subaru diesel

[Philippe Vessaire]

Hello

Torque curve page 6

http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf

by
--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬

[Morgans[_2_]]

"Philippe Vessaire" > wrote in message
news:19459447.yEvPs9oxTh@GastonCoute...
> Hello
>
> Torque curve page 6
>
> http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>
>
Holy crap! That thing has the peak torque, and it is almost a level line,
from about 1600 rpm to about 2400 rpm!

That sucker should really pull a big prop, and well!
--
Jim in NC

[Blueskies]

"Morgans" > wrote in message ...
>
> "Philippe Vessaire" > wrote in message
> news:19459447.yEvPs9oxTh@GastonCoute...
>> Hello
>>
>> Torque curve page 6
>>
>> http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>>
>>
> Holy crap! That thing has the peak torque, and it is almost a level line,
> from about 1600 rpm to about 2400 rpm!
>
> That sucker should really pull a big prop, and well!
> --
> Jim in NC
>
>


Is the price of diesel fuel 25% above gasoline prices everywhere?
Jet A costs the same as 100LL now also, so what is the benefit?

[clare at snyder dot ontario dot canada]

On Fri, 21 Mar 2008 22:06:30 -0400, "Morgans"
> wrote:

>
>"Philippe Vessaire" > wrote in message
>news:19459447.yEvPs9oxTh@GastonCoute...
>> Hello
>>
>> Torque curve page 6
>>
>> http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>>
>>
>Holy crap! That thing has the peak torque, and it is almost a level line,
>from about 1600 rpm to about 2400 rpm!
>
>That sucker should really pull a big prop, and well!

Like I said!

--
Posted via a free Usenet account from http://www.teranews.com

[clare at snyder dot ontario dot canada]

On Sat, 22 Mar 2008 20:00:35 -0400, "Blueskies"
> wrote:

>
>"Morgans" > wrote in message ...
>>
>> "Philippe Vessaire" > wrote in message
>> news:19459447.yEvPs9oxTh@GastonCoute...
>>> Hello
>>>
>>> Torque curve page 6
>>>
>>> http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>>>
>>>
>> Holy crap! That thing has the peak torque, and it is almost a level line,
>> from about 1600 rpm to about 2400 rpm!
>>
>> That sucker should really pull a big prop, and well!
>> --
>> Jim in NC
>>
>>
>
>
>Is the price of diesel fuel 25% above gasoline prices everywhere?
>Jet A costs the same as 100LL now also, so what is the benefit?
>
>
>
The only benefits are slightly lower fuel burn (in pounds per hour -
sig ificantly more difference in gallons per hour) and less liklihood
of not being able to get correct fuelin the mid-long term.
Jet A will be around for a while. 100LL has a limited lifespan, and
non-aviation gasoline is always a moving target.

--
Posted via a free Usenet account from http://www.teranews.com

[Dale Scroggins[_2_]]

"Blueskies" > wrote in message
...
>
> "Morgans" > wrote in message
> ...
>>
>> "Philippe Vessaire" > wrote in message
>> news:19459447.yEvPs9oxTh@GastonCoute...
>>> Hello
>>>
>>> Torque curve page 6
>>>
>>> http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>>>
>>>
>> Holy crap! That thing has the peak torque, and it is almost a level
>> line, from about 1600 rpm to about 2400 rpm!
>>
>> That sucker should really pull a big prop, and well!
>> --
>> Jim in NC
>
>
> Is the price of diesel fuel 25% above gasoline prices everywhere?
> Jet A costs the same as 100LL now also, so what is the benefit?
>
>
>
1. Most diesels wear more slowly than gas engines. The fuel is a better
lubricant than gasoline is, and the combustion products are a bit more
benign.
2. No ignition system needed.
3. Turbocharging a diesel is a win-win proposition. EGT is lower, so turbo
system parts last as long as the engine, usually. Turbocharging improves
both performance and fuel efficiency (not always true for gassers).
4. Full power available up to about 15K feet for most auto-type
turbodiesels.
5. Automatic mixture control.
6. No carb icing or vapor lock.
7. Lower fire risks.
8. I can make biodiesel for 67 cents a gallon. You or I can buy off-road
diesel or heating oil for much less than either auto gas, avgas or jet A.
9. For a given trip, less fuel is needed, both in volume and weight. 25%
to 35%, depending on the trip profile. If the diesel is turbocharged and
gasser is not, the diesel's ability to cruise significantly higher may
result in a bigger efficiency spread.
10. Props are more efficient at lower RPMs, usually. Diesels have torque
to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving maybe
another 5% efficiency gain, and a quieter cabin to boot.

Given time, I can think of more. Please note that gas engines were
abandoned decades, nay, scores of years ago in other transportation sectors.
It will be the same in aviation if the weight difference shrinks enough.

