Augustine's 16th Law

Augustine's Laws are a collection of tips from a decades of government contracting. One of them observed that the price of fighter aircraft was growing faster than the US defense budget:

Law Number XVI: In the year 2054, the entire defense budget will purchase just one aircraft. This aircraft will have to be shared by the Air Force and Navy 3-1/2 days each per week except for leap year, when it will be made available to the Marines for the extra day.

This R script attempts to verify this law.

• FDEX
• GDP
• Combat aircraft prices

Some concerns about the data sets:

• Are they all nominal prices or is there a mix of real (inflation adjusted) and nominal?
• How accurate are the prices? Wikipedia F-35 disagrees, for instance.
• What happens when FDEX > GDP?
• Does it make sense to do linear extrapolation on log of nominal prices?
• Is it true that everything looks linear on a log/log scale?