Loads on Aircraft Structures Questions and Answers

Answer: C

The first two are correct. The third has it backwards: below the corner speed the wing stalls first and protects the structure, while above it full deflection would exceed the limit. That is why turbulence penetration speeds are set at or below VA.

Answer: D

The first two are correct and are the two largest contributors to the spectrum. The third confuses the two disciplines: fatigue is driven by the accumulation of many cycles, not by one extreme event, which is what static strength analysis addresses.

Answer: A

The first two are correct. The third is false and is what makes the relationship so useful: the load factor in a level turn depends on bank angle alone, and is the same for a glider and a heavy transport at the same bank.

Answer: B

These four speeds bound the flight envelope from left to right. The margin between VC and VD is prescribed so that an inadvertent overspeed does not immediately take the aircraft beyond the condition it was designed for.

Answer: C

Correct answer: A-2, B-1, C-4, D-3

The four categories rise in severity with the manoeuvres each is expected to perform: a transport is limited to 2.5 g, a normal light aeroplane to 3.8, a utility aeroplane cleared for spins and steep turns to 4.4, and an aerobatic aeroplane to 6.0. The transport figure is the lowest because passenger aircraft are never intentionally manoeuvred hard.

Answer: D

Different parts of an airframe are sized by quite different cases, which is why load analysis produces a family of conditions rather than a single worst case. A structure critical in one case may have ample margin in every other.

Answer: A

Correct answer: A-2, B-1, C-4, D-3

Four terms from four different parts of the analysis. The load factor is lift over weight. Inertia relief is the bending reduction that comes from mass distributed along the wing opposing the lift. The gust alleviation factor corrects the idealised sharp-edged gust for the gradual build-up of a real one. And the margin of safety is allowable over applied stress, less one, so that zero means exactly adequate.

Answer: B

The spectrum a transport is assessed against is dominated by the two once-per-flight cycles and filled in by the gust content. Ultimate load, by contrast, is a strength requirement that the aircraft is never expected to meet in service at all.

Answer: C

Correct answer: Braked rolling over a rough runway

Braking and runway roughness are ground loads: the aircraft is on its wheels, and the load path runs through the undercarriage. The other three are all flight cases - a gust, a rudder reversal and a symmetric pull-up all load the airframe aerodynamically with the wheels off the ground.

Answer: D

Correct answer: Above it the wing stalls before the structural limit is reached

That has the comparison the wrong way round. Below VA a full control deflection stalls the wing before the limit load factor is reached, which is what makes the manoeuvre safe; above VA the structural limit arrives first, so full deflection can break the aeroplane. The other three statements, including \( V_A = V_s\sqrt{n} \), are correct.