Dudley,

I think you are mixing up the terms 'coordinated control pressures' and
'coordinated flight'. I have never seen a definition of coordinated flight
(in the context that we are discussing here - 'head orientation in _turns_'
or barrel rolls for that matter) that would mean 'coordinated control
pressures' as you define it.

From the FAA handbook of aeronautical knowledge:

"True, an airplane may be banked to 90° but not in a coordinated

turn; an airplane which can be held in a 90°

banked slipping turn is capable of straight knifeedged

flight."

An aircraft doing a straight line knife edge is not in coordinated flight.
It may even be argued if the term 'coordinated flight' is applicable for
non-turning flight but you can always interpret straight-line flight as a
turn of infinite diameter. In any case, the nose of the airplane is not
aligned with it's flightpath, the ball is not centered, the plane is not in
coordinated flight during a knife edge.

http://www.faasafety.gov/gslac/ALC/l...ro+Slidesli p

"Sideslip is the angle with which the relative wind meets the longitudinal
axis of the airplane. In all-engine flight with symmetrical power, zero
sideslip occurs with the ball of the slip-skid indicator centered. Pilots
know this concept as "coordinated flight." "

The conditions characterizing 'coordinated flight' mentioned in the text
above clearly do not apply to knife-edge flight: Ball not centered, the
relative wind is not meeting the longitudinal axis of the a/c at 0 deg.

Sierk

"Dudley Henriques" wrote in message
news:2007061123362943658-dhenriques@rcncom...
On 2007-06-11 23:13:58 -0400, "Maxwell" said:


"Dudley Henriques" wrote in message
news:2007061121444816807-dhenriques@rcncom...
On 2007-06-10 22:41:49 -0400, "Maxwell" said:

That is either untrue, or real misleading. The Blues fly with a
different
purpose, keep the aircraft on trajectory. When they are flying a knife
edge,
they are hardly coordinated, as with many other maneuvers.

A 1g barrel roll can be done, but the required trajectory of the
aircraft
is
not going to be one that is necessarily eye pleasing for ground
demonstration purposes.

Actually, when the Blues or anyone else is in knife edge, they are
indeed
in coordinated flight. You hold the aircraft in knife edge with top
rudder
and forward neutral stick; this control pressure combination has to be
perfectly coordinated to maintain knife edge.
You are confusing coordinated with meaning the control pressures must be
complementary which is a common mistake often made.
The first lesson we teach in aerobatics is that "coordinated" has
absolutely nothing whatsoever to do with the controls not being crossed.
Actually, any good flight instructor will teach this to a new primary
student during the first hour of dual :-)
Dudley Henriques


Then define coordinated.

Surely.
Coordinated as that applies to control pressures while in flight defines
ANY application of controls in ANY DIRECTION where the pressure applied to
each individual control achieves a specific desired resulting change in
the flight path of the aircraft .
A non slipping or skidding ball centered turn entry or exit is a
coordinated control movement. In this case the control pressures applied
are in the same direction and uncrossed.
Conversely, a deliberate slip or a slow roll is also a coordinated control
movement resulting in a specific change and effect in the flight path of
the aircraft. In this case the controls are not applied in the same
direction and are said to be crossed.
Again, crossed controls does NOT mean uncoordinated.
Dudley Henriques