Using ship fuel as aviation fuel?

Hi Gord,

Yep...very good Friedrich...that's exactly as I see it...one
point, you use the term 'preignition' and although I see how you
meant it now (and you're correct) I never use that term unless
I'm describing the occurance of spark, it can be confused with
that..

possibly my mistake - I'm not a native English speaker. What you
described to me would have been "ignition advance" - the crank angle
before TDC when the spark occurs. What term would you use for occurence
of ignition before flamefront or before spark?

"Detonation will be evidenced by a rapid rise in cylinder head
temp, a rapid rise in oil temp, a rapid drop in torque closely
followed by structural parts of the engine emitting from the
exhaust stacks"

LOL! (not that it's funny when it happens to you in flight...)

I think they used that to scare the snot outta us engineers (it
worked too!)

Not so much on us automotive engineers today... A lot of modern
automotive engines are run right along the knock limit for efficiency,
with knock control constantly operating. To do this, there has to be a
knock event every now and then for the knock control to be able to
detect the limit. (Knock control just detects knock events and retards
the ignition. When there is no knock, ignition is advanced again until
the next knock occurs.) This normally works fine. However on some (not
all) engine types, on high load testbed runs this has recently led to
very rare statistical occurence of "super-knock" events, with
disastrous results.

I will be interested to see, how the proposed GAMI PRISM system is
going to work in this respect. As far as I understand it, the knock
detection principle is much more advanced than what you can afford on
an automotive engine (something about continuously measuring the
cylinder pressure), but there still has to be the occasional knock for
the system to know where the limit is.

regards,
Friedrich

--
for personal email please remove "entfernen" from my adress

"Thomas Schoene" wrote in message thlink.net...
R. David Steele wrote:
On 14 Apr 2004 22:44:09 -0700, (KDR)
wrote:

If necessary, is it possible to use F-76 as aviation fuel? I've read
somewhere that the RN's Invincible class carrier can trade off her
endurance for embarked air group's endurance by using ship fuel tanks
as 'swing tanks'. Can anyone confirm this one way or the other?

Thanks in advance

Do a little research.

I suggest the same for you, especialy before you dismiss a reasonable
question from a regualr, and usually well-informed, poster.

1) Ship power plants are not "jet engines" -- they are marine gas turbines.
Sometimes these are derived from aircraft jet engines, but they are not the
same. Terminology matters.

2) Marine gas turbines can burn fuels, like F76 diesel, that are not
considered suitable for aircraft engines. They can also burn jet fuel, but
the reverse is not true. A jet aircraft probably cannot burn F76, at least
not for very long. So I'd agree with several earlier posts that this
"swing" tankage would be jet fuel diverted to ship propulsion if need be,
rather than F76 diverted to aircraft use.

Most modern destroyers and cruisers are
powered by jet engines. The Ticonderoga ( CG-47) class and
the Spruance class (DD-963) plus new DD-X series (DD-21) are jet
powered (four engines to two shafts). The Perry class frigate
had two engines.

They have not announced how many engines DD(X) will use, but they have said
that it will probably be Rolls Royce MT-30s, not the GE LM2500s used in
other USN ships. DD(X)'s arrangements may be substantially different from
the other ships, since all-electric propulsion means that none of the
engines will be coupled directly to a propellor shaft.


Originally they were the same engines as used
by the L1011 (2500).

Nope. The L-1011 used the Rolls Royce RB211. I don't know if this has a
direct marine derivative.

I suppose the MT30/Trent could be regarded as the great-great great
grand-daughter of the RB211-22B on the Tristar

David


The GE LM2500 is derived from the TF39 (military) and CF6 (commercial) engin
es. These are used in the C-5 as well as the DC-10 and many other
airliners, but not the L-1011.

wrote:

of Keflavik. On reducing power from wet power (full) to METO
(climb) I noticed that number 3 engine's torque was about 20
pounds high (other engines were at ~140 pounds), by the time I
looked at the fuel flows and noticed that number 3 was much lower
than the others that engine started popping and banging and the
torque started to fall off rapidly. We punched it out and
continued climbing. Seeing as how the weather was fine all over
we continued to Summerside.

You had some sort of torque meter to watch?

I wasn't aware such an instrument was used on aircraft, or
actually anything off of a dyno.


SMH

wrote:

of Keflavik. On reducing power from wet power (full) to METO
(climb) I noticed that number 3 engine's torque was about 20
pounds high (other engines were at ~140 pounds), by the time I
looked at the fuel flows and noticed that number 3 was much lower
than the others that engine started popping and banging and the
torque started to fall off rapidly. We punched it out and
continued climbing. Seeing as how the weather was fine all over
we continued to Summerside.

You had some sort of torque meter to watch?

I wasn't aware such an instrument was used on aircraft, or
actually anything off of a dyno.


SMH

"Friedrich Ostertag" wrote:

Hi Gord,

Yep...very good Friedrich...that's exactly as I see it...one
point, you use the term 'preignition' and although I see how you
meant it now (and you're correct) I never use that term unless
I'm describing the occurance of spark, it can be confused with
that..

possibly my mistake - I'm not a native English speaker. What you
described to me would have been "ignition advance" - the crank angle
before TDC when the spark occurs. What term would you use for occurence
of ignition before flamefront or before spark?


