Quiet Airliners of the Future?

[Larry Dighera]

A new generation of barely audible, fuel-efficient passenger
aircraft described as "flying wings" with "virtual windows"
could arrive in two decades, engineers from Britain's Cambridge
University said. "The noise level we're looking for would be to
take it below the background noise that people experience
outside airports ... below traffic noise levels," said Paul
Collins, a mechanical engineer with the "Silent Aircraft
Initiative." It will be 20 years or more before the concept,
which looks more like the U.S. military's B-2 Stealth Bomber
than a jumbo jet, could enter service. But a noise reduction
approach that goes beyond the aircraft's frame and engines
means there could be benefits much sooner for those living
beneath flight paths. Working with air-traffic controllers, the
researchers hope they can begin flight tests with conventional
aircraft as early as next year to look at a new, steeper
landing approach that would limit the amount of time planes
spend at low altitudes. The scientists hope that, with oil
prices at record highs, their new designs will make economic as
well as environmental sense. For a list of companies backing the
project, click the "More..." link.
(Reuters 11:13 AM ET 09/09/2005)

More:
http://q1.schwab.com/s/r?l=248&a=1128500&m=1006243220db700022136a&s=rb050909

[Dave Stadt]

The way the airlines are running their businesses now days I suspect we will
be seeing quite a large number of "quiet airliners" in much less that 20
years. Of course getting somewhere in them might be a challenge.


"Larry Dighera" > wrote in message
...
>
>
>
> A new generation of barely audible, fuel-efficient passenger
> aircraft described as "flying wings" with "virtual windows"
> could arrive in two decades, engineers from Britain's Cambridge
> University said. "The noise level we're looking for would be to
> take it below the background noise that people experience
> outside airports ... below traffic noise levels," said Paul
> Collins, a mechanical engineer with the "Silent Aircraft
> Initiative." It will be 20 years or more before the concept,
> which looks more like the U.S. military's B-2 Stealth Bomber
> than a jumbo jet, could enter service. But a noise reduction
> approach that goes beyond the aircraft's frame and engines
> means there could be benefits much sooner for those living
> beneath flight paths. Working with air-traffic controllers, the
> researchers hope they can begin flight tests with conventional
> aircraft as early as next year to look at a new, steeper
> landing approach that would limit the amount of time planes
> spend at low altitudes. The scientists hope that, with oil
> prices at record highs, their new designs will make economic as
> well as environmental sense. For a list of companies backing the
> project, click the "More..." link.
> (Reuters 11:13 AM ET 09/09/2005)
>
> More:
>
http://q1.schwab.com/s/r?l=248&a=1128500&m=1006243220db700022136a&s=rb050909

[Ben Hallert]

There's been a lot of work over the years at Boeing on the Blended Wing
Body, I wonder if this is the same airplane, just retasked as a quiet
plane as well as a fuel efficient/large one.

http://en.wikipedia.org/wiki/Blended_Wing_Body

[Larry Dighera]

On Mon, 12 Sep 2005 21:58:24 GMT, "Dave Stadt" >
wrote in >::

>The way the airlines are running their businesses now days I suspect we will
>be seeing quite a large number of "quiet airliners" in much less that 20
>years.

How are airlines running their businesses now days?

The trend toward quieter aircraft is welcome by all. Helos are
substantially quieter than they were in the '70s, and today's airliner
compared with 4-engined B-707s of that era are too.

>Of course getting somewhere in them might be a challenge.

What makes you say that, the extent to which security measures will
have escalated by the time these aircraft are in production? Or are
you concerned by the necessary tradeoff between reducing dB and
performance?

[Peter Duniho]

"Larry Dighera" > wrote in message
...
>>Of course getting somewhere in them might be a challenge.
>
> What makes you say that, the extent to which security measures will
> have escalated by the time these aircraft are in production? Or are
> you concerned by the necessary tradeoff between reducing dB and
> performance?

I understood his post to mean that the airliners would be quiet because they
would not be in operation.

You can certainly see how an airliner not actually operating might have
limited use for transportation.

Pete

[Larry Dighera]

On Mon, 12 Sep 2005 16:12:32 -0700, "Peter Duniho"
> wrote in
>::



>I understood his post to mean that the airliners would be quiet because they
>would not be in operation.
>
>You can certainly see how an airliner not actually operating might have
>limited use for transportation.
>

As long as there is a demand for air travel, there will be someone to
supply it. I guess I'm missing some implied point.

[Dave Stadt]

"Larry Dighera" > wrote in message
...
> On Mon, 12 Sep 2005 16:12:32 -0700, "Peter Duniho"
> > wrote in
> >::
>
>
>
> >I understood his post to mean that the airliners would be quiet because
they
> >would not be in operation.
> >
> >You can certainly see how an airliner not actually operating might have
> >limited use for transportation.
> >
>
> As long as there is a demand for air travel, there will be someone to
> supply it. I guess I'm missing some implied point.

You need to read the news a little more often Larry.

[Peter Duniho]

"Larry Dighera" > wrote in message
...
> As long as there is a demand for air travel, there will be someone to
> supply it. I guess I'm missing some implied point.

All he said was "large number" and "some". He didn't say ALL airliners
would be "quiet".

[Larry Dighera]

On Tue, 13 Sep 2005 03:58:03 GMT, "Dave Stadt" >
wrote in >::

>> As long as there is a demand for air travel, there will be someone to
>> supply it. I guess I'm missing some implied point.
>
>You need to read the news a little more often Larry.

