A negative contribution to the static longitudinal stability of conventional ? [ Formation assignment ]

Question 235-1 : The fuselage the tail a fixed trim position a fixed elevator deflection

exemple 335 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 The fuselage.

A jet transport aeroplane exhibits pitch up when thrust is suddenly increased ?

Question 235-2 : Cg drag line of action neutral point centre of pressure

exemple 339 Cg. — . /com en/com080 526 jpg.thrust line is below the center of gravity if thrust is suddenly increased it creates a pitching moment Cg.

The aeroplane motion schematically illustrated in the annex is an example of a ?

Question 235-3 : Unstable periodic motion indifferent periodic motion stable periodic motion indifferent aperiodic motion

exemple 343 Unstable periodic motion. — Unstable periodic motion.

The aerodynamic contribution to the static longitudinal stability of the ?

Question 235-4 : Positive negative zero maximum during cruise

exemple 347 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 Positive.

Stick force per g ?

Question 235-5 : Is dependent on cg location is selected by the pilot by electronic means before each flight does not change with increasing altitude has a maximum value related to acceptable controllability the minimum value is of no concern

exemple 351 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 Is dependent on cg location.

Static lateral stability should not be too large because ?

Question 235-6 : Too much aileron deflection would be required in a crosswind landing too much rudder deflection would be required in a crosswind landing constant aileron deflection would be required during cruise in case of crosswind the roll trim sensitivity would increase sharply

exemple 355 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 Too much aileron deflection would be required in a crosswind landing.

Positive static stability of an aeroplane means that following a disturbance ?

Question 235-7 : The initial tendency is to return towards its equilibrium condition the initial tendency is to diverge further from its equilibrium condition the tendency is to move with an oscillatory motion of decreasing amplitude the tendency is to move with an oscillatory motion of increasing amplitude

exemple 359 The initial tendency is to return towards its equilibrium condition. — The initial tendency is to return towards its equilibrium condition.

Positive static longitudinal stability means that a ?

Question 235-8 : Nose down moment occurs after encountering an up gust nose up moment occurs with a speed change at constant angle of attack nose down moment occurs with a speed change at constant angle of attack nose up moment occurs after encountering an up gust

exemple 363 Nose-down moment occurs after encountering an up-gust. — Nose-down moment occurs after encountering an up-gust.

Static lateral stability should not be too small because ?

Question 235-9 : The aeroplane would show too strong a tendency to spiral dive after a disturbance around the longitudinal axis the aeroplane would show too strong a tendency to return to the original attitude the stick force per g would become unacceptably small the aeroplane would show too strong a tendency to dutch roll

exemple 367 The aeroplane would show too strong a tendency to spiral dive. — The aeroplane would show too strong a tendency to spiral dive.

The effect on static lateral stability of an aeroplane with a high wing as ?

Question 235-10 : A positive dihedral effect a negative dihedral effect no effect as it is only used to improve aeroplane loading zero dihedral effect

exemple 371 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 A positive dihedral effect.

The effect of the wing downwash on the static longitudinal stability of an ?

Question 235-11 : Negative negligible positive smallest at high values of the lift coefficient

exemple 375 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 Negative.

The effect of a wing with sweepback on static directional stability is as ?

Question 235-12 : Stabilizing effect no effect destabilizing dihedral effect negative dihedral effect

exemple 379 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. Stabilizing effect.

If the nose of an aeroplane yaws left this causes ?

Question 235-13 : A roll to the left a decrease in relative airspeed on the right wing an increase in lift on the left wing a roll to the right

exemple 383 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 A roll to the left.

If the elevator trim tab is deflected up the cockpit trim indicator shows ?

Question 235-14 : Nose down neutral nose up nose left

If an aeroplane exhibits insufficient stick force per g this problem can be ?

Question 235-15 : A bobweight in the control system which pulls the stick forwards a spring which pulls the stick backwards a spring which pushes the stick forwards a bobweight in the control system which pulls the stick backwards

exemple 391 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 A bobweight in the control system which pulls the stick forwards.

How can the designer of an aeroplane with straight wings increase the static ?

Question 235-16 : By increasing the aspect ratio of the vertical stabiliser whilst maintaining a constant area by fitting a ventral fin a fin at the under side of the aeroplane by applying wing twist by increasing anhedral

exemple 395 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 By increasing the aspect ratio of the vertical stabiliser, whilst maintaining a constant area.

If the total sum of moments about one of its axes is not zero an aeroplane would ?

Question 235-17 : Experience an angular acceleration about that axis be difficult to control fly a path with a constant curvature not be affected because the situation is normal

exemple 399 Experience an angular acceleration about that axis. — Experience an angular acceleration about that axis.

