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Date: Tue, 15 Oct 2013 07:53:14 -0400
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From: George Braly <gwbraly@gami.com>
Subject: RE: [LML] Re: Discussed engine management with the team from
 Continental Motors
Thread-Topic: [LML] Re: Discussed engine management with the team from
 Continental Motors
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Neal,

I agree with the comments about hair-splitting numbers.   However, I do not=
 agree that the use of the target fuel flow for LOP operations is inappropr=
iate.=20

Let me try to explain why I and others hold that view:

The target fuel flow is also verified during the leaning process by the obs=
ervation of a deceleration and loss of a small amount of speed.

The combination of those two factors makes it almost impossible - -  for th=
e fuel flow to be too high when LOP - - and thus the EGT/TIT to be too clos=
e to peak EGT/TIT. =20

But, as a third level of assurance that the mixture is set appropriately LO=
P - - the pilots are also trained to observe the subsequent CHT values.

Unless the pilot is in Alaska in the winter - - any mixture that is "not le=
an enough" - -  will result in CHTs that exceed the normally recommended 38=
0 d F value for continuous operation in cruise.   When that happens - - the=
 pilot is taught to reduce the target fuel flow slightly until the CHT drop=
s below 380dF.


Over the years - -  the use of the leaning paradigm described as  "slowly f=
ind peak on the first to peak cylinder - - then more slowly go ROP by xx de=
grees  (or find peak on the last to peak and then go LOP by yy degrees) "  =
is a methodology that works wonders for teaching a pilot to understand his =
engine and the relationship between fuel flow and engine operating conditio=
ns.  =20

However,  that paradigm has proven itself to also be unnecessary and even s=
ub-optimal for routine daily use.

Regards,  George

=20


-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Neal=
 George
Sent: Monday, October 14, 2013 12:18 PM
To: lml@lancaironline.net
Subject: [LML] Re: Discussed engine management with the team from Continent=
al Motors

Gentlemen -=20

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

The salient point of this subject is that the fuel flow indicated on airfra=
me-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/humi=
dity/density/RPM/et al can be both educational and entertaining.  But the t=
ypical ready-to-fly engine installation is not a laboratory-quality environ=
ment and the sharp-pencil, hair-splitting numbers derived on paper and adju=
sted 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. The=
n lean to achieve the recommended EGT (typically 75 deg F ROP or 50 deg F L=
OP).  Finally, observe the RESULTING fuel flow.  And either accept it or st=
art over with a different target for resulting power.=20

In other words, no matter how many times you have run the experiment in you=
r airplane and no matter how accurate and repeatable you believe your engin=
e 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
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=20
> correlated to HP, and that the fuel conversion HP/GPH is not a value=20
> measure of HP output.  His advice: best to use the graph provided in=20
> the manual (which is limited in RPM and not depicting LOP operations=20
> with precision).  He was saying that 19 GPH fuel flow at=20
> 34"/2500/19GPH is not the same HP engine output as 31.5"/2500/19GPH=20
> (still LOP at 19 GPH but closer to peak); this is different from what=20
> 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 airf=
low) is associated with HP production and LOP HP production in which only F=
F 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 knowl=
edge 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 Cont=
inental 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 dis=
cussing engine management settings commonly used, with opportunity for othe=
rs to listen and others to explain why they do what they do, perhaps modera=
ted by a Continental guy or GAMI people and/or an exemplary Lancair authori=
ty.  Old wives tales would be debunked, poor techniques would be scolded, a=
nd new settings could be integrated into all phases of flight for each indi=
vidual.
>=20
> One thing that was clearly stated by TCM: we should cruise at power setti=
ng no more than our Maximum Recommended Cruise.  If you don't have access t=
o 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(r) AIRCRAFT ENGINE PERMOLD SERIES ENGINE ENGINE INSTALLATION=
=20
> AND OPERATION MANUAL
>=20
> In my TSIO-550E, the maximum recommended cruise is 262 BHP @ 2500 RPM, wh=
ich is 75% of 350HP.  Elsewhere in the manual, this Rich of Peak (ROP) oper=
ation (75%) is listed to be at 29GPH fuel flow (ROP).
>=20
> Based on prior LML discussions with help from GAMI experts, and engine co=
mpression calculations, the Lean of Peak (LOP) fuel flow (GPH) to horsepowe=
r (HP) conversion ration for my TSIO550E is 13.73 HP/GPH (for 7.5:1 compres=
sion 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 di=
fferent prop RPM settins (2500-2540-2400-2350-2300) that the Hartzell Simit=
ar 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, independ=
ent 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 limit=
ed 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 differe=
nt from what our friends at GAMI have said.
>=20
> Comments welcomed.
>=20
> Jeff L
>=20
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>=20
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>=20
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