Using ship fuel as aviation fuel? [Archive]

John R Weiss

April 15th 04, 06:32 PM

"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?

I believe the ship can burn the jet fuel, but the jets cannot burn the ship's
diesel/turbine fuel.

Many modern jet engines are very sensitive to fuel type because of the high
temps and close tolerances within the engines. The older J-85 could use JP4 or
5; Jet A, A1, or B; and 115 AvGas; I don't remember if it could use F-76.
However, the J-52 could not use AvGas.

In the US navy, the nuclear powered carriers only carry JP4 or JP8 (and all
on-board diesel-powered equipment use the JP), so any smaller ships that refuel
from the carrier (a relatively common practice) get the jet fuel. I've talked
with several "oil kings" in the past, and they all told me the diesels much
preferred diesel fuel over JP because of its lubricity and energy content. The
big turbines didn't much care.

Another problem would be the aircraft engines' lesser tolerance for water
contamination. The ship would have to keep the higher contamination standards
for any fuel transferred to aircraft.

Harry Andreas

April 15th 04, 06:34 PM

In article >,
(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?

http://www.stormingmedia.us/31/3168/A316873.html

The Universal Fuel at Sea: Replacing F-76 with JP-5
Authors: Sermarini, Joseph T.; NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Abstract: This research investigates the feasibility, benefits, impacts
and costs of replacing F-76 with JP-5 and adopting JP-5 as the single
"universal fuel at sea". Joint Publication 4-03, Joint Bulk Petroleum
Doctrine states, "Department of Defense components should minimize the
number of bulk petroleum products that must be stocked and distributed".
DoD currently stores and distributes two fuels, F-76 and JP-5, for
shipboard use. As the universal fuel at sea JP-5 would replace F-76. All
shipboard systems, including boilers, turbine engines and diesel engines
that currently operate with F-76 should operate satisfactorily with JP-5.
Adopting JP-5 as the single fuel stocked and distributed for shipboard use
would simplify logistics support, maximize flexibility, and enhance the
readiness and sustainability of U.S. forces at sea.

Limitations: APPROVED FOR PUBLIC RELEASE

Description: Master's thesis

and an excellent tutorial at
http://www.uscg.mil/hq/elcbalt/docs/fueltest/PROPULSION%20FUEL%20GUIDE%201.pdf

--
Harry Andreas
Engineering raconteur

Tarver Engineering

April 15th 04, 06:44 PM

"John R Weiss" > wrote in message
news:7Hzfc.44106$xn4.148857@attbi_s51...

<snip>
> I've talked
> with several "oil kings" in the past, and they all told me the diesels
much
> preferred diesel fuel over JP because of its lubricity and energy content.
The
> big turbines didn't much care.

The high compression ratios for diesel piston engines cause detonation using
wide cut jet fuel.

Andrew C. Toppan

April 16th 04, 02:18 AM

On Fri, 16 Apr 2004 01:12:24 GMT, R. David Steele
/OMEGA> wrote:

>Do a little research. Most modern destroyers and cruisers are
>powered by jet engines. The Ticonderoga ( CG-47) class and

Research, indeed. None of the classes you cited burn jet fuel in
their engines. Maybe you should have researched that point?

>the Spruance class (DD-963) plus new DD-X series (DD-21) are jet

DD-21 was cancelled years ago.

>by the L1011 (2500). And the new series of LH(X) assault ships
>are also jet powered.

You mean LHD 8, and LHD(R)? There's no such thing as LHX.

--
Andrew Toppan --- --- "I speak only for myself"
"Haze Gray & Underway" - Naval History, DANFS, World Navies Today,
Photo Features, Military FAQs, and more - http://www.hazegray.org/

Thomas Schoene

April 16th 04, 02:56 AM

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.

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.

--
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

Thomas Schoene

April 16th 04, 02:57 AM

Andrew C. Toppan wrote:
> On Fri, 16 Apr 2004 01:12:24 GMT, R. David Steele
> /OMEGA> wrote:
>
>> Do a little research. Most modern destroyers and cruisers are
>> powered by jet engines. The Ticonderoga ( CG-47) class and
>
> Research, indeed. None of the classes you cited burn jet fuel in
> their engines.

Well, they can (and sometimes do) burn jet fuel, but they don't have to.

--
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

David Lesher

April 16th 04, 03:48 AM

"John R Weiss" > writes:

>In the US navy, the nuclear powered carriers only carry JP4 or JP8 (and all
>on-board diesel-powered equipment use the JP), so any smaller ships that refuel
>from the carrier (a relatively common practice) get the jet fuel.

?? I thought the Navy forbit anything but JP5 on board. To the extent
a Navy plane refueled at an AF base was not allowed below decks, until
"clean"...

JP4 was kero/gasoline/naptha/tolune or such; nasty low-flash stupf.
JP5's basically Jet-A, I think. And Jet-A is ultra-pure kero.

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

John R Weiss

April 16th 04, 05:34 AM

"David Lesher" > wrote...
>
> ?? I thought the Navy forbit anything but JP5 on board. To the extent
> a Navy plane refueled at an AF base was not allowed below decks, until
> "clean"...
>
> JP4 was kero/gasoline/naptha/tolune or such; nasty low-flash stupf.
> JP5's basically Jet-A, I think. And Jet-A is ultra-pure kero.

When the USAF started transitioning to JP-8 in the '80s, the Navy was relatively
slow to follow suit. When I was at China Lake in the early 90s, there was still
a mix of JP-4, JP-5, and JP-8 found at various USAF and Navy shore bases, though
JP-5 was still used exclusively on ships. However, there was talk at the time
about JP-8 eventually replacing both JP-4 and JP-5 (though that may have been
based on economic and/or political concerns, not on safety concerns). I haven't
followed the transition since I left the Navy in '94, so I don't know how widely
JP-8 was[n't] adopted for use at sea.

Also I don't know how provisions for Army/USMC vehicles are made on various
amphib and Maritime Prepositioning ships -- F-76/diesel, JP-5, JP-8, or some
combination. The most recent document I could find is DOD Directive 4140.25,
August 25, 2003 (http://www.dtic.mil/whs/directives/corres/text/d414025p.txt).
It designates F-76 as primary for ship propulsion, JP-5 as primary for sea-based
aircraft, and JP-8 for ground vehicles (though JP-5 can be substituted). So,
apparently JP-8 never came into accepted use at sea.

Eunometic

April 16th 04, 08:10 AM

"Tarver Engineering" > wrote in message >...
> "John R Weiss" > wrote in message
> news:7Hzfc.44106$xn4.148857@attbi_s51...
>
> <snip>
> > I've talked
> > with several "oil kings" in the past, and they all told me the diesels
> much
> > preferred diesel fuel over JP because of its lubricity and energy content.
> The
> > big turbines didn't much care.
>
> The high compression ratios for diesel piston engines cause detonation using
> wide cut jet fuel.