DS

[Bill Daniels]

"Dale Scroggins" > wrote in message
...
>
> "Blueskies" > wrote in message
> ...
>>
>> "Morgans" > wrote in message
>> ...
>>>
>>> "Philippe Vessaire" > wrote in message
>>> news:19459447.yEvPs9oxTh@GastonCoute...
>>>> Hello
>>>>
>>>> Torque curve page 6
>>>>
>>>> http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>>>>
>>>>
>>> Holy crap! That thing has the peak torque, and it is almost a level
>>> line, from about 1600 rpm to about 2400 rpm!
>>>
>>> That sucker should really pull a big prop, and well!
>>> --
>>> Jim in NC
>>
>>
>> Is the price of diesel fuel 25% above gasoline prices everywhere?
>> Jet A costs the same as 100LL now also, so what is the benefit?
>>
>>
>>
> 1. Most diesels wear more slowly than gas engines. The fuel is a better
> lubricant than gasoline is, and the combustion products are a bit more
> benign.
> 2. No ignition system needed.
> 3. Turbocharging a diesel is a win-win proposition. EGT is lower, so
> turbo system parts last as long as the engine, usually. Turbocharging
> improves both performance and fuel efficiency (not always true for
> gassers).
> 4. Full power available up to about 15K feet for most auto-type
> turbodiesels.
> 5. Automatic mixture control.
> 6. No carb icing or vapor lock.
> 7. Lower fire risks.
> 8. I can make biodiesel for 67 cents a gallon. You or I can buy off-road
> diesel or heating oil for much less than either auto gas, avgas or jet A.
> 9. For a given trip, less fuel is needed, both in volume and weight. 25%
> to 35%, depending on the trip profile. If the diesel is turbocharged and
> gasser is not, the diesel's ability to cruise significantly higher may
> result in a bigger efficiency spread.
> 10. Props are more efficient at lower RPMs, usually. Diesels have torque
> to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving
> maybe another 5% efficiency gain, and a quieter cabin to boot.
>
> Given time, I can think of more. Please note that gas engines were
> abandoned decades, nay, scores of years ago in other transportation
> sectors. It will be the same in aviation if the weight difference shrinks
> enough.
>
> DS

Of course there are all kinds of diesels just like there are all kinds of
spark ignition engines. Generalizations need to be made carefully. Over
the road diesels are heavy to absorb the heavy bottom end loads with less
expensive cast iron blocks. Automobile diesels tend to be heavy since there
is no compelling reason to make them light.

The one absolute is that diesel fuel will be around for a long time in one
form or another. The 'gotcha' is that the rest of the world runs on diesel
and when developing economies like India and China demand more fuel it will
be diesel they are after so the price is likely to remain high. Hopefully,
biodiesel will be cheap.

Aircraft diesels are very special since they need to be both powerful and
light demanding high tech metalurgy like titanium rods. To keep the weight
down, 2-stroke diesels look good. Opposed piston 2-stroke diesels look even
better since the bottom end loads are spread across two crankshafts.

The Subaru oil burner looks good but then so does the DeltaHawk and the
little opposed piston aircraft diesels from the UK.

Bill D

[Morgans[_2_]]

"Bill Daniels" <bildan@comcast-dot-net> wrote

> The Subaru oil burner looks good but then so does the DeltaHawk and the
> little opposed piston aircraft diesels from the UK.

Do let me know when the Delta Hawk is available for sale.

I won't be holding my breath, until then.

I can't survive without breathing that long.
--
Jim in NC

[[email protected]]

On Mar 22, 9:33 pm, "Dale Scroggins" >
wrote:
> "Blueskies" > wrote in message
>
> ...
>
>
>
> > "Morgans" > wrote in message
> ...
>
> >> "Philippe Vessaire" > wrote in message
> >>news:19459447.yEvPs9oxTh@GastonCoute...
> >>> Hello
>
> >>> Torque curve page 6
>
> >>>http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>
> >> Holy crap! That thing has the peak torque, and it is almost a level
> >> line, from about 1600 rpm to about 2400 rpm!
>
> >> That sucker should really pull a big prop, and well!
> >> --
> >> Jim in NC
>
> > Is the price of diesel fuel 25% above gasoline prices everywhere?
> > Jet A costs the same as 100LL now also, so what is the benefit?

<SNIP>
> 2. No ignition system needed.

Not to be a ball-buster, but the injection systems for the new
generation of diesels is incredibly fancy. From a risk analysis
standpoint, it is hard to say whether this system in place of magnetos
is a gain or a loss.

> 3. Turbocharging a diesel is a win-win proposition. EGT is lower, so turbo
> system parts last as long as the engine, usually. Turbocharging improves
> both performance and fuel efficiency (not always true for gassers).

True, but boost levels in diesels inversely effect their reputation
for reliability.

<SNIP>

> 8. I can make biodiesel for 67 cents a gallon. You or I can buy off-road
> diesel or heating oil for much less than either auto gas, avgas or jet A.

Biodiesel gels at a higher temp than does winter diesel, and be damned
sure you have no rubber in the fuel system. And the 67 cents is
quoted for recycled oil. Not my first pick at altitude.

