To be fair though, the A400M is billed a competitor to the C-130J rather than the C-17, so you could swap out C-17 in your post with A400M to get the same argument as to how the A400M is much better than the C-130J.
Excellent point. On the other hand C-17 was billed as a competitor to both the C-130
and the C-5. There was no A400. C-17 was designed to land at 90+% of the airfields a C-130 could land on, and deliver a C-5 dimensional payload, and nearly a C-5 mass payload to the C-130 runway, at strategic range. It's what USAF called
direct delivery. Instead of delivering large/heavy loads from a large base to another large base in or near the theater, where the load was broken down for further forwarding using C-130 and if oversize by driving overland, the C-17 could deliver literally any combat equipment in the US Army inventory (including fully armed M1 tanks which the C-5 could
not carry) over a strategic range directly into an austere forward base in the theater.
Is it right that they have similar short austere field performance? Genuine question.
Short field performance is similar in that the takeoff distance with little or no load is the same for both (2500 ft) and the landing performance with a 60,000 lb load is also the same (under 2800 ft). With a full assault load the C-17 needs more runway than A400M (3100 ft vs 2800 ft). C-17 also needs stronger runways than A400M, as you said CBR 12 vs CBR 6. But CBR 6 is about equivalent to a plowed field and while very impressive, does not sound to me like a likely real world tasking. To me, if a force needs to go into a plowed field, they'd use helicopters, not a fixed wing airlifter. But I don't know how the British Army operates, so maybe a bad assumption. By comparison the C-27 also has CBR 6, but its 1/4 the size of A400 and in US service never used that capability.
Also C-17 CBR 12 is for 12 passes (or four sorties, where each sortie requires one landing pass, one back taxi pass, and one take off pass. This assumes landing and takeoff into the wind in the same direction. And like tubro props with reversible propellers, C-17 can back under its own power, in C-17 case at MTOGW up a 2% slope.) A400M CBR 6 is for 24 passes. Don't know how many passes at CBR 12. On the other hand C-17 delivers more payload per sortie, so fewer sorties (and thus passes) are required. There are too many variables for a head to head comparison.
Don't get me wrong, the A400 is an impressive airplane for what it was designed to do. I just don't understand its design requirements. C-17 design requirements were based on the following US Army loads:
payload weight: fully armed M1 tank with supporting fuel truck
payload width: two HEMMT 8x8 heavy trucks side-by-side
payload height: AH-64 Apache helo with rotor mast installed under the wing and CH-53 with rotor mast removed behind the wing
payload length: 18 463L pallets.
And all the above must be deliverable over strategic range into an austere, unpaved field of 3500 ft or less.
There were of course many other requirements but the above drove the wing size/loading, fuel capacity, cargo floor width and length, cargo floor strength, cargo compartment height, installed thrust, and high lift systems. I've asked many times but no one seems to know what the requirements drivers were for the A400. Can anyone help out there? What is the A400 design trying to accomplish other than carrying twice a C-130 payload over a slightly greater range? It clearly does that and seems to do it well (at least so far), but what else was it designed to do?