I was hoping you might enlighten me.

Again here are a couple of questions for you:


>
>On Mon, 12 Sep 2005 21:58:24 GMT, "Dave Stadt" >
>wrote in >::
>
>>The way the airlines are running their businesses now days I suspect we will
>>be seeing quite a large number of "quiet airliners" in much less that 20
>>years.
>
>How are airlines running their businesses now days?
>
>The trend toward quieter aircraft is welcome by all. Helos are
>substantially quieter than they were in the '70s, and today's airliner
>compared with 4-engined B-707s of that era are too.
>
>>Of course getting somewhere in them might be a challenge.
>
>What makes you say that, the extent to which security measures will
>have escalated by the time these aircraft are in production? Or are
>you concerned by the necessary tradeoff between reducing dB and
>performance?
>

[Dave Stadt]

"Larry Dighera" > wrote in message
...
> On Tue, 13 Sep 2005 03:58:03 GMT, "Dave Stadt" >
> wrote in >::
>
> >> As long as there is a demand for air travel, there will be someone to
> >> supply it. I guess I'm missing some implied point.
> >
> >You need to read the news a little more often Larry.
>
> I was hoping you might enlighten me.
>
> Again here are a couple of questions for you:
>
>
> >
> >On Mon, 12 Sep 2005 21:58:24 GMT, "Dave Stadt" >
> >wrote in >::
> >
> >>The way the airlines are running their businesses now days I suspect we
will
> >>be seeing quite a large number of "quiet airliners" in much less that 20
> >>years.
> >
> >How are airlines running their businesses now days?

Based on the number that are out of busines or currently in severe financial
trouble (word is Delta will soon be filing for chapter 11 protection) I
would have to say the majority have not developed a very good business
model.

> >The trend toward quieter aircraft is welcome by all. Helos are
> >substantially quieter than they were in the '70s, and today's airliner
> >compared with 4-engined B-707s of that era are too.
> >
> >>Of course getting somewhere in them might be a challenge.
> >
> >What makes you say that, the extent to which security measures will
> >have escalated by the time these aircraft are in production? Or are
> >you concerned by the necessary tradeoff between reducing dB and
> >performance?

My concern is many airliners will be sitting out in the desert somewhere
which I guess is one way of reducing noise.

[Larry Dighera]

On Tue, 13 Sep 2005 13:00:15 GMT, "Dave Stadt" >
wrote in >::

>
>"Larry Dighera" > wrote in message
...
>> On Tue, 13 Sep 2005 03:58:03 GMT, "Dave Stadt" >
>> wrote in >::
>>
>> >> As long as there is a demand for air travel, there will be someone to
>> >> supply it. I guess I'm missing some implied point.
>> >
>> >You need to read the news a little more often Larry.
>>
>> I was hoping you might enlighten me.
>>
>> Again here are a couple of questions for you:
>>
>>
>> >
>> >On Mon, 12 Sep 2005 21:58:24 GMT, "Dave Stadt" >
>> >wrote in >::
>> >
>> >>The way the airlines are running their businesses now days I suspect we
>will
>> >>be seeing quite a large number of "quiet airliners" in much less that 20
>> >>years.
>> >
>> >How are airlines running their businesses now days?
>
>Based on the number that are out of busines or currently in severe financial
>trouble (word is Delta will soon be filing for chapter 11 protection) I
>would have to say the majority have not developed a very good business
>model.

I would have to agree. These air carriers are a product of the period
when our government regulated them. Perhaps it's time for them to get
more competitive, or failing their ability to successfully transition,
they should fail. That way they could shrug off their debt and
crippling employment contracts, and start afresh.

>> >The trend toward quieter aircraft is welcome by all. Helos are
>> >substantially quieter than they were in the '70s, and today's airliner
>> >compared with 4-engined B-707s of that era are too.
>> >
>> >>Of course getting somewhere in them might be a challenge.
>> >
>> >What makes you say that, the extent to which security measures will
>> >have escalated by the time these aircraft are in production? Or are
>> >you concerned by the necessary tradeoff between reducing dB and
>> >performance?
>
>My concern is many airliners will be sitting out in the desert somewhere
>which I guess is one way of reducing noise.

I would guess that much of the inefficient airline fleet would not be
competitive in tomorrow's airline industry, and should be relegated to
the junkyards. How else will tomorrows airlines be able to be
competitive?

You've got to break eggs to make omelets.

I have little doubt that airliners of the future will be quieter and
more fuel efficient. Change is inevitable.

[Larry Dighera]

On 12 Sep 2005 15:55:39 -0700, "Ben Hallert" >
wrote in . com>::

>There's been a lot of work over the years at Boeing on the Blended Wing
>Body, I wonder if this is the same airplane, just retasked as a quiet
>plane as well as a fuel efficient/large one.
>
>http://en.wikipedia.org/wiki/Blended_Wing_Body



Jack Northrop knew in the early days of aviation, before 1927, that
the path of aircraft evolution was necessarily going to eliminate the
empennage. After successfully designing a tailless bomber*, he
conceived of flying wing passenger airliners:
http://www.warbirdforum.com/paxwing.htm

* http://www.wpafb.af.mil/museum/fta/fta198.htm

[Blueskies]

"Dave Stadt" > wrote in message . ..
>
> The way the airlines are running their businesses now days I suspect we will
> be seeing quite a large number of "quiet airliners" in much less that 20
> years. Of course getting somewhere in them might be a challenge.
>
>

Actually, that would be quiet airlines...

