A Q on horizontal turns

During a cruise, just pressing on one of the rudders should make an
aircraft turn horizontally in that direction, when no ailerons are
used. Reducing power in the opposite engine should logically accelerate
such a turn.

Makes me wonder why then was it that, in the crash at the end of 2001
just outside of NY, the A300's rear bulkhead came loose when the pilot
used the rudder to correct a yaw induced by probably a wake vortex ?
Ramapriya

"Ramapriya" wrote

Makes me wonder why then was it that, in the crash at the end of 2001
just outside of NY, the A300's rear bulkhead came loose when the pilot
used the rudder to correct a yaw induced by probably a wake vortex ?
Ramapriya


Google for that discussion, but in short, the rudder was used rapidly going
from full deflection, to other side full deflection. The plane was not
designed for that, and it failed. Part of the fault seems to lie with the
airline, for not properly training its pilots.
--
Jim in NC

Morgans wrote:

Google for that discussion, but in short, the rudder was used rapidly
going
from full deflection, to other side full deflection. The plane was
not
designed for that, and it failed. Part of the fault seems to lie
with the
airline, for not properly training its pilots.
--
Jim in NC

No Jim, I actually know that report, and the statements of both the
airline and Airbus too. The surprise is in knowing that such action,
which I think is natural, isn't automatically built into in the design
of an aircraft. Why do you think that's so? Aren't such boat-turns
normal? Should be, isn't it?

Ramapriya

"Ramapriya" wrote:
No Jim, I actually know that report, and the statements of both the
airline and Airbus too. The surprise is in knowing that such action,
which I think is natural,

Rapid, opposite deflections of the rudder are not "natural,"
particularly in a jet transport aircraft.

isn't automatically built into in the design
of an aircraft. Why do you think that's so?

Because designers cannot allow for every conceivable misuse of the
equipment.

Aren't such boat-turns
normal?

Not in that kind of airplane--besides, he wasn't just making a rudder
turn, he was wagging the rudder back and forth.

Should be, isn't it?

Not necessarily. Airplanes are designed for performance that meets a
particular mission. Airliners are not the same as aerobatic aircraft,
for instance.
--
Dan
C172RG at BFM

"Morgans" wrote in message
...

"Ramapriya" wrote

Makes me wonder why then was it that, in the crash at the end of 2001
just outside of NY, the A300's rear bulkhead came loose when the pilot
used the rudder to correct a yaw induced by probably a wake vortex ?
Ramapriya


Google for that discussion, but in short, the rudder was used rapidly
going
from full deflection, to other side full deflection. The plane was not
designed for that, and it failed. Part of the fault seems to lie with the
airline, for not properly training its pilots.
--
Jim in NC



And there are many people that fault Airbus for not making this "design
feature" known more widely. I remember reading in Aviation Week shortly
after the crash that Airbus didn't make much effort to notify customers that
full deflection of the rudder could cause a catstrophic accident because
they decided nobody would want to apply full-deflection as it would be
dangerous.

--

Scott

"Ramapriya" wrote in message
oups.com...


No Jim, I actually know that report, and the statements of both the
airline and Airbus too. The surprise is in knowing that such action,
which I think is natural, isn't automatically built into in the design
of an aircraft. Why do you think that's so? Aren't such boat-turns
normal? Should be, isn't it?

Ramapriya


Turns in aircraft are most often intended to be what is called
"coordinated." That is the ailerons and rudder are used in conjunction so
that there are *no* purely horizontal forces felt by the passengers. In
airline and corporate flying this is sometimes called "not making the ice
cubes clink." You try to maneuver the aircraft so that the passengers, and
their drinks, are not disturbed.

Making these boat turns would be like filling a station-wagon automobile
with children, accelerating to highway speeds, and then making an abrupt
turn of the steering wheel. The children wuld go sliding all over the car's
cabin.



--

Scott

tscottme wrote:

And there are many people that fault Airbus for not making this "design
feature" known more widely.

Actually, they did. There was that letter which Airbus, Boeing and the
FAA (yes, all three, together, in one letter!) wrote to the operator
pointing out exactly this and asking for a change in pilot training. But
of course, "many people" in the USA welcome any rumour which could be
used against Airbus.

Stefan

tscottme wrote:

Making these boat turns would be like filling a station-wagon
automobile
with children, accelerating to highway speeds, and then making an
abrupt
turn of the steering wheel. The children wuld go sliding all over
the car's
cabin.

Scott,
Not having been in an aircraft boat-turn before, I find your example a
wee addling. The kids would get hurled across the seats because the
station wagon is trying to turn horizontally about its axis while being
restricted in its lateral movement by the tires that are grounded. In
an aircraft, there's just thin air outside, so I'd presume it'll mildly
keep sliding sidewards too (in the opposite direction) while turning
about its axis. It might just feel like in a briskish whirligig.
Or does it?

Ramapriya
ayirpamar@gmail

Ramapriya wrote:

In
an aircraft, there's just thin air outside, so I'd presume it'll mildly
keep sliding sidewards too (in the opposite direction) while turning
about its axis. It might just feel like in a briskish whirligig.

I've never been in a briskish whirligig, so I don't know, but, when you make a
rudder turn, momentum attempts to have the contents continue in a straight line.
In some areas of a large aircraft, unsecured cargo would slide sideways in such
a turn. In a coordinated turn, the forces of momentum and gravity balance out.

As far as passengers are concerned, uncoordinated maneuvers tend to make them
nauseous. This effect is stronger the further away from the center of the wing
they sit.

George Patterson
The desire for safety stands against every great and noble enterprise.

"Stefan" wrote in message
...
tscottme wrote:

And there are many people that fault Airbus for not making this
"design
feature" known more widely.

Actually, they did. There was that letter which Airbus, Boeing and the
FAA (yes, all three, together, in one letter!) wrote to the operator
pointing out exactly this and asking for a change in pilot training.
But of course, "many people" in the USA welcome any rumour which could
be used against Airbus.

Stefan

I'm not all that familiar with this accident, but if I recall correctly,
a checklist item before takeoff on the airplane was to select the yaw
damper to "ON" which would have limited the rudder deflection. This
wasn't done, and if not, would have been a direct contributor in this
accident.
I believe Airbus properly supplied the operator with a valid checklist
that included the yaw damper select. The crew missed it, or ignored
it...either way, the damper was selected "OFF" when the investigators
found the sub panel .When that rudder was deflected as they entered the
turbulence from the departing aircraft ahead of them, instead of
applying a damped rudder throw as would have been the case had the
damper been properly selected to "ON", the pilot flying the aircraft at
the time applied and was given full rudder command. This, and the
inertia forces encountered in both the initial throw and the reverse,
coupled with the turbulence, was too much for the vertical stabilizer.
Had the damper been selected properly as called for by the checklist,
this accident might not have happened.
Keep in mind, I haven't even read the report. I'm just going on what was
relayed to me by an associate friend of mine with the FAA.
Dudley Henriques
International Fighter Pilots Fellowship
Commercial Pilot/CFI Retired
for private email; make necessary changes between ( )
dhenriques(at)(delete all this)earthlink(dot)net