I’m up at ArmstrongDryden today, getting an overview on NASA’s low-boom supersonics program. The focus seems to be entirely on noise reduction, but I’ll be interested in hearing what they’re doing to reduce wave drag.
Kevin McCarthy is here (I spoke to him briefly about some space regulatory issues), but he hasn’t spoken.
[Update a few minutes later
The QueSST aircraft has an L/D of 6 at Mach 1.4, in response to a question from me. In response to my question about what they’re doing about wave drag, the answer is “that’s a question for another day.” Peter Cohen from Langley actually shouted that from the back of the room, to my amusement.
…but I’ll be interested in hearing what they’re doing to reduce wave drag.
My money’s on reducing the thickness to chord ratio. But I’m old school.
“That is not a question for today.” — Peter Cohen from Langley. At lunch interviews, they conceded that L/D remains a big problem.
The SR-71 had an L/D of “slightly more than 6” at Mach 3, and the Concorde 7.3 at Mach 2. ( http://aero-comlab.stanford.edu/Papers/machone.pdf) Now, it’s true that the drag coefficient peaks around M=1.1, so maybe M=1.4 isn’t a good reference. But if that’s also the design point, they’re really not doing things right.
They were pretty clear that this was a single-purpose X-plane designed to test out the acoustic concepts within a budget, not to demonstrate efficiency.