lycomings use of the term "approximately" and how that is
reflected on the figure in the change you noted from 75 - 80% power.
C) EVEN IF YOU DON'T AGREE WITH THE ABOVE
For the purposes of certification I would argue that Figure 3-34 gives
the manufactures data as concerns percentage power based upon fuel flow
when the engine is operated by the manufacures stated practices. I would
also argue that ALL the test flights whereby data was derived for the
certification of the "cowling" were operated in strict compliance with
the engine manufacures practices as stated in the manufactures manual
and therefore the manufacture provided data ie Figure 3-34 and ALL the
flight test derived data is authoritative and accurate. I would also
make it clear that the Lycoming Operators Manual States on Page 2 that
it is APPROVED BY FAA and because it is APPROVED BY FAA that there is no
question as to the applicability or validity of the data contained
therein to answer the current question / requirement posed by the FAA
D) I understand what you, Gary stated in PROBLEM 2.
I learned about that during my MT prop arguements with those that
argued going from 2500 to 2700rpm was going to get some additional 16 or
32 hp depending upon who was reading what curve...if the correct curve
is used one finds that only 6hp is gained.
I would not be concerned with PROBLEM 2. If for some reason you don't
like or cannot use the argument above based upon figure 3-34 then pick
another figure from the operators manual and make the same argument of
logic proposed in C) above.
Figure 3-34 gives the right engineering answer as far as Lycoming data
for power. The other figures may or may not give the right answer...BUT
it doesn't matter. What you need is to answer the FAA. They don't care
what or whether it's based upon right they just want it from an FAA
APPROVED source even if it's BS. Focus on giving them what they want and
not on what you'd like them to know!
Best Regards,
ned
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cowling: Percent power. How to calculate? |
Gary.... what was the manifold pressure reading at the 5000 ft measurement point
of your first post?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=241656#241656
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Cowling: Percent power. How to calculate? |
Gary, the link to the Benchmark website might help. It has downloadable software for calculating the HP of the 0-360 lycoming. It extrapolates from the Lycoming sea level power charts. http://www.seqair.com/benchmark/index.html
P. J. Kelsey
Vice President/Co-owner
ReliantAir
-----Original Message-----
From: owner-teamgrumman-list-server@matronics.com [mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of teamgrumman@aol.com
Sent: Friday, April 24, 2009 7:19 PM
Subject: TeamGrumman-List: Cowling: Percent power. How to calculate?
Please read and make comments and recommendations if you have any
additional information.
OK, so, the FAA has been working on the paperwork submitted by myself
and the DER for the last month or so. There seems to be a hitch in the
giddy-up: I used the POH to compute percent power for a 30F OAT, 5000
feet, and 10.8 gph for 75% power. (Note: altimeter setting was 29.84
at 120 MSL with an OAT on the ground of 52F)
Problem 1: The POH I used is not an FAA approved document.
Apparently, the FAA wants the equivalent computation
based on the charts in the Lycoming Engine handbook. They could not
tell me if the handbook was or was not FAA approved. It isn't marked
as such.
Problem 2: The Lycoming Engine handbook itself.
The problem is, based on feedback from LyCon Engine
Rebuilder's engine/performance specialist, that the charts in the
Lycoming handbook are built from full throttle operation with a
constant speed propeller used to limit RPM at a given manifold
pressure.
I've researched articles from the Lycoming website. Specifically,
"Lycoming Flyer." Case in point: From Lycoming Flyer, General
Operation, page 22-23 (Note: material in "quotes" is quoted from the
Lycoming Flyer article.)
"As an example, the standard fixed pitch propeller supplied with an
aircraft may allow the engine to dev
elop 180 horsepower at 2700 RPM at
full throttle, in flight at sea level, with a standard temperature. The
Lycoming O-360-A Series normally aspirated engine illustrates this
example."
