Does a large advanced turboprop make sense with $100/barrel oil?
thad beier
oil might finally be over. I'm wondering what the implications of this
might be for Boeing and Airbus. Might some time be well spent
developing even more fuel efficient airplanes?
Boeing's 787 is probably about as miserly a plane that you can make and
have it still meet noise regs and fly faster than Mach .75. It appears
that they have left no stone unturned in the pursuit of efficiency --
the 787 is as radical a departure from the previous airplane design
paradigm as was the 707 or the 747. It's still not clear to me that
the composite fuselage bet is going to pay off, it's a huge gamble.
But, the 787 was designed a couple of years ago, when oil was
$15/barrel or so. It's a lot more expensive now, and shows no signs of
abating. Airline ticket prices are going to have to go up quite a bit.
Just as an example, for the quarter just ended, America West's
percentage of expenses that were fuel went from 18% a year ago to 22.5%
now, as the fuel price went from $1.05 to $1.42/gallon. If it goes up
to $3.50/gallon, not out of the question by any means, then fuel costs
will be more like 45% of their expenses. It makes sense to look at
substantially more efficient airplanes.
Boeing experimented with advanced turboprot designs from Allison and GE
back in the early-to-mid 80's, with their proposed 7J7. Recall that
when that plane was first mooted, oil prices peaked at $90/barrel in
today's dollars (measuring inflation over 25 years is not an exact
science, needless to say, but $90/barrel is probably as good an
estimate as any.) As oil prices eased, Boeing killed the 7J7.
The big problem with the 7J7 was noise -- two rows of contrarotating
blades hanging out in the breeze are going to make a lot of noise.
This was a problem not just in the area surrounding the airport, but
for people inside the plane and even people under planes at cruise (as
the planes reached high mach numbers in cruise, the noise levels went
up tremendously.) I don't think that there's been anything done in the
last 20 years that will make the engines much quieter.
One possibility is to fly slower. As I understand it (but would love
to be corrected if I'm wrong!) if you are going to fly at .75 Mach you
are going to need to have contrarotating propellers or the losses due
to swirl are going to devastate the efficiency of the engines. But, if
you're flying only .6 Mach, say, perhaps a larger, slower
single-rotating prop would work well.
Now, slow planes are historically anathema to the airline industry.
Faster planes carry more people-miles per hour, and the only reason
people fly is for the speed. If the planes were slow, then rail or
even driving become competitive. But, we note that Boeing has seen the
writing on the wall by shelving the Sonic Cruiser -- a cool plane, but
one that just doesn't make sense as fuel becomes more dear.
I'm just wondering if the big airframe manufacturers are seriously
considering what very high fuel prices might mean over the next 20
years. After all, they only make profits on planes if they sell well
over an extended period of time. One would think that Boeing and
Airbus would be hedging their bets to some extent, with advanced but
hyper-efficient turboprop concepts ready to be brought into service
quickly if necessary.
More expensive fuel is going to happen. As China and India modernize,
they are going to develop insatiable appetites for deisel fuel, and the
oil producers and refiners are already stretched to the limit. How
will we adapt?
Thad Beier
D.M. Procida
> Now, slow planes are historically anathema to the airline industry.
> Faster planes carry more people-miles per hour, and the only reason
> people fly is for the speed. If the planes were slow, then rail or
> even driving become competitive.
Not for a flight across the Atlantic, certainly. If a slower, lazily
chugging aircraft could offer fuel savings that made a significant
difference to passenger/cargo prices, then I think that would be viable
- particularly for cargo, which unlike people minds less about having to
spend an extra hour or two in a sardine can.
A slower aircraft would also presumably have to deal with lower
stresses, and could be built and maintained more cheaply.
Daniele
--
JF Mezei
> Over the last few months, it has begun to appear that the era of cheap
> oil might finally be over. I'm wondering what the implications of this
> might be for Boeing and Airbus.
