An aircraft is certificated to \( +3.8 \) g in the normal category. Its ultimate design load factor is
Answer: C
Correct answer: 5.7
\[ 3.8 \times 1.5 = 5.7. \] The certificated figure of \( +3.8 \) g is the limit load factor; multiplying by the standard 1.5 factor of safety gives the ultimate design load factor at which the structure must not fail.
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An aircraft of \( 400 \) kN weight is in a 45 degree banked level turn. The lift required is nearest to
Answer: D
The load factor is \( 1/\cos 45^\circ = 1.414 \), so the lift is \( 1.414 \times 400 = 566 \) kN. The extra forty per cent must come from angle of attack, which is why a steep level turn requires both back pressure and additional thrust.
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A structure is tested to \( 1.5 \) times limit load and must hold it for
Answer: A
The requirement is that ultimate load be sustained for three seconds without failure. Permanent deformation is acceptable at that level; it is at limit load that the structure must return to shape without detrimental permanent set.
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Assertion (A): An aircraft cannot be over-stressed by elevator alone below its manoeuvring speed.
Reason (R): Below that speed the wing stalls before the limit load factor is reached.
Select the correct answer from the options below.
Answer: B
Both are true and the second explains the first. The stall boundary lies below the structural limit at those speeds, so the wing simply cannot generate the lift needed to exceed it. The protection applies to a single control input, not to abrupt reversals or combined manoeuvres.
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Assertion (A): A heavily loaded aircraft rides more smoothly through turbulence than a light one.
Reason (R): The gust load factor increment varies inversely with wing loading.
Select the correct answer from the options below.
Answer: C
Both statements are true and the second is the reason for the first. The same gust produces much the same lift increment, but dividing it by a larger weight yields a smaller load factor. It is why a transport barely notices turbulence that throws a light aircraft about.
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Assertion (A): Fuel is retained in the outboard tanks for as long as practicable on many transports.
Reason (R): Mass carried outboard opposes the lift and reduces the root bending moment.
Select the correct answer from the options below.
Answer: D
Both are true and the second explains the first. Inertia relief is worth a real reduction in structural weight, so the fuel management schedule is written with the wing bending in mind as much as the centre of gravity.
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Assertion (A): Gust loads frequently govern the design of a large transport wing.
Reason (R): Transport aircraft are certificated to a manoeuvre limit of only about 2.5 g.
Select the correct answer from the options below.
Answer: A
Both statements are true and the second explains the first. With a modest manoeuvre limit, the gust envelope can reach beyond it at cruise speeds, particularly at light weight. Both envelopes are constructed and the outer boundary at each speed governs.
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Assertion (A): The ground-air-ground cycle is a major contributor to wing fatigue damage.
Reason (R): It reverses the wing bending completely, once per flight.
Select the correct answer from the options below.
Answer: B
Both are true and the second is the reason for the first. A full reversal from ground droop to flight load produces a large stress range, and stress range is what drives crack growth. One such cycle per flight accumulates rapidly over tens of thousands of flights.
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Assertion (A): A flexible swept wing carries a lower root bending moment than a rigid analysis predicts.
Reason (R): Bending of a swept wing twists the outer sections nose-down and sheds load inboard.
Select the correct answer from the options below.
Answer: C
Both statements are true and the second explains the first. The aeroelastic redistribution is worth having, and computing loads on a rigid wing would give an unnecessarily heavy structure, so flexible load distributions are used as a matter of course.
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Assertion (A): The structure must show no detrimental permanent deformation at ultimate load.
Reason (R): Ultimate load is 1.5 times the limit load in civil design.
Select the correct answer from the options below.
Answer: D
The assertion is false and the reason is true. The no-permanent-deformation requirement applies at limit load. At ultimate the structure must merely not fail, and permanent set there is entirely acceptable since the aircraft is not expected to fly again.
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