Conceptual Design Process Questions and Answers

Answer: A

Conceptual design explores configurations and sizes them, preliminary design refines the chosen one and settles the major structure and systems, and detail design produces the drawings and data needed to manufacture. Each phase narrows the options and deepens the fidelity.

Answer: B

The aim is to explore the space and choose well, not to be precise about any one option. Methods are deliberately fast and approximate, since a wrong choice made accurately is far worse than a right choice made roughly.

Answer: C

A heavier aircraft needs more fuel, and carrying more fuel makes it heavier still. Guessing a take-off weight, computing the fuel and empty weight fractions and recomputing until the estimate settles is the standard resolution.

Answer: D

Correct answer: Statistics from existing aircraft

At the start of conceptual design almost nothing has been defined, so there is no structure to analyse and no shape to test. What is available is the record of aircraft already built, from which empty weight fraction correlates well against take-off weight within a class. A regression on that data gives a usable first estimate in minutes. Finite element analysis, wind tunnel work and part-by-part accounting all require a design that does not yet exist, and they arrive in later phases as the definition firms up.

Answer: A

Regressions describe the aircraft that were built, not the ones that could be. A blended wing body or a strut-braced wing sits outside the sample and needs physics-based estimation instead, which is slower and less certain.

Answer: B

These choices interact strongly and are largely irreversible once detail design begins. A high wing suits a freighter and a low wing a passenger transport, and each carries consequences for gear, engines and structure.

Answer: C

Loading vehicles at truck-bed height and keeping the propellers or nacelles away from unprepared surfaces both follow from the wing position. The penalties are a heavier wing carry-through and an undercarriage that must be stowed in fuselage fairings.

Answer: D

Correct answer: Bending relief, and easy access

An engine hung ahead of and below the wing puts its weight outboard, so in flight its inertia acts downward against the upward lift and reduces the bending moment the wing root must carry - bending relief, worth real structural weight. The pod is also reachable from a stand, which shortens maintenance and allows an engine change without disturbing the airframe. It needs a pylon rather than eliminating one, and it does not shorten the span.

Answer: A

Correct answer: Disciplines are revisited with more fidelity

The design wheel represents the process as a spiral through aerodynamics, weights, propulsion, structures, performance and cost, returning to each discipline on every turn but at a higher level of detail than before. The point is that a single pass is impossible: a weight estimate changes the wing area, which changes the drag, which changes the fuel, which changes the weight again. The design converges by circling, and it is complete when a turn produces no significant change.

Answer: B

Optimising each discipline in isolation gives a worse aircraft than a compromise found across all of them together, since the interactions dominate. The difficulty is the cost of evaluating the coupled system often enough to search it.