[Dave Stadt]

" Blueskies" > wrote in message
...
>
> "Dave Stadt" > wrote in message
. ..
> >
> > The way the airlines are running their businesses now days I suspect we
will
> > be seeing quite a large number of "quiet airliners" in much less that 20
> > years. Of course getting somewhere in them might be a challenge.
> >
> >
>
> Actually, that would be quiet airlines...

Works both ways.

[Paul kgyy]

If empennage elimination is such an "obvious" improvement, how come
it's taking so long?

I'm guessing that controllability is the major problem, and developers
are trying to fix that with electronic control systems?

[Larry Dighera]

On 14 Sep 2005 10:22:51 -0700, "Paul kgyy" > wrote
in om>::

>If empennage elimination is such an "obvious" improvement, how come
>it's taking so long?

You have to look at it from a 1927 perspective. First, the empennage
was moved from the front (Wright) to the rear (Curtiss), then the
bi-wing was reduced to a monoplane, and then the wing was fully
cantilevered. What possible further revolutionary design changes
remain?

To Jack Northrop, the answer to that fundamental question was obvious:

http://www.wpafb.af.mil/museum/fta/fta198.htm
The year 1946 brought the Northrop Flying Wing B-35 bomber, a
bomber which dwarfed all previously built versions of all-wing
aircraft. It measured 172 feet in span, and was built for an
overload gross weight of 209,000 pounds, more than 104 tons. Four
Pratt & Whitney Wasp Major engines, developing a combined 12,000
horsepower, drove counter rotating propellers which pushed the sky
giant through the air. Elimination of the fuselage and tail
surfaces increased its efficiency by cutting down drag and
reducing the airplane to a nearly pure supporting surface in which
every part contributed to weight-lifting ability. The B-35 had a
range of more than 5,000 miles with a 10,000 pound payload.

The XB-49 was a jet-powered version of the B-35, containing eight
TG-180 (J33) Allison turbojet engines within the wings. Its gross
weight was approximately 206,000 pounds, and was capable of a
4,000 mile range with a 10,000 pound payload at 450 miles per
hour, (over 500 miles per hour maximum cruise speed), an
outstanding achievement in the era of that airplane, 1946. The
airplane had full power irreversible controls, the first aircraft
to incorporate this feature. It was also the first aircraft to
incorporate artificial stability augmentation. The airplane had
accommodations for a crew of 10, with four bunks, a gallery, and
head. An interesting feature of the XB-49 was the main control
arrangement... the pilot, co-pilot, navigator bombardier, flight
engineer, and the forward gunner, all were located together, being
able to see and speak to each other at all times. The maximum
length of the airplane, including sweepback, was 53 feet, and had
a wing thickness at maximum cockpit section, of seven feet. It had
a fantastic rate of climb and was extremely maneuverable.

The XB-49 was followed by the YB-49 Flying Wing bomber in 1947,
also powered by eight turbojet engines. It, like the B-35 and
XB-49, was an all-metal, tailless bombardment type airplane built
on the true Flying Wing design principle, with no tail surfaces,
using "elevon" controls as both elevators and ailerons, as did the
B-35 and XB-49. Its maximum weight, loaded, was 213,000 pounds. It
had a wing span of 172 feet, and had speeds in the 500-mph class.
The YB-49 was powered by eight General electric designed
Allison-built TG-190 (J35) turbojets, developing 4000 pounds of
thrust each.

The YRB-49A Flying Wing (1950) was an all-wing six engined
photo-reconnaissance type turbojet aircraft built to the Flying
Wing configuration. It had a span of 172 feet, the same as its
predecessors, the B-35 and YB-49. Six Allison TG-190 J35 turbojet
engines provided the power. Four of the engines were wholly
enclosed within the wing; two were suspended on pods.

>I'm guessing that controllability is the major problem, and developers
>are trying to fix that with electronic control systems?

Northrop's visionary aircraft were relegated to the scrap heap by
politics.

The story printed in the December 8, 1980 issue of the Los Angeles
Times newspaper states:

...
Then, in 1949, Flying Wing [B-36] production was abruptly canceled
and all test planes were ordered destroyed.

For three decades, Northrop has refused to discuss why his
promising airplane -- the culmination of his lifelong dream --
was scrapped so suddenly.

But in a dramatic taped interview broadcast last week, the
85-year-old Northrop Corp, founder finally told his secret. The
Flying Wing was canceled, he said, because he refused to obey an
Air Force order that he merge his then-fledgling company with a
more established competitive firm. When he balked, Northrop said,
the Air Force summarily awarded the bomber contract to the
competing firm.

Northrop said he kept quiet for all these years because he feared
the Pentagon would blackball his company if he disclosed the
story. He said he even committed perjury before Congress to hide
the facts.

Northrop's allegation shed new light on a generation-old
controversy that has become one of the biggest mysteries in
American aviation. ...

Northrop's story was corroborated by Richard W. Millar, 81, who
witnessed the drama as chairman of the Hawthorne-based aerospace
company at the time and who still serves as Northrop vice
chairman. ...

The Air Force secretary accused of issuing the merger order,
former Sen. Stuart Symington (D-Mo), 79, refused to be interviewed
...

