Is rudder required for coordinated turns?

"Rudder" is required to make coordinated rolls into banks in most aircraft.
The next question would be: is the rudder applied automatically by the
movement of the lateral controls? If not, then the pilot may have to
displace the rudder himself. Some aircraft have rudder input applied
automatically when the control column/stick is displaced.

One example of that is the B-58 which has a rudder/elevon interconnect which
uses a computer to determine when, if, how much, and in what direction the
rudder should be moved when the pilot makes a lateral input to the elevons.
In subsonic flight the rudder is normally displaced in the same direction as
the lateral input. In transonic flight the shock wave hits the vertical
stabilizer producing a "rudder" force which has to be corrected. At some
speeds the rudder is actually moved in the opposite direction since the
shockwave force on the vertical stabilizer produces more "rudder" input that
is desirable. The automatic rudder input changes more as the aircraft
accelerates to mach 2.

The B-52 is different also, in that the H model (that I flew) has no
ailerons and uses hydraulic spoilers on the top of the wings to produce the
required roll input. With no speed brakes deployed a roll input causes the
spoilers on the downward moving wing to be deployed, spoiling lift and
dropping the wing. The resultant drag makes a rudder input in that
direction to not be required. Because the spoilers are aft of the center of
lift, deploying a spoiler on a clean wing also causes an undesired pitch up.
In the traffic pattern speed brakes are normally deployed to an intermediate
position. In this case a roll input to the left will cause the left
speedbrake/spoilers to rise further and the right speedbrake/spoilers to
lower somewhat. This about eliminates the pitchup and makes flying more
stable.

That said, most aircraft require a pilot input of rudder to coordinate a
roll input. Little, if any, rudder is required once the roll stops and a
constant bank is maintained. Fancier aircraft have yaw dampers which also
reduces the required pilot rudder input. So, to answer your original
question it is necessary to change your question somewhat. Change the word
"turns" to "rolls", since most rudder coordination is necessary only while
rolling into a bank and little is needed once bank is established to further
coordinate the turn while bank stays constant. In light aircraft the amount
of wing dihedral can affect turn coordination.
--
Darrell R. Schmidt
B-58 Hustler Web Site URL (below)
http://members.cox.net/dschmidt1/

"Mxsmanic" wrote in message
...
Is it always necessary to use the rudder to execute a coordinated
turn? When I turn (in simulation) it seems that just rolling the
aircraft suffices, as long as the bank angle isn't too steep. (And
no, I don't have automatic rudder control enabled.)

--
Transpose mxsmanic and gmail to reach me by e-mail.

Darrell S schrieb:

That said, most aircraft require a pilot input of rudder to coordinate a
roll input. Little, if any, rudder is required once the roll stops and a
constant bank is maintained.

Ever flown a glider? You'd be surprized! A coordinated turn is *always*
a turn around all three axis.

If some powered airplanes don't require rudder, it's because a) the
rudder is somehow coupled to the ailerons, b) the weight of the engine
will cause the nose to drop enough without rudder or c) the pilot
doesn't care enough about being coordinated. My experience says that
power-only pilots tend to solution c). (Note: The ball is a pretty
coarse instrument.)

Stefan

Darrell S schrieb:

That said, most aircraft require a pilot input of rudder to coordinate a
roll input. Little, if any, rudder is required once the roll stops and
a
constant bank is maintained.

Ever flown a glider? You'd be surprized! A coordinated turn is *always*
a turn around all three axis.

If some powered airplanes don't require rudder, it's because a) the
rudder is somehow coupled to the ailerons, b) the weight of the engine
will cause the nose to drop enough without rudder or c) the pilot
doesn't care enough about being coordinated. My experience says that
power-only pilots tend to solution c). (Note: The ball is a pretty
coarse instrument.)

Stefan

I've only had one introductory flight in a glider and that was more than 20
years ago in a two place Blanick.

The most memorable thing, aside from being about the most fun a person can
have in daylight, is that turn cooridination is much more than rolling in
and rolling out. Due to the combination of slow forward speed (when
spiralling at minimum rate of descent) and long wing span, the wing toward
the inside of the turn is much closer to the stall and a noticeable amount
of cross control is required.

Typically, powered aircraft are rarely flown in that portion of the flight
envelope and many pilots regard turns at low airspeed as extremely dangerous
and an invitation to an unintentional spin. Most of us were taught that the
low end of the airspeed envelope is hazardous and to be avoided in flight,
with the result that very few powered airplane pilots maintain proficiency
in very slow flight. Also, since the wings are short and the stall speeds
are generally higher, I doubt that the effect is ever really noticeable.

As to "c", the yaw string is a lor more sensitive, but takes a little more
practice than I was able to give it--since the doggoned thing works
backward!

Peter
Just my $0.02

"Peter Dohm" wrote in message
...
Most of us were taught that the
low end of the airspeed envelope is hazardous and to be avoided in flight,
with the result that very few powered airplane pilots maintain proficiency
in very slow flight.

Probably true, but (as with everything else in the PP PTS) we're taught that
we *should* practice slow flight (just above stall speed) on occasion (if
for no other reason than to be able to recognize and properly respond to
very low airspeed should we inadvertently find ourselves in that situation
during normal flight).

--Gary

Most of us were taught that the
low end of the airspeed envelope is hazardous and to be avoided in
flight,
with the result that very few powered airplane pilots maintain
proficiency
in very slow flight.

Probably true, but (as with everything else in the PP PTS) we're taught
that
we *should* practice slow flight (just above stall speed) on occasion (if
for no other reason than to be able to recognize and properly respond to
very low airspeed should we inadvertently find ourselves in that situation
during normal flight).

--Gary


Hangar flying is not statistically usefull, but annecdotal evidence suggests
that more of us *should* practice slow flight, including turns and
configuration changes, at a safe altitude.

However, you're right and I was wrong to imply a statistic that can't be
documented.

Peter

"Darrell S" wrote in message
news:60eQg.26$rS.9@fed1read05...

That said, most aircraft require a pilot input of rudder to coordinate a
roll input. Little, if any, rudder is required once the roll stops and a
constant bank is maintained.

Without rudder input, the yaw required to change the heading of the aircraft
(as its flight path progresses around the turn) must come from the aircraft
being in a slip.

In an aircraft at high speed and/or with high directional stability, the yaw
rate required is low and the slip angle required is small, almost
unoticeable. The ball will be almost centered

In an aircraft at low speed and/or with low directional stability, the yaw
rate required is high and the slip angle required is therefore large. The
ball will be way off to the side.

Thus glider pilots learn to use their feet rather more than fast jet pilots.

Julian