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Question 265-1 : Which statement is correct.i. stick force per g is independent of altitude..ii. stick force per g increases when the centre of gravity moves forward. ? [ Theoretical lift off ]
I is incorrect, ii is correct.
.stick force per g is dependent of altitude rho changes with altitude, pressure on the control surface will change..if the cg moves forward, static longitudinal stability increases and controllability decreases stick force increases a very high stick forces are required to pitch because the aircraft is very stable. the magnitude of the stick force required to pitch, for an aircraft with manual controls, is determined by the distance the cg is forward of the neutral point.
Question 265-2 : Which statement is correct ?
The short period oscillation should always be heavily damped.
. /com en/com080 483a.jpg. /com en/com080 483.jpg..vdo925.the short period oscillation should always be heavily damped. short period oscillation is dangerous because structural failure usually results if the oscillation is not damped immediately. short period oscillations affect airplane and control surfaces alike and reveal themselves as porpoising in the airplane, or as in buzz or flutter in the control surfaces.
Question 265-3 : Which statement is correct ?
During a phugoid altitude varies significantly, but during a short period oscillation it remains approximately constant.
Question 265-5 : An aeroplane exhibits static longitudinal stability, if, when the angle of attack changes ?
The change in total aeroplane lift acts aft of the centre of gravity.
Question 265-6 : A negative contribution to the static longitudinal stability of conventional jet transport aeroplanes is provided by ?
The fuselage.
. 686.generally, the contributions of the wing, fuselage, and nacelles is de stabilizing together these components generate nonrestoring pitching moments when changes in lift coefficient occur. if the airplane is to possess static longitudinal stability, the horizontal tail must be designed to overcome the destabilizing influence of the remainder of the airplane's components. the contribution of the horizontal tail to static longitudinal stability is powerful and almost always strongly stabilizing.
Question 265-7 : A jet transport aeroplane exhibits pitch up when thrust is suddenly increased from an equilibrium condition, because the thrust line is below the ?
Cg.
. /com en/com080 526.jpg.thrust line is below the center of gravity if thrust is suddenly increased, it creates a pitching moment.
Question 265-8 : The aeroplane motion, schematically illustrated in the annex, is an example of a dynamically.. err a 081 529 ?
Unstable periodic motion.
Question 265-9 : The aerodynamic contribution to the static longitudinal stability of the nacelles of aft fuselage mounted engines is ?
Positive.
. static stability refers to the initial tendency, or direction of movement, back to equilibrium. in aviation, it refers to the aircraft's initial response when disturbed from a given aoa, slip, or bank..positive static stability is the initial tendency of the aircraft to return to the original state of equilibrium after being disturbed... longitudinal, lateral and directional stability.. /com en/com080 547a.jpg..here, we are talking about aft fuselage mounted nacelles.. /com en/com080 547b.jpg..and they are not a symmetrical body, they are curved like aerofoils, airflow around them produce aerodynamic forces it generates a nose up moment. the plan area of the engines, stub mountings and so on acts like an extra horizontal tail, that aerodynamic force is stabilising. it is the same as having a larger tailplane which gives positive longtitudinal stability.
Question 265-10 : Stick force per g ?
Is dependent on cg location.
.the magnitude of the stick force required to pitch, for an aircraft with manual controls, is determined by the distance the cg is forward of the neutral point..when the centre of gravity moves forward, the stick force per g increases.
Question 265-11 : Static lateral stability should not be too large, because ?
Too much aileron deflection would be required in a crosswind landing.
.high lateral stability results in high stick forces with the aircraft attempting to maintain a wing level attitude. during a crosswind landing the aircraft will tend to yaw and sideslip..the sideslip component will result in lateral stability attempting to level the wing. you therefore have to hold this roll off by applying aileron, which if the stability is too high will require a larger aileron deflection.
Question 265-12 : Positive static stability of an aeroplane means that following a disturbance from the equilibrium condition ?
The initial tendency is to return towards its equilibrium condition.
Question 265-13 : Positive static longitudinal stability means that a ?
Nose down moment occurs after encountering an up gust.
Question 265-14 : Static lateral stability should not be too small because ?
The aeroplane would show too strong a tendency to spiral dive.
Question 265-15 : The effect on static lateral stability of an aeroplane with a high wing as compared with a low wing is ?
A positive dihedral effect.
.an aircraft that tends to return to wings level flight after it has been disturbed is considered to be laterally stable. mounting the wings above the centre of gravity aids lateral stability because the weight of the aircraft will act as a pendulum to restore level flight..'positive dihedral effect' when a wing goes down, dihedral effect will tend to decrease bank angle and roll the wing back up this is a positive contribution to the static lateral stability.
Question 265-16 : The effect of the wing downwash on the static longitudinal stability of an aeroplane is ?
Negative.