To select a bomber to succeed World War II's B-29s, the Air Force
pitted Northrop's Flying Wing, designated the B-36 in 1948 and
later the B-49, against a traditionally configured bomber built by
Consolidated Vaultee Aircraft Corp. (Convair), which later became
a division of General Dynamics Corp. The Flying Wing won a
competition against Convair's B-36 in 1948 and the Air Force
awarded Northrop a contract to build 35-bombers, with the
possibility of ultimately producing 200 to 300 planes.

But Northrop's elation turned into disbelief when he and company
chairman Millar were summoned to meet Symington shortly after
winning the contract in June 1948, according to their taped
statements.

Noting that his was "a vary strange story and perhaps difficult to
believe," Northrop told KCET reporter Roberts that Symington
launched into a "lengthy diatribe" about how the Air Force did not
want to sponsor any new aircraft companies because the Pentagon
could not afford to support them with continuing business on
declining post-war budgets. Then, Northrop said, Symington
demanded that Northrop corp. merge with Convair.

At that point, Northrop recalled, Brig. Gen. Joseph T. McMarney,
commander of the Air Materiel Command and subsequently president
of Convair said, "Oh Mr. Secretary, you don't mean that the way it
sounds."

"You're ... right I do," Symington answered, according to Northrip
and Millar.

Northrip and Millar told KCET's Roberts that they then visited
Floyd Odlum, head of Atlas Corp., which controlled Convair, to
discuss a possible merger. But talks soon ended, Northrop said,
because Odlum's demands were "grossly unfair to Northrop."

A few days later, Northrop recalled, Symington telephoned him and
said, "I am canceling all your Flying Wing Aircraft."

"I said, 'Oh, Mr. Secretary, why?"

"He said, 'I've had an adverse report,' and hung up," Northrop
recounted. "and that was the last time I talked to him and the
last time we could reach him by phone or any other way."

As part of the cancellation, Millar added, the Air Force ordered
the destruction of seven Flying Wings then under construction.
"Those airplanes were destroyed in front of the employees and
everybody who had their heart and soul in it," said Millar, his
voice cracking.

After the Air Force canceled the Flying Wing and awarded the
contract to the competing Convair B-36, a House Armed Services
subcommittee held hearings in 1949 to investigate allegations that
the Pentagon used coercion in its aircraft procurement practices.

According to the press accounts at the time, the investigation was
prompted by "ugly rumors" about Symington and other Pentagon
officials. One rumor investigated - and denied by whiteness at
the hearing - was that Symington had been considered to head the
firm that would result from the proposed merger between
Consolidated Vaultee and Northrop.

Among the witnesses who denied seeing any evidence of Pentagon
coercion was John K. Northrop.

Northrop testified that he did not "feel there was any
unjustifiable or unreasonable pressure in the cancellation of the
B-49 contract. I would call the move reasonable and logical."
When asked under oath if he was in fear of Pentagon reprisal,
Northrip laughed and said, "have no fear of reprisal."

Thirty-one years later, when asked about his testimony by reporter
Roberts, Northrop responded, " My reaction is that under pressure
of the life or death of Northrip Corp., I committed one of the
finest jobs of perjury that I've ever heard."

Northrop said in the taped interview that he did not tell the full
story until now because he feared that Symington would cause the
"complete obliteration" of his company. Millar said that the
meeting with Symington was so "brutal and bare-faced" that "you
almost had to assume that he would be prepared to take further
steps if we didn't do as good boys and go along."

After serving as Air Force Secretary, Symington was elected to the
U. S. Senate, where he remained for 24 years. He was an
influential member of both the Armed Services and Foreign
Relations committees, and unsuccessfully ran for the Democratic
presidential nomination in 1960. ...

[In early 1979] NASA already decided, however, to put the Flying
Wing design "on a back burner" because it was best suited for much
larger cargo planes than will be needed by the military or
commercial users for the next two decades, Kayten told The Times.

None the less, in a letter sent to Northrop after the meeting,
NASA Administrator Robert A. Frosch acknowledged Northrop's
pioneering work and said "our analyses confirmed your much
earlier conviction as to the load-carrying and efficiency
advantages of the design approach."

In 1988 the Secretary of the Air Force announced on April 20 that the
first flight of the Advanced Technology Bomber, or B-2, is currently
scheduled for this fall. Northrop Corporation is the prime contractor
on the B-2 program.

[Chris Kennedy]

Paul kgyy wrote:

> If empennage elimination is such an "obvious" improvement, how come
> it's taking so long?

In the case of passenger aircraft, the problem with a Jack Northrop
style flying wing (as opposed to a Sonic Cruiser style blended thing)
has much more to do with passenger comfort than technical issues.

The long aluminum tube places all of the passengers close to the
longitudinal axis, so that relative displacement of the passenger
compartment in roll is small. The opposite is true of a flying wing
design, so you end up with crap sliding off seat back trays, drinks
spilling and other passenger-unfriendly annoyances. Then there's the
distinct lack of windows, which also turns out to be an issue.

Flying wings are great for freight (including the explosive sort), but
not so hot for people.

> I'm guessing that controllability is the major problem, and developers
> are trying to fix that with electronic control systems?

Nah. Jack figured this out a long time ago, although computers have
allowed control systems to become even more clever.

[Larry Dighera]

On Wed, 14 Sep 2005 22:15:12 GMT, Chris Kennedy >
wrote in >::

>The long aluminum tube places all of the passengers close to the
>longitudinal axis, so that relative displacement of the passenger
>compartment in roll is small.

Agreed.

>The opposite is true of a flying wing
>design, so you end up with crap sliding off seat back trays, drinks
>spilling and other passenger-unfriendly annoyances.