This implications are that with ticket prices rising, discretionary
flying will go down. This means that low cost carriers will lose a lot
of their clientele, but will probably steal equal amounts of business
travelers from legacy carriers.
IF high oil prices are here permanently, as opposed to just until the
USA signs Kyoto or son-of-Kyoto to send a strong signal that its oil
consumption will become under control, then yes, big structural changes
will be needed. If the USA agrees to control its unrestrained oil
consumption habits, the example will be set to also tell China and India
to start to control their oil ASAP before they get out of hand, at which
point, oil prices will moderate. Aircraft are long term investments and
both Boeing and Airbus have to look beyond short term political climate.
> Boeing's 787 is probably about as miserly a plane that you can make and
> have it still meet noise regs and fly faster than Mach .75. It appears
> that they have left no stone unturned in the pursuit of efficiency
Long range aircraft have no viable competition. The Queen Mary 2 is more
expensive than first class tickets on aircraft and does a very limited
number of trips/destinations. And I am not sure that such ships would be
viable in the pacific during typhoon /cyclone seasons.
For Boeing and Airbus, while there may be less demand for long range
aircraft, such demand will continue because there really isn't any other
viable way to get people to destination in reasonable time. However, the
whole "fragmentation" theory would fall apart and airlines would focus
on operating the fewest long range flights necessary on the biggest,
most fuel efficient aircraft.
Consider the the 767 is on its way out, and that the 787 is a bigger
aircraft. Some point-to-point markets big enough for 767 may no longer
be big enough for the 787. With high fiel prices, airlines won't want to
operate long hauls with low load factors, even if the 787 with few pax
will be cheaper to operate than a 767 with same number of pax.
> But, the 787 was designed a couple of years ago, when oil was
> $15/barrel or so. It's a lot more expensive now, and shows no signs of
> abating.
Considering that the engine is still being designed, there is probably
some room for further improvement. GE knows about the high price of
fuel. And it has pressure from both Boeing and Airbus to do something
really good, especially if the same engine will be used for the 747.
> The big problem with the 7J7 was noise -- two rows of contrarotating
> blades hanging out in the breeze are going to make a lot of noise.
Since the 1980s, sound/vibration dampening technology was developped and
is in daily use on dash-8s around the world (Q series). It is supposedly
extremely effective and makes cabin noise and vibration equivalent to
that of a jet aircraft.
Does anyone have fuel consumption numbers for Dash-8 versus CRJ for say
a 500km hop ? Would the Dash-8 have a huge edge or would the two be
roughly the same in terms of fuel costs ?
> I'm just wondering if the big airframe manufacturers are seriously
> considering what very high fuel prices might mean over the next 20
> years.
My bet is that both Boeing and Airbus , as well as engine manufacturers
are seriously looking at this. However, it isn't a given that the prices
will remain this high forever. New refineries will come in asia to
serve china and india and that would ease the current strain and the
big oil consuming countries will eventually sign treaties to reduce oil
consumption/emissions, that would also go a long way towards easing
fears of greater demand than supply.
Air travel is public transportation. As such, when government impose
policies to essentially prioritise the use of oil though taxation, I
suspect that air travel, while perpaps not right at the top with trains,
will be up there, and it will be personal travel (cars and light
aviation) wich will see very high fuel costs to dissuade their use.
The other option is to look at alternate sources of fuel. Turbines can
use a variety of fuel from natural gas to hydrogen. The disadvantage is
that storing those fuels in a wing isn't as easy, safe and efficient as
storing jet fuel.
Note that a country in south america (I think bolivia, but not sure) has
developped a natural gas powered locomotive. That country has natural
gas, but no oil. So it made sense. The LNG is stored in a separate car,
a bit like the steam locomotives pulled a car filled with coal.
> How
> will we adapt?