The manoeuvre stability of a large jet transport aeroplane is 280 n/g what ?

Question 235-18 : 420 n 770 n 630 n 1050 n

exemple 403 420 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 420 n.

Which of the following provides a positive contribution to static directional ?

Question 235-19 : A dorsal fin a forward swept wing a low wing as compared with a high wing moving the center of gravity aft

The primary purpose of dihedral is to ?

Question 235-20 : Increase static lateral stability increase dynamic stability decrease sensitivity to dutch roll increase static directional stability

exemple 411 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 Increase static lateral stability.

A conventional stabiliser on a stable aeroplane in a normal cruise condition .1 ?

Question 235-21 : 2 3 and 4 1 3 and 4 1 and 3 1 and 4

During a take off roll with a strong crosswind from the right a four engine jet ?

Question 235-22 : The right outboard engine the left outboard engine the right inboard engine the left inboard engine

exemple 419 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. The right outboard engine.

In general directional controllability with one engine inoperative on a multi ?

Question 235-23 : 2 3 6 1 4 5 1 4 6 2 3 5

exemple 423 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 2, 3, 6.

The most aft cg location may be limited by .1 insufficient stick force ?

Question 235-24 : 1 3 1 2 4 1 4 2 3

exemple 427 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 1, 3.

An example of a combined lateral and directional aperiodic motion is a ?

Question 235-25 : Spiral dive short period oscillation dutch roll phugoid

exemple 431 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 Spiral dive.

An aeroplane's bank angle is defined as the angle between its ?

Question 235-26 : Lateral axis and the horizontal plane speed vector and longitudinal axis longitudinal axis and the horizontal plane speed vector and the horizontal plane

exemple 435 Lateral axis and the horizontal plane. — Lateral axis and the horizontal plane.

Low speed pitch up can be caused by a significant thrust ?

Question 235-27 : Increase with podded engines located beneath a low mounted wing increase with engines located on the rear fuselage decrease with podded engines located beneath a low mounted wing decrease with engines located on the rear fuselage

exemple 439 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 Increase with podded engines located beneath a low-mounted wing.

When a jet transport aeroplane takes off with the cg at the forward limit and ?

Question 235-28 : Rotation will be normal using the normal rotation technique there will be a tendency to over rotate early nose wheel raising will take place rotation will require a higher than normal stick force

exemple 443 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 Rotation will be normal using the normal rotation technique.

When a jet transport aeroplane takes off with the cg at the aft limit and the ?

Question 235-29 : Early nose wheel raising will take place there will be a tendency to under rotate rotation will be normal using the normal rotation technique rotation will require higher than normal stick force

exemple 447 Early nose wheel raising will take place. — Early nose wheel raising will take place.

Negative tail stall is ?

Question 235-30 : A sudden reduction in the downward aerodynamic force on the tailplane flow reversal on the fin leading to flow re attachment a typical aerodynamic problem for canards flow separation at the rear of the lower surface of the wing

exemple 451 A sudden reduction in the downward aerodynamic force on the tailplane. — A sudden reduction in the downward aerodynamic force on the tailplane.

Which statement about negative tail stall is correct ?

Question 235-31 : When negative tail stall occurs the aeroplane will show an uncontrollable pitch down moment negative tail stall is a stall of the tailplane when the aerodynamic force is in upward direction when negative tail stall occurs the aeroplane will show an uncontrollable pitch up moment negative tail stall is a stall of the fin with a negative sideslip angle nose pointing to the right of the relative airflow

exemple 455 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. When negative tail stall occurs, the aeroplane will show an uncontrollable pitch-down moment.

An aeroplane has static directional stability if when in a sideslip with the ?

Question 235-32 : Nose of the aeroplane tends to yaw left right wing tends to go down nose of the aeroplane does not move nose of the aeroplane tends to yaw right

exemple 459 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 Nose of the aeroplane tends to yaw left.

As the stability of an aeroplane decreases ?

Question 235-33 : Its manoeuvrability increases its manoeuvrability decreases also its tendency to tuck under decreases there is no effect on its stability

exemple 463 Its manoeuvrability increases. — Its manoeuvrability increases.

Aeroplane manoeuvrability increases for a given control surface deflection when ?

Question 235-34 : Ias increases flaps are retracted at constant ias ias decreases the cg moves forward

exemple 467 Ias increases. — .the capability of an airplane to respond to the pilot's control greatly depends on the airflow speed on the control surface Ias increases.

Static lateral stability will be decreased by ?

Question 235-35 : The use of a low rather than high wing mounting increasing the size of the vertical tail reducing wing anhedral increasing wing sweepback

exemple 471 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 . 684.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 The use of a low, rather than high, wing mounting.