In a _coordinated_ turn, which necessitates a bank, or roll, on
longitudinal axis, there will be no such lateral displacement as you
predict, however, turbulence may produce some if that. If the roll
rate is brisk, there may be some increase in G felt by passengers in
the rising wind, and decrease in G felt by those in the descending
wing, but with today's computerized fly-by-wire control systems, all
these concerns could be largely eliminated in nearly all cases.

[Dave Stadt]

"Paul kgyy" > wrote in message
ups.com...
> If empennage elimination is such an "obvious" improvement, how come
> it's taking so long?

It didn't take long at all. Read up on Jack Northrop

> I'm guessing that controllability is the major problem, and developers
> are trying to fix that with electronic control systems?

Jack Northrop had it figured out and working extremely well back in the
'40s.

[Chris Kennedy]

Larry Dighera wrote:

> On Wed, 14 Sep 2005 22:15:12 GMT, Chris Kennedy >
> wrote in >::
>
>
>>The long aluminum tube places all of the passengers close to the
>>longitudinal axis, so that relative displacement of the passenger
>>compartment in roll is small.
>
>
> Agreed.
>
>
>>The opposite is true of a flying wing
>>design, so you end up with crap sliding off seat back trays, drinks
>>spilling and other passenger-unfriendly annoyances.
>
>
> In a _coordinated_ turn, which necessitates a bank, or roll, on
> longitudinal axis, there will be no such lateral displacement as you
> predict, however, turbulence may produce some if that.

You'll note that I didn't say anything about a turn, I said roll. Yes,
most commanded roll is for the purpose of turns, and there's no reason
why such turns should be uncoordinated in transport aircraft, but the
issue is with uncommanded roll as a consequence of turbulence.

> If the roll
> rate is brisk, there may be some increase in G felt by passengers in
> the rising wind, and decrease in G felt by those in the descending
> wing, but with today's computerized fly-by-wire control systems, all
> these concerns could be largely eliminated in nearly all cases.

Unless you're suggesting that fly by wire could automatically limit the
roll rate to limit the acceleration felt by outboard passengers I'm
unclear how it would address the problem.

There's also the roller coaster effect -- being on the high side and
looking down the width of the cabin at what seems like an exaggerated
angle -- but I suppose one could deal with that with dividers of some
sort. There's also the issue of just how one evacuates such an aircraft.

As I said, good for freight, but I'd take some convincing before I flew
in one. Of course I'm not too thrilled with the idea of riding in an
A380, either.

[Larry Dighera]

On Wed, 14 Sep 2005 23:46:10 GMT, Chris Kennedy >
wrote in >::

>but the
>issue is with uncommanded roll as a consequence of turbulence.

If the aircraft is not maneuvering (or even if it were), the
electronically augmented control system would detect an incipient wing
displacement before a human could detect it, and issue the appropriate
control input to counter it. These commands would occur so rapidly as
to be virtually undetectable by the occupants.

Think of the electronic suspension systems available on some of
today's automobiles*. They are capable of providing a smooth ride
over the roughest of roads by sensing body dip, and immediately
extending the suspension to prevent further excursions. These
corrections happen in milliseconds; it verges on magic.

>> If the roll
>> rate is brisk, there may be some increase in G felt by passengers in
>> the rising wing, and decrease in G felt by those in the descending
>> wing, but with today's computerized fly-by-wire control systems, all
>> these concerns could be largely eliminated in nearly all cases.
>
>Unless you're suggesting that fly by wire could automatically limit the
>roll rate to limit the acceleration felt by outboard passengers I'm
>unclear how it would address the problem.

I'm confident that an electronic control system could dampen all but
the most severe turbulence induced excursions, in addition to seeing
that the commanded roll rate was strictly met.

>There's also the roller coaster effect -- being on the high side and
>looking down the width of the cabin at what seems like an exaggerated
>angle -- but I suppose one could deal with that with dividers of some
>sort.

Exactly. First class would be along the longitudinal axis with coach
toward the wing tips with obscure partitions separating them.

>There's also the issue of just how one evacuates such an aircraft.

Umm... Crashworthyness would be an issue less amenable to resolution
than evacuation.

>As I said, good for freight, but I'd take some convincing before I flew
>in one.

In the event of an in flight electrical failure disabling the
electronic control augmentation, it could get "interesting." What
does Airbus use to overcome that issue?

>Of course I'm not too thrilled with the idea of riding in an
>A380, either.

Right. In the event of a 800+ passenger stampede, one would likely be
trampled before he could clear the aircraft. :-)




* http://tinyurl.com/ah236
http://www.edmunds.com/insideline/do/Features/articleId=100444
The optional F55 Magnetic Selective Ride Control suspension
adjusts the shock damping rates instantly in response to changing
conditions. http://www.corvettecenter.com/magneticrc.htm

http://www.modernracer.com/history/chevroletcorvettec6history.html
optional F55 Magnetic Selective Ride Control suspension features
magneto-rheological dampers able to detect road surfaces and
adjust the damping rates to those surfaces almost instantly for
optimal ride and body control. Magnetic Ride Control debuted on
the 2003 50th Anniversary Edition Corvette, and is the world’s
fastest reacting suspension, replacing mechanical valves with
nearly instantaneous reactions of magneto-rheological fluid. The
system has been improved for the 2005 Corvette, allowing drivers
more differentiation in character between the system’s two
settings, “Tour” and “Sport.”

