Preparation > civilian : How will the density and static temperature change in a supersonic flow from a ?

Question 214-1 : Density will increase static temperature will increase density will increase static temperature will decrease density will decrease static temperature will increase density will decrease static temperature will decrease

exemple 314 density will increase, static temperature will increase. — density will increase, static temperature will increase.

In order to provide an adequate 'buffet boundary' at the commencement of the ?

Question 214-2 : Increased to 191 knots drag will increase and air distance per kg of fuel will decrease increased to 191 knots drag will decrease and air distance per kg of fuel will increase increased to 202 knots but since the same angle of attack is used drag and range will remain the same unaffected as vs always occurs at the same angle of attack

exemple 318 increased to 191 knots, drag will increase and air distance per kg of fuel will decrease. — .value of 1 3vs at 135000 kg = 180 x sqrt 135000 / 120000..value of 1 3vs at 135000 kg = 180 x 1 0607...value of 1 3vs at 135000 kg = 190 926 kt.'sqrt' means 'square root' increased to 191 knots, drag will increase and air distance per kg of fuel will decrease.

The speed range between high and low speed buffet ?

Question 214-3 : Increases during a descent at a constant ias increases during climb decreases during a descent at a constant mach number is always positive at mach numbers below mmo

exemple 322 increases during a descent at a constant ias. — Mach buffet boundaries .mach buffet is a function of the speed of the airflow over the wing not necessarily the speed of the aircraft any time that too great a lift demand is made on the wing whether from too fast an airspeed or from too high an aoa near the mmo the 'high speed' buffet occurs there are also occasions when the buffet can be experienced at much lower speeds known as the 'low speed mach buffet' .an aircraft flown at a speed too slow for its weight and altitude necessitating a high aoa is the most likely situation to cause a low speed mach buffet this very high aoa has the effect of increasing airflow velocity over the upper surface of the wing until the same effects of the shock waves and buffet occur as in the high speed buffet situation the aoa of the wing has the greatest effect on inducing the mach buffet at either the high speed or low speed boundaries for the aircraft.if the ias remains constant during a descent the mach number will also steadily reduce this is because tas reduces and the local speed of sound increases low speed buffet will therefore occur at a lower mach number the speed range between high and low speed buffet will increase increases during a descent at a constant ias.

'tuck under' is caused by i movement of the centre of pressure of the wing and ?

Question 214-4 : I aft ii decreasing i forward ii decreasing i aft ii increasing i forward ii increasing

exemple 326 (i) aft (ii) decreasing. — /com en/com080 418 jpg. (i) aft (ii) decreasing.

What is the significance of the maximum allowed cruising altitude based on the ?

Question 214-5 : A manoeuvre with a load factor of 1 3 will cause buffet onset a manoeuvre with a load factor of 1 3 will cause mcrit to be exceeded a manoeuvre with a load factor of 1 3 will cause a mach number at which accelerated low speed stall occurs exceeding a load factor of 1 3 will cause permanent deformation of this aeroplane

exemple 330 a manoeuvre with a load factor of 1.3 will cause buffet onset. — .in order to maintain a minimum margin against buffeting and ensure good aircraft maneuverability it is necessary to determine an acceptable load factor limit below which buffeting shall never occur this load factor limit is generally fixed to 1 3 this value is an operating limitation but not a regulatory one the corresponding altitude is called the '1 3g buffet limited altitude' or 'buffet ceiling' a manoeuvre with a load factor of 1.3 will cause buffet onset.

When the mach number is slowly increased in straight and level flight the first ?

Question 214-6 : On the upper surface at the wing root on the lower surface of the wing somewhere on the fin somewhere on the horizontal tail

exemple 334 on the upper surface at the wing root. — on the upper surface at the wing root.

A transonic mach number is a mach number ?

