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Subject: Re: [LML] Re: Discussed engine management with the team from Continental Motors
From: Colyn Case <colyncase@earthlink.net>
In-Reply-To: <list-6540426@logan.com>
Date: Mon, 14 Oct 2013 22:25:53 -0400
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Message-Id: <FBC7BA49-2782-42DE-947C-EF8BDB195EDC@earthlink.net>
References: <list-6540426@logan.com>
To: "Lancair Mailing List" <lml@lancaironline.net>

Good reminder.  Thanks Neal.

On Oct 14, 2013, at 1:18 PM, Neal George wrote:

Gentlemen -=20

It's been a busy week and I've slept since then, so I don't remember =
exactly how the conversation got to that point, but I don't think that's =
quite what I said.  Perhaps I said it poorly.=20

The salient point of this subject is that the fuel flow indicated on =
airframe-mounted instruments is not a parameter to be set.  It is a =
result.=20

The absolute physics of the fuel-air-power equation are not in dispute.  =
In the abstract, a technical discussion centered on the math of =
fuel/air/humidity/density/RPM/et al can be both educational and =
entertaining.  But the typical ready-to-fly engine installation is not a =
laboratory-quality environment and the sharp-pencil, hair-splitting =
numbers derived on paper and adjusted in the test cell may not apply in =
the real world.=20

We set MAP and RPM per the charts to achieve the desired percent power. =
Then lean to achieve the recommended EGT (typically 75 deg F ROP or 50 =
deg F LOP).  Finally, observe the RESULTING fuel flow.  And either =
accept it or start over with a different target for resulting power.=20

In other words, no matter how many times you have run the experiment in =
your airplane and no matter how accurate and repeatable you believe your =
engine monitor to be, DO NOT lean to a target fuel flow.  EGTs are the =
parameter for leaning. Fuel flow is the result.=20

Neal George
Continental Motors=20
Technical Support
Sent from my iPhone

> On Oct 14, 2013, at 7:14 AM, "Walter Atkinson" =
<walter@advancedpilot.com> wrote:
>=20
> Jeff:
>=20
> **Interestingly, the TCM guy said that LOP operations is not =
correlated to HP, and that the fuel conversion HP/GPH is not a value =
measure of HP output.  His advice: best to use the graph provided in the =
manual (which is limited in RPM and not depicting LOP operations with =
precision).  He was saying that 19 GPH fuel flow at 34"/2500/19GPH is =
not the same HP engine output as 31.5"/2500/19GPH (still LOP at 19 GPH =
but closer to peak); this is different from what our friends at GAMI =
have said.**
>=20
> His comment is simply not in harmony with the laws of physics with =
which all scientific sources agree.
>=20
> He seems to be confused between HP production ROP in which RPM (mass =
airflow) is associated with HP production and LOP HP production in which =
only FF is a factor.  If you would be so kind as to provide me with his =
name in a PM to the email below, I will help Bill Ross (VP at TCM) =
improve his knowledge on the matter.=20
>=20
> Walter Atkinson
> <walter@advancedpilot.com>
> (225) 939-7508
>=20
>=20
>=20
>=20
>=20
> On Oct 12, 2013, at 6:00 PM, jeffrey liegner wrote:
>=20
> LML PIlots,
>=20
> At LOBO Greenville, I discussed engine management with the team from =
Continental Motors.  They provided their slides from their presentations =
(which I have reviewed) and I asked them many questions.  I communicated =
to Jeff Edwards that the group would definitely benefit from a group =
open forum discussing engine management settings commonly used, with =
opportunity for others to listen and others to explain why they do what =
they do, perhaps moderated by a Continental guy or GAMI people and/or an =
exemplary Lancair authority.  Old wives tales would be debunked, poor =
techniques would be scolded, and new settings could be integrated into =
all phases of flight for each individual.
>=20
> One thing that was clearly stated by TCM: we should cruise at power =
setting no more than our Maximum Recommended Cruise.  If you don't have =
access to the TCM engine manual for turbocharged TSIO550 series engines, =
here's the link:
>=20
> http://www.tcmlink.com/pdf2/MaintenanceManuals/OI-18/OI-18.pdf
> CONTINENTAL=AE AIRCRAFT ENGINE PERMOLD SERIES ENGINE=20
> ENGINE INSTALLATION AND OPERATION MANUAL=20
>=20
> In my TSIO-550E, the maximum recommended cruise is 262 BHP @ 2500 RPM, =
which is 75% of 350HP.  Elsewhere in the manual, this Rich of Peak (ROP) =
operation (75%) is listed to be at 29GPH fuel flow (ROP).
>=20
> Based on prior LML discussions with help from GAMI experts, and engine =
compression calculations, the Lean of Peak (LOP) fuel flow (GPH) to =
horsepower (HP) conversion ration for my TSIO550E is 13.73 HP/GPH (for =
7.5:1 compression ratio).  So LOP operations at 75% cruise (263HP) would =
be 19.15 GPH.
>=20
> I will occassionally cruise at 2500/34.0"/19GPH, when the flight is =
three hours or less, which some at LOBO felt is TOO MUCH cruise power =
(not that this is still below 75% power).
>=20
> I also occassionally cruise at 2500/31.5"/18 GPH, which is an OK =
setting for speed and economy.
>=20
> For long flights (and super economy), I will cruise at =
2350/31.5"/16.3GPH (64%).  If facing a headwind, I'll give it more gas =
to 17.1GPH (67%).
>=20
> I have noticed through a detailed study of indicated airspeed (IAS) at =
different prop RPM settins (2500-2540-2400-2350-2300) that the Hartzell =
Simitar 3-Blade prop's highest efficiency seems to be at 2350 RPM.  That =
is, IAS is best at same LOP fuel flows when the prop is turning 2350 =
RPM, independent of MAP.
>=20
> I'm sharing these engine settings in case anyone has comments.
>=20
> Interestingly, the TCM guy said that LOP operations is not correlated =
to HP, and that the fuel conversion HP/GPH is not a value measure of HP =
output.  His advice: best to use the graph provided in the manual (which =
is limited in RPM and not depicting LOP operations with precision).  He =
was saying that 19 GPH fuel flow at 34"/2500/19GPH is not the same HP =
engine output as 31.5"/2500/19GPH (still LOP at 19 GPH but closer to =
peak); this is different from what our friends at GAMI have said.
>=20
> Comments welcomed.
>=20
> Jeff L
>=20
> --
> For archives and unsub =
http://mail.lancaironline.net:81/lists/lml/List.html
>=20
>=20
>=20
> --
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