Originally Posted by
Trumpet_trousers
Where to start.....
.... wrong.
....The customer specified/demanded the choice of powerplant.
Other than a reported CBR 6 capability for the A400, what tactical capabilities does the A400 have that the C-17 does not?
The A400 started out as FIMA (Future International Military Airlifter) and the FIMA group included Lockheed. It was a slightly enlarged C-130/C-160 and intended as a C-130/C-160 replacement. That program went nowhere. Lockheed pulled out and developed the C-130J on their own. The European consortium did not want to compete with the J, so they proposed a bigger airplane that became known as FLA (Future Large Aircraft.) There were multiple versions of FLA and the first iterations had turbofans. But they did not want to appear to be competing with C-17, so the consortium went with a turboprop and proposed that to the various governments. The government "specification/demand" for a turboprop was the FLA consortium's own doing, as the governments specified what the consortium offered. The point being that the turboprop "requirement" locked out C-17. Eventually Airbus took over the FLA consortium and by that time, the turboprops were well established and Airbus, for whatever reason, did not want to switch to turbofans. Speculation was that SNECMA had the political clout to keep the program sold to the governments since they were developing an engine based on the M88 core. But that core was too heavy and not efficient enough, so they had to go with a clean sheet design, which cost even more to develop. But turboprops over turbofans added nothing to performance (indeed in some areas they degrade performance) but they were perceived as effective in locking out C-17.
The thing about the TP400 is that it's the most powerful single-rotation propulsion system ever developed. There are more powerful turboprops, but they all have two contra-rotating prop discs. A400 is in uncharted territory which is proving to be rather problematic and in hindsight may be a bad choice. But that's what happens when politics drive engineering decisions.