Question 214-7 : At which both subsonic and supersonic local speeds occur between the buffet onset mach number and the mach number corresponding to total supersonic flow at which only supersonic local speeds occur in the range between mcrit and mmo

exemple 338 at which both subsonic and supersonic local speeds occur. — at which both subsonic and supersonic local speeds occur.

During a climb at a constant ias the mach number will ?

Question 214-8 : Increase decrease initially and increase subsequently remain constant increase initially and remain constant subsequently

As the mach number increases in straight and level flight a shock wave on the ?

Question 214-9 : Move towards the trailing edge move towards the leading edge not move disappear

exemple 346 move towards the trailing edge. — move towards the trailing edge.

During which type of stall does the angle of attack have the smallest value ?

Question 214-10 : Shock stall accelerated stall low speed stall deep stall

exemple 350 shock stall. — .a shock stall is a stall caused by the airflow over an aircraft's wings being disturbed by shock waves when flying at or near to the aircraft's critical mach number.shock stall is the separation of the boundary layer behind the shock wave. bcg160 .i would like to request a brief explanation or definition about accelerated stall thanks..an accelerated stall is caused by abrupt or excessive control movement an accelerated stall can occur during a sudden change in the flight path during manoeuvres such as steep turns or a rapid recovery from a dive it is called an 'accelerated stall' because it occurs at a load factor greater than 1g an accelerated stall is usually more violent than a low speed stall 'normal' stall at 1g and is often unexpected because of the relatively high airspeed shock stall.

A normal shock wave is a discontinuity plane ?

Question 214-11 : That is always normal to the local flow across which the temperature drops suddenly across which the pressure drops suddenly that is always normal to the surface

exemple 354 that is always normal to the local flow. — that is always normal to the local flow.

An aeroplane is flying through the transonic range whilst maintaining straight ?

Question 214-12 : A pitch up input of the stabiliser a stability augmentation system to improve dynamic stability much more thrust from the engines a higher ias to compensate the nose down effect

exemple 358 a pitch up input of the stabiliser. — .as the mach number inscreases in the transonic range the centre of pressure will move aft .a corrective pitch up input on the stabiliser is required. 685..to maintain equilibrium an increase in downward force is required the blue arrow vector of the total aerodynamic lift vertical to the centre of pressure moves aft red point is the centre of gravity.transonic range starts at mcrit up to mach 1 3 a pitch up input of the stabiliser.

If the mach number is 0 8 and the tas is 400 kt what is the speed of sound ?

Question 214-13 : 500 kt 320 kt 480 kt 600 kt

exemple 362 500 kt. — Jamacof .mach no formula .mach no = tas / lss....mach no is mach number..tas is true airspeed expressed in knots..lss is local speed of sound expressed in knots....so in this question...0 8 = 400/lss..0 8 lss = 400..lss = 400 0 8..lss = 500 kt 500 kt.

In supersonic flight all disturbances produced by an aeroplane are ?

Question 214-14 : Within a conical zone dependent on the mach number outside a conical zone dependent on the mach number in front of the aeroplane very weak and negligible

exemple 366 within a conical zone, dependent on the mach number. — within a conical zone, dependent on the mach number.

Mach buffet occurs ?

Question 214-15 : At the mach number at which shock wave induced boundary layer separation occurs when the mach number has increased to mcrit directly after exceeding mcrit when the stall angle of attack is exceeded

exemple 370 at the mach number at which shock wave induced boundary layer separation occurs. — at the mach number at which shock wave induced boundary layer separation occurs.

In the event of failure of the mach trimmer ?

Question 214-16 : The mach number must be limited the centre of gravity must be moved aft the speed must be kept constant the aeroplane mass must be limited

exemple 374 the mach number must be limited. — the mach number must be limited.

In the transonic range the aeroplane characteristics are strongly determined by ?

Question 214-17 : Mach number tas ias cas

exemple 378 mach number. — .transonic flight regime between sonic and supersonic speeds only part of the airflow over the wing is above the speed of sound .the mach number is the speed used in transonic range mach number.

