Today's Message Index:
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1. 01:55 AM - M14P RPM, manifold pressure (boost), power, fuel consumption (psb777)
2. 05:37 AM - Re: M14P RPM, manifold pressure (boost), power, fuel consumption (A. Dennis Savarese)
3. 05:49 AM - Re: M14P RPM, manifold pressure (boost), power, fuel consumption (psb777)
4. 05:53 AM - Re: Re: Low Boost? (A. Dennis Savarese)
Message 1
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| Subject: | M14P RPM, manifold pressure (boost), power, fuel consumption |
Following on from the "low boost" discussion, I have added a few columns to the table provided in the M14P maintenance manual and that enhanced table can be found here: http://bit.ly/M14P-fuel-consumption
Note that Po is atmospheric pressure and, as Dennis points out, that is 760 mmHg
at STP (sea level). With the engine off, the MP gauge should read atmospheric
pressure, a point only obvious to me after it was pointed out!
The supercharger on the M14P, according to this table, provides max 125 mmHg boost
at max RPM. This is only 5 inches boost in USA/imperial units.
--------
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=311785#311785
Message 2
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| Subject: | Re: M14P RPM, manifold pressure (boost), power, fuel consumption |
Very well done!
For anyone who is interested, here is the link on my web site which may
make understanding the M14 power chart a little clearer.
http://www.yak-52.com/Power%20Settings.htm
Dennis
----- Original Message -----
From: psb777
To: yak-list@matronics.com
Sent: Wednesday, September 08, 2010 3:54 AM
Subject: Yak-List: M14P RPM, manifold pressure (boost), power, fuel
consumption
Following on from the "low boost" discussion, I have added a few
columns to the table provided in the M14P maintenance manual and that
enhanced table can be found here: http://bit.ly/M14P-fuel-consumption
Note that Po is atmospheric pressure and, as Dennis points out, that
is 760 mmHg at STP (sea level). With the engine off, the MP gauge should
read atmospheric pressure, a point only obvious to me after it was
pointed out!
The supercharger on the M14P, according to this table, provides max
125 mmHg boost at max RPM. This is only 5 inches boost in USA/imperial
units.
--------
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=311785#311785
Message 3
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| Subject: | Re: M14P RPM, manifold pressure (boost), power, fuel consumption |
If I had known about your chart I wouldn't have had to do anything at all!
--------
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=311797#311797
Message 4
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RPM hunting - just for the heck of it, have you recently removed and
cleaned the prop governor oil/finger screen on the right side of the
nose case? Most likely not related to the manifold pressure
question/issue.
I would like to know what your field elevation is. As you know, the
manifold pressure gauge reads atmospheric pressure with the engine off.
Assuming your manifold pressure gauge is reasonably calibrated (from
what I have seen, many are not), 735 mm with the engine off would
suggest your field elevation is about 1000 feet or about 300 meters.
You can easily check the calibration of your manifold pressure gauge by
setting your field elevation on your altimeter and reading the Kollsman
window. US altimeters will need to be converted from inches to
millimeters. Compare the MP gauge to the altimeter. The MP gauge can
be adjusted. There is a small covered hole in the rear of the MP gauge.
If I remember correctly, it is a little stick-on cover. Remove it and
you will see the adjustment screw inside. You will need a special
slotted tool to adjust it. But it can be done.
Have you tightened all of the intake tube gland nuts and the intake tube
collars? If you have an intake drain kit, check to make sure there are
no leaks from the fittings on the intake drain kit. Any leaks around
the intake tubes will cause a reduction in manifold pressure. Check
the flexible hose from the top of the supercharger to the manifold
pressure gauge. The hose itself may be leaking.
Dennis
----- Original Message -----
From: Yakbaas
To: yak-list@matronics.com
Sent: Tuesday, September 07, 2010 3:22 PM
Subject: Yak-List: Re: Low Boost?
I have 735mm with engine off and only get 830mm on take-off
roll.Still get 99% on rpm.
Had 2 take-offs in the last 20 hours where the rpm "hunt" between 99%
and 89% (WOT),came back to 80% and still hunting 5% up and down.Only
when I set 70% and 700mm it stabilized.Never done it again!
I don't think the 2 are related though.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=311727#311727
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