Boeing Launches 7E7

"Olivers" wrote in message
...
Nik muttered....



Now my point is that if the 7E7 is to be 15-20% more efficient than
the 767/A300 then this size of the plane might be the optimal. When
you start stretching it to get into the A330 market it will be
relatively less efficient and hence will represent even less of a
direct competitor.


As your logic doesn't work with ocean going vessels (where extending
waterline length actually increases hull speed), it doesn't necessarily
work with a/c either.

The MD80s, long stretches of the original DC-9 fuselage had a
substantially
lower passeenger mile operating cost, more seats and about equal fuel
consumption (except on takeoff), and IIRC an actual few knots increase in
economical cruise speed.

Many "stretch" a/c actually outperform their original versions.

TMO

Isn't dynamic drag to a large extent dependent on weight? (To my knowledge,
this issue doesn't really apply to ocean going vessels).


Nik

Nik

In article ,
"Nik" wrote:


No the 7E7's efficiency gain possibly comes from being able to replace a
second generation aircraft with a third generation FBW composite build one.
I strongly doubt that the improvements in design techniques and knowledge
about aerodynamic on its own would allow for a 20 percent efficiency gain

One factor is the wing tip which is similar to what is found on some
737NGs. The Aviation Partners design works well enough that airlines
are starting to retrofit it to their a/c (i.e., it's worth the
investment). Have a look at how much better climb rate, range, payload
are increased and fuel consumption and noise decreased. Continental is
launching design to retrofit 757s.

"Not the Karl Orff" wrote in message
...
In article ,
"Nik" wrote:


No the 7E7's efficiency gain possibly comes from being able to replace a
second generation aircraft with a third generation FBW composite build
one.
I strongly doubt that the improvements in design techniques and
knowledge
about aerodynamic on its own would allow for a 20 percent efficiency
gain

One factor is the wing tip which is similar to what is found on some
737NGs. The Aviation Partners design works well enough that airlines
are starting to retrofit it to their a/c (i.e., it's worth the
investment). Have a look at how much better climb rate, range, payload
are increased and fuel consumption and noise decreased. Continental is
launching design to retrofit 757s.

Well - the A330 also have wing tips...

I'm not saying that the A330 cannot be improved. What I say is that to get a
significant improvement you'll likely have to introduce some kind of
concept. Therefore the 20 percent is most likely over the 767 and the A300.

Nik.

Nik

Nik extrapolated from data available...


"Olivers" wrote in message
...
Nik muttered....



Now my point is that if the 7E7 is to be 15-20% more efficient than
the 767/A300 then this size of the plane might be the optimal. When
you start stretching it to get into the A330 market it will be
relatively less efficient and hence will represent even less of a
direct competitor.


As your logic doesn't work with ocean going vessels (where extending
waterline length actually increases hull speed), it doesn't
necessarily work with a/c either.

The MD80s, long stretches of the original DC-9 fuselage had a
substantially
lower passeenger mile operating cost, more seats and about equal fuel
consumption (except on takeoff), and IIRC an actual few knots
increase in economical cruise speed.

Many "stretch" a/c actually outperform their original versions.

TMO

Isn't dynamic drag to a large extent dependent on weight? (To my
knowledge, this issue doesn't really apply to ocean going vessels).


Obviously, there's an penalty, and greater takeoff weight requires more
fuel to climb and to cruuise, but the derived result in some stretches,
starting with the "Stretch 8" offset some of the potential.

Of course, in modern a/c, the vast advances in engine economy make
comparisons difficult, but certainly the 757 was an attempt to profit from
a longer fuselage and reduced cross section.

As for ships, the "weight" problem is expressed a different way...Stretch
it (without changing beam or hull lines), and the volume of the extension
and weight of the new materials cause an increase in "displacement", the
volume of water displaced by the ship. The increased displacement is in
almost every case of which I'm aware, offset by the increased "hullspeed"
available from a longer waterline. The "Cut off" square transom sterns
which are popular are an artificial method by which the hull "acts" longer.

I suspect the short fat 747, was it the SP?, were a venture in another
direction, reduced structural weight, lower pax/cargo weight, allowing
longer range from the same size tanks.

TMO

In article ,
"Nik" wrote:

n to retrofit 757s.

Well - the A330 also have wing tips...

And so do others but the question is whether they work as well as those
ones used on some of the the 737NGs

I'm not saying that the A330 cannot be improved. What I say is that to get a
significant improvement you'll likely have to introduce some kind of
concept. Therefore the 20 percent is most likely over the 767 and the A300.

I think that's not disputed.

At any rate it is Wweight.

"Not the Karl Orff" wrote in message
...
In article ,
"Nik" wrote:

n to retrofit 757s.

Well - the A330 also have wing tips...

And so do others but the question is whether they work as well as those
ones used on some of the the 737NGs


That is right. However, I do believe that wing tips is a part of an
aircraft's structure that might be the easiest to modify if the need should
occur.

Nik