One of the major differences between military aircraft is the amount of money it costs to keep them operational. This is usually given in cost per flight hour (for fuels, spare parts and maintenance) or annual operating costs (including upgrades). The following data is for 2014. One of the little known aspects of this is that the most expensive U.S. Air Force aircraft to operate is not the twenty B-2 stealth bombers (which costs $129,000 per flight hour for 5,984 hours and $39 million each per year) but the four E-4 aircraft that flew a total of 1,577 hours. These are 747 transports converted into flying command posts, to be used during a nuclear war. Each costs $155,000 per flight hour or $63 million each per year.
The cheapest combat aircraft are the 152 Predator and 151 Reaper UAVs (Unmanned Aerial Vehicles). The Predators flew 1,274 hours (on average) each and cost $4,000 per flight hour and $5.2 million a year to operate. For the larger (and newer) Reaper the numbers were 1,233 hours, $3,300 and $4.1 million.
The most numerous combat aircraft, the 971 F-16s flew 200 hours each and cost $21,500 and $4.4 million. For the newest fighter, the 187 F-22s flew 161 hours each and the costs were $53,000 and $9.4 million. The hardest working aircraft, the 222 C-17 transports cost $21,000 and $21 million.
The 37 F-35s, which is just entering service, flew 102 hours each and cost $68,000 and $10 million. One of the oldest combat aircraft, the 298 A-10s, were also among the cheapest. They flew 280 hours each and cost $19,000 and $5.4 million.