[Chris Kennedy]

Larry Dighera wrote:

>>but the
>>issue is with uncommanded roll as a consequence of turbulence.
>
>
> If the aircraft is not maneuvering (or even if it were), the
> electronically augmented control system would detect an incipient wing
> displacement before a human could detect it, and issue the appropriate
> control input to counter it. These commands would occur so rapidly as
> to be virtually undetectable by the occupants.

Most contemporary transport aircraft have gust alleviation systems (not
so much for ride comfort than to reduce structural loads); the B-2 has a
similar system. The systems have only limited ability to counter roll
but it's not for want of trying -- it's sort of entertaining looking out
and watching twitchy spoilers trying to keep the wings level -- or the
wingtips from trying to touch.

Actuator response times, interactions with the stability of the design
and the possibility that the roll rate induced by gust could exceed the
roll rate of the aircraft place limits on the magic that you can
perform. It's not to say that you can't come close.

> Think of the electronic suspension systems available on some of
> today's automobiles*. They are capable of providing a smooth ride
> over the roughest of roads by sensing body dip, and immediately
> extending the suspension to prevent further excursions. These
> corrections happen in milliseconds; it verges on magic.

Yet more technology grafted on from Lotus. I was never quite understood
why they never commercialized that technology -- save for the fact that
it sucked power and had really bad failure modes.

>>Unless you're suggesting that fly by wire could automatically limit the
>>roll rate to limit the acceleration felt by outboard passengers I'm
>>unclear how it would address the problem.
>
>
> I'm confident that an electronic control system could dampen all but
> the most severe turbulence induced excursions, in addition to seeing
> that the commanded roll rate was strictly met.

That's sort of my point. Unless you limit commanded roll rate to
something small you haven't done anything to address the problem of G
(un)loading for the outboard passengers, and setting the roll rate limit
low creates its own class of problems.

>>There's also the roller coaster effect -- being on the high side and
>>looking down the width of the cabin at what seems like an exaggerated
>>angle -- but I suppose one could deal with that with dividers of some
>>sort.
>
>
> Exactly. First class would be along the longitudinal axis with coach
> toward the wing tips with obscure partitions separating them.

Yeah, that's the notion I was after.

>>There's also the issue of just how one evacuates such an aircraft.
>
>
> Umm... Crashworthyness would be an issue less amenable to resolution
> than evacuation.

Both would be -um- problematic.

> In the event of an in flight electrical failure disabling the
> electronic control augmentation, it could get "interesting." What
> does Airbus use to overcome that issue?

They don't. Everything is inputs to the redundant autopilot system;
stick and throttle are suggestions, not really commands. Raise your
hand if you've had to sit on the ramp while they do a complete engine
shut down in order to reboot an A320 series aircraft prior to departure
(it's happened to me twice).

>>Of course I'm not too thrilled with the idea of riding in an
>>A380, either.
>
>
> Right. In the event of a 800+ passenger stampede, one would likely be
> trampled before he could clear the aircraft. :-)

That's assuming that you weren't in the middle of a refreshing mud bath
with cucumber slices on your eyes (if you believe for a moment the
claims of Airbus and Branson that A380s will have such amenities as
opposed to high density seating).

[Capt.Doug]

>"Larry Dighera" wrote in message > I would guess that much of the
inefficient airline fleet >would not be
> competitive in tomorrow's airline industry, and should be relegated to
> the junkyards. How else will tomorrows airlines be able to be
> competitive?

Here's a question. Will replacing a $3mil medium by-pass jet with a $28mil
high bypass jet save money? Lower mortgage apyment of lower fuel bill, which
is better?

D. (answer to follow)

[Larry Dighera]

On Fri, 16 Sep 2005 02:46:39 GMT, "Capt.Doug" >
wrote in >::

>>"Larry Dighera" wrote in message > I would guess that much of the
>inefficient airline fleet >would not be
>> competitive in tomorrow's airline industry, and should be relegated to
>> the junkyards. How else will tomorrows airlines be able to be
>> competitive?
>
>Here's a question. Will replacing a $3mil medium by-pass jet with a $28mil
>high bypass jet save money? Lower mortgage apyment of lower fuel bill, which
>is better?
>
>D. (answer to follow)
>

I suppose Boeing would have the answer to that question. I doubt
they'd be considering producing the aircraft if air carriers were not
going to operate it.

[john smith]

In article >,
"Capt.Doug" > wrote:

> >"Larry Dighera" wrote in message > I would guess that much of the
> inefficient airline fleet >would not be
> > competitive in tomorrow's airline industry, and should be relegated to
> > the junkyards. How else will tomorrows airlines be able to be
> > competitive?
>
> Here's a question. Will replacing a $3mil medium by-pass jet with a $28mil
> high bypass jet save money? Lower mortgage apyment of lower fuel bill, which
> is better?

Depends, "How long do you plan on keeping it?"
What is the depreciation schedule?

[Blueskies]

"Capt.Doug" > wrote in message ...
> >"Larry Dighera" wrote in message > I would guess that much of the
> inefficient airline fleet >would not be
>> competitive in tomorrow's airline industry, and should be relegated to
>> the junkyards. How else will tomorrows airlines be able to be
>> competitive?
>
> Here's a question. Will replacing a $3mil medium by-pass jet with a $28mil
> high bypass jet save money? Lower mortgage apyment of lower fuel bill, which
> is better?
>
> D. (answer to follow)
>
>

Doesn't everyone lease the planes (or powerplants) these days, or at least have some sort of power by the hour
performance based logistics maintenance program these days?