For the test plane used (65 inch pitch), we could easily exceed 2700
rpm in level flight at 5000 feet. Therefore, we had to reduce manifold
pressure (throttle) just to maintain engine operation below the 2700
rpm redline. (Note: the 65 inch pitch propeller is the maximum pitch
certified for this engine/plane combination)
"Next, let us assume that this same engine/propeller combination is
operated at 75% power with a best economy fuel/air mixture setting.
Again, assume sea level and standard temperature to simplify and
standardize the discussion.
75% power will require about 2450 RPM with a brake-specific fuel
consumption of .435 pounds per brake horsepower hour. Also, 75% of the
180 rated horsepower is equal to 135 horsepower. Fuel usage at this
power and mixture setting will be 58.7 pounds per hour or 9.8 gallons
per hour."
Again, this is based on sea level operation. At 5000 feet, more
throttle is required, i.e., fuel flow, to obtain 75% power. The only
tool available to the owner/operator of the plane is the POH. So, now
what?
"With this information as background, it is easy to see that setting a
desired power with a fixed-pitch propeller can only be accomplished if
the pilot has a chart tha
t applies to the specific
aircraft/engine/propeller combination. Although the power chart for a
new aircraft may come from data obtained by test flying with a
calibrated torque meter, a fairly accurate chart can be derived for any
fixed-pitch propeller and engine combination. Briefly, this is done by
finding the maximum available RPM at any particular altitude and
applying data from the propeller load curve.
To conclude, the purpose of this article is to make readers more aware
of some operational aspects of the fixed-pitch propeller. Usually, it
is only necessary to accept the material provided by the airframe
manufacturer and to use the engine/propeller as directed."
As quoted by Lycoming in their own reference, "the airframe
manufactures data should be used. "
=======================
Gary
PS, any feedback is welcome.
E-mail message checked by Spyware Doctor (6.0.0.386)
Database version: 5.12230
http://www.pctools.com/en/spyware-doctor-antivirus/
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cowling: Percent power. How to calculate? |
Gary,
If you don't care about certification delays and you want to show your
local FAA guys how stupid they are, then you can make the argument that
what you have already calculated for them IS APPROVE BY FAA because the
guidance you followed is THE FAA APPROVED POH. THE Lycoming POH tells
one to use the AIRFRAME POH as follows from the quote below...so tell
The FAA tards that what you did is already blessed I mean APPROVED by
the FAA by default and cram it down their throats...or do it as
discussed previously ...
Page 3-7
2) "Operate the engine at maximum power mixture for performance cruise
powers and at best economy mixture for economy cruise power,
*******unless otherwise specified in the airplane owners manual."******
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cowling: Percent power. How to calculate? |
Gary... if I read this chart correctly, and you had 25 inches of manifold pressure,
then you were just over 160 HP at 2700 rpm.
gil A
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=241679#241679
Attachments:
http://forums.matronics.com//files/lyc_power001_859.pdf
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Percent power. How to calculate? . . . Survey says! |
My test condition had to be 30 F degree air for the carb heat rise
test.
I found 30 F degree air at roughly 5000 feet.
My next steps were:
(1) I used the POH (which is not FAA approved) to determine where 75%
power should be.
(2) I eye-balled the 5000 foot condition and it showed that I needed
roughly 2600 rpm and 11 gallons/hour
(2a) The plane had fuel flow so that part was easy.
(2b) The mechanical tach was plus or minus 20 rpm most of the
time.
(3) We did the carb heat rise test. We got the required 90 degree F
temperature rise.
(4) I then went into the POH and iterated on the data to determine the
values for the final test condition of
(4a) 5120 MSL
(4b) 30 F degree air
(4c) 2590 rpm
(4d) 10.8 gph.
(5) The final calculation for 75% power was 2592 rpm at 10.8 gph at 30F
at 2590 feet MSL.
So, my eyeball was close.
Note: I did not have a manifold pressure gauge since a manifold
pressure gauge is not required in a plane with a fixed pitch propeller.
I used the POH since that is what most of the pilots use to determine
percent power.
