Fig. 6. Mature industry: Production rate curve. recurring costs at this point are intimately mixed with nonrecurring costs. The cost analyst therefore uses an accounting artifice: the theoretical first unit cost. This is determined by extrapolating backwards along a historical experience learning curve, i.e., using cost records from production program, to unit #1. Thus the term “theoretical.” The theoretical (learning curve) costs of the first few units are subtracted from the amalgam of nonrecurring and recurring costs and the balance is accounted as DDT&E. Cost models such as the Boeing PCM then resynthesize the cost picture for a new program by forecasting DDT&E and theoretical first unit (TFU) costs. Learning curves as experienced on airplane and missile programs reflect three phenomena: • Mechanical/technical job familiarization, dominant through perhaps unit #10; • Production plan shakedown, eliminating: o excessive change activity o out-of-sequence or traveled work o parts and equipment logistics foul-ups — dominant factors from unit #10 to perhaps unit #1000; • Production plan improvement, dominant beyond unit #1000 Learning curve slopes typically range from 0.9 for rocket engines and low- productionrate avionics, through 0.85 to 0.88 for structures and mechanical subsystems. If high production rates are planned, it is frequently appropriate to consider production rate factors. These are related to production plan improvement and reflect the influence of automation. Production rate slopes on the order of 70% have been experienced in a variety of industries, as suggested by Fig. 6. This largely explains why consumer electronic products cost far less than 1% of a spacecraft electronics unit of equivalent sophistication. Production rate factors and learning curve factors
RkJQdWJsaXNoZXIy MTU5NjU0Mg==