In the aircraft industry, certain key ingredients comprise the cost of aircraft, including aluminum usage and manpower. The Yardstick Board discovered the most expressive measure of aircraft production efficiency was:

Efficiency Index = weights of airframes produced (pounds) / production space (square feet) / month

The Board found that this efficiency averaged about 1.2 lb./sq. ft./month. The productive plant area per laborer was 1.45 square feet, and generally about 81% to 85% of the aircraft plant area was actually productive. It might be possible to incorporate this data into a Europa aircraft production system, basing output on numbers of workers committed to the aircraft industry, airframe plant square footage and the weight of aircraft produced.

The Board discovered other facts, including:

• The average pounds per month per worker was 80 pounds, with average subcontracting of work being 20%.
• U.S. aircraft plants grew more efficient in 1943 and '44 with their productive area increasing to 85% and accounting for the upper end of the 81-85% range.
• In the late 30s and early 40s some countries, such as the Low Countries, Yugoslavia, and even Germany to some extent, built aircraft almost by hand before the initiation of mass production. In these nations, this space efficiency could drop as low as 70%.

Weight is a key factor. Britain and Germany are often compared in aircraft production figures. For example, in 1939 Great Britain produced 15,000 aircraft and Germany 10,200 aircraft. The structural weight of the output was the same, however, because German production was heavily weighted toward bombers. Production in the U. K. peaked in '43 at just over 26,000 aircraft, at which point annual German production was at 25,200, yet the weight of aircraft produced by Britain was then 25% higher than Germany's.

By 1944, German production had climbed in raw numbers to 40,000 to the UK 26,500, but this change was primarily due to product mix. Germany was then producing mostly fighters, while the British were now emphasizing heavy bombers.

Simple bean counting won't be enough to reflect reality. Heavier aircraft consume more raw materials, more manpower, and more production floor space. Production floor space is a factor that might be easy to mistakenly ignore. Determining individual space requirements per aircraft type by multiplying length times wingspan to find net area, we get:

Spitfire 1110 sq. ft.
Blenheim 2,464 sq. ft.
Lancaster 7,140 sq. ft.

Building a group of Lancasters therefore takes more than six times as much space as does a group of Spitfires.

There are other factors to be considered as well. For example, floor space for fighters was less efficient because of the increased demand for machine shop and process work required for modem fighters. But hopefully, the above calculations can provide a formula for determining national aircraft building capacity in the Europa economic model.