===========
Using the Lycoming Engine Manual:
(1) I have the Lycoming book. In it, my Figure 3-17 on my page 3-33 is
for O-360-A series with a MA-4/5 carb.
OK, the carb shouldn't make that much difference.
(2) I talked to Ken and Gary at Lycon and they tell me they have run
into this problem before with this figure, for fixed pitch props.
Their thought, the Lycoming data was determined from constant rpm at
specific manifold pressures. That is, using a constant speed
propeller, they determined percent power at specific manifold
pressures. The fuel flow they got was for those conditions.
(3) The resolution on the temperature scale on the figures in the
Lycoming book is guesswork at best.
(3a) Let's say, I pick 2600 rpm and 24 inches MAP (roughly wide
open throttle) for A at 5000 feet.
(3b) I use the same starting condition for B
(3c) if I pick, on the figure 3-17 for my Ts, at 5000 feet, I get
something like 40-45 F. Resolution really sucks.
(3d) drawing from C to D, I get about my test condition.
(4) Calculating the correction factor, I get about 1.01 to 1.06. So HP
= 152*1.01 or 1.016 = 153.4 or 154 for E
(5) going back across the chart to 2600 rpm for F,
(6) and dropping down to 2600 rpm for G, my fuel flow should be 12.8
gph and a lot more than 75% power.
(7) Conclusion. Test condition at 5000 feet, is no where near 75%
power with 24 inches MAP and full throttle.
Note: the charts are generated for full throttle operation at constant
rpms.
============
Three ways to compute % power.
(1) Using the POH from my plane, 75% power is at roughly 10.8 gph. (at
134 knots). Mixture recommended leaned.
(2) Using an FAA approved Flight Manual from a 2005 Tiger, 75% power is
at roughly 11.4 gph
with the mixture at best power. TAS is 128 knots Note: No
reference to rpm in Flight Manual.
(3) Using Lycomings chart, 75% power comes in at 11 gph at 2600, back
calculating . . . .
BUT, ONLY IF I START WITH AN INITIAL CONDITION OF 21.5 MAP AT
2600 RPM.
(3a) I could say this to the FAA, that these were my conditions,
but, without manifold pressure, I couldn't substantiate it.
============
In hind site, I wish I had installed a manifold pressure gauge. Both
the DER and I believed the POH is what pilots would be using to fly at
75% power. We had no idea that 75% power meant different things in
different references. We had no idea the FAA approved flight manual
for the AG5B would be a gallon an hour more under the same conditions.
============
Question (1) : Does anyone use the POH (or FAA approved Flight Manual)
to fly at percent power?
Question (2): IF so, just for grins, given what you know,
IF you were flying at 5000 feet and 30 degree air
What rpm and fuel flow would you be aiming for?
Question (3): Do you use the Lycoming reference to determine percent
power?
Question (4): What speed (TAS) would you expect to see?
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Percent power. How to calculate? . . . Survey |
says!
My 1979 Grumman Tiger's POH is published by Gulfstream Aerospace, Issued
9/30/76 and last revised (rev. 4) 5/12/1983. The title page contains the
this statement: "THIS HANDBOOK INCLUDES THE MATERIAL REQUIRED TO BE
FUNISHED TO THE PILOT BY FAR PART 23". Since it contains performance
information I would assume that it is required by the FAR'S and meets those
requirements, but who knows.
To answer your four questions:
- I have always used the POH to set power.
- 5,000' @ 30 degree pwr setting would be 2600 rpm 10.7 gph. Interpolated
because 30F degrees is not an option in the charts.
- I only use the Lycoming power chart with Turbo charged engines.
- I would expect to see 134 Kts.
-----Original Message-----
From: owner-teamgrumman-list-server@matronics.com
[mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of
teamgrumman@aol.com
Sent: Tuesday, April 28, 2009 3:26 PM
Subject: TeamGrumman-List: Percent power. How to calculate? . . . Survey
says!
My test condition had to be 30 F degree air for the carb heat rise
test.