[Capt.Doug]

>" Blueskies" wrote in message > Doesn't everyone lease the planes (or
powerplants) these >days, or at least have some sort of power by the hour
> performance based logistics maintenance program these days?

In most jet airlines, fuel is 50% of the cost. One year ago, jet-A was
around $1.26/gal for my employer. Now it is just under $2.00/gal (not
considering hedges). Replacing an MD-80 with a B-737NG or an A-320 results
in 30% fuel savings. Even with the higher lease payments, my employer saves
$200,000.00 per airplane replaced in the first year.

It's a Catch-22 for the legacy carriers who are stuck paying high fuel costs
because they don't have the cash to update their fleet. They don't have the
cash to update because they have high fuel costs. Of the discount carriers
ringing up a profit, how many are flying high bypass engines and how many
are flying medium bypass engines? Everytime I see a Northwest DC-9, I wonder
how long before they file for bancruptcy (question recently answered- longer
than I expected).

Why did Boeing discontinue the B757? I'm not sure, but I do know that the
A-321 hauls nearly as many passengers and yet the A-321 has a MGTOW that is
60,000 pounds lower. It takes a lot of fuel to haul around an extra 60,000
pounds. What will the new B-787 weigh? Why did Airbus feel threatened enough
to counter with the launch of the A-350 program? It's about saving fuel.

As for leasing, there are many ways to structure a lease. Many times, large
shareholders will own an aircraft (though the paper trail may be long and
convoluted) and lease it to the airline, often at a sweetheart rate. With
this method, the shareholder makes money on it's investment in the airline
even if the airline doesn't make money.

Power by the hour contracts are available for both old and new engine
series. The difference is that the newer engine models have fewer
life-limited component times resulting in less down time. The same thing
applies to other components. Brake overhauls can be contracted for old and
new planes. The difference is that the old style steel brakes have more down
time, and man-hours required for replacing, than the new style carbon
brakes. Contract or not, someone has to pay the difference.

D.

[Capt.Doug]

>"Larry Dighera" wrote in message > In the event of an in flight electrical
failure disabling the
> electronic control augmentation, it could get "interesting." What
> does Airbus use to overcome that issue?

Airbus's first answer is that it has never happened.

If an engine generator drops offline, the other generator picks up the load.
The APU generator can pick-up the load if the second engine generator drops
offline. The ram air turbine powers a back-up generator if all 3 main
generators crap out. Even if the RAT doesn't deploy, the batteries provide
at least 25 minutes of electricity. The engines' FADEC units have their own
independent generators.

Augmentation may be the wrong word. It refers to the levels of protection
afforded to the flight envelope. As long as you have a generator or a
battery, you will have control. 'Complete electrical failure' is the wording
I believe you wanted.

Try flying a light twin without touching the yoke. You have throttles,
rudder, and elevator trim, but no elevator, ailerons, flaps, or instruments.
And the gear probably won't extend. The A-320 stalls like a C-172, lots of
buffet and drops straight ahead. With calm winds and a long runway, you can
make your dinner reservations at Nanno's.

The real danger is if you lose all 3 hydraulic systems.

D.

[Capt.Doug]

>"Chris Kennedy" wrote in message
> They don't. Everything is inputs to the redundant autopilot system;
> stick and throttle are suggestions, not really commands.

This true when operating in normal law mode (99% of the time). However, when
degraded to direct law mode, the A-320 operates like a normal airplane. The
reboot is not because it can't fly, but because we like everything to work
so as to provide the safest flight we can (and we are lazy and don't want to
handfly a whole leg).

D. (it tunes it's own VORs)

[Larry Dighera]

On Sat, 17 Sep 2005 03:41:46 GMT, "Capt.Doug" >
wrote in >::

>>"Larry Dighera" wrote in message > In the event of an in flight electrical
>failure disabling the
>> electronic control augmentation, it could get "interesting." What
>> does Airbus use to overcome that issue?
>
>Airbus's first answer is that it has never happened.

That smacks of the argument used in assuring security against the
September 11, 2001 attacks. :-)

>If an engine generator drops offline, the other generator picks up the load.
>The APU generator can pick-up the load if the second engine generator drops
>offline. The ram air turbine powers a back-up generator if all 3 main
>generators crap out. Even if the RAT doesn't deploy, the batteries provide
>at least 25 minutes of electricity. The engines' FADEC units have their own
>independent generators.

At first glance, five levels of electrical power source redundancy
would seem safe in guarding against 'Complete electrical failure',
however there are other points of failure in electrically operated
systems. Each electrical circuit is fed through a circuit breaker.
How many circuit breakers are involved in the Airbus flight control
system? How many electrical buses?

>Augmentation may be the wrong word. It refers to the levels of protection
>afforded to the flight envelope. As long as you have a generator or a
>battery, you will have control. 'Complete electrical failure' is the wording
>I believe you wanted.

No, that is the phrase that describes the issue you addressed. I'm
more concerned about single points of failure.

If the circuit breaker (an electrical/mechanical device) feeding the
electrical bus supplying the flight control system were to
malfunction, regardless of power being available, the bus could be
de-energized, and no amount of available power would bring the flight
control system back into operation, unless you know of additional
redundancy designed in to the Airbus control system that you have not
yet discussed.

>Try flying a light twin without touching the yoke. You have throttles,
>rudder, and elevator trim, but no elevator, ailerons, flaps, or instruments.
>And the gear probably won't extend.

