You forgot maintenance for older aircraft like C-5a and C-5b??? I would go with more C-17 but keep the old C-5b for heavy lift operations. And use ships as much as possible. Of course I am no expert on this stuff

where do you get 150t for the a380? I thought is it was nowhere near that.....

You're also missing the fact that the 747 and A-380 cannot carry outsize cargo (try packing a M939 5-ton truck in a 747-400 and you'll see where the problems start). On top of that the A380 actually doesn't have a high enough clearance for some vehicles for its cargo variant and I believe the floor capacity is rated at something along the lines of 7 to 7.3 psi. The 747-400 freighters have an actually higher loading capacity at about 9.9psi (this difference is much higher when you get pure military transports who are designed to carry the dense and heavy milspec equipment like tanks and whatnot). Thats a key difference between civvie freighters and military variants. Once thats outta the way THEN you can start comparing on a cost and maintenance basis per craft.

PPR wrote: "Since most air cargo is not going to be M-1's I suspect more small, cheap aircraft would be more practical." To some extent this is true, but the smaller transports are slower and don't have the same range as larger aircraft like the C-17. There are many factors that go in to determining the proper mix of light and heavy transports. The only way to get a reasonably accurate picture is to model common usage patterns with different mixes and aircraft. And any time you talk government purchases, you can't ignore political factors.

The maximum load for a A-380F is 330,695 lbs (actually a bit more than 150 tons). However, there have been production problems with the A-380, so I'm not even sure that it will do that. I have to say though that probably our best investment in terms of air transport is the Civil Reserve Air Fleet in which our military promises business to civilian air carriers in exchange for the ability to basically "draft" the aircraft into service in a time of war. At a cost of about $485 million a year (about the cost of 2 large modern jets), the military gains access to about 1100 civilian jets (including 785 capable of international travel). http://www.af.mil/factsheets/factsheet.asp?id=173

"The maximum load for a A-380F is 330,695 lbs (actually a bit more than 150 tons)." Thats 150.000729 metric tons (or tonnes) or 165 short tons (US). Depends on what metric ya use. Usually when it comes to payload it tends to be referred to in metric weight rather than US or British weights (hence short ton vs long ton).

The required mix is interesting the CRF fleet is great for simple transport needs to improved fields. The C-17 can do well with a good sized load where short fields are required. For the heavy lifting, you can't beat the C-5, especially after their modernization to fix their lousy reliability problems and finally the C-130J fills a very nice niche with the short rugged capability of a tactical transport, but with the range of a strategic plane.