I found 30 F degree air at roughly 5000 feet.
My next steps were:
(1) I used the POH (which is not FAA approved) to determine where 75%
power should be.
(2) I eye-balled the 5000 foot condition and it showed that I needed
roughly 2600 rpm and 11 gallons/hour
(2a) The plane had fuel flow so that part was easy.
(2b) The mechanical tach was plus or minus 20 rpm most of the
time.
(3) We did the carb heat rise test. We got the required 90 degree F
temperature rise.
(4) I then went into the POH and iterated on the data to determine the
values for the final test condition of
(4a) 5120 MSL
(4b) 30 F degree air
(4c) 2590 rpm
(4d) 10.8 gph.
(5) The final calculation for 75% power was 2592 rpm at 10.8 gph at 30F
at 2590 feet MSL.
So, my eyeball was close.
Note: I did not have a manifold pressure gauge since a manifold
pressure gauge is not required in a plane with a fixed pitch propeller.
I used the POH since that is what most of the pilots use to determine
percent power.
===========
Using the Lycoming Engine Manual:
(1) I have the Lycoming book. In it, my Figure 3-17 on my page 3-33 is
for O-360-A series with a MA-4/5 carb.
OK, the carb shouldn't make that much difference.
(2) I talked to Ken and Gary at Lycon and they tell me they have run
into this problem before with this figure, for fixed pitch props.
Their thought, the Lycoming data was determined from constant rpm at
specific manifold pressures. That is, using a constant speed
propeller, they determined percent power at specific manifold
pressures. The fuel flow they got was for those conditions.
(3) The resolution on the temperature scale on the figures in the
Lycoming book is guesswork at best.
(3a) Let's say, I pick 2600 rpm and 24 inches MAP (roughly wide
open throttle) for A at 5000 feet.
(3b) I use the same starting condition for B
(3c) if I pick, on the figure 3-17 for my Ts, at 5000 feet, I get
something like 40-45 F. Resolution really sucks.
(3d) drawing from C to D, I get about my test condition.
(4) Calculating the correction factor, I get about 1.01 to 1.06. So HP
= 152*1.01 or 1.016 = 153.4 or 154 for E
(5) going back across the chart to 2600 rpm for F,
(6) and dropping down to 2600 rpm for G, my fuel flow should be 12.8
gph and a lot more than 75% power.
(7) Conclusion. Test condition at 5000 feet, is no where near 75%
power with 24 inches MAP and full throttle.
Note: the charts are generated for full throttle operation at constant
rpms.
============
Three ways to compute % power.
(1) Using the POH from my plane, 75% power is at roughly 10.8 gph. (at
134 knots). Mixture recommended leaned.
(2) Using an FAA approved Flight Manual from a 2005 Tiger, 75% power is
at roughly 11.4 gph
with the mixture at best power. TAS is 128 knots Note: No
reference to rpm in Flight Manual.
(3) Using Lycomings chart, 75% power comes in at 11 gph at 2600, back
calculating . . . .
BUT, ONLY IF I START WITH AN INITIAL CONDITION OF 21.5 MAP AT
2600 RPM.
(3a) I could say this to the FAA, that these were my conditions,
but, without manifold pressure, I couldn't substantiate it.
============
In hind site, I wish I had installed a manifold pressure gauge. Both
the DER and I believed the POH is what pilots would be using to fly at
75% power. We had no idea that 75% power meant different things in
different references. We had no idea the FAA approved flight manual
for the AG5B would be a gallon an hour more under the same conditions.
============
Question (1) : Does anyone use the POH (or FAA approved Flight Manual)
to fly at percent power?
Question (2): IF so, just for grins, given what you know,
IF you were flying at 5000 feet and 30 degree air
What rpm and fuel flow would you be aiming for?
Question (3): Do you use the Lycoming reference to determine percent
power?
Question (4): What speed (TAS) would you expect to see?