> 9. For a given trip, less fuel is needed, both in volume and weight. 25%
> to 35%, depending on the trip profile. If the diesel is turbocharged and
> gasser is not, the diesel's ability to cruise significantly higher may
> result in a bigger efficiency spread.

This is dependent on tuning the boost map, and whether the blower is
big enough. Off the shelf this may or may not be true. I have not read
flight tests for any new European diesels which have been impressive
in high altitude performance. I doubt this is because of any
fundemental flaws, but rather performance tuning.

> 10. Props are more efficient at lower RPMs, usually. Diesels have torque
> to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving maybe
> another 5% efficiency gain, and a quieter cabin to boot.
>
> Given time, I can think of more. Please note that gas engines were
> abandoned decades, nay, scores of years ago in other transportation sectors.
> It will be the same in aviation if the weight difference shrinks enough.
>
> DS

I dig your enthusiasm. Please post if you hear of any new diesel/
biodiesel aviation projects. I would be interested in reading any
related results. I believe that the new generation of diesels are the
long term solution for keeping GA operating costs down. But it will
take a while.

-Matt

[Dale Scroggins[_2_]]

> wrote in message
...
> On Mar 22, 9:33 pm, "Dale Scroggins" >
> wrote:

SNIP

> <SNIP>
>> 2. No ignition system needed.
>
> Not to be a ball-buster, but the injection systems for the new
> generation of diesels is incredibly fancy. From a risk analysis
> standpoint, it is hard to say whether this system in place of magnetos
> is a gain or a loss.

Fuel control systems for new generation turbine engines are also incredibly
fancy. They have more redundancy than automotive systems, and some have
mechanical back-up, but from recent news reports, aren't utterly reliable.
But they seem to be tolerably reliable.

Subaru appears to be using common rail and electronic injection control, but
it's likely their engine could be adapted to a more basic mechanical system
if desired. Subaru probably doesn't build the injection components, but
purchases them from a specialty manufacturer. The VW TDI engine, for
example, uses electronic injection control when installed in a Jetta, but
when sold as a stationary engine, uses a purely mechanical injection system
provided by Bosch.

Even mechanical diesel injection systems have failure modes, of course. So
do gasoline injection systems and carburetors. None of them are utterly
reliable, but all seem to be tolerably reliable.

Leaving fuel control concerns aside for now, however, the fact remains that
diesels do not require electrical ignition systems. A gas engine depends
upon air, compression, fuel control, and ignition. The diesel depends upon
air, compression, and fuel control.

Aircraft ignition systems are high cost, high maintenance, and can interfere
with other aircraft systems. I've maintained, troubleshot, and repaired
these systems for thirty years. I would not miss them if they fell from
favor. During the same period, I've maintained, troubleshot, and repaired
aircraft fuel control systems from carburetors to FADEC. Diesel electronic
fuel control systems are not any more complex and need not be any less
reliable than these systems.

>
>> 3. Turbocharging a diesel is a win-win proposition. EGT is lower, so
>> turbo
>> system parts last as long as the engine, usually. Turbocharging improves
>> both performance and fuel efficiency (not always true for gassers).
>
> True, but boost levels in diesels inversely effect their reputation
> for reliability.

As do boost levels in gasoline engines. However, turbo-normalization does
not usually impact reliability, if sufficient engine cooling is available at
altitude. Turbodiesels normally see about 10" of boost, and operate
reliably regardless of ambient pressure, as long as the turbocharger and
cooling system can cope.
>
> <SNIP>
>
>> 8. I can make biodiesel for 67 cents a gallon. You or I can buy
>> off-road
>> diesel or heating oil for much less than either auto gas, avgas or jet A.
>
> Biodiesel gels at a higher temp than does winter diesel, and be damned
> sure you have no rubber in the fuel system. And the 67 cents is
> quoted for recycled oil. Not my first pick at altitude.

I fly mostly in the southern US in the spring, summer, and fall. If temps
at altitude (or on the ground) were below safe limits for biodiesel, I would
choose another fuel. However, much like turbine engines do, diesels return
large quantities of warm fuel back to the fuel tanks in flight. Fuel temps
rarely drop to ambient temperature. I agree, however, that it isn't a risk
worth taking.

I've made fuel from waste oil, but my current supply is virgin oil that was
rejected as a food ingredient. Eight thousand gallons of it. It should
last a while.

>> 9. For a given trip, less fuel is needed, both in volume and weight.
>> 25%
>> to 35%, depending on the trip profile. If the diesel is turbocharged and
>> gasser is not, the diesel's ability to cruise significantly higher may
>> result in a bigger efficiency spread.
>
> This is dependent on tuning the boost map, and whether the blower is
> big enough. Off the shelf this may or may not be true. I have not read
> flight tests for any new European diesels which have been impressive
> in high altitude performance. I doubt this is because of any
> fundemental flaws, but rather performance tuning.
>
Agreed. Cooling is also an issue. Even with liquid cooling, thin air at
altitude may limit the installation's ability to shed waste heat.
Turbocharged gas engines face the same problem. However, several
manufacturers have produced piston aircraft capable of sustained cruising
in the lower Flight Levels. Diesels theoretically produce a bit less waste
heat than gasoline engines. It would be interesting to experiment with one.

