Fuselage Design and Layout Questions and Answers

Answer: C

Certification requires the full complement to be evacuated within ninety seconds using half the exits, and exit type and number follow from the seat count. A stretch that adds seats frequently forces an additional exit pair.

Answer: D

Carrying the box straight through lets the left and right wing bending moments react against each other rather than being fed into the fuselage. Interrupting it would demand enormous fittings and a heavy carry-through structure.

Answer: A

Correct answer: Intruding on floor or hold space

The wing centre section must be carried continuously through the fuselage so the bending moment passes across without a joint, and that box occupies real volume.

On a low-wing transport it sits below the cabin floor and eats into the hold, which is why the hold is divided into forward and aft compartments with the centre section between. On a high-wing aircraft it crosses above the cabin instead. Width and pressurisation are unaffected; it is depth that is lost.

Answer: B

Putting the box under the floor keeps the cabin unobstructed and the hold usable, and it puts the gear where it can retract into the wing root. Freighters take the opposite view, since a low floor matters more to them than hold depth.

Answer: C

Correct answer: The repeat distance between rows

Seat pitch is the distance from a point on one seat to the same point on the next, so it includes the seat's own thickness as well as the legroom.

That is why a pitch reduction costs less legroom than it appears to: a thinner seat back recovers part of it. Pitch multiplied by the number of rows gives the cabin length required, which is the calculation behind every stretch and every densification decision.

Answer: D

Stretching adds weight and moves the centre of gravity, so the carry-through, gear and attachment structure must be able to absorb it. Designing the first variant slightly strong there is far cheaper than redesigning later.

Answer: A

A parallel middle section can be lengthened by inserting plugs fore and aft of the wing, which is how nearly every family stretch is achieved. It also makes frames, panels and tooling repeatable rather than each one unique.

Answer: B

Containers and pallets have to be got in and moved along the deck, so a large door, roller tracks and locks, and a floor designed for concentrated loads are all needed. Converted passenger aircraft receive exactly these modifications.

Answer: C

Correct answer: Cockpit view angles and radar

Two requirements shape the nose. The crew must see the required angles down and to the sides for approach and taxiing, which fixes the windscreen geometry and the profile ahead of it.

And the weather radar needs an unobstructed radome of adequate diameter and a shape transparent to it. Aerodynamics refines the result rather than driving it, and the cabin, undercarriage and wetted area are all settled elsewhere.

Answer: D

Correct answer: Wetted area and differential

Two things dominate. Wetted area sets how much skin, stringer and frame there is to build, so weight grows with the surface rather than with the seat count directly.

Pressure differential sets how thick that skin and how heavy those frames must be, since hoop stress is proportional to it. Seat count matters only through the length it demands, and cruise Mach and wing aspect ratio affect other parts of the aircraft.