E-mail message checked by Spyware Doctor (6.0.0.386)
Database version: 5.12250
http://www.pctools.com/en/spyware-doctor-antivirus/
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Percent power. How to calculate? |
What does Fred Kokoska have to say about your dilemma?
David
**************Access 350+ FREE radio stations anytime from anywhere on the
web. Get the Radio Toolbar!
(http://toolbar.aol.com/aolradio/download.html?ncid=emlcntusdown00000003)
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Percent power. How to calculate? |
why would I ask him?
-----Original Message-----
From: GOLDPILOT@aol.com
Sent: Tue, 28 Apr 2009 7:44 pm
Subject: TeamGrumman-List: Percent power. How to calculate?
What does Fred Kokoska have to say about your dilemma?
David
------------------------------------------------------------
Access 350+ FREE radio stations anytime from anywhere on the web. Get
the Radio Toolbar!
Message 13
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Percent power. How to calculate? . . . Survey |
says!
I flew a 2005 Tiger today with a JPI EDM 800 in it. The 800, as you
know, calculates percent power. It also has manifold pressure.
Between Concorde and Auburn at 5500 feet I found 2 C degree air (38.6
F).
Altimeter setting was 30.50 inches.
I went full throttle and got 23.8 inches of manifold pressure.
(Now, as we all should know by now, the inlet on the AG5B eats
about an inch of pressure so I would suspect the actual manifold
pressure should have been 24.5 inches or so.)
The MAX RPM I could turn was 2650 rpm. Leaned.
The JPI showed 78 percent power.
Fuel flow was 11.7 gph.
----------------------------------------------------------------------
I throttled back to 2590 rpm,
I set the fuel flow for 10.8 gph
MAP was 22.8 inches
The calculated percent power was 75%
It did bounce up to 76% for about 5 minutes so it could
have been on the edge of the calculated power band.
True Air Speed was 132 knots. as measure on the Garmin 430.
----------------------------------------------------------------------
Note, this is no where near the calculated values from the Lycoming
Operators manual.
Note, it is very close to my POH.
Note, compared to the approved flight manual (FM) in the 2005 Tiger
LLC,
what I saw was a faster plane on less fuel at 75% power than
the FM claims.
Note, Given 23.8 MAP and 2650 rpm, at wide open throttle
if I use figure 3-17, Lycoming's Sea-Level and Altitude
Performance, I get 155 hp at 13.5 gph.
(that's 86% power)
----------------------------------------------------------------------
Something is not copasetic.
----------------------------------------------------------------------
I wish my plane was back together. I'd like to run a comparison with
mine and the same airbox/inlet as on the test plane.
-----Original Message-----
From: Phil Kelsey <Phil@ReliantAir.com>
Sent: Tue, 28 Apr 2009 2:47 pm
Subject: RE: TeamGrumman-List: Percent power. How to calculate? . . .
Survey says!
<Phil@ReliantAir.com>
My 1979 Grumman Tiger's POH is published by Gulfstream Aerospace, Issued
9/30/76 and last revised (rev. 4) 5/12/1983. The title page contains
the
this statement: "THIS HANDBOOK INCLUDES THE MATERIAL REQUIRED TO BE
FUNISHED TO THE PILOT BY FAR PART 23". Since it contains performance
information I would assume that it is required by the FAR'S and meets
those
requirements, but who knows.
To answer your four questions:
- I have always used the POH to set power.
- 5,000' @ 30 degree pwr setting would be 2600 rpm 10.7 gph.
Interpolated
because 30F degrees is not an option in the charts.
- I only use the Lycoming power chart with Turbo charged engines.
- I would expect to see 134 Kts.
-----Original Message-----
From: owner-teamgrumman-list-server@matronics.com
[mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of
teamgrumman@aol.com
Sent: Tuesday, April 28, 2009 3:26 PM
Subject: TeamGrumman-List: Percent power. How to calculate? . . . Survey
says!
My test condition had to be 30 F degree air for the carb heat rise
test.
I found 30 F degree air at roughly 5000 feet.