Which statement is correct about an expansion wave in supersonic flow .1 the ?

Question 214-18 : 1 is correct and 2 is incorrect 1 and 2 are correct 1 is incorrect and 2 is correct 1 and 2 are incorrect

exemple 382 1 is correct and 2 is incorrect. — .the effect on pressure temperature density and velocity is the opposite in expansion waves to oblique/normal shock waves. chrism .supersonic flight is no longer part of the learning objectives i believe..learning objectives 081 02 01 05 subdivision of aerodynamic flow . list the subdivision of aerodynamic flow . subsonic flow . transonic flow . supersonic flow . describe the characteristics of the flow regimes listed above 1 is correct and 2 is incorrect.

What is the relation between the mach angle mu and the corresponding mach number ?

Question 214-19 : Sin mu = 1/m sin mu = m tan mu= 1/m sin2mu = 1/m

exemple 386 sin mu = 1/m — . /com en/com080 602 jpg. sin mu = 1/m

Which type of buffet will occur if a jet aeroplane slowly accelerates in level ?

Question 214-20 : Mach buffet flutter speed buffet accelerated stall buffet low speed buffet

Which speeds are used and in which sequence if an emergency descent is carried ?

Question 214-21 : Mmo vmo vmo mmo mne vne md vd

exemple 394 mmo, vmo. — .vmo/mmo is defined as the maximum operating limit speed vmo is expressed in knots calibrated airspeed kcas while mmo is expressed in mach number the vmo limit is usually associated with operations at lower altitudes and deals with structural loads and flutter the mmo limit is associated with operations at higher altitudes and is usually more concerned with compressibility effects and flutter at lower altitudes structural loads and flutter are of concern at higher altitudes compressibility effects and flutter are of concern.in descent and at low altitude vmo .in climb and at high altitude mmo.at first at high altitude mmo must be taken in consideration and after passing the 'crossosver altitude' the altitude at which a specified cas and mach value represent the same tas value vmo must be used mmo, vmo.

Aileron flutter can be caused by ?

Question 214-22 : Cyclic deformations generated by aerodynamic inertial and elastic loads on the wing the elastic centre of the wing section coinciding with the centre of gravity of that wing section continuous deformations in one direction generated by bending and twisting of the wing aileron reversal

exemple 398 cyclic deformations generated by aerodynamic, inertial and elastic loads on the wing. — cyclic deformations generated by aerodynamic, inertial and elastic loads on the wing.

Regarding the transonic speed range ?

Question 214-23 : Both subsonic and supersonic speeds exist in the flow around the aeroplane it starts at a mach number just above 1 it starts at a mach number equal to 1 it starts at mcrit and extends to mach number equal to 1

exemple 402 both subsonic and supersonic speeds exist in the flow around the aeroplane. — .subsonic range is from 0 and ends at mcrit .transonic range starts at mcrit up to mach 1 3 .supersonic range is from mach 1 3 to approximately mach 5 .above mach 5 the hypersonic speed range both subsonic and supersonic speeds exist in the flow around the aeroplane.

The subsonic speed range ?

Question 214-24 : Ends at mcrit ends at a mach number just above m = 1 ends at m = 1 implies both subsonic and supersonic speeds exist in the flow around the aeroplane

exemple 406 ends at mcrit. — .subsonic range is from 0 and ends at mcrit .transonic range starts at mcrit up to mach 1 3 .supersonic range is from mach 1 3 to approximately mach 5 .above mach 5 the hypersonic speed range ends at mcrit.

Which of these statements about the supersonic speed range is correct ?

Question 214-25 : The airflow everywhere around the aeroplane is supersonic the supersonic speed range starts at a mach number below m = 1 and extends to mach numbers above m = 1 the airflow around the aeroplane is transonic the supersonic speed range starts at m = 1 and ends at mcrit

exemple 410 the airflow everywhere around the aeroplane is supersonic. — .subsonic range is from 0 and ends at mcrit .transonic range starts at mcrit up to mach 1 3 .supersonic range is from mach 1 3 airflow everywhere around the aeroplane is supersonic to approximately mach 5 .above mach 5 the hypersonic speed range the airflow everywhere around the aeroplane is supersonic.