Multi-fuel diesel engines can be built and frequently are for the
military vehicles such as tanks. It involves specialy adjustable
injection systems and other provisions to do with lubriticity.
Running on Jet fuel or Gaoline is not problem in the short term for
such engines.

A critical factor for the diesel engine is the "cetane number" and it
is important to have a high centane number. A high cetane number
means that the fuel will ignite easily but burn slowly.

One problem that the German Fischer Tropsh snthetic fuel plants had in
WW2 was that the fuel had far to high a cetane number and burned a
little to slowly. This lowered efficiency and increased exhaust
temperature althout it had to be used frequently. The solution was to
blend the fuel with the low cetane output of the Bergius Hydrogenation
plants.

At one point prior to WW2 kerosene powered spark ignition were quite
popular and they still have their proponents.

Gas turbines are ofcourse indifferent to both centane number and
octane rating and even viscosity and are uneffected in life or
efficiency (whuch reduce in multifuel diesels)

At the moment there are attempts to develop 'photo detonation'
internal combustion engines that do not rely on deflageration
combustion (ie combustion along a flame front rather than by infra red
light) and thus will be indifferent to octane ratings.

scott s.

April 16th 04, 09:21 AM

"Thomas Schoene" > wrote in
hlink.net:

>
> 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.

In the 963/47 classes, there are cross connects from the JP-5 system
to the FO service system. We did a test, back in the 70s, running
one of the Allison GTGs on JP-5 only. I think NAVSEA was interested in
the impact on the fuel nozzles. I don't think the results showed that
JP-5 was cost effective as a replacement for Nato F-76.

IIRC, the emergency diesel (tandem Detroit Diesel) on the 1052s
were fed JP-5? I'm having a "senior moment" on that.

I suppose it could be fixed, but once JP-5 gets into the ship's service
system, I don't think you're allowed to use it in aircraft.

I don't recall ever getting JP-5 from any CV, but what I did get was
crap. I think CVs just use the opportunity to offload their off-spec
fuel.

I can't remember now what we burned at Great Lakes, either. Probably
commercial diesel.

scott s.
..

Friedrich Ostertag

April 16th 04, 09:40 AM

Hi NG,

> The high compression ratios for diesel piston engines cause
detonation using
> wide cut jet fuel.

Diesel engines cannot "detonate". The term "detonation" applies to
preignition of part of the charge before ignition or before the
flamefront has reached that portion of the charge. Sometimes if the
flamefront goes supersonic this is also called "detonation". Neither
can happen on a diesel engine, as the charge contains only air and the
fuel burnes as it is injected.

As said before, Diesel engines will burn jetfuel, however the
lubrication properties are much lower so the injection system has to be
designed to live with that. (As a matter of fact, the same thing
applies to Diesel engines for GA aircraft, which are just hitting the
market now, and all of which run on Jetfuel!) Also energy content is
somewhat lower. If designed for it, this can be compensated by
increasing the amount of injected fuel accordingly.

regards,
Friedrich

--
bitte für persönliche Antworten die offensichtliche Änderung an meiner
Adresse vornehmen

Tarver Engineering

April 16th 04, 03:44 PM

"Friedrich Ostertag" > wrote in message
...
> Hi NG,
>
> > The high compression ratios for diesel piston engines cause
> detonation using
> > wide cut jet fuel.
>
> Diesel engines cannot "detonate". The term "detonation" applies to
> preignition of part of the charge before ignition or before the
> flamefront has reached that portion of the charge.

Detonation refers to more energy being imparted to the fuel air mixture by
compression heating than can be absorbed without igniting the fuel.
Detonation damages rod bearings and is a serious problem over the long term
in reciprocating engines.

John R Weiss

April 16th 04, 04:51 PM

"Tarver Engineering" > wrote>...
>
> The high compression ratios for diesel piston engines cause detonation using
> wide cut jet fuel.

AFAIK, neither JP-5 nor JP-8 nor Jet A -- the 3 jet fuels currently in common
use -- are "wide cut."

Tarver Engineering

April 16th 04, 05:41 PM

"John R Weiss" > wrote in message
news:PhTfc.150671$w54.1052744@attbi_s01...
> "Tarver Engineering" > wrote>...
> >
> > The high compression ratios for diesel piston engines cause detonation
using
> > wide cut jet fuel.
>
> AFAIK, neither JP-5 nor JP-8 nor Jet A -- the 3 jet fuels currently in
common
> use -- are "wide cut."

One of them seems to be number one diesel, from what other posters have
posted here.

Friedrich Ostertag

April 16th 04, 09:43 PM

Hi,

> > Diesel engines cannot "detonate". The term "detonation" applies to
> > preignition of part of the charge before ignition or before the
> > flamefront has reached that portion of the charge.
>
> Detonation refers to more energy being imparted to the fuel air
mixture by
> compression heating than can be absorbed without igniting the fuel.

On a diesel, the fuel is not there until the very moment when it is
supposed to ignite. You cannot ignite pure air, no matter how much
energy you impart on it.

> Detonation damages rod bearings and is a serious problem over the
long term
> in reciprocating engines.

Detonation can do much more than that, serious detonation can kill an
engine within seconds. I have personally seen melted pistons after such
an event. But still detonation is only possible in spark ignition
engines, or to be more precise, in engines with external mixture
building.

regards,
Friedrich

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

Tarver Engineering

April 17th 04, 12:37 AM

"Friedrich Ostertag" > wrote in message
...
> Hi,
>
> > > Diesel engines cannot "detonate". The term "detonation" applies to
> > > preignition of part of the charge before ignition or before the
> > > flamefront has reached that portion of the charge.
> >
> > Detonation refers to more energy being imparted to the fuel air
> mixture by
> > compression heating than can be absorbed without igniting the fuel.
>
> On a diesel, the fuel is not there until the very moment when it is
> supposed to ignite. You cannot ignite pure air, no matter how much
> energy you impart on it.

In a turbine engine what you write is true, but you are going to have to
educate me as to the process further to make me believe. Note that not all
diesels are the same and I believe I have heard detonation in diesel engines
on starting fluid.

> > Detonation damages rod bearings and is a serious problem over the long
term
> > in reciprocating engines.
>
> Detonation can do much more than that, serious detonation can kill an
> engine within seconds. I have personally seen melted pistons after such
> an event. But still detonation is only possible in spark ignition
> engines, or to be more precise, in engines with external mixture
> building.

I don't buy it.

Jim E

April 17th 04, 07:15 AM

"Eunometic" > wrote in message
om...

>
> At the moment there are attempts to develop 'photo detonation'
> internal combustion engines that do not rely on deflageration
> combustion (ie combustion along a flame front rather than by infra red
> light) and thus will be indifferent to octane ratings.