My next steps were:
(1) I used the POH (which is not FAA approved) to determine where 75%
power should be.
(2) I eye-balled the 5000 foot condition and it showed that I needed
roughly 2600 rpm and 11 gallons/hour
(2a) The plane had fuel flow so that part was easy.
(2b) The mechanical tach was plus or minus 20 rpm most of the
time.
(3) We did the carb heat rise test. We got the required 90 degree F
temperature rise.
(4) I then went into the POH and iterated on the data to determine the
values for the final test condition of
(4a) 5120 MSL
(4b) 30 F degree air
(4c) 2590 rpm
(4d) 10.8 gph.
(5) The final calculation for 75% power was 2592 rpm at 10.8 gph at 30F
at 2590 feet MSL.
So, my eyeball was close.
Note: I did not have a manifold pressure gauge since a manifold
pressure gauge is not required in a plane with a fixed pitch propeller.
I used the POH since that is what most of the pilots use to determine
percent power.
===========
Using the Lycoming Engine Manual:
(1) I have the Lycoming book. In it, my Figure 3-17 on my page 3-33 is
for O-360-A series with a MA-4/5 carb.
OK, the carb shouldn't make that much difference.
(2) I talked to Ken and Gary at Lycon and they tell me they have run
into this problem before with this figure, for fixed pitch props.
Their thought, the Lycoming data was determined from constant rpm at
specific manifold pressures. That is, using a constant speed
propeller, they determined percent power at specific manifold
pressures. The fuel flow they got was for those conditions.
(3) The resolution on the temperature scale on the figures in the
Lycoming book is guesswork at best.
(3a) Let's say, I pick 2600 rpm and 24 inches MAP (roughly wide
open throttle) for A at 5000 feet.
(3b) I use the same starting condition for B
(3c) if I pick, on the figure 3-17 for my Ts, at 5000 feet, I get
something like 40-45 F. Resolution really sucks.
(3d) drawing from C to D, I get about my test condition.
(4) Calculating the correction factor, I get about 1.01 to 1.06. So HP
= 152*1.01 or 1.016 = 153.4 or 154 for E
(5) going back across the chart to 2600 rpm for F,
(6) and dropping down to 2600 rpm for G, my fuel flow should be 12.8
gph and a lot more than 75% power.
(7) Conclusion. Test condition at 5000 feet, is no where near 75%
power with 24 inches MAP and full throttle.
Note: the charts are generated for full throttle operation at constant
rpms.
============
Three ways to compute % power.
(1) Using the POH from my plane, 75% power is at roughly 10.8 gph. (at
134 knots). Mixture recommended leaned.
(2) Using an FAA approved Flight Manual from a 2005 Tiger, 75% power is
at roughly 11.4 gph
with the mixture at best power. TAS is 128 knots Note: No
reference to rpm in Flight Manual.
(3) Using Lycomings chart, 75% power comes in at 11 gph at 2600, back
calculating . . . .
BUT, ONLY IF I START WITH AN INITIAL CONDITION OF 21.5 MAP AT
2600 RPM.
(3a) I could say this to the FAA, that these were my conditions,
but, without manifold pressure, I couldn't substantiate it.
============
In hind site, I wish I had installed a manifold pressure gauge. Both
the DER and I believed the POH is what pilots would be using to fly at
75% power. We had no idea that 75% power meant different things in
different references. We had no idea the FAA approved flight manual
for the AG5B would be a gallon an hour more under the same conditions.
============
Question (1) : Does anyone use the POH (or FAA approved Flight Manual)
to fly at percent power?
Question (2): IF so, just for grins, given what you know,
IF you were flying at 5000 feet and 30 degree air
What rpm and fuel flow would you be aiming for?
Question (3): Do you use the Lycoming reference to determine percent
power?
Question (4): What speed (TAS) would you expect to see?
E-mail message checked by Spyware Doctor (6.0.0.386)
Database version: 5.12250
http://www.pctools.com/en/spyware-doctor-antivirus/
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|