Well, basically the term "preignition" I'd use to describe some
event 'prior to ignition' (or the 'time' of normal ignition -
spark), so if the mixture was ignited by a hot-spot somewhere in
the cylinder then that's 'preignition' (a verb referring to the
fact that it occurred prior to 'the time of ignition'. (a noun)

English is weird sometimes, I don't think you can refer to
preignition (as a verb) when describing any ignition event so I
usually refer to it as a noun (the time that the spark occurs -
or should occur)

"Detonation will be evidenced by a rapid rise in cylinder head
temp, a rapid rise in oil temp, a rapid drop in torque closely
followed by structural parts of the engine emitting from the
exhaust stacks"

LOL! (not that it's funny when it happens to you in flight...)

I think they used that to scare the snot outta us engineers (it
worked too!)

Not so much on us automotive engineers today... A lot of modern
automotive engines are run right along the knock limit for efficiency,
with knock control constantly operating. To do this, there has to be a
knock event every now and then for the knock control to be able to
detect the limit. (Knock control just detects knock events and retards
the ignition. When there is no knock, ignition is advanced again until
the next knock occurs.) This normally works fine. However on some (not
all) engine types, on high load testbed runs this has recently led to
very rare statistical occurence of "super-knock" events, with
disastrous results.


Yes, that's quite interesting to me, and it backs my opinion of
using low test fuel in my cars...I never use high test fuel at
all, mind you, I only use standard domestic vehicles but I
consider high test wasteful in modern engines with 'knock
control'.

I will be interested to see, how the proposed GAMI PRISM system is
going to work in this respect. As far as I understand it, the knock
detection principle is much more advanced than what you can afford on
an automotive engine (something about continuously measuring the
cylinder pressure), but there still has to be the occasional knock for
the system to know where the limit is.

regards,
Friedrich

Yes, I understand that, another good system that GAMI is looking
at is their accurate fuel injectors to enable automobile engines
to be run lean. We run (perhaps ran might be more accurate) large
recip aircraft engines at '10% lean from best power' (by manually
leaning them during cruise) for many thousands of hours and they
worked fine in that condition, matter of fact they'll continue to
run fine as much as about 30% lean before they get unstable, they
seem to love lean mixtures!...
--

-Gord.

Stephen Harding wrote:

wrote:

of Keflavik. On reducing power from wet power (full) to METO
(climb) I noticed that number 3 engine's torque was about 20
pounds high (other engines were at ~140 pounds), by the time I
looked at the fuel flows and noticed that number 3 was much lower
than the others that engine started popping and banging and the
torque started to fall off rapidly. We punched it out and
continued climbing. Seeing as how the weather was fine all over
we continued to Summerside.

You had some sort of torque meter to watch?

I wasn't aware such an instrument was used on aircraft, or
actually anything off of a dyno.


SMH

Oh yes Stephen, it's just about the main engine instrument, very
handy indeed...most large recips and even some turboprop a/c use
them...the C-130, P-3 Orion, Convair 580 to name a few, on these
three the torque gauges are called "Horse Power' but they
actually measure the amount of torque applied to the prop-shaft
by the engine.
--

-Gord.

We run (perhaps ran might be more accurate) large recip aircraft engines at
'10% lean from best power' (by manually
leaning them during cruise) for many thousands of hours and they worked fine
in that condition, matter of fact they'll continue to run fine as much as about
30% lean before they get unstable, they seem to love lean mixtures!..

Been there. Done that (R3350s). One problem is that the power curve is quite
steep on the lean side -- pilot has to be more careful. Never did it but have
been told if one can see the exhaust stacks, it is easier at night. One leans
until one gets the shape/color of exhaust flame that is "correct." Beyond me.

Quent

wrote:

In rec.aviation.military Peter Stickney wrote:

# Heating Oil is similar, but doesn't have the Dyes placed in U.S. #2
Diesel fuel to show that the necessary fuel taxes have been paid.

Uh, just a minor quibble, but my understanding is that they
dye the non-taxed stuff so that they can see the dye in over the
road trucks that have been cheating. I know, dying the non-taxed
seems backwards but that is what I have always seen on various web
pages related to diesel fuel issues. Here is a link to an EPA
document to support what I have said.

I know that you're right Bill, at least as far as Canada is
concerned...I remember on my grandfather's farm when he'd order
gasoline for use in farm vehicles the truck driver would pour a
little bottle of red dye into the storage tank after he had
filled it, this stuff will stain the carb on any vehicle red, I
don't know how in 'ell it gets out to do that but I assure you
that it does!...
--

-Gord.

(KDR) wrote in message om...
If necessary, is it possible to use F-76 as aviation fuel? I've read
somewhere that the RN's Invincible class carrier can trade off her
endurance for embarked air group's endurance by using ship fuel tanks
as 'swing tanks'. Can anyone confirm this one way or the other?

Thanks in advance

Many thanks for all the replies. Compared with F-76, how expensive is
JP-5? Is there any official move in the RN or USN to adopt JP-5 as a
single universal fuel?

KDR wrote:

Many thanks for all the replies. Compared with F-76, how expensive is
JP-5?

http://www.sd.fisc.navy.mil/FUEL/FUEL-INFOR-PAGE.HTML

JP-5 $1.03/gallon
DFM $0.98/gallon (DFM is Diesel fuel, Marine, another term for F-76)

That's roughly 5% difference. It may not seem like much, but considering
the Navy's overall fuels budget, it can really add up.


Is there any official move in the RN or USN to adopt JP-5 as a
single universal fuel?

Not that I've ever heard of.

--
Tom Schoene Replace "invalid" with "net" to e-mail
"Our country, right or wrong. When right, to be kept right, when
wrong to be put right." - Senator Carl Schurz, 1872