|
Flying
Handbook Menu > Basic
Flight Maneuvers > Straight-And-Level Flight
It is impossible to emphasize too strongly
the necessity for forming correct habits in flying straight
and level. All other flight maneuvers are in essence a deviation
from this fundamental flight maneuver. Many flight instructors
and students are prone to believe that perfection in straight-and-level
flight will come of itself, but such is not the case. It is
not uncommon to find a pilot whose basic flying ability consistently
falls just short of minimum expected standards, and upon analyzing
the reasons for the shortcomings to discover that the cause
is the inability to fly straight and level properly. Straight-and-level
flight is flight in which a constant heading and altitude are
maintained. It is accomplished by making immediate and measured
corrections for deviations in direction and altitude from unintentional
slight turns, descents, and climbs. Level flight, at first,
is a matter of consciously fixing the relationship of the position
of some portion of the airplane, used as a reference point,
with the horizon. In establishing the reference points, the
instructor should place the airplane in the desired position
and aid the student in selecting reference points. The instructor
should be aware that no two pilots see this relationship exactly
the same. The references will depend on where the pilot is sitting,
the pilot’s height (whether short or tall), and the pilot’s
manner of sitting. It is, therefore, important that during the
fixing of this relationship, the pilot sit in a normal manner;
otherwise the points will not be the same when the normal position
is resumed. In learning to control the airplane in level flight,
it is important that the student be taught to maintain a light
grip on the flight controls, and that the control forces desired
be exerted lightly and just enough to produce the desired result.
The student should learn to associate the apparent movement
of the references with the forces which produce it. In this
way, the student can develop the ability to regulate the change
desired in the airplane’s attitude by the amount and direction
of forces applied to the controls without the necessity of referring
to instrument or outside references for each minor correction.
The pitch attitude for level flight (constant altitude) is usually
obtained by selecting some portion of the airplane’s nose
as a reference point, and then keeping that point in a fixed
position relative to the horizon. [figure3-3] Using the principles
of attitude flying, that position should be cross-checked occasionally
against the altimeter to determine whether or not the pitch
attitude is correct. If altitude is being gained or lost, the
pitch attitude should be readjusted in relation to the horizon
and then the altimeter rechecked to determine if altitude is
now being maintained. The application of forward or back-elevator
pressure is used to control this attitude. The pitch information
obtained from the attitude indicator also will show the position
of the nose relative to the horizon and will indicate whether
elevator pressure is necessary to change the pitch attitude
to return to level flight. However, the primary reference source
is the natural horizon. In all normal maneuvers, the term “increase
the pitch attitude” implies raising the nose in relation
to the horizon; the term “decreasing the pitch attitude”
means lowering the nose. Straight flight (laterally level flight)
is accomplished by visually checking the relationship of the
airplane’s wingtips with the horizon. Both wingtips should
be equidistant above or below the horizon (depending on whether
the airplane is a high-wing or low-wing type), and any necessary
adjustments should be made with the ailerons, noting the relationship
of control pressure and the airplane’s attitude. [figure
3-4] The student should understand that anytime the wings are
banked, even though very slightly, the airplane will turn. The
objective of straight-and-level flight is to detect small deviations
from laterally level flight as soon as they occur, necessitating
only small corrections. Reference to the heading indicator should
be made to note any change in direction Continually observing
the wingtips has advantages other than being the only positive
check for leveling the wings. It also helps divert the pilot’s
attention from the airplane’s nose, prevents a fixed stare,
and automatically expands the pilot’s area of vision by
increasing the range necessary for the pilot’s vision
to cover. In practicing straight and-level-flight, the wingtips
can be used not only for establishing the airplane’s laterally
level attitude or bank, but to a lesser degree, its pitch attitude.
This is noted only for assistance in learning straight-andlevel
flight, and is not a recommended practice in normal operations.
The scope of a student’s vision is also very important,
for if it is obscured the student will tend to look out to one
side continually (usually the left) and consequently lean that
way. This not only gives the student a biased angle from which
to judge, but also causes the student to exert unconscious pressure
on the controls in that direction, which results in dragging
a wing. With the wings approximately level, it is possible to
maintain straight flight by simply exerting the necessary forces
on the rudder in the desired direction. However, the instructor
should point out that the practice of using rudder alone is
not correct and may make precise control of the airplane difficult.
Straight–and-level flight requires almost no application
of control pressures if the airplane is properly trimmed and
the air is smooth. For that reason, the student must not form
the habit of constantly moving the controls unnecessarily. The
student must learn to recognize when corrections are necessary,
and then to make a measured response easily and naturally. To
obtain the proper conception of the forces required on the rudder
during straight-and-levelflight, the airplane must be held level.
One of the most common faults of beginning students is the tendency
to concentrate on the nose of the airplane and attempting to
hold the wings level by observing the curvature of the nose
cowling. With this method, the reference line is very short
and the deviation, particularly if very slight, can go unnoticed.
Also, a very small deviation from level, by this short reference
line, becomes considerable at the wingtips and results in an
appreciable dragging of one wing. This attitude requires the
use of additional rudder to maintain straight flight, giving
a false conception ofm neutral control forces. The habit of
dragging one wing, and compensating with rudder pressure, if
allowed to develop is particularly hard to break, and if not
corrected will result in considerable difficulty in mastering
other flight maneuvers.
figure3-3. Nose reference for straight-and-level
flight.
figure3-4. Wingtip reference for straight-and-level
flight.
For all practical purposes, the airspeed will remain constant
in straight-and-level flight with a constant power setting.
Practice of intentional airspeed changes, by increasing or decreasing
the power, will provide an. excellent means of developing proficiency
in maintaining straight-and-level flight at various speeds.
Significant changes in airspeed will, of course, require considerable
changes in pitch attitude and pitch trim to maintain altitude.
Pronounced changes in pitch attitude and trim will also be necessary
as the flaps and landing gear are operated. Common errors in
the performance of straight-andlevel flight are:
• Attempting to use improper reference points on the airplane
to establish attitude.
• Forgetting the location of preselected reference points
on subsequent flights.
• Attempting to establish or correct airplane attitude
using flight instruments rather than outside visual reference.
• Attempting to maintain direction using only rudder control.
• Habitually flying with one wing low.
• “Chasing” the flight instruments rather
than adhering to the principles of attitude flying.
• Too tight a grip on the flight controls resulting in
overcontrol and lack of feel.
• Pushing or pulling on the flight controls rather than
exerting pressure against the airstream.
• Improper scanning and/or devoting insufficient time
to outside visual reference. (Head in the cockpit.)
• Fixation on the nose (pitch attitude) reference point.
• Unnecessary or inappropriate control inputs.
• Failure to make timely and measured control inputs when
deviations from straight-and-level flight are detected.
• Inadequate attention to sensory inputs in developing
feel for the airplane.
 |
|
|
