Where to begin?????
Both Airbus and Boeing will have generally accurate numbers on performance for both the B-787 and A-350 by now. This is not the days of designing the B-707 any more. Yes, the two new airplanes, like the B-707 have and will continue wind tunnel testing.
Both the A-350 and B-787 have been in testing for some time now. Just like the A-380 has been for about 10 years now. The flight testing is simply another phase of testing.
The B-787 and A-350 have and will continue with both wind tunnel testing and computer testing as the performance numbers get refined further. No, this is not some revamped version of Flight Simulator 2006, both Boeing and Airbus actually KNOW what they are doing.
By now, both designs are pretty much down to weight elimination, but maintane full strenght. Just as it is with the A-380, weight will be one of the determinations on if the airplanes are a success or not. It will not be unusual for the first few B-787s and A-350s to show up over weight, from the contract agreements. The A-380 did.
But, that will not be the portion of testing that will make or break these sales deals. The airlines already know these two airplanes will, initally, be over weight. The portion that will effect them the most is the structural loads testing. This is where the A-380 is going to have some problems, as we all know, the wing failure testing did not break at the required 150% of strenght, it only reached 147%, nor did it break where it was predicted to break. That is going to have a significant impact on the airplanes built until a strenghtened design is tested and certified. These airplanes will not be allowed to fly at the designed maximum gross weight. The weight will need to be reduced so that wing strenght cannot be exceeded by the FAA/JAA requirement of 150%. These airplanes will eventually be modified to full strenght, but at the cost of additional weight, at least for the first few airplanes (10 or so).
But, back to the B-787 and A-350. Both the US and European airplane manufactures have a reasonable amount of experience with building composet airplanes. Military fighters have been built with these materials for years. A commerical airplane will never be flown in an abusive and high G enviornment that fighters are. They just fly for more years, hours, and cycles. Commerical airplanes are built to a 2.5 G load factor (thus the required wing strenght of 150%, since the airplane just sitting on the ground, not moving is at 1 G). Fighters, like the F-15, F-16, F-117, Euro-Fighter, and Tornado are built to withstand, up to a 12 G instantanious load factor, and up to a 9 G sustained load factor. These airplane have large amounts of composets in them. In the case of the F-117, it is all composets. Now Airbus and Boeing will just have to learn how to build these composet airplanes in a larger size.
BTW, the $100M discount Airbus is offering to the Russian airlines only amounts to about $5M per airplane, based on a 20 airplane buy. This is not a big discount, unless it is in addition to some other discounts. But, if the Boeing performance numbers are close, and I believe they are, saving $3.5M per year, per airplane will go a long way towards sealing this deal. That is a savings of $70M per airplane over a 20 year life span, when compared to the A-350.