Where can I learn more about this?
Curious old school gear head here

Jim E

John Keeney

April 17th 04, 07:26 AM

"Tarver Engineering" > wrote in message
...
>
> "Friedrich Ostertag" > wrote in message
> ...
> > Hi NG,
> >
> > > The high compression ratios for diesel piston engines cause
> > detonation using
> > > wide cut jet fuel.
> >
> > Diesel engines cannot "detonate". The term "detonation" applies to
> > preignition of part of the charge before ignition or before the
> > flamefront has reached that portion of the charge.
>
> Detonation refers to more energy being imparted to the fuel air mixture by
> compression heating than can be absorbed without igniting the fuel.
> Detonation damages rod bearings and is a serious problem over the long
term
> in reciprocating engines.

John, every power stroke of a diesel engine fits that definition.
Diesels, by definition, compress the fuel & air to the point the
fuel ignites.

Fred J. McCall

April 17th 04, 08:30 AM

"John R Weiss" > wrote:

:In the US navy, the nuclear powered carriers only carry JP4 or JP8 (and all
:on-board diesel-powered equipment use the JP), so any smaller ships that refuel
:from the carrier (a relatively common practice) get the jet fuel.

The US Navy uses neither of these fuels at sea, even to fill aircraft,
much less to fill large ship's tanks. The Navy switched from JP4
(which is a hideously dangerous fuel) to JP5 about half a century ago.
The Air Force later switched from JP4 to JP8 (essentially Jet-A).

The Navy currently uses JP8 ashore (because it's cheaper and easier to
get) and JP5 at sea (because it's safer).

--
"Insisting on perfect safety is for people who don't have the balls to
live in the real world." -- Mary Shafer, NASA Dryden

scott s.

April 17th 04, 11:23 AM

Fred J. McCall > wrote in
:

> "John R Weiss" > wrote:
>
>:In the US navy, the nuclear powered carriers only carry JP4 or JP8
>:(and all on-board diesel-powered equipment use the JP), so any smaller
>:ships that refuel from the carrier (a relatively common practice) get
>:the jet fuel.
>
> The US Navy uses neither of these fuels at sea, even to fill aircraft,
> much less to fill large ship's tanks. The Navy switched from JP4
> (which is a hideously dangerous fuel) to JP5 about half a century ago.
> The Air Force later switched from JP4 to JP8 (essentially Jet-A).

IIRC the minimum allowed flash point is 140F. I uderstand that even
a little JP4, if mixed with JP5, can dangerously lower flash point.

scott s.
..

Friedrich Ostertag

April 17th 04, 01:55 PM

Hi Mr. Tarver,

> > > > Diesel engines cannot "detonate". The term "detonation" applies
to
> > > > preignition of part of the charge before ignition or before the
> > > > flamefront has reached that portion of the charge.
> > >
> > > Detonation refers to more energy being imparted to the fuel air
> > mixture by
> > > compression heating than can be absorbed without igniting the
fuel.
> >
> > On a diesel, the fuel is not there until the very moment when it is
> > supposed to ignite. You cannot ignite pure air, no matter how much
> > energy you impart on it.
>
> In a turbine engine what you write is true, but you are going to have
to
> educate me as to the process further to make me believe.

What exactly is it you don't understand? You surely are aware, that a
diesel engine will intake pure air, compress it (much further than a
gasoline engine compresses the mixture - temperatures get really hot
just from the adiabatic compression), and then injects the fuel into
the compressed (and hot!) air, where it immediately ignites due to the
high temperature of the compressed air. Thus my comment, that the fuel
cannot preignite, as it is not there prior to the time it is supposed
to ignite. No preignition -> no detonation.

> Note that not all
> diesels are the same and I believe I have heard detonation in diesel
engines
> on starting fluid.

Now that's a different question, of course. As starting fluid is mixed
with the intake air, it will (on a diesel) ignite at a time of it's
choosing, when the compressed air is just hot enough.

But this has nothing to do with the question of detonation during
regular operation of a diesel engine on jetfuel.

> > > Detonation damages rod bearings and is a serious problem over the
long
> term
> > > in reciprocating engines.
> >
> > Detonation can do much more than that, serious detonation can kill
an
> > engine within seconds. I have personally seen melted pistons after
such
> > an event. But still detonation is only possible in spark ignition
> > engines, or to be more precise, in engines with external mixture
> > building.
>
> I don't buy it.

You do now?

regards,
Friedrich

--
bitte für persönliche Antworten die offensichtliche Änderung an meiner
Adresse vornehmen

Friedrich Ostertag

April 17th 04, 01:58 PM

Hi John,

> > Detonation refers to more energy being imparted to the fuel air
mixture by
> > compression heating than can be absorbed without igniting the fuel.
> > Detonation damages rod bearings and is a serious problem over the
long
> term
> > in reciprocating engines.
>
> John, every power stroke of a diesel engine fits that definition.
> Diesels, by definition, compress the fuel & air to the point the
> fuel ignites.

only air is compressed, but well beyond the point where fuel will
ignite! But the fuel is only added at the moment when it is supposed to
ignite.

regards,
Friedrich

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

Vince Brannigan

April 17th 04, 02:49 PM

Friedrich Ostertag wrote:

> Hi Mr. Tarver,
>
>
>>>>>Diesel engines cannot "detonate". The term "detonation" applies
>
> to
>
>>>>>preignition of part of the charge before ignition or before the
>>>>>flamefront has reached that portion of the charge.
>>>>
>>>>Detonation refers to more energy being imparted to the fuel air
>>>
>>>mixture by
>>>
>>>>compression heating than can be absorbed without igniting the
>
> fuel.
>
>>>On a diesel, the fuel is not there until the very moment when it is
>>>supposed to ignite. You cannot ignite pure air, no matter how much
>>>energy you impart on it.
>>
>>In a turbine engine what you write is true, but you are going to have
>
> to
>
>>educate me as to the process further to make me believe.
>
>
> What exactly is it you don't understand? You surely are aware, that a
> diesel engine will intake pure air, compress it (much further than a
> gasoline engine compresses the mixture - temperatures get really hot
> just from the adiabatic compression), and then injects the fuel into
> the compressed (and hot!) air, where it immediately ignites due to the
> high temperature of the compressed air. Thus my comment, that the fuel
> cannot preignite, as it is not there prior to the time it is supposed
> to ignite. No preignition -> no detonation.
>

actually you were fine down to this point. what you mean is that when
ther is no "premixing" there is no detonation. Detonation involves a
supersonic combustion wave moving through the mixture.

good discussion at http://www.safetynet.de/Seiten/articles/CMRNov99.pdf

Peter Stickney

April 17th 04, 03:03 PM

In article >,
"Friedrich Ostertag" > writes:
> Hi John,
>
>> > Detonation refers to more energy being imparted to the fuel air
> mixture by
>> > compression heating than can be absorbed without igniting the fuel.
>> > Detonation damages rod bearings and is a serious problem over the
> long
>> term
>> > in reciprocating engines.
>>
>> John, every power stroke of a diesel engine fits that definition.
>> Diesels, by definition, compress the fuel & air to the point the
>> fuel ignites.
>
> only air is compressed, but well beyond the point where fuel will
> ignite! But the fuel is only added at the moment when it is supposed to
> ignite.

