Conceptual Design Process Questions and Answers

Answer: C

Correct answer: Broad and rough, then narrow and exact

Conceptual design surveys a wide field of configurations with fast, approximate methods, because the object is to choose well rather than to compute precisely. As the field narrows the methods deepen, until detail design treats a single configuration exactly. The reverse order is impossible: high-fidelity analysis of every candidate would exhaust the schedule before the configuration was chosen, and precision applied to the wrong concept buys nothing.

Answer: D

Conceptual design chooses among configurations and sizes the chosen one against the requirements. Every structural, aerodynamic and systems question that follows is answered within the configuration this phase settles.

Answer: A

Empty weight fraction, cabin volume and structural arrangement all differ so much from a tube and wing that the correlations offer no guidance. Physics-based estimation is required, which is slower and carries more uncertainty.

Answer: B

A configuration outside all experience carries estimates nobody can underwrite with confidence, and a programme costing billions is rarely committed on that basis. The technical merit may be real and still insufficient.

Answer: C

The strut carries part of the bending, so the wing can be made more slender without the weight penalty that a cantilever of the same span would incur. The strut's own drag and the interference at its junctions are the costs.

Answer: D

Computing \( 82 \times 1.12 = 91.8 \) t, which exceeds the conventional design's estimate. The advantage is real at the central estimate but is not established once the uncertainty is carried, which is exactly the difficulty such configurations face.

Answer: A

Both are true and the second explains the first. A central estimate showing an advantage is not enough when the uncertainty band overlaps the conventional answer, and multi-billion programmes are not committed on overlapping bands.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 are correct and together describe the real difficulty of unconventional work: the statistical shortcut is unavailable, and the physics-based estimate that replaces it is less certain than a regression would have been for a conventional aircraft. Statement 3 is wrong. Investment follows commercial and risk judgements as much as technical merit, and many technically sound unconventional configurations have never been funded.

Answer: C

Correct answer: It eliminates the wing’s bending moment entirely

A strut does not eliminate the bending moment; it provides an intermediate support that greatly reduces the root bending moment, which is a different and more modest claim. The genuine attractions are the other three: for a given structural weight the wing can be given a much higher aspect ratio, the greater span cuts induced drag, and the combination offers a route to significantly lower fuel burn - at the cost of the strut’s own interference drag and its junction design.

Answer: D

Correct answer: Choosing well beats analysing precisely

The whole shape of conceptual design follows from this. The configuration chosen here commits most of the lifetime cost, and no amount of later precision can recover a poor choice; conversely a good configuration analysed roughly will still be a good aircraft once the analysis deepens. Hence fast approximate methods applied across many candidates, assumptions recorded so they can be tested, and the fidelity reserved for the phases in which the choice is already made.