. /com en/com080 557a.jpg.the downwash behind the wing will have a negative contribution on the static longitudinal stability because it tends to push the tail down as angle of attack increases, you will have a more important nose up attitude...longitudinal stability is on the lateral axis. 686.note a t tail aircraft keeps the tail out of downwash and of propeller wash, but in extreme nose high attitudes, t tail aircraft pitches up viciously when stalled. because, if the horizontal tail surfaces become buried in the wing's wake, the elevator may lose all effectiveness, making it impossible to reduce pitch attitude and break the stall.
Question 265-17 : The effect of a wing with sweepback on static directional stability is as follows ?
Stabilizing effect.
.wing sweepback aids in directional stability. if the aircraft is rotated about the vertical axis, the aircraft will be forced sideways into the relative wind..because of sweepback this causes the leading wing to present more frontal area to the relative wind than the trailing wing. this increased frontal area creates more drag, which tends to force the aircraft to return to its original direction of flight.. /com en/com080 558.jpg
Question 265-18 : If the nose of an aeroplane yaws left, this causes ?
A roll to the left.
.if the nose yaw left, a part of the left wing will be shadowed by the fuselage. you will have more lift on the right wing, inducing a roll to the left.. /com en/com080 567.jpg.this phenomenon is increasing to an airplane with dihedral, the right wing has a slightly increased angle of attack and therefore higher lift which causes more roll to the left.
Question 265-19 : If the elevator trim tab is deflected up, the cockpit trim indicator shows ?
Nose down.
Question 265-20 : If an aeroplane exhibits insufficient stick force per g, this problem can be resolved by installing ?
A bobweight in the control system which pulls the stick forwards.
.when you pull the stick back, and if the stick force is judge to weak, you may quickly suffer from g force, with a risk of lost consciousness, or even worse, destroying the airplane..by installing a bobweight in the control system, it will be subjected to acceleration g force and it pulls the stick forwards..the more the g force is, the more the effect will be important.
Question 265-21 : How can the designer of an aeroplane with straight wings increase the static lateral stability ?
By increasing the aspect ratio of the vertical stabiliser, whilst maintaining a constant area.
.by making the tail fin taller while keeping the same area you are moving the cp of the fin further away from the aircraft cg, giving more moment arm and thus more correcting roll force.
Question 265-22 : If the total sum of moments about one of its axes is not zero, an aeroplane would ?
Experience an angular acceleration about that axis.
Question 265-23 : The manoeuvre stability of a large jet transport aeroplane is 280 n/g. what stick force is required, if the aeroplane is pulled to the limit manoeuvring load factor from a trimmed horizontal straight and steady flight cruise configuration ?
420 n.
.limitation for transport aircraft is 2.5 g..difference between 2.5 g and 1 g is 1.5 g...to reach the limit manoeuvring load factor, force to be applied will be 280 x 1.5 = 420 n.
Question 265-24 : Which of the following provides a positive contribution to static directional stability ?
A dorsal fin.
Question 265-25 : The primary purpose of dihedral is to ?
Increase static lateral stability.
.when a wing goes down, dihedral effect will tend to decrease bank angle and roll the wing back up this is a positive contribution to the static lateral stability the dihedral effect is an increase in angle of attack on the lower wing compared to the upper wing.
Question 265-26 : A conventional stabiliser on a stable aeroplane in a normal cruise condition.1 always provides negative lift.2 contributes to the total lift of the aeroplane.3 may stall before the wing, in icing conditions, with large flap settings, unless adequate design and/or operational precautions are ?
2, 3 and 4.
Question 265-27 : During a take off roll with a strong crosswind from the right, a four engine jet aeroplane with wing mounted engines experiences an engine failure. the failure of which engine will cause the greatest control problem ?
The right outboard engine.
.in case of a failure of one engine, the aircraft will yaw on the side where the engine failure occurs...with wind, the yaw movement will see the aircraft nose coming into the wind the aircraft tends to face the wind due to the large surface area of his vertical fin..with a strong crosswind from the right, in order to counteract this tendency, you must apply rudder to the left. now if the right outboard engine fails, thrust from the left engines will combined and it might be impossible to counteract the turning moment.. /com en/com080 646.jpg
Question 265-28 : In general, directional controllability with one engine inoperative on a multi engine aeroplane is adversely affected by.1 high temperature.2 low temperature.3 aft cg location.4 forward cg location.5 high altitude.6 low altitude.the combination that regroups all of the correct statements is ?
2, 3, 6.
It's because thrust is lower in the less dense air high temperature and high altitude so the asymmetric effect is lessened...now with regards to the centre of gravity we have to take into account the perpendicular distance. whether forward or aft, the position of the centre of gravity doesn't affect the perpendicular distance from the thrust line created by the live engine to the aircraft's longitudinal axis about which the centre of gravity moves..if we look at the perpendicular distance from the lift force generated by the rudder, as the force is at an angle to the longitudinal axis assuming the rudder is deflected to counteract the moment from the live engine , an aft centre of gravity would reduce the perpendicular distance and so reduce the moment created by the rudder...vmca speed is cas based, so engine thrust is reduced, but control forces and effects on the rudder remain unaffected in a less dense atmosphere.