I've not had that experience, but in a light single engine aircraft
with exclusively mechanical controls, its occupants would probably
walk away from the "landing." In the event that a mechanical
malfunction in its control system, it would only affect the control of
a single axis (like the Alaska flight that went down off the Ventura,
California coast five years ago :-(), not the entire 3-axis flight
control system. But Airbus products do have mechanical elevator trim,
IIRC, so in the event of the electrical portion of the flight control
system failing, there would still be some control of one (important)
axis.

>The A-320 stalls like a C-172, lots of
>buffet and drops straight ahead. With calm winds and a long runway, you can
>make your dinner reservations at Nanno's.

So you're intimating that only the ailerons and elevator are
electrically operated?

>The real danger is if you lose all 3 hydraulic systems.

Are you saying there are three hydraulic actuators, one from each
hydraulic system, attached to each control surface?

[Capt.Doug]

>"Larry Dighera" wrote in message
> At first glance, five levels of electrical power source redundancy
> would seem safe in guarding against 'Complete electrical failure',
> however there are other points of failure in electrically operated
> systems. Each electrical circuit is fed through a circuit breaker.
> How many circuit breakers are involved in the Airbus flight control
> system? How many electrical buses?

Airbus understood from inception that their company would live or die by the
integrity of their fly-by-wire design. There are 7 computers responsible for
the primary flight control surfaces. Three are ELACs (elevator-aileron).
They perform the same functions with slight differences. Each is
manufactured by a different vendor with different computer code so that if
one assembly line has a batch of bad parts or bad code, the other two are
not affected. The same goes for the 2 SECs (spoiler-elevator) and the 2 FACs
(rudder plus flight protections). One ELAC, one SEC, and one FAC are powered
by a DC essential bus which switches automatically to any of the power
sources mentioned (AC or DC). The sister computers are powered by other
busses which are normally powered by a seperate main bus. A failure of any
single computer results in nothing more than a message to the crew. A
failure of any 2 like computers results in some crosswind limitations for
landing.

> No, that is the phrase that describes the issue you addressed. I'm
> more concerned about single points of failure.

Which was a concern of my sceptical way of viewing engineer's creations. I
couldn't find any single points of failure which would cause much concern.
However I have just begun to look.

> If the circuit breaker (an electrical/mechanical device) feeding the
> electrical bus supplying the flight control system were to
> malfunction, regardless of power being available, the bus could be
> de-energized, and no amount of available power would bring the flight
> control system back into operation, unless you know of additional
> redundancy designed in to the Airbus control system that you have not
> yet discussed.

There is more than one bus feeding the flight control computers. The two
main busses have independent power supplies. The enormous amount of
redundancy explains why it takes 6 weeks of training to ultimately flip on
the autopilot at 100'AGL.

> So you're intimating that only the ailerons and elevator are
> electrically operated?

Electrically "controlled" and hydraulically "actuated", as are all the
flight control surfaces in normal operations. Each flight control surface
has multiple actuators receiving hydraulic power from seperate hydraulic
systems. For example, there are 3 spoilers on each wing used for roll
control (the forth is for speedbrake and the fifth is for ground spoiler).
Each spoiler has 2 actuators which are powered by different hydraulic
systems. A loss of any single hydraulic system won't affect control. A loss
of any 2 hydraulic systems will result in a loss of 1 of the 3 spoilers.

> Are you saying there are three hydraulic actuators, one from each
> hydraulic system, attached to each control surface?

There are at least 2 actuators, each from a different hydraulic system. All
control surfaces are hydraulically "actuated". In the event that all 3
hydraulic systems are lost, none of the control surfaces will move. The
pilots would have only engine thrust for control, just like the United DC-10
that crashed at Sioux City.

In the event of complete electrical loss, there is still hydraulic pressure,
and the pilots can manually control the hydraulic actuators for the rudder
and the horizontal stabilizer in addition to controlling engine thrust.

Hope it's all clear now :-)

D.

[Larry Dighera]

On Mon, 19 Sep 2005 06:17:24 GMT, "Capt.Doug" >
wrote in >::

>Hope it's all clear now :-)

While we haven't thoroughly exhausted all possible failure modes of
the complex Airbus flight control systems, the information you have
provided has convinced me that minds trained in the disciplines
required to engineer these systems have spent significantly more time
analyzing their design than I am willing to commit. Thank you for
elucidating the arcana of Airbus' computerized electro-hydrolytic
flight control systems. It is enlightening indeed.

[Stefan]

Larry Dighera wrote:

> minds trained in the disciplines
> required to engineer these systems have spent significantly more time
> analyzing their design than I am willing to commit.

What a surprize! :-P

Stefan

[Capt.Doug]

>"Larry Dighera" < wrote in message
> While we haven't thoroughly exhausted all possible failure modes of
> the complex Airbus flight control systems, the information you have
> provided has convinced me that minds trained in the disciplines
> required to engineer these systems have spent significantly more time
> analyzing their design than I am willing to commit. Thank you for
> elucidating the arcana of Airbus' computerized electro-hydrolytic
> flight control systems. It is enlightening indeed.

You're most welcome.
An interesting side note- During a sim session break, I strolled over to the
A330/340 sim and peeked inside. It looked almost exactly the same as the
A320 sim. The transition course is 4 days. The A380 and A350 transition
courses are expected be the same. To change the 330 sim into a 340 sim, a
sim tech changes the throttle quadrant and reboots. It takes about 5 minutes
total.

D.