<SNIP>

> I dig your enthusiasm. Please post if you hear of any new diesel/
> biodiesel aviation projects. I would be interested in reading any
> related results. I believe that the new generation of diesels are the
> long term solution for keeping GA operating costs down. But it will
> take a while.
>
> -Matt

The SmartCar aluminum diesel engine and the Toyota Yaris engine (Europe,
aluminum diesel) might be good candidates for small aircraft. However, this
Subaru seems to be an ideal candidate since its power and weight specs fit
so many available airframes. PRSUs are also available. I suspect we will
see these engines installed fairly quickly in European experimentals.

DS

[Philippe Vessaire]

Bill Daniels wrote:


>
> The Subaru oil burner looks good but then so does the DeltaHawk and
> the little opposed piston aircraft diesels from the UK.

Not really as good as someone think... It's too heavy (178kg, 400lb).

I prefer a true airplane engine like WAM120 or WAM160
http://www.wilksch.com/

They shipped some 120Hp 3 cylinder engines, but I don' know if they
shipped any 160HP 4 cylinder engines.

Both engines will work fine in a RV9...

At this time, the WAM creator will be hired by Continental...
Is WAM engines will be certified and continetal branded?

About diesel mania, remember the avgas cost is twice the diesel cost
in Europe; 100LL cost more than $10 one gallon.


By
--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬

[Philippe Vessaire]

clare at snyder dot ontario dot canada wrote:

>>> Torque curve page 6

>>> http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf

>>Holy crap! That thing has the peak torque, and it is almost a level
>>line, from about 1600 rpm to about 2400 rpm!
>>
>>That sucker should really pull a big prop, and well!
>
> Like I said!

At 2400 rpm, you only got 90KW or 120Hp, not enough for a 400lb
engine.

Remember: power matter for flight.....


By
--
Volem rien foutre al païs!
Philippe Vessaire Ò¿Ó¬

[Blueskies]

> wrote in message ...
> On Mar 22, 9:33 pm, "Dale Scroggins" >
> wrote:
>> "Blueskies" > wrote in message
>>
>> ...
>>
>>
>>
>> > "Morgans" > wrote in message
>> ...
>>
>> >> "Philippe Vessaire" > wrote in message
>> >>news:19459447.yEvPs9oxTh@GastonCoute...
>> >>> Hello
>>
>> >>> Torque curve page 6
>>
>> >>>http://www.subaru.fr/special/pdf/documentation_diesel_lo_08.pdf
>>
>> >> Holy crap! That thing has the peak torque, and it is almost a level
>> >> line, from about 1600 rpm to about 2400 rpm!
>>
>> >> That sucker should really pull a big prop, and well!
>> >> --
>> >> Jim in NC
>>
>> > Is the price of diesel fuel 25% above gasoline prices everywhere?
>> > Jet A costs the same as 100LL now also, so what is the benefit?
>
> <SNIP>
>> 2. No ignition system needed.
>
> Not to be a ball-buster, but the injection systems for the new
> generation of diesels is incredibly fancy. From a risk analysis
> standpoint, it is hard to say whether this system in place of magnetos
> is a gain or a loss.
>
>> 3. Turbocharging a diesel is a win-win proposition. EGT is lower, so turbo
>> system parts last as long as the engine, usually. Turbocharging improves
>> both performance and fuel efficiency (not always true for gassers).
>
> True, but boost levels in diesels inversely effect their reputation
> for reliability.
>
> <SNIP>
>
>> 8. I can make biodiesel for 67 cents a gallon. You or I can buy off-road
>> diesel or heating oil for much less than either auto gas, avgas or jet A.
>
> Biodiesel gels at a higher temp than does winter diesel, and be damned
> sure you have no rubber in the fuel system. And the 67 cents is
> quoted for recycled oil. Not my first pick at altitude.
>
>> 9. For a given trip, less fuel is needed, both in volume and weight. 25%
>> to 35%, depending on the trip profile. If the diesel is turbocharged and
>> gasser is not, the diesel's ability to cruise significantly higher may
>> result in a bigger efficiency spread.
>
> This is dependent on tuning the boost map, and whether the blower is
> big enough. Off the shelf this may or may not be true. I have not read
> flight tests for any new European diesels which have been impressive
> in high altitude performance. I doubt this is because of any
> fundemental flaws, but rather performance tuning.
>
>> 10. Props are more efficient at lower RPMs, usually. Diesels have torque
>> to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving maybe
>> another 5% efficiency gain, and a quieter cabin to boot.
>>
>> Given time, I can think of more. Please note that gas engines were
>> abandoned decades, nay, scores of years ago in other transportation sectors.
>> It will be the same in aviation if the weight difference shrinks enough.
>>
>> DS
>
> I dig your enthusiasm. Please post if you hear of any new diesel/
> biodiesel aviation projects. I would be interested in reading any
> related results. I believe that the new generation of diesels are the
> long term solution for keeping GA operating costs down. But it will
> take a while.
>
> -Matt


Why any sort of reciprocating engine?...small turboprops would be the best solution of they can get the mass fuel flow
problems resolved...