The international energy commission has calculated that the USA could
drop its fuel consumption by 3% tomorrrow just by lowering the speed
limits on its highways. I realise that this can't happen now, but by the
end of this decade, it might be possible.
wes...@graphics.cornell.nospam.edu.retro.com
And there was an advanced turboprop engine option for the MD-90
series. Dropped for lack of interest. Perhaps this would offer a
lower-risk approach: a rear-engine airframe puts the "unducted fans"
as they were called by some aft of the cabin, thus dealing with the
cabin noise issue, and using an existing airframe means that there is
little lost investment if the idea doesn't catch on.
But the difficulty here is the same one that always seems to kill
advanced fuel-saving ideas: the price of oil is basically arbitrary.
A sudden increase in oil production would drive down prices, making
lots of ideas uneconomical. It's impossible to plan for such an
unstable future.
--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.
matt weber
>
>Boeing experimented with advanced turboprot designs from Allison and GE
>back in the early-to-mid 80's, with their proposed 7J7. Recall that
>when that plane was first mooted, oil prices peaked at $90/barrel in
>today's dollars (measuring inflation over 25 years is not an exact
>science, needless to say, but $90/barrel is probably as good an
>estimate as any.) As oil prices eased, Boeing killed the 7J7.
>
>The big problem with the 7J7 was noise -- two rows of contrarotating
>blades hanging out in the breeze are going to make a lot of noise.
>This was a problem not just in the area surrounding the airport, but
>for people inside the plane and even people under planes at cruise (as
>the planes reached high mach numbers in cruise, the noise levels went
>up tremendously.) I don't think that there's been anything done in the
>last 20 years that will make the engines much quieter.
The noise problem wasn't the engine per se, the problem was the
contra-rotating props in the 'Prop-Fan' or Unducted Fan were
supersonic by a comfortable margin. A supersonic prop is kind of a
fact of life if you want to cruise much above 400mph.
The tips on the fan of many large turbo fans are supersonic as well,
about M1.3 at takeoff power, but since they are inside a duct, you can
do a lot to capture the shockwave/noise inside the duct, which is
exactly what they do. That isn't an option without the duct however.
Paul Hovnanian P.E.
Correct. The compromise is to make higher bypass ratio engines. This
leads, inevitably, to larger cowl diameters and longer landing gear. I'm
wondering if, at some point, the trend toward larger engines will make
the manufacturers revisit high wing designs. These would create more
room under the wing to hang big engines.
One other consideration in unducted fan vs ducted fan engines is blade
containment. Fan shrouds help quite a bit in containing broken blade
fragments that might otherwise hit the fuselage.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
Have gnu, will travel.
tomst...@gmail.com
hands had grown thinner, and her skin more transparent, and her
breath shorter; and how, when she ran or played in the garden,
as she once could for hours, she became soon so tired and languid.
He had heard Miss Ophelia speak often of a cough, that all her
medicaments could not cure; and even now that fervent cheek and
little hand were burning with hectic fever; and yet the thought
that Eva's words suggested had never come to him till now.
Has there ever been a child like Eva? Yes, there have been;
but their names are always on grave-stones, and their sweet smiles,
their heavenly eyes, their singular words and ways, are among the
buried treasures of yearning hearts. In how many families do you
hear the legend that all the goodness and graces of the living are
nothing to the peculiar charms of one who _is not_. It is as if
heaven had an especial band of angels, whose office it was to
sojourn for a season here, and endear to them the wayward human
heart, that they might bear it upward with them in their homeward
flight. When you see that deep, spiritual light in the eye,--when
the little soul reveals itself in words sweeter and wiser than the
ordinary words of children,--hope not to retain that child; for
the seal of heaven is on it, and the light of immortality looks
out from its eyes.
Even so, beloved Eva! fair star of thy dwelling! Thou are
passing away; but they that love thee dearest know it not.
The colloquy between Tom and Eva was interrupted by a hasty
call from Miss Ophelia.
"Eva--Eva!--why, child, the dew is falling; you mustn't be
out there!"
Eva and Tom hastened in.
Miss Ophelia was old, and skilled in the tactics of nursing