Cost Estimation in Aircraft Design Questions and Answers

Answer: A

Correct answer: Both Statement I and Statement II are correct

Both statements are correct, and the second is simply the first stated concretely. Discounting converts future sums to present value by dividing by \( (1+r)^n \), so the further away a cost lies the less weight it carries in today's decision.

At 7 per cent, a sum twenty years away is worth about a quarter of its face value. This has a real consequence for life cycle cost analysis: it systematically favours designs with low acquisition cost over those with low operating cost, and the discount rate chosen can decide a trade study on its own.

Answer: B

Correct answer: Both Statement I and Statement II are correct

Both statements are correct and the second explains the first. In the parametric relations, engineering hours, tooling hours and manufacturing hours are each fitted as a power of empty weight - so a single variable drives all three of the largest cost elements at once.

That makes empty weight the most influential design variable in cost estimation, and it reinforces its influence on operating cost through fuel burn. Weight reduction is therefore the design change that pays on both sides of the life cycle, which is why so much effort is devoted to it.

Answer: C

Correct answer: 2, 1, 4, 3

The elements follow the programme's life. Research, development, test and evaluation (2) comes first, before any aircraft is delivered. Production (1) follows, and overlaps the early operating period as the run continues.

Operation and support (4) begins with the first delivery and continues for decades, accumulating the largest share of the total. Disposal (3) comes last, at retirement - a small element for a transport, but a substantial one for aircraft with hazardous materials or classified equipment to be dealt with.

Answer: D

Correct answer: 2, 4, 1, 3

Each step supplies the input to the next. Empty weight and performance are estimated from the design (2), since they are what the cost relations take as arguments. Engineering, tooling and manufacturing hours are then computed from them (4).

The learning curve is applied across the production run (1) to give the cost of each successive aircraft rather than of a notional first unit. Finally the development cost is amortised over the planned quantity (3) and added, giving the cost each aircraft must recover.

Answer: A

Correct answer: 2, 4, 1, 3

In ascending order of share: disposal (2) is smallest, usually a small percentage of the total for a transport. Research and development (4) comes next - large in absolute terms but spread over the whole production run.

Production (1) is larger still, and operation and support (3) is the largest of all, since fuel, crew, maintenance and fees accumulate over twenty-five or thirty years of service. That ordering is the central fact of life cycle costing, and the reason design trades favour operating economy over acquisition price.

Answer: B

The saving works through two separate routes at once, which is why weight discipline is worth so much more than either effect alone would suggest. The chain runs outward from a single design decision to the whole life cycle cost.

Answer: C

Money goes out long before any comes in, the first aircraft are the most expensive to build, and only after the run is well advanced does the programme recover its development. Many technically fine aircraft never reach the last step.

Answer: D

Correct answer: Only three

Three pairs are right. Depreciation is fixed, accruing with the calendar whether the aircraft flies or not; fuel is variable, consumed only in flight; and landing fees are variable, charged per movement.

The fourth is wrong. Insurance is a fixed cost - the hull and liability premium is set annually on the aircraft's value and the operator's record, and it is payable whether the aircraft flies a thousand hours or none. Applying the test - does it accrue if the aircraft stays on the ground? - settles each case.

Answer: A

The first three name their drivers correctly. Fuel cost follows the mission, the aerodynamic efficiency and the fuel price as well as the weight, and no single design variable governs it in the way weight governs the others.

Answer: B

Correct answer: Only three

Three pairs are right. Life cycle cost is the total from concept to disposal; breakeven quantity is the number of units at which cumulative revenue meets cumulative cost; and a learning curve expresses the cost reduction per doubling of cumulative output.

The fourth is wrong. Direct operating cost covers only what it takes to fly the aircraft - fuel, crew, maintenance, depreciation, insurance, fees - and specifically excludes administration and marketing, which are indirect. The exclusion is what makes it a fair basis for comparing aircraft types.