[Morgans[_2_]]

"Dale Scroggins" > wrote

> The SmartCar aluminum diesel engine and the Toyota Yaris engine (Europe,
> aluminum diesel) might be good candidates for small aircraft. However,
> this Subaru seems to be an ideal candidate since its power and weight
> specs fit so many available airframes. PRSUs are also available. I
> suspect we will see these engines installed fairly quickly in European
> experimentals.

No need for a PSRU. The torque band makes it perfect for direct drive.
--
Jim in NC

[clare at snyder dot ontario dot canada]

On Sun, 23 Mar 2008 08:31:29 -0400, "Morgans"
> wrote:

>
>"Dale Scroggins" > wrote
>
>> The SmartCar aluminum diesel engine and the Toyota Yaris engine (Europe,
>> aluminum diesel) might be good candidates for small aircraft. However,
>> this Subaru seems to be an ideal candidate since its power and weight
>> specs fit so many available airframes. PRSUs are also available. I
>> suspect we will see these engines installed fairly quickly in European
>> experimentals.
>
>No need for a PSRU. The torque band makes it perfect for direct drive.

And the weight is not necessarily a killer. Likely a lot that can be
removed from the automotive application - and there have been many
heavier, lower powered engines thoughout aviation history.

Think Model "A" Ford. 28 HP and 200+ pounds. Lots of others too.

--
Posted via a free Usenet account from http://www.teranews.com

[Capt. Geoffrey Thorpe]

"Dale Scroggins" > wrote in message
...
>
<...>>
> 1. Most diesels wear more slowly than gas engines. The fuel is a better
> lubricant than gasoline is, and the combustion products are a bit more
> benign.

Except, of course, for the particulates. Particulates are hell on bearings,
and lungs, and...
NOx tends to run higher and isn't usually clasified as "benign"

> 5. Automatic mixture control.

"mixture control is irrelevent" would be a more accurate statement.

> 7. Lower fire risks.

Not really.

> 10. Props are more efficient at lower RPMs, usually. Diesels have torque
> to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving
> maybe another 5% efficiency gain, and a quieter cabin to boot.

Depends on how the engine was designed, not how the fuel is ignited.

>
> Given time, I can think of more. Please note that gas engines were
> abandoned decades, nay, scores of years ago in other transportation
> sectors. It will be the same in aviation if the weight difference shrinks
> enough.
>

Well, there's the problem, isn't it. Making a light weight diesel that will
last.

Note: I'm not suggesting that diesels are a bad idea - they do have there
advantages. But, let's not over sell...

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[Dale Scroggins[_2_]]

"Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote in message
news:N6adnXfOAtwpgHXanZ2dnUVZ_sWdnZ2d@wideopenwest .com...
> "Dale Scroggins" > wrote in message
> ...
>>
> <...>>
>> 1. Most diesels wear more slowly than gas engines. The fuel is a better
>> lubricant than gasoline is, and the combustion products are a bit more
>> benign.
>
> Except, of course, for the particulates. Particulates are hell on
> bearings, and lungs, and...
> NOx tends to run higher and isn't usually clasified as "benign"

The specific comparison I had in mind was a current-production piston
aircraft engine burning 100LL, compared to a current-production automotive
diesel engine. Given a choice of the lead compounds that collect within and
are emitted by the gasser, and the low levels of particulates deposited and
emitted by a current-production automotive diesel, I'd prefer the
particulates.

As to oxides of nitrogen, given that current production gas aviation engines
run with advanced ignition timing, have no EGR, and operate at elevated EGT
most of the time, I doubt a current production auto diesel would produce
more NOx, and would likely produce less. I'm open to numbers, if you have
them.

Again, my comparison was between current diesels and current gas aircraft
engines, not current automotive gas engines.

>
>> 5. Automatic mixture control.
>
> "mixture control is irrelevent" would be a more accurate statement.

For a turbodiesel, "automatic mixture control" is a more accurate statement.
Mixture control is quite relevent, and automatically managed.

>
>> 7. Lower fire risks.
>
> Not really.

Hmm. So the dozens of induction fires (some of which caused substantial
damage) that I've witnessed over the years are just as likely with a diesel
engine? And all the extra precautions we followed over the years when
fueling and defueling avgas (or mogas), compared to jetA, were a waste of
time?

>
>> 10. Props are more efficient at lower RPMs, usually. Diesels have
>> torque to turn props slow in cruise, like a turboprop (1800-1900 RPM),
>> giving maybe another 5% efficiency gain, and a quieter cabin to boot.
>
> Depends on how the engine was designed, not how the fuel is ignited.

Hmm again. So the burn characteristics of the fuel, the ability to inject
additional fuel after initiation of combustion, and the surplus of available
oxygen have no impact on engine torque curves?