Just so, Friedfrich.
To get to teh original point, In the U.S.,(Or NATO, for that matter,
Kerosene, #1 Diesel, and Jet-A type (JP-5 and JP-8) are considered
interchangable.
The U.S. Army, and, IIRC, all of NATO, by now, is using JP-8 as its
sole aviation adn diesel fuel. in order to ease logistical demands.
Jet-B type fuels, (Jet-B, JP-4), aren't considered suitable for use in
Diesels. (THey've got gasoline in them)

#2 Diesel fuel, used in warmer climates in the U.S., had a higher
sulphur content (It doesn't anymore, pollution, you know) and some
engines used the greater viscosity that they brought about to
lubricate parts of teh fuel system (Injector pumps, usually). Of
course, without the sulphur, it doesn't do that anymore, so there are
additives available for the engines which need it. (Sort of like the
aftermarket Lead Substitutes for older gasoline engines).
# 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.
(Note for homeowners between Heating Oil deliveries - These dyes tend
to leave residues in the cumbustor of the furnace that can shorten its
life. If you need a small dollop of additional fuel, use Kerosene
instead)

I note the Tarver has popped in. Just to translate from Tarver to
English, "Cut and Paste" means Performed Research - in this case,
sources are Chevron's Technical Notes on Fuels, and the NATO logistics
manuals. Mine are hard copies, buy they are probably available on the
Web.
As for hands-on experience, current Diesels in the family Truck Park
include a 1945 Cable-Lift Catepillar D-6, and a 1959 Mack B61.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

Tarver Engineering

April 17th 04, 05:00 PM

"John Keeney" > wrote in message
...
>
> "Tarver Engineering" > wrote in message
> ...
> >
> > "Friedrich Ostertag" > wrote in
message
> > ...
> > > Hi NG,
> > >
> > > > The high compression ratios for diesel piston engines cause
> > > detonation using
> > > > wide cut jet fuel.
> > >
> > > Diesel engines cannot "detonate". The term "detonation" applies to
> > > preignition of part of the charge before ignition or before the
> > > flamefront has reached that portion of the charge.
> >
> > Detonation refers to more energy being imparted to the fuel air mixture
by
> > compression heating than can be absorbed without igniting the fuel.
> > Detonation damages rod bearings and is a serious problem over the long
term
> > in reciprocating engines.
>
> John, every power stroke of a diesel engine fits that definition.
> Diesels, by definition, compress the fuel & air to the point the
> fuel ignites.

Then I am correct that the diesel reciprocating engine can experiance
detonation from too short a carbon molecule.

Thanks, Mr. Keeney, the thread was starting to confuse me.

Tarver Engineering

April 17th 04, 05:02 PM

"Friedrich Ostertag" > wrote in message
...
> Hi Mr. Tarver,
>
> > > > > Diesel engines cannot "detonate". The term "detonation" applies
> to
> > > > > preignition of part of the charge before ignition or before the
> > > > > flamefront has reached that portion of the charge.
> > > >
> > > > Detonation refers to more energy being imparted to the fuel air
> > > mixture by
> > > > compression heating than can be absorbed without igniting the
> fuel.
> > >
> > > On a diesel, the fuel is not there until the very moment when it is
> > > supposed to ignite. You cannot ignite pure air, no matter how much
> > > energy you impart on it.
> >
> > In a turbine engine what you write is true, but you are going to have
> to
> > educate me as to the process further to make me believe.
>
> What exactly is it you don't understand? You surely are aware, that a
> diesel engine will intake pure air, compress it (much further than a
> gasoline engine compresses the mixture - temperatures get really hot
> just from the adiabatic compression), and then injects the fuel into
> the compressed (and hot!) air, where it immediately ignites due to the
> high temperature of the compressed air. Thus my comment, that the fuel
> cannot preignite, as it is not there prior to the time it is supposed
> to ignite. No preignition -> no detonation.

So then a diesel engine is like a turbojet? Are the two stroke diesels the
same as the 4 stroke version in this?

Tarver Engineering

April 17th 04, 05:07 PM

"Peter Stickney" > wrote in message
...

> #2 Diesel fuel, used in warmer climates in the U.S., had a higher
> sulphur content (It doesn't anymore, pollution, you know) and some
> engines used the greater viscosity that they brought about to
> lubricate parts of teh fuel system (Injector pumps, usually).

Nice cut and paste Pete, but there is more to #2 diesel than what you write.
California made #2 diesel madatory, so that the injector clearances can be
tightened. More recently, California has required additives to #2 diesel
that cause the engine's seals to disintegrate. This change has managed to
run this County's long haul trucking businesses to Oklahoma and other
operators to evade California road taxes by filling up before entering the
State.

David Lesher

April 17th 04, 05:34 PM

"Friedrich Ostertag" > writes:

>As said before, Diesel engines will burn jetfuel, however the
>lubrication properties are much lower so the injection system has to be
>designed to live with that.

Indeed. When I worked on a pipeline delivering JetA to CLE, we'd
chat with the mechanics that maintained the refueling trucks. They
were run on JetA, as was much of the ramp lice. The logistical
advantage of doing so must have exceeded the cost difference of
trucking in #2.

The mechanics told me that neither Detroit or Cummings recommended
#1, and it likely reduced the time between overhauls, but it still
made sense on the bottom line.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

David Lesher

April 17th 04, 05:36 PM

Also, are not both the Hummers and the M1 are rated to "run on
anything that burns" -- be it #1, #2, gasoline, moonshine, etc?

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Tarver Engineering

April 17th 04, 05:47 PM

"David Lesher" > wrote in message
...
> "Friedrich Ostertag" > writes:
>
>
> >As said before, Diesel engines will burn jetfuel, however the
> >lubrication properties are much lower so the injection system has to be
> >designed to live with that.
>
> Indeed. When I worked on a pipeline delivering JetA to CLE, we'd
> chat with the mechanics that maintained the refueling trucks. They
> were run on JetA, as was much of the ramp lice. The logistical
> advantage of doing so must have exceeded the cost difference of
> trucking in #2.

Number 2 will tun into jelly if it gets too cold, so most truck operators
avoid it unless there is some State requirement to use it.

John R Weiss

April 17th 04, 05:52 PM

"Fred J. McCall" > wrote...
>
> :In the US navy, the nuclear powered carriers only carry JP4 or JP8
>
> The US Navy uses neither of these fuels at sea, even to fill aircraft,
> much less to fill large ship's tanks. The Navy switched from JP4
> (which is a hideously dangerous fuel) to JP5 about half a century ago.
> The Air Force later switched from JP4 to JP8 (essentially Jet-A).