Static lateral stability will be decreased by ?

Question 235-36 : Reducing wing sweepback increasing the size of the vertical tail the use of a high rather than low wing mounting reducing wing anhedral

.sweepback angle is the angle at which the wing points backwards from the root to the tip . /com en/com080 467 png.sweepback is used mainly on high speed aircraft and its primary purpose is to delay the formation of sonic shock waves which are produced at high speeds and cause a large increase in drag .the secondary effect of sweepback is to improve lateral stability when a side slip occurs the lower wing presents a larger span as seen from the direction of the approaching air and as with dihedral the effect is to roll the aircraft back towards the horizontal if the sweepback angle is reduced the static lateral stability decreases

How can a pilot recognise static stick force stability in an aeroplane during ?

Question 235-37 : To maintain a speed above the trim speed requires a push force to maintain a speed above the trim speed requires a pull force when speed decreases the push force increases the elevator stick force remains constant with speed changes

exemple 479 To maintain a speed above the trim speed requires a push force. — .when an aeroplane is properly trimmed a push force is required to increase airspeed and a pull force is required to decrease airspeed in this manner the aeroplane would have positive stick force stability with a stable 'feel' for airspeed .warning this question exists in the database but with the other possible answer .to maintain a speed below the trim speed requires a pull force To maintain a speed above the trim speed requires a push force.

Which design features reduce static lateral stability .1 high wing.2 low wing.3 ?

Question 235-38 : 2 4 1 3 1 4 2 3

exemple 483 2, 4. — .for static lateral stability to be present an aircraft must have stopped rolling and be side slipping .the design features that provide static lateral stability are . the dihedral effect increase in angle of attack on the lower wing compared to the upper wing . high wing and low cg pendulous affect . keel effect the keel/side surface above the centre of gravity will be presented to the relative airflow which will give a force to help in correcting the roll and a low cg .an aircraft can have one or a combination of the above to provide the required amount of static lateral stability although some aircraft may be too stable and methods such as anhedral wings are used to reduce static lateral stability .more information on vertical and ventral fin .dorsal and ventral fins contribute in exactly the same way to directional static stability a dorsal fin contributes positively to lateral static stability . /com en/com080 618a jpg.if the aircraft is yawed to the left the dorsal and ventral fins will create a side force to the left the line of action of this force is well aft of the aircraft cg giving a yawing moment to the right a stabilising effect . /com en/com080 618b jpg.the ventral fin being below the aircraft cg has a negative influence on lateral static stability . /com en/com080 618c jpg. 2, 4.

Which of the following statements about static longitudinal stability is ?

Question 235-39 : I is correct ii is correct i is incorrect ii is correct i is correct ii is incorrect i is incorrect ii is incorrect

exemple 487 I is correct, ii is correct. — .aerodynamic center is a stationary point located at the 25% chord of the wing only when airflow is subsonic .a wing considered alone is statically unstable because the aerodynamic centre is in front of the centre of gravity a vertical gust will momentarily increase the angle of attack and increase lift which when multiplied by the arm will generate a nose up pitching moment about the centre of gravity this tends to increase the angle of attack further an unstable pitching moment .now lets look at a wing together with a tailplane .the tailplane is positioned to generate a stabilizing pitching moment about the centre of gravity the same vertical gust will increase the angle of attack of the tailplane and increase tail plane lift which when multiplied by the arm will generate a negative nose down pitching moment about the centre of gravity .if the tail moment is greater than the wing moment the sum of the moments will not be zero resulting in a nose down moment with an angular acceleration about the centre of gravity .nose down angular acceleration about the centre of gravity returns the aircraft to its original position of equilibrium the greater the tail moment relative to the wing moment the greater the rate of acceleration towards the original equilibrium position .the length of both arms wing and tailplane to centre of gravity is dependent on centre of gravity position if the centre of gravity is more forward the tail arm is larger and the wing arm smaller .a more forward cg position increases static longitudinal stability .if the nose down negative tail moment is greater than the nose up positive wing moment the aircraft will have static longitudinal stability I is correct, ii is correct.

Which of these statements are correct or incorrect regarding a sideslip with ?

Question 235-40 : I is correct ii is correct i is incorrect ii is incorrect i is correct ii is incorrect i is incorrect ii is correct

exemple 491 I is correct, ii is correct. — .a side slip with the relative airflow coming from the right is the slip of the tail to the right the nose goes left .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 right . /com en/com080 74 jpg.in a side slip to the right the lower wing is the right one and it presents a larger span as seen from the direction of the approaching air and as with dihedral the effect is to roll the aircraft back towards the horizontal the initial tendency of the left wing is to move down I is correct, ii is correct.

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