>
>>
>> Given time, I can think of more. Please note that gas engines were
>> abandoned decades, nay, scores of years ago in other transportation
>> sectors. It will be the same in aviation if the weight difference shrinks
>> enough.
>>
>
> Well, there's the problem, isn't it. Making a light weight diesel that
> will last.
>
> Note: I'm not suggesting that diesels are a bad idea - they do have there
> advantages. But, let's not over sell...

Wasn't the prospect of a relatively light weight diesel available to
homebuilders the point of this thread? No one knows if Subaru's diesel will
match the durability of a current-production avgas engine. However, newer
diesel injection methods have helped reduce internal engine forces, so
durable, light diesel engines are on the horizon.

What do you see as the advantages of diesel aircraft engines?

DS

[Dale Scroggins[_2_]]

"Morgans" > wrote in message
...
>
> "Dale Scroggins" > wrote
>
>> The SmartCar aluminum diesel engine and the Toyota Yaris engine (Europe,
>> aluminum diesel) might be good candidates for small aircraft. However,
>> this Subaru seems to be an ideal candidate since its power and weight
>> specs fit so many available airframes. PRSUs are also available. I
>> suspect we will see these engines installed fairly quickly in European
>> experimentals.
>
> No need for a PSRU. The torque band makes it perfect for direct drive.
> --
> Jim in NC

It's going to need a starter; diesels are hard to hand prop. And the engine
is not likely designed to handle thrust and gyroscopic loads. So, because
of starter placement and need for a well-supported prop shaft, a nose-piece
casting with bearings and a prop shaft will be needed. Incorporating
reduction gearing (or belt) and a device to smooth power pulses wouldn't add
much additional weight.

The torque curve isn't flat to maximum power. If a fixed-pitch prop is
installed that is efficient at low RPM, the engine may not be able to make
take-off RPM without a bit of mechanical advantage - or variable pitch,
which leads back to the PSRU. Since Subaru is hinting that a 200 hp version
is on its way (giving even better hp/weight ratio), a variable pitch prop
should be considered.

DS

[Morgans[_2_]]

"Dale Scroggins" > wrote

> It's going to need a starter; diesels are hard to hand prop. And the
> engine is not likely designed to handle thrust and gyroscopic loads.

Many auto engine cranks have done well with these loads, and no extra help.

> So, because of starter placement

Alternate starter schemes may be developed, and might save weight.

> and need for a well-supported prop shaft, a nose-piece casting with
> bearings and a prop shaft will be needed.

Not a given, IMHO.

> Incorporating reduction gearing (or belt) and a device to smooth power
> pulses

Smoothing power pulses results in heating up the device, which means it is
robbing power and efficiency. Double or triple bad thing. Weight, power,
and reliability.

> wouldn't add much additional weight.

I've heard that so many times, and it all adds up to an overweight airplane.

> The torque curve isn't flat to maximum power.

True, but how much extra power will have to be made, to haul around the
extra weight?

>If a fixed-pitch prop is installed that is efficient at low RPM, the engine
>may not be able to make take-off RPM without a bit of mechanical
>advantage - or variable pitch, which leads back to the PSRU.

PSRU's are HEAVY! Why add one, if it is not absolutely needed? Extra
weight has to be well justified, as does the possibility of extra components
causing possible extra failures. It is hard to imagine that hauling around
the extra weight could be justified, with a torque curve like that engine.
It would need to make a lot of extra HP to justify a PSRU, to me.

> Since Subaru is hinting that a 200 hp version is on its way (giving even
> better hp/weight ratio), a variable pitch prop
> should be considered.

Why?

With conventional aircraft engines, they make best power and torque at up
around 2700 RPM. If you have to run too big of a prop to utilize 200 HP,
then you need constant speed to keep from breaking supersonic.

If you have an engine running best power (or close to it) and best torque at
23 or 24 hundred RPM, you can run a bigger prop, and keep the tips slow
enough, without the extra weight and complexity of constant speed props.

Don't get me wrong. I'm not against PSRU's in all cases. I am against
extra weight and complexity when it is not absolutely necessary. I don't
think a clear case has been made, for this engine.

Wait until it is being used, and see how well it does, is my opinion. It
will let us know, by how it does after it has been eXperimented with, I
believe. You may be surprised. I might be, too. Until then, keep an open
mind.
--
Jim in NC

[Barnyard BOb]

Morgans" wrote:

>
>"Dale Scroggins" > wrote
>
>> It's going to need a starter; diesels are hard to hand prop. And the
>> engine is not likely designed to handle thrust and gyroscopic loads.
>
>Many auto engine cranks have done well with these loads, and no extra help.

Name 'em and define what you mean by 'no extra help'?

>> and need for a well-supported prop shaft, a nose-piece casting with
>> bearings and a prop shaft will be needed.
>
>Not a given, IMHO.

YES.... 'a given' or something very close to one for safety sake.