Yep! That was a typo -- I meant JP5 or JP8. Thanks for the catch.

> The Navy currently uses JP8 ashore (because it's cheaper and easier to
> get) and JP5 at sea (because it's safer).

OK. It appears sanity won over economics. There was talk in the late 80s/early
90s to transition from JP5 to JP8 at sea as well as the JP4 - JP8 transition
ashore.

Fred J. McCall

April 17th 04, 05:59 PM

"John R Weiss" > wrote:

:"Fred J. McCall" > wrote...
:>
:> :In the US navy, the nuclear powered carriers only carry JP4 or JP8
:>
:> The US Navy uses neither of these fuels at sea, even to fill aircraft,
:> much less to fill large ship's tanks. The Navy switched from JP4
:> (which is a hideously dangerous fuel) to JP5 about half a century ago.
:> The Air Force later switched from JP4 to JP8 (essentially Jet-A).
:
:Yep! That was a typo -- I meant JP5 or JP8. Thanks for the catch.
:
:> The Navy currently uses JP8 ashore (because it's cheaper and easier to
:> get) and JP5 at sea (because it's safer).
:
:OK. It appears sanity won over economics. There was talk in the late 80s/early
:90s to transition from JP5 to JP8 at sea as well as the JP4 - JP8 transition
:ashore.

I'm not positive, but I think the regs say something to the effect
that if you land with ANY JP4 on board, you have to be fully defueled.
If you have JP8, I think they'll allow a 50/50 mix with JP5 on a
refuel.

The latter presumably makes it more convenient for folks coming out
from shore bases just to do carrier quals.

--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney

John R Weiss

April 17th 04, 06:03 PM

"scott s." > wrote...
>
> IIRC the minimum allowed flash point is 140F. I uderstand that even
> a little JP4, if mixed with JP5, can dangerously lower flash point.

True.

However, the problem is not as pronounced with JP5/JP8 mixtures. The reduction
of flash point from JP5's 140 to JP8's 100 is roughly linear with the mixture
ratio.

Friedrich Ostertag

April 17th 04, 11:05 PM

Hi Peter

> > diesel engine will intake pure air, compress it (much further than
a
> > gasoline engine compresses the mixture - temperatures get really
hot
> > just from the adiabatic compression), and then injects the fuel
into
> > the compressed (and hot!) air, where it immediately ignites due to
the
> > high temperature of the compressed air. Thus my comment, that the
fuel
> > cannot preignite, as it is not there prior to the time it is
supposed
> > to ignite. No preignition -> no detonation.
> >
>
> actually you were fine down to this point. what you mean is that when
> ther is no "premixing" there is no detonation. Detonation involves a
> supersonic combustion wave moving through the mixture.

good point. The proper definition of detonation in general is
supersonic combustion, as you pointed out. The proper term for what
happens, when the fuel-air mixture or part of it on a spark ignition
engine preignites, would be "knock". However quite often the two terms
can be heard used interchangeably when discussing engines, because the
result is very similar as far as the engine is concerned. Both lead to
a much higher pressure-gradient in the cylinder. And it is really
difficult to tell, whether a portion of the mixture preignited before
it was reached by the flamefront, or whether the combustion went
supersonic and just got there quicker.

In any case, both will never happen on a diesel engine.

> good discussion at
http://www.safetynet.de/Seiten/articles/CMRNov99.pdf

very interesting paper, thanks.

regards,
Friedrich

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

Friedrich Ostertag

April 17th 04, 11:10 PM

Hi Mr. Tarver,

> So then a diesel engine is like a turbojet?

In that the fuel immediately burnes when it is injected, yes. Of
course, the diesel is still a reciprocating engine while a turbojet is
operating continuously. Therefore diesels have much more in common with
spark ignition engines than with turbines.

> Are the two stroke diesels the
> same as the 4 stroke version in this?

Yes.

regards,
Friedrich

Tarver Engineering

April 18th 04, 01:54 AM

"Friedrich Ostertag" > wrote in message
...
> Hi Mr. Tarver,
>
> > So then a diesel engine is like a turbojet?
>
> In that the fuel immediately burnes when it is injected, yes. Of
> course, the diesel is still a reciprocating engine while a turbojet is
> operating continuously. Therefore diesels have much more in common with
> spark ignition engines than with turbines.
>
> > Are the two stroke diesels the
> > same as the 4 stroke version in this?
>
> Yes.

Interesting, I got to learn something in this thread.

John Keeney

April 18th 04, 05:53 AM

"Friedrich Ostertag" > wrote in message
...
> Hi John,
>
> > > Detonation refers to more energy being imparted to the fuel air
> mixture by
> > > compression heating than can be absorbed without igniting the fuel.
> > > Detonation damages rod bearings and is a serious problem over the
> long
> > term
> > > in reciprocating engines.
> >
> > John, every power stroke of a diesel engine fits that definition.
> > Diesels, by definition, compress the fuel & air to the point the
> > fuel ignites.
>
> only air is compressed, but well beyond the point where fuel will
> ignite! But the fuel is only added at the moment when it is supposed to
> ignite.

Hmmm, you're right of course and I never meant to imply
otherwise. I can see where it could be taken that I did though.

[email protected]

April 18th 04, 10:17 PM

Peter Skelton > wrote:

>
>Why must knock be supersonic?
>
>Peter Skelton

Well, it's not exactly supersonic actually, it's more like
'instantaneous'.

As the normal flame front progresses across the combustion
chambre, it moves the piston and progressively compresses the
REMAINING fuel/air mixture raising it's pressure and temperature
until it reaches the limit of the fuel/air mixture to resist
detonation...THEN, the remaining area DETONATES ALL AT ONCE,
because almost all of it has reached the critical temp/press.
THAT'S why it results in an extremely sharp spike of pressure and
is so devastating. The piston can cope quite well with the
comparatively slow rise of pressure of a normal flame-front, but
the instantaneous extreme spike of pressure from the exploding
amount of fuel/air is so fast rising that the piston's inertia
won't allow it to 'get out of the way' (so to speak).

Someone on here awhile ago mentioned how devastating detonation
is and I entirely agree. I used to fly the Argus as a flight
engineer and had first hand experience with that phenomenon out
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.

I found out much later that that engine was completely trashed,
and that the problem was that the 'derichment valve' had failed
and didn't restore normal fuel flow when the 'water injection'
was turned off, so the engine was operating at 'best power' at
'climb power' with no excess fuel for cooling...a disasterous
combination. Less than a half minute with heavy detonation
wrecked it. Don't futz around with detonation!. It'll bite yer
butt!.
--

-Gord.

