Design Requirements and Specifications Questions and Answers

Answer: C

Correct answer: 0.27

Both engines contribute, so

A figure near 0.27 is typical of a twin-engined transport, which must be able to climb away on one engine after failure at the critical point. A fighter runs above 1.0 and can accelerate vertically; the difference in the number expresses the whole difference in mission.

Answer: D

Correct answer: 10 per cent

The shortfall is taken on the requirement:

Ten per cent of range is not a detail: it may put a city pair out of reach and remove a large part of the market case. The response is either to find the range - through weight, drag or fuel capacity - or to renegotiate the requirement with the customer before the design is frozen.

Answer: A

Correct answer: 2 m per side

The span must be reduced by 4 m in total, and a wing folds symmetrically:

Taking the whole 4 m from one side would give an asymmetric aircraft on the ground and is not what is meant. Two metres per side is a modest fold, which keeps the hinge outboard where the loads and the structural depth are small.

Answer: B

Correct answer: 42.75 t

The margin is held back from the teams, so they work to a target below the true limit:

The 2.25 t difference is the programme’s reserve against the weight growth that detail design almost always brings. Giving the teams the full 45 t would consume the margin before design began, leaving nothing for the surprises.

Answer: C

Correct answer: 7.3

The figure of merit is the weighted sum:

The weights sum to unity, so the result is on the same scale as the individual scores and can be compared directly with another option’s. Adding the raw scores instead, giving 28, ignores the weighting entirely and would treat the least important criterion as equal to the most.

Answer: D

Correct answer: 7.5

Applying the same weights to the second option,

so this option edges out the first, 7.5 against 7.3, despite scoring lower on the most heavily weighted criterion. A margin that narrow is exactly the case for a sensitivity check: a small change in the weights would reverse the ranking, so the decision should not rest on the total alone.

Answer: A

Correct answer: 20.8 kg

Divide the fuel by passengers and by thousands of kilometres:

This normalised figure is how transports of different size and range are compared, and it has fallen from around 50 kg for early jets to below 20 for the most efficient current aircraft. It is also directly proportional to the carbon emitted per passenger kilometre.

Answer: B

Correct answer: 3750 tonnes of fuel

Five per cent of the 25 t burnt on each flight is 1.25 t, and over 3000 flights,

A few per cent of fuel burn, which sounds like a detail in a design review, is thousands of tonnes and many millions of currency units across a fleet’s life. This arithmetic is why airlines will pay for a small aerodynamic or engine improvement.

Answer: C

Correct answer: Not verifiable; adequate is undefined

A requirement must be capable of being closed by a test, an analysis, an inspection or a demonstration, and that means it needs a number, a condition and a tolerance - for instance, 6000 km with 20 t of payload in ISA conditions. “Adequate” leaves the judgement open, so no one can say whether the aircraft complies, and the disagreement surfaces at the worst possible moment. Customer agreement does not repair the defect; it merely postpones it.

Answer: D

Correct answer: 300 kg

The additions accumulate:

Each individual 20 kg seemed negligible, which is precisely how requirements creep works. And 300 kg of equipment is not 300 kg on the aircraft: with a growth factor of two or three it becomes 600 to 900 kg of take-off weight once the structure and fuel to carry it are counted.