>Wait until it is being used, and see how well it does, is my opinion. It
>will let us know, by how it does after it has been eXperimented with, I
>believe. You may be surprised. I might be, too. Until then, keep an open
>mind.

Aw phoof!

A promising answer or solution is always just around the corner.
In the meantime, I guess you can fly around in a baloon filled with
the hot air generated here!

- Barnyard BOb -

[Barnyard BOb]

On Tue, 25 Mar 2008 08:39:12 -0500, Barnyard BOb
> wrote:

>
>Morgans" wrote:
>
>>
>>"Dale Scroggins" > wrote
>>
>>> It's going to need a starter; diesels are hard to hand prop. And the
>>> engine is not likely designed to handle thrust and gyroscopic loads.
>>
>>Many auto engine cranks have done well with these loads, and no extra help.
>
>Name 'em and define what you mean by 'no extra help'?
>
>>> and need for a well-supported prop shaft, a nose-piece casting with
>>> bearings and a prop shaft will be needed.
>>
>>Not a given, IMHO.
>
>YES.... 'a given' or something very close to one for safety sake.
>
>>Wait until it is being used, and see how well it does, is my opinion. It
>>will let us know, by how it does after it has been eXperimented with, I
>>believe. You may be surprised. I might be, too. Until then, keep an open
>>mind.
>
>Aw phoof!
>
>A promising answer or solution is always just around the corner.
>In the meantime, I guess you can fly around in a baloon filled with
>the hot air generated here!
>
>- Barnyard BOb -

P.S.

Morgans....
Dunt waist yer tyme tellin mee howe too speal balloon, o-kay?

- Barnyard BOb-

[Morgans[_2_]]

"Barnyard BOb" > wrote

> Morgans....
> Dunt waist yer tyme tellin mee howe too speal balloon, o-kay?


O.K., but I thought you were going for baboon! ;-)
--
Jim in NC

[Barnyard BOb]

On Tue, 25 Mar 2008 12:12:50 -0400, "Morgans"
> wrote:

>
>"Barnyard BOb" > wrote
>
>> Morgans....
>> Dunt waist yer tyme tellin mee howe too speal balloon, o-kay?
>
>
> O.K., but I thought you were going for baboon! ;-)
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

If I was mean spirited..... you would be corrrect.
I would have called you a hot air BABOON!

However, I'm still just the classic grouch, Jim!!!!

Bless you and all the world's Corvairs. 8-)


- Barnyard BOb -

[Capt. Geoffrey Thorpe]

"Dale Scroggins" > wrote in message
...
>
> "Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote in message
> news:N6adnXfOAtwpgHXanZ2dnUVZ_sWdnZ2d@wideopenwest .com...
<...>
> Hmm. So the dozens of induction fires (some of which caused substantial
> damage) that I've witnessed over the years are just as likely with a
> diesel engine?

Probably not, since there is no fuel in the induction system.

>>
>>> 10. Props are more efficient at lower RPMs, usually. Diesels have
>>> torque to turn props slow in cruise, like a turboprop (1800-1900 RPM),
>>> giving maybe another 5% efficiency gain, and a quieter cabin to boot.
>>
>> Depends on how the engine was designed, not how the fuel is ignited.
>
> Hmm again. So the burn characteristics of the fuel, the ability to inject
> additional fuel after initiation of combustion, and the surplus of
> available oxygen have no impact on engine torque curves?
>

On the contrary. The inabilty to mix the fuel with the air is the reason
that typical diesel torque curves flatten out at low speeds - a gas engine
can better use the air and generates more torque at the higher speeds. So
the TENDANCY is to select bore/stroke ratio's and displacements that favor
lower speeds in diesels. But there are lots of exceptions.

<..>
> Wasn't the prospect of a relatively light weight diesel available to
> homebuilders the point of this thread? No one knows if Subaru's diesel
> will match the durability of a current-production avgas engine. However,
> newer diesel injection methods have helped reduce internal engine forces,
> so durable, light diesel engines are on the horizon.
>
> What do you see as the advantages of diesel aircraft engines?
>

Primary advantage is fuel consumption - higher compression, lower pumping
losses (minor benifit for aircraft) and reduced heat loss due to the
stratified nature of the combustion all help to improve efficiency.
Increased fuel density also gives a boost to "miles per gallon" - but for
aircraft it's about "miles per pound".

Primary disadvantage is power to weight. Diesels are typically smoke
limited - they can't use all the air, so the power is limited - that's why
turbos are so popular on diesels. The higher combustion pressures also
require a heavier block and a heavier bottom end which, well, being heavier,
adds weight.

Secondary advantage is no ignition system. Secondary disadvantage is a
somewhat fussy fuel system (and, with a common rail system, you are just as
reliant on electricity as an electronic fuel injected gas engine). Probably
less of a problem for aircraft use when compared to small marine
applications - do a search on "fuel polishing"...

