A400M - why the props
The simple answer: It replaces aircraft that have props as well - since they were made for tactical missions.
Originally Posted by
VinRouge
you also get a lot of lift off the prop flow meaning smaller wing area which is useful in austere areas and (may be talking garbage here) the energised flow over the leading edge of the wing means you don’t need leading edge slats, which significantly cuts down on complexity of the design.
Also compare the A400M's rather modest flap system to the massive blown flaps that an airlifter with turbofans like the C-17 needs for tactical purposes.
Google "AERODYNAMIC DESIGN OF THE A400M HIGH-LIFT SYSTEM" for a paper written by an Airbus engineer (I'm not yet allowed to post links).
Originally Posted by
tdracer
So, props have better low speed performance (e.g. takeoff), jets have better high speed performance.
Props also have better low-altitude performance and efficiency. One of the A400M's requirements was extended low-altitude flights. Props save fuel, which leaves more weight for the cargo.
Originally Posted by
atakacs
But in any case, is that capability worth 10bn€ (low ball guestimate) in R&D and many years delay in the program ? Wasn't the only issue but clearly engineering those from scratch was a very risky proposition. I don't see the reward to be commensurate, so I guess there were other matters considered...
It was the turn of the millennium. How many utopian dreams were linked to that date? There was a high tech stock bubble, everything seemed possible. France was thinking in "Grands Projets", Airbus developed the A400M AND the A380 in parallel ...