flight controls Flashcards
aerodynamic devices allowing a pilot to adjust and control the aircraft’s flight attitude
aircraft flight control surfaces
credited with developing the first practical control surfaces
wright brothers
main part of wright brothers’ patent on flying
first practical control surface
made hinged control surfaces, the same type of concept first patented some four decades earlier in the United Kingdom
Glen Curtiss
have the advantage of not causing stresses that are a problem of wing warping and are easier to build into structures
hinged control surfaces
early system for lateral (roll) control of a fixed-wing aircraft
wing warping
consisted of a system of pulleys and cables to twist the trailing edges of the wings in opposite direction. this approach is similar to that used to trim the performance of a paper airplane by curling the paper at the back of its wings.
wing warping
“an imaginary line about which a body
rotates”
axis
where each will intersect at the aircraft
center of gravity
An aircraft in flight maneuvers in how many dimensions
three dimensions
Axis that extends lengthwise (nose through tail)
longitudinal axis
rotation about the longitudinal axis
roll
axis that extends crosswise (wing tip through wing tip)
lateral axis
rotation about the lateral axis
pitch
axis that passes vertically through the center of gravity (when the aircraft is in level flight )
vertical axis
rotation about the vertical axis
yaw
means by which a pilot controls the direction and attitude of an aircraft in flight
Aircraft flight controls
subdivided into what are referred to as primary and secondary flight controls.
flight controls system
required to safely control an aircraft during flight and consist of ailerons, elevators (or, in some installations, stabilator) and rudder.
primary flight controls
intended to improve the aircraft performance characteristics or to relieve excessive control loading, and consist of high lift devices such as slats and flaps as well as flight spoilers and trim systems.
secondary flight controls
carefully designed to provide adequate responsiveness to control inputs while allowing a natural feel
aircraft control systems
usually feel soft and sluggish, and the aircraft responds slowly to control applications
low airspeeds
the controls become increasingly firm and aircraft response is more rapid.
higher airspeeds
limit the amount of deflection of flight control surfaces.
design features
It controls roll about the longitudinal axis
ailerons
It is attached to the outboard trailing edge of each wing and move in the opposite direction from each other.
ailerons
connected by cables, bell cranks, pulleys, and/or push-pull tubes which are controlled by a control/cyclic stick.
ailerons
is attached to the trailing edge of the wing, increase both lift and induced drag for any given AOA. It is caused by higher drag on the outside wing that is producing more lift.
flaps
four common types of flaps
plain flap, split flap, slotted flap, fowler
It is the simplest of the four types of flaps. It increases the airfoil camber, resulting in a significant increase in the coefficient of lift (CL) at a given AOA.
plain flap
It is deflected from the lower surface of the airfoil and produces a slightly greater increase in lift than the plain flap. More drag is created because of the turbulent air pattern produced behind the airfoil. When fully extended, both plain and this produce high drag with little additional lift.
split flap
it is the most popular flap on aircraft today. It increases the lift coefficient significantly more than plain or split flaps. It contains a gap that vastly increases airflow across the entire flap, enhancing its effectiveness.
slotted flap
this flap design not only changes the camber of the wing, it also increases the wing area. Instead of rotating down on a hinge, it slides backwards on tracks. In the first portion of its extension, it increases the drag very little, but increases the lift a great deal as it increases both the area and camber.
fowler flaps
leading edge device types
fixed slots, movable slats, leading edge flaps, leading edge cuffs
It directs airflow to the upper wing surface and delay airflow separation at higher angles of attack. The slot does not increase the wing camber, but allows a higher maximum CL because the stall is delayed until the wing reaches a greater AOA.
fixed slots
Consists of leading edge segments that move on tracks. At low angles of attack, each slat is held flush against the wing’s leading edge by the high pressure that forms at the wing’s leading edge..
movable slats
Are used to increase both CL-MAX and the camber of the wings. This type of leading edge device is frequently used in conjunction with trailing edge flaps and can reduce the nose-down pitching movement produced by the latter.a small increment of these increases lift to a much greater extent than drag. As flaps are extended, drag increases at a greater rate than lift.
