On 2007-06-12 08:40:42 -0400, "Sierk Melzer" said:

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


You could indeed stretch a point on this and you would be absolutely correct.
Pilots (and especially aerobatic instructors like myself) have a strong
tendency to teach coordinated control pressure to produce desired
result rather than any coined definition of coordinated flight. At our
stage of performance, the term "coordinated" must indeed be redefined
to include the extended envelope of the aircraft in which we operate.
For example, in going to knife edge, if the control pressures are not
perfectly timed and applied with the exact "coordinnated" pressure
necessary to change the aircraft's flight path from where it is to
where it must be to produce knife edge, the maneuver is blown. This is
coordinated movement producing the desired result. To us, this is
coordinated flight and is as normal a control application as a
coordinated turn entry with the ball centered might be to a pilot
flying within the normal definition for "coordinated".
I believe you are correct in defining coordinated flight as you are and
have no problem with that.
In turn, you should consider that there are "extended levels" in flying
an airplane where pilots must redefine the basic definitions for
coordinated flight.
Dudley Henriques