Eunometic

April 19th 04, 07:31 AM

"Jim E" > wrote in message >...
> "Eunometic" > wrote in message
> om...
>
> >
> > At the moment there are attempts to develop 'photo detonation'
> > internal combustion engines that do not rely on deflageration
> > combustion (ie combustion along a flame front rather than by infra red
> > light) and thus will be indifferent to octane ratings.
>
> Where can I learn more about this?
> Curious old school gear head here
>
> Jim E

Use the advanced options in google groups search to find this thread:

Message-ID: >

Friedrich Ostertag

April 19th 04, 01:07 PM

Hi Gord (and Peter),

> >Why must knock be supersonic?
> >
> >Peter Skelton
>
> Well, it's not exactly supersonic actually, it's more like
> 'instantaneous'.

It's actually two different things. "Detonation" means supersonic
combustion. "Knock" means preignition of part of the charge before it
is reached by the flamefront (or in extreme cases the whole charge even
before the spark). However one can lead to the other and the result is
pretty much the same anyway: extreme pressure gradients. Therefore the
terms are sometimes used interchangeably.

> Less than a half minute with heavy detonation
> wrecked it. Don't futz around with detonation!. It'll bite yer
> butt!.

true ...

regards,
Friedrich

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

[email protected]

April 19th 04, 03:59 PM

"Friedrich Ostertag" > wrote:

>Hi Gord (and Peter),
>
>> >Why must knock be supersonic?
>> >
>> >Peter Skelton
>>
>> Well, it's not exactly supersonic actually, it's more like
>> 'instantaneous'.
>
>It's actually two different things. "Detonation" means supersonic
>combustion. "Knock" means preignition of part of the charge before it
>is reached by the flamefront (or in extreme cases the whole charge even
>before the spark). However one can lead to the other and the result is
>pretty much the same anyway: extreme pressure gradients. Therefore the
>terms are sometimes used interchangeably.
>
>> Less than a half minute with heavy detonation
>> wrecked it. Don't futz around with detonation!. It'll bite yer
>> butt!.
>
>true ...
>
>regards,
>Friedrich

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..

A little levity for a sober subject. Our 'dash one' for the Argus
describes detonation like this.

"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"

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

-Gord.

[email protected]

April 19th 04, 06:11 PM

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.

http://www.epa.gov/otaq/consumer/f99029.pdf

Bill Ranck
Blacksburg, Va.

Tarver Engineering

April 19th 04, 07:01 PM

> wrote in message ...
> 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.
>
> http://www.epa.gov/otaq/consumer/f99029.pdf

Bill is of course, correct.

Harry Andreas

April 19th 04, 08:43 PM

In article .net>,
"Thomas Schoene" > wrote:

> 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.
>
Looking at the specs, and the tutorial, it appears that F76 and JP-5 are
essentially the same except for the anti-icing additives in JP-5.

Both can be used in marine turbines and marine diesels.
F76 is cheaper.
JP-5 burns cleaner.

You could probably use F76 in a helo that is not going to high altitude
(in a pinch, probably not specifically approved).

JP-5 and JP-8 also have anti-static additives that are not needed
aboard ship for marine use.

--
Harry Andreas
Engineering raconteur

Mary Shafer

April 19th 04, 10:56 PM

On Sat, 17 Apr 2004 16:59:12 GMT, Fred J. McCall
> wrote:

> I'm not positive, but I think the regs say something to the effect
> that if you land with ANY JP4 on board, you have to be fully defueled.
> If you have JP8, I think they'll allow a 50/50 mix with JP5 on a
> refuel.

Four refuelings before an airplane that had taken JP4 on board could
be struck below to the hangar deck. Until then, it stayed on the
flight deck. No need to drain the tanks.

Mary

--
Mary Shafer Retired aerospace research engineer

Tarver Engineering

April 19th 04, 11:01 PM

"Mary Shafer" > wrote in message
...
> On Sat, 17 Apr 2004 16:59:12 GMT, Fred J. McCall
> > wrote:
>
> > I'm not positive, but I think the regs say something to the effect
> > that if you land with ANY JP4 on board, you have to be fully defueled.
> > If you have JP8, I think they'll allow a 50/50 mix with JP5 on a
> > refuel.
>
> Four refuelings before an airplane that had taken JP4 on board could
> be struck below to the hangar deck. Until then, it stayed on the
> flight deck. No need to drain the tanks.

You can float JP-4 on water and light it with a match.

ZZBunker

April 20th 04, 04:00 AM

"scott s." > wrote in message >...
> Fred J. McCall > wrote in
> :
>
> > "John R Weiss" > wrote:
> >
> >:In the US navy, the nuclear powered carriers only carry JP4 or JP8
> >:(and all on-board diesel-powered equipment use the JP), so any smaller
> >:ships that refuel from the carrier (a relatively common practice) get
> >:the jet fuel.
> >
> > The US Navy uses neither of these fuels at sea, even to fill aircraft,
> > much less to fill large ship's tanks. The Navy switched from JP4
> > (which is a hideously dangerous fuel) to JP5 about half a century ago.
> > The Air Force later switched from JP4 to JP8 (essentially Jet-A).
>
> IIRC the minimum allowed flash point is 140F. I uderstand that even
> a little JP4, if mixed with JP5, can dangerously lower flash point.

Naptha mixed with gasoline with lower the flashpoint
of just about anything from whatever it was
before mixing to a nice cozy room temperature.

> scott s.
> .

Keith Willshaw

April 20th 04, 09:23 AM

Friedrich Ostertag

April 20th 04, 09:29 AM

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

David McArthur

April 20th 04, 11:22 AM

"Thomas Schoene" > wrote in message .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.

Stephen Harding

April 20th 04, 12:35 PM

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

Stephen Harding

April 20th 04, 12:38 PM

[email protected]

April 20th 04, 08:28 PM

"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.

[email protected]

April 20th 04, 08:35 PM

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.

QDurham

April 20th 04, 08:40 PM

>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

[email protected]

April 20th 04, 08:48 PM

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

April 21st 04, 01:52 AM

(KDR) wrote in message >...
> 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?

Thomas Schoene

April 21st 04, 02:46 AM

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

[email protected]

April 21st 04, 02:49 AM

(QDurham) wrote:

>>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

That might be so Quent, these were 3350's also but the engineer
can't see the stacks from his position so that's out. I've looked
at them from the overwing hatch window at night and it's hard to
see any flame, just a pale blue flame maybe a few inches out of
the stack, you should see the flame at full power during
takeoff!...bright orange/red/yellow right back off the rear of
the wing! wooHoo...
--

-Gord.

QDurham

April 21st 04, 04:18 AM

>you should see the flame at full power during
>takeoff!...bright orange/red/yellow right back off the rear of
>the wing! wooHoo...

Oh Indeeedy! WooooooooHoooooooo!!!!!!!

I was in P2V Neptunes. Seem to recall exhaust flames were quite visible. Long
time ago.