Which of these statements about an oblique shock wave are correct or incorrect ?

Question 214-26 : I is correct ii is correct i is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is incorrect

exemple 414 i is correct, ii is correct. — i is correct, ii is correct.

Which of these statements about an oblique shock wave are correct or incorrect ?

Question 214-27 : I is correct ii is correct i is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is incorrect

exemple 418 i is correct, ii is correct. — i is correct, ii is correct.

Which of these statements about an oblique shock wave are correct or incorrect ?

Question 214-28 : I is correct ii is correct i is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is incorrect

exemple 422 i is correct, ii is correct. — . /com en/normal and oblic shock wave jpg.air is warmer behind the shock wave thus local speed of sound is higher lss is directly proportional to air temperature i is correct, ii is correct.

Which of these statements about 'tuck under' are correct or incorrect .i a ?

Question 214-29 : I is incorrect ii is incorrect i is correct ii is incorrect i is incorrect ii is correct i is correct ii is correct

exemple 426 i is incorrect, ii is incorrect. — .'tuck under' is the tendency to nose down when speed is increased into the transonic flight regime as the mach number inscreases in the transonic range the centre of pressure will move aft . /com en/com080 418 jpg.'tuck under' is caused by a reduction in the downwash angle at the location of the horizontal stabiliser i is incorrect, ii is incorrect.

Which of these statements about an oblique shock wave are correct or incorrect ?

Question 214-30 : I is correct ii is correct i is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is incorrect

exemple 430 i is correct, ii is correct. — . oblique/normal wave. /com en/normal and oblic shock wave jpg. i is correct, ii is correct.

The speed range from approximately m=1 3 to approximately m=5 is called the ?

Question 214-31 : Supersonic range transonic range hypersonic range subsonic range

exemple 434 supersonic range. — .subsonic range is from 0 and ends at mcrit .transonic range starts at mcrit up to mach 1 3 .supersonic range is from mach 1 3 to approximately mach 5 .above mach 5 the hypersonic speed range supersonic range.

What is the highest speed possible without supersonic flow over the wing ?

Question 214-32 : Critical mach number tuck under speed m = 1 initial mach buffet speed

exemple 438 critical mach number. — .the critical mach number of an aerofoil is the free stream mach number at which sonic speed m=1 is first reached on the upper surface . /com en/com080 152 jpg. critical mach number.

When the speed over an aerofoil section increases from subsonic to supersonic ?

Question 214-33 : Moves from approximately 25% to about 50% of the chord moves aft by approximately 10% of the chord does not move moves slightly forward

exemple 442 moves from approximately 25% to about 50% of the chord. — .the aerodynamic center is a point somewhere between the leading edge and the trailing edge where there will be no change in the pitching moment of the aerofoil as the pressure pattern on the aerofoil changes this point on the aerofoil does not move as you change angle of attack and the pitching moment of a wing is always constant about it..in the transonic region the formation of shock waves on the wing surface and the resulting separated flow causes movement of the wing aerodynamic center .the magnitude of the aerodynamic center movement depends on the design parameters of the wing the aft shift of the aerodynamic center results in an increase in longitudinal stability at a constant mach number or an increase in angle of attack stability the aft shift of the aerodynamic center is analogous to moving the airplane center of gravity forward moves from approximately 25% to about 50% of the chord.

What is the value of the mach number if the mach angle equals 45° ?

Question 214-34 : 1 4 2 0 7 1 2

exemple 446 1.4 — The formula is .mach angle = sin^&8722 1 x 1/machnumber .45° = sin^ 1 x 1/m .sin 45° = 1/m.m = 1 41 1.4

If the mach number is 0 8 and the tas is 480 kt what is the speed of sound ?