leading edge flaps
Are also used to increase both CL-MAX and the camber of the wings. Unlike leading edge flaps and trailing edge flaps, these are fixed aerodynamic devices. In most cases, these extend the leading edge down and forward. This causes the airflow to attach better to the upper surface of the wing at higher angles of attack, thus lowering an aircraft’s stall speed.
leading edge cuffs
deployed from the wings to spoil the smooth airflow, reducing lift and increasing drag
spoilers
used to relieve the pilot of the need to maintain constant pressure on the flight controls, and usually consist of flight deck controls and small hinged devices attached to the trailing edge of one or more of the primary flight control surfaces. Designed to help minimize a pilot’s workload, these aerodynamically assist movement and position of the flight control surface to which they are attached.
trim systems
manually operated by a small, vertically mounted control wheel. However, a trim crank may be found in some aircraft. The flight deck control includes a trim tab position indicator. Placing the trim control in the full nose-down position moves the trim tab to its full up position. With the trim tab up and into the airstream, the airflow over the horizontal tail surface tends to force the trailing edge of the elevator down. This causes the tail of the aircraft to move up and the nose to move down
trim tabs
Looks like trim tabs and are hinged in approximately the same places as trim tabs. The essential difference between the two is that the this is coupled to the control surface rod so that when the primary control surface is moved in any direction, the tab automatically moves in the opposite direction. The airflow striking the tab counterbalances some of the air pressure against the primary control surface and enables the pilot to move the control more easily and hold the control surface in position.
balance tabs
it is a small portion of a flight control surface that deploys in such a way that it helps to move the entire flight control surface in the direction that the
pilot wishes it to go. dynamic device that deploys to decrease the pilots work load and de-stabilize the aircraft. these are sometimes referred to as flight tabs and are used primarily on large aircraft.
servo tabs
work in the same manner as balance tabs except, instead of moving in the opposite direction, they move in the same direction as the trailing edge of the stabilator. In addition to decreasing the sensitivity of the stabilator, an this tab also functions as a trim device to relieve control pressure and maintain the stabilator in the desired position.
antiservo tabs
Many small aircraft have a non-movable metal trim tab on the rudder. This tab is bent in one direction or the other while on the ground to apply a trim force to the rudder. The correct displacement is determined by trial and error.
ground adjustable tabs
Rather than using a movable tab on the trailing edge of the elevator, some aircraft have this. With this arrangement, linkages pivot the horizontal stabilizer about its rear spar. This is accomplished by the use of a jackscrew mounted on the leading edge of the stabilator.
adjustable stabilizer
They aid the pilot in moving the control surface and in holding it in the desired
position. Only the this moves in response to movement of the pilot’s flight control, and the force of the airflow on the this then moves the primary control surface.
servo tabs
It controls pitch about the lateral axis
It is connected to the control column in the flight deck by a series of mechanical
linkages.
It is hinged to the horizontal stabilizer.
The movement of flight control is either upward or downward.
It is controlled by the collective lever.
elevator
It control the movement yaw about the vertical axis.
It is hinged to the vertical stabilizer.
The movement of the rudder is left or right.
It is controlled by the rudder/anti-torque pedals.
rudder
one aileron is raised a greater distance
than the other aileron and is lowered for a given movement of the control wheel or control stick. This produces an increase in drag on the descending wing. The greater drag results from
deflecting the up aileron on the descending wing to a greater angle than the down aileron on the rising wing.
differential aileron
when pressure is applied to the control
wheel, or control stick, the aileron that is being raised pivots on an offset hinge. This projects the leading edge of the aileron into the airflow and creates drag. It helps equalize the drag
created by the lowered aileron on the opposite wing and reduces adverse yaw.
frise-type aileron
forms a slot so air flows smoothly over the lowered aileron, making it more effective at high angles of attack.
frise-type aileron
Since the downward deflected aileron produces more lift as evidenced by the wing raising, it also produces more drag. This added drag causes the wing to slow down slightly. This results in the aircraft yawing toward the wing which had experienced an increase in lift (and drag). From the pilot’s perspective, the yaw is opposite the direction of the bank.
adverse yaw