Quent

RON

April 21st 04, 05:22 AM

On two cycle diesels, Detroit Diesels are what I am familiar with,
number 1 fuel is not recommended because of its poor lubricating
quality. Diesel fuel must cool and lubricate the mechanical injectors.
To prevent the wax in #2 from falling out of suspension in cold weather
it can be mixed with #1 to lower the pour point.
It's usually better to lower the pour point on on road applications
chemically but you do what you have to do to keep them running.
Ron

Friedrich Ostertag

April 21st 04, 01:07 PM

Hi Gord,

>> 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'.

Well, it depends...

Normally you won't damage an engine with knock control by using lower
grade fuel than recommended, however within limits. If you use very low
octane fuel on a high compression or a turbocharged engine, ignition
might occur before the spark just from the compression, as we
discussed. There is nothing knock control can do about that. Also,
depending on your driving profile, you might find that fuel consumption
increases with the lower grade fuel, as retarded ignition reduces
engine efficiency. This is especially valid at high engine loads and
low engine speed, where the biggest retard is neccessary. Wether the
increase in consumption will eat up the price advantage of the lower
grade can only be determined by experiment.

> 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.

Now that is a new one to me! I know about GAMIs injectors for GA piston
engines and all the LOP-operation stuff, wich are around for a while
now, and which I think are a big improvement. I didn't know that they
are planning on entering the automotive market and I'm quite surprised.
Automotive engines, different from aviation, run stoechiometric
basically anywhere on the map exept full load. (stoechiometric mixture
is more or less peak EGT). Due to their design, mostly liquid cooled,
temperatures are not a problem. Of course you could run such an engine
lean (LOP), but you won't pass any emissions test for sure. I don't
think you really need special injectors to do it, but you would need to
retune the ECU. And the fuel savings compared to running stoechiometric
are only a fraction of what you save if otherwise you have to run rich.

The Japanese car makers had lean running engines on the market for a
while, and some of the direct injection gaoline engines being developed
now also run lean by creating a stratified charge. But that's far
beyond an aftermarket improvement.

> 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!...

Do you by chance know whether these had direct injection (injecting the
fuel into the cylinder instead of the manifold)? To my knowledge there
have been direct injection piston engines among the big radials, but I
haven't found any further information about it so far.

regards,
Friedrich

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

Peter H. Granzeau

April 21st 04, 08:00 PM

On Wed, 21 Apr 2004 01:46:47 GMT, "Thomas Schoene"
> wrote:

>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.

As long ago as 1960, my Diesel-powered ship made a NATO exercise and
was refueled during the exercise with JP-5 (the oilers were carrying
no Diesel fuel). I believe the fuel comsumption was slightly worse.
I don't know the long-term effects on the Diesel engines, as JP-5 is
missing some lubricant as compared to JP-5, I understand. This was
just one two-month exercise, of course, but the matter was being
considered even then.

Do modern gas turbine powered ships use Diesel fuel, or is there yet
another formulation of fuel for them?

Harry Andreas

April 21st 04, 10:10 PM

In article et>, "Thomas
Schoene" > wrote:

> 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)

In the tutorial URL I posted, they made a definite distinction between
F-76 and DFM.

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

That's $500 for a 10K gallon fill up. Substantial enough savings.
Anyone know how much fuel a DDG takes on at a time?

> > 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.

Just proposals.

--
Harry Andreas
Engineering raconteur

Thomas Schoene

April 22nd 04, 01:38 AM

Harry Andreas wrote:
> In article et>,
> "Thomas Schoene" > wrote:
>> JP-5 $1.03/gallon
>> DFM $0.98/gallon (DFM is Diesel fuel, Marine, another term
>> for F-76)
>
> In the tutorial URL I posted, they made a definite distinction between
> F-76 and DFM.

No, they made a distinction between F-76 and *commercial* marine distillate
fuel. Commercial fuel can be all over the map quality-wise.

The term "DFM" is used throughout the Navy as a synonym for F-76 (the NATO
supply code for the same fuel). Technically, it seems that DFM might not be
specific enough, as F-76 implies conformance to a specific MIL-SPEC while
DFM does not. But the two terms seem to be interchangable in everyday use.

For example:

www.msc.navy.mil/instructions/doc/35007b.doc
"Ships requiring DFM (NATO Symbol F-76) may be accomplished via barge or
ship."

http://www.nor.fisc.navy.mil/home/SupplyChest/18APR03SC.pdf
"Zuiderkruis took on 19,000 barrels of diesel fuel marine (DFM/F-76)..."

www.jiatfs.southcom.mil/j4/Maritime/OPSTASK/UAnxDApp4TabIPuertoRico.doc
"(U) Fuel. DFM (F-76) and JP-5 (F-44) available."

>> That's roughly 5% difference. It may not seem like much, but
>> considering the Navy's overall fuels budget, it can really add up.
>
> That's $500 for a 10K gallon fill up. Substantial enough savings.
> Anyone know how much fuel a DDG takes on at a time?

From a quick search, an UNREP of 150,000 gallons would seem to be typical.

I figure a destroyer's total capacity is around 500,000 gallons. That's
based on F-76 at 300 gallons per ton and the Combat Fleets figure that a
Spruance carries 1,650 tons of fuel. No fuel figures available for DDGs,
but that's a decent ballpark estimate anyway. Plenty of money to be saved
here.

--
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

[email protected]

April 22nd 04, 01:46 AM

"Friedrich Ostertag" > wrote:

>> 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!...
>
>Do you by chance know whether these had direct injection (injecting the
>fuel into the cylinder instead of the manifold)? To my knowledge there
>have been direct injection piston engines among the big radials, but I
>haven't found any further information about it so far.
>
>regards,
>Friedrich

Well, just a comment about domestic automobiles, I didn't mean to
indicate that I operate them below the manufacturers specified
octane ratings, after all, I believe that the manufacturer knows
his engine best and I'd never try to second guess him, but I have
all kinds of friends and relatives who use hi octane fuel in
their cars even though low octane is recommended. (complete waste
I feel) Another thing that I NEVER do is 'recommend to anyone'
what fuel to use. You're bound to get blamed sometime in your
life because a friend's wife got preggy if you do... :)

About the direct injection, the Argus (ASW aircraft) used by the
Canadian Armed Forces had Wright R-3350-EA1 engines (3700 BHP)
which had direct fuel injection into the cylinder (not just prior
to the intake valve). The Wright R-3350-89A fitted to the
Fairchild C-119 Packet had 'spinner injection', where the fuel
was injected into the spinner of the supercharger, and the P2V-7
Neptune was set up this way too.

--

-Gord.

Friedrich Ostertag

April 23rd 04, 08:58 PM

Hi Gord,

> Well, just a comment about domestic automobiles, I didn't mean to
> indicate that I operate them below the manufacturers specified
> octane ratings, after all, I believe that the manufacturer knows
> his engine best and I'd never try to second guess him, but I have
> all kinds of friends and relatives who use hi octane fuel in
> their cars even though low octane is recommended. (complete waste
> I feel)

Ah, you're absolutely right there! Sorry for the misunderstanding.
There is no point in using higher octane than what the engine was
designed for. Even knock control will not advance ignition beyond the
calibrated map for the designated fuel.