Question 214-35 : 600 kt 384 kt 750 kt 560 kt

exemple 450 600 kt. — Jamacof .m = tas lss..0 8 = 480 lss.lss = 600 600 kt.

One advantage of a supercritical wing aerofoil over a conventional one is ?

Question 214-36 : It allows a wing of increased relative thickness to be used for approximately the same cruise mach number a lower value of mcrit at the same relative thickness improved dutch roll damping at cruise altitude that there is no need for spoilers

exemple 454 it allows a wing of increased relative thickness to be used for approximately the same cruise mach number. — it allows a wing of increased relative thickness to be used for approximately the same cruise mach number.

The sonic boom of an aeroplane flying at supersonic speed is created by ?

Question 214-37 : Shock waves around the aeroplane aerodynamic heating the expansion flow behind the aeroplane the centre of pressure which is moving aft on the aerofoil

exemple 458 shock waves around the aeroplane. — shock waves around the aeroplane.

A supercritical wing ?

Question 214-38 : Will develop no noticeable shock waves when flying just above mcrit always cruises at mcrit will be free of mach buffet in the transonic range will develop no transonic flow just above mcrit

exemple 462 will develop no noticeable shock waves when flying just above mcrit. — Celsohernandez .what is a supercritical wing..when the speed of an aircraft approaches the speed of sound the local airflow about the airplane particularly above the upper surface of the wing may exceed the speed of sound such a condition is called supercritical flow on previous aircraft this supercritical flow resulted in the onset of a strong local shock wave above the upper surface of the wing illustration 'a' this local wave caused an abrupt increase in the pressure on the surface of the wing which may cause the surface boundary layer flow to separate from the surface with a resulting severe increase in the turbulence of the flow the increased turbulence leads to a severe increase in drag and loss in lift with a resulting decrease in flight efficiency . /com en/com080 969 jpg.supercritical airfoils are shaped to substantially reduce the strength of the shock wave and to delay the associated boundary layer separation illustration 'b' since the airfoil shape allows efficient flight at supercritical flight speeds a wing of such design is called a supercritical wing.just above mcrit a supercritical wing will develop no noticeable shock waves will develop no noticeable shock waves when flying just above mcrit.

The aft movement of the centre of pressure during the acceleration through the ?

Question 214-39 : Increase in static longitudinal stability decrease the longitudinal stability decrease the static lateral stability increase the static lateral stability

exemple 466 increase in static longitudinal stability. — Transonic flight regime between sonic and supersonic speeds only part of the airflow over the wing is above the speed of sound.the aft movement of the centre of pressure during the acceleration through the transonic flight regime will increase the static longitudinal stability.as the mach number increases in the transonic range the centre of pressure will move aft .a corrective pitch up input on the stabiliser is required . 685.to maintain equilibrium an increase in downward force is required the blue arrow vector of the total aerodynamic lift vertical to the centre of pressure moves aft red point is the centre of gravity .transonic range starts at mcrit up to mach 1 3.the aft movement of the centre of pressure will increase the initial tendency to return to the original state of equilibrium after being disturbed on the lateral axis longitudinal stability because more down force on the tail is required to maintain level flight thus a more important force will be necessary for disturbing this equilibrium the static longitudinal stability is increased . 686.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.notice lateral stability decreases in the transonic range but it is not caused by the centre of pressure shift it is caused by asymmetric shock wave generation on either wing increase in static longitudinal stability.

What is the effect of aeroplane mass on shock wave intensity at constant mach ?

Question 214-40 : Increasing mass increases shock wave intensity decreasing mass increases shock wave intensity decreasing mass increases shock wave intensity at below standard temperatures a change in mass does not influence shock wave intensity

.shock wave intensity is determined by the aircraft design the altitude the size and weight of the aircraft the power or volume of the shock wave is dependent on the quantity of air that is being accelerated thus increasing aeroplane mass will increase the quantity of air that is being accelerated at constant mach number

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