FWIW - look for the press propaganda on Ford's "Eco-Boost" - turbo charged,
direct injection, spark ignited gas - looks like they are shooting to get
closer to diesel fuel economy without the cost (diesel aftertreatment is
REAL expensive at the lower emission standards). Improving power to weight
lets them downsize the engine, down size vehicle componants, etc.

Of course, one could say that direct injection gasoline has all the
disadvantages of both gasoline and diesel engines. ;-)

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[Capt. Geoffrey Thorpe]

"Blueskies" > wrote in message
t...
<...>
>
> Why any sort of reciprocating engine?...small turboprops would be the best
> solution of they can get the mass fuel flow problems resolved...
>

Nothing like the laws of thermodynamics and material limitations to ruin a
good party.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[Capt. Geoffrey Thorpe]

"Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote in message
...
> "Dale Scroggins" > wrote in message
> ...
>>
>> "Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote in
>> message news:N6adnXfOAtwpgHXanZ2dnUVZ_sWdnZ2d@wideopenwest .com...
> <...>
<...>>
>> What do you see as the advantages of diesel aircraft engines?
>>
>
> Primary advantage is fuel consumption - higher compression, lower pumping
> losses (minor benifit for aircraft) and reduced heat loss due to the
> stratified nature of the combustion all help to improve efficiency.
> Increased fuel density also gives a boost to "miles per gallon" - but for
> aircraft it's about "miles per pound".

Oh, I forgot, they can run on Jet fuel if the injector pump will tolerate
it...



On the downside, diesel fuel is good for growing algae, dunno about jet
fuel - but given the number of hanger queens at the typical airport, I
assume we will find out when diesels make a dent in the aircraft market.







--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[Morgans[_2_]]

"Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote

> Nothing like the laws of thermodynamics and material limitations to ruin a
> good party.

Yep. Small turbine engines are not fuel efficient, and yet they are
expensive. The materials are exotic, and so are the methods that have to be
used to construct the engine.

The gains that have been made with small turbines are amazing enough to me,
but they still have not gone to where they need to be, to be practical.

That said, I still want one of those rigid skydiving wings, with the 4 pack
of model jet engines! What a rush that HAS to be!
--
Jim in NC

[Peter Dohm]

"Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote in message
news:mLWdneP7Q9QVCXTanZ2dnUVZ_sqinZ2d@wideopenwest .com...
>>
>> Primary advantage is fuel consumption - higher compression, lower pumping
>> losses (minor benifit for aircraft) and reduced heat loss due to the
>> stratified nature of the combustion all help to improve efficiency.
>> Increased fuel density also gives a boost to "miles per gallon" - but for
>> aircraft it's about "miles per pound".
>
> Oh, I forgot, they can run on Jet fuel if the injector pump will tolerate
> it...
>
AFAIK, the newly demanded ultra low sulphur diesel fuel is nasty stuff for
the pumps, because the hurriedly implemented refining process also strips
lubricants from the fuel. I have no idea whether this will be a continuing
problem or whether other processes maintain the lubricity of the fuel.
>
>
> On the downside, diesel fuel is good for growing algae, dunno about jet
> fuel - but given the number of hanger queens at the typical airport, I
> assume we will find out when diesels make a dent in the aircraft market.
>
>
I don't know about the kerosene based jet fuel sold here in the U.S., but
some of the foreign stuff is (or at least was) a feeding ground for
micro-organisms. The Eastern Airlines L-1011 that went down in the Florida
Everglades some years ago was apparently full of the stuff after having been
previously refuelled in Israel.

BTW, I'm glad someone remembers what a hangar queen is. ;-))

Peter

[cavelamb himself[_4_]]

Morgans wrote:

> "Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote
>
>
>>Nothing like the laws of thermodynamics and material limitations to ruin a
>>good party.
>
>
> Yep. Small turbine engines are not fuel efficient, and yet they are
> expensive. The materials are exotic, and so are the methods that have to be
> used to construct the engine.
>
> The gains that have been made with small turbines are amazing enough to me,
> but they still have not gone to where they need to be, to be practical.
>
> That said, I still want one of those rigid skydiving wings, with the 4 pack
> of model jet engines! What a rush that HAS to be!


If you got the money, I got the time!



--
(remove the X to email)

It's never too late to be the person you might have been.
George Elliot

[cavelamb himself[_4_]]

cavelamb himself wrote:

> Morgans wrote:
>
>> "Capt. Geoffrey Thorpe" <The Sea Hawk At Wow Way D0t C0m> wrote
>>
>>
>>> Nothing like the laws of thermodynamics and material limitations to
>>> ruin a good party.
>>
>>
>>
>> Yep. Small turbine engines are not fuel efficient, and yet they are
>> expensive. The materials are exotic, and so are the methods that have
>> to be used to construct the engine.
>>
>> The gains that have been made with small turbines are amazing enough
>> to me, but they still have not gone to where they need to be, to be
>> practical.
>>
>> That said, I still want one of those rigid skydiving wings, with the 4
>> pack of model jet engines! What a rush that HAS to be!
>
>
>
> If you got the money, I got the time!
>
>
>


But YOU are doing the first flight!