Question 265-29 : The most aft cg location may be limited by.1. insufficient stick force stability.2. insufficient flare capability.3. excessive in flight manoeuvrability.4. insufficient in flight manoeuvrability.the combination that regroups all of the correct statements is ?
1, 3.
.because an aft cg equals less longitudinal stability makes the aircraft respond too rapidly, which is the same thing as having too low a stick force per g and is the same thing as having too much manoeuvre ability. and vice versa, where a forward cg makes a sluggish aircraft and, for example, may leave you unable to raise the nose for landing.
Question 265-30 : An example of a combined lateral and directional aperiodic motion is a ?
Spiral dive.
.a spin may be defined as an aggravated stall that results in what is termed 'autorotation' wherein the airplane follows a downward corkscrew path. as the airplane rotates around a vertical axis, the rising wing is less stalled than the descending wing creating a.rolling, yawing, and pitching motion. the airplane is basically being forced downward by gravity, rolling, yawing, and pitching in a spiral path.. /com en/com080 684.jpg..'periodic' means recurring at regular intervals. 'aperiodic' adds the greek prefix 'a' meaning 'not' or 'without'..'dutch roll', 'phugoid' and 'short period oscillation' are continuous oscillations with a period of oscillation, a spiral dive is a continuous divergence.
Question 265-31 : An aeroplane's bank angle is defined as the angle between its ?
Lateral axis and the horizontal plane.
Question 265-32 : Low speed pitch up can be caused by a significant thrust ?
Increase with podded engines located beneath a low mounted wing.
. /com en/com080 690.jpg.low speed flight means an increasing angle of attack. the centre of pressure moves forward the cg, and the horizontal stabilizer must produce lift instead of producing a downforce in normal cruise flight..lift generates by the horizontal stabilizer is affected by the disturbed flow from the wing, and if you increase thrust, additional arm moment comes in force, due to the podded engines located beneath the cg.
Question 265-33 : When a jet transport aeroplane takes off with the cg at the forward limit and the trimmable horizontal stabiliser ths is positioned at the maximum allowable nose up position for take off ?
Rotation will be normal using the normal rotation technique.
.the forward cg limit is defined as the most nose heavy loading condition that will allow the aircraft to be rotated on takeoff and flared upon landing. futhermore, if trimmable horizontal stabiliser ths is positioned at the maximum allowable nose up position for take off, rotation will be normal using the normal rotation technique.
Question 265-34 : When a jet transport aeroplane takes off with the cg at the aft limit and the trimmable horizontal stabiliser ths is positioned at the maximum allowable nose up position for take off ?
Early nose wheel raising will take place.
Question 265-35 : Negative tail stall is ?
A sudden reduction in the downward aerodynamic force on the tailplane.
Question 265-36 : Which statement about negative tail stall is correct ?
When negative tail stall occurs, the aeroplane will show an uncontrollable pitch down moment.
.negative tail stall is a sudden reduction in the downward aerodynamic force on the tailplane it means that previously the tail was producing a downward force cg is forward of cp.. /com en/com080 699.jpg..
Question 265-37 : An aeroplane has static directional stability if, when in a sideslip with the relative airflow coming from the left, initially the ?
Nose of the aeroplane tends to yaw left.
.a side slip to the left is the slip of the tail to the left. the nose goes right..if an aeroplane has static directional stability, the intial tendency is to come back in the flight pattern of the aircraft through the air the nose of the aeroplane is to move to the left.. /com en/com080 1085.jpg..directional stability is accomplished by placing a vertical stabilizer or fin to the rear of the centre of gravity on the upper portion of the tail section.
Question 265-38 : As the stability of an aeroplane decreases ?
Its manoeuvrability increases.
Question 265-39 : Aeroplane manoeuvrability increases for a given control surface deflection when ?
Ias increases.
.the capability of an airplane to respond to the pilot's control greatly depends on the airflow speed on the control surface.
Question 265-40 : Static lateral stability will be decreased by ?
The use of a low, rather than high, wing mounting.
An aircraft's stability is expressed in relation to each axis..lateral stability stability in roll , directional stability stability in yaw and longitudinal stability stability in pitch..rolling is the rotation of the aeroplane about the longitudinal axis.. 2389..static stability refers to the aircraft's initial response to a disturbance. a statically unstable aircraft will uniformly depart from a condition of equilibrium...mounting the wings above the centre of gravity aids lateral stability because the weight of the aircraft will act as a pendulum to restore level flight. therefore, the use of a low wing mounting will decrease the static lateral stability.
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