Originally Posted by
Ed Harley
What's the deal with the wing? How is it that Douglas would build the same wing for 50 years with little improvement? I'm guessing that if Douglas were still around today, they would still be building the same wing that poops out once you get into the low 30's. It also seems like an airplane that is not stall friendly. Seems like if you were to stall it below 10,000' on a clean wing, you're as good as dead.
There must be some advantage to this wing though because the design was apparently bought by the Chinese a few years ago.
My insights into Douglas came from a number of friends who worked there in flight test. The Company's reluctance to spend money on engineering, only to spend a fortune on fixing the finished product can still be seen today in the 787 program (post merger with Douglas).
There is no advantage to the wing other than the tooling was already built. Douglas had hoped Chinese production would result in a huge MD8X/90 order from the Chinese, but that never happened. The Chinese kept the fuselage jigs and eventually had the Russians design a better wing for their ARJ-21.
The DC9 wing was OK for what it was designed to do, when it was designed to do it. Today it is a near textbook example of every error that could be made as it approaches trans sonic speeds. Mach airflow separation begins at about M 0.745. Drag increases exponentially beyond that point. Still amazing something designed for a 80,000 pound jet was being spun up to somewhere around 174,000 pounds during development of a MD90 successor.
Part of the MD11's problem was Douglas reluctance to design a new wing ....