However a lot of people over here fell for a marketing trick of Shell
Oil: Instead of the 98 octane highest grade fuel sold in Germany and
most euroean countries they offered a 100 octane (by the way, this is
ROZ, not ROZ+MOZ/2 as in the US) fuel called "V-power" with supposedly
all kinds of mysterious additives at 10 ct / Liter premium over other
oil company's 98 octane. Lots of car magazines and also the ADAC (your
AA) tested it in various models and found no difference whatsoever in
power and consumption. Yet Shell sells 10% of it's turnout in V-Power
while the other's only sell 5% 98. Talk about snake oil...

> Another thing that I NEVER do is 'recommend to anyone'
> what fuel to use. You're bound to get blamed sometime in your
> life because a friend's wife got preggy if you do... :)

:-)

> About the direct injection, the Argus (ASW aircraft) used by the
> Canadian Armed Forces had Wright R-3350-EA1 engines (3700 BHP)
> which had direct fuel injection into the cylinder (not just prior
> to the intake valve). The Wright R-3350-89A fitted to the
> Fairchild C-119 Packet had 'spinner injection', where the fuel
> was injected into the spinner of the supercharger, and the P2V-7
> Neptune was set up this way too.

I always find it intriguing, that almost everything we develop today as
supposedly latest techology has been there half a century ago. The only
really new thing in engines today is electronic control.

regards,
Friedrich

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

[email protected]

April 24th 04, 06:29 PM

"Friedrich Ostertag" > wrote:

>
>I always find it intriguing, that almost everything we develop today as
>supposedly latest techology has been there half a century ago. The only
>really new thing in engines today is electronic control.
>
>regards,
>Friedrich

Exactly...and it's one of the reasons that, although I consider
myself quite knowledgeable engine wise, when I open the hood of
an ailing engine I quickly close it and get on the fone for a
towtruck...there's just so much complication in all the
electronic sensors, computers etc to squeeze every ounce of
efficiency out of a litre of fuel that I find it daunting.

My wife's Corolla just finished it's lease and I bought it and
leased another Toyota for her. A 'Matrix'. They have an
intriguing feature called VVTi (Variable Valve Timing). Neat
system!...hope it's rugged!...

Cheers
--

-Gord.

[email protected]

April 24th 04, 09:21 PM

Alisha's Addict

April 26th 04, 09:28 PM

On Fri, 23 Apr 2004 21:58:30 +0200, "Friedrich Ostertag"
> wrote:

>Hi Gord,
>
>> Well, just a comment about domestic automobiles, I didn't mean to
>> indicate that I operate them below the manufacturers specified
>> octane ratings, after all, I believe that the manufacturer knows
>> his engine best and I'd never try to second guess him, but I have
>> all kinds of friends and relatives who use hi octane fuel in
>> their cars even though low octane is recommended. (complete waste
>> I feel)
>
>Ah, you're absolutely right there! Sorry for the misunderstanding.
>There is no point in using higher octane than what the engine was
>designed for. Even knock control will not advance ignition beyond the
>calibrated map for the designated fuel.
>
>However a lot of people over here fell for a marketing trick of Shell
>Oil: Instead of the 98 octane highest grade fuel sold in Germany and
>most euroean countries they offered a 100 octane (by the way, this is
>ROZ, not ROZ+MOZ/2 as in the US) fuel called "V-power" with supposedly
>all kinds of mysterious additives at 10 ct / Liter premium over other
>oil company's 98 octane. Lots of car magazines and also the ADAC (your
>AA) tested it in various models and found no difference whatsoever in
>power and consumption. Yet Shell sells 10% of it's turnout in V-Power
>while the other's only sell 5% 98. Talk about snake oil...

Definitely agree with you there ... The Puma that I have has a
reaction to the higher octane 98 RON Optimax fuel that Shell sell over
here.

It's not a good reaction, like increased power or economy, it's a bad
one. The bad reaction takes the shape of the engine management
struggling for the first couple of miles to get used to the differing
octane rating. Symptoms included poor running including reluctance to
idle. I suspect that the anti-knock control was self adjusting itself
for the increased octane rating. It also takes a little while to get
used to 95 RON unleaded when that goes back in.

Anyway, no measurable economy improvement (I nerdishly track my mpg)
and no perceptible power improvement. Although other people reckon
they see power improvements with other cars.

Pete Lilleyman

(please get rid of ".getrid" to reply direct)
(don't get rid of the dontspam though ;-)

Alisha's Addict

April 26th 04, 09:38 PM

On Sat, 24 Apr 2004 17:29:50 GMT, "Gord Beaman" )
wrote:

>"Friedrich Ostertag" > wrote:
>
>>
>>I always find it intriguing, that almost everything we develop today as
>>supposedly latest techology has been there half a century ago. The only
>>really new thing in engines today is electronic control.
>>
>>regards,
>>Friedrich
>
>Exactly...and it's one of the reasons that, although I consider
>myself quite knowledgeable engine wise, when I open the hood of
>an ailing engine I quickly close it and get on the fone for a
>towtruck...there's just so much complication in all the
>electronic sensors, computers etc to squeeze every ounce of
>efficiency out of a litre of fuel that I find it daunting.

I like to think I know a pretty decent amount about engines, enough to
do my own maintenance when I was too poor to go to garages. But when I
got the Puma, I didn't even bother opening the bonnet. I knew I
wouldn't recognize much of what was under there and that the key
things would be hidden from view. All I needed to convince me that the
running gear was in excellent shape was a flying trip down the local
dual carriageway :-) (Happily 3 years later nothing serious has gone
wrong)

>My wife's Corolla just finished it's lease and I bought it and
>leased another Toyota for her. A 'Matrix'. They have an
>intriguing feature called VVTi (Variable Valve Timing). Neat
>system!...hope it's rugged!...

This is on the Puma too, as Variable Cam Timing. I think it's fairly
failsafe. Taking a mechanical engineer (which I'm not - I'm an elec)
view, I'd say they do it by retarding/advancing the valve timing
according to revs and load. So if the system fails or degrades, the
valve timing wouldn't adjust but the cams would still go round and the
valves would go up or down. Not heard of rampant engine trouble in the
variable timing cars so they must have got it licked.

It seems to work on the Puma ... I moved from Rover 2.0 16 valve to
Ford 1.7 16 valve and the Ford unit has just about equal power but
it's far more flexible across the rev range. The Rover unit was fairly
quiet until about 3250 rpm where it would take off. The Ford unit has
usable power down at about 1800/2000 rpm.

Pete Lilleyman

(please get rid of ".getrid" to reply direct)
(don't get rid of the dontspam though ;-)