I was about to comment on what skunk works did with the U2 and the SR71, but then i saw that virgin wanted to go at 4x the service ceiling of these two planes.

I was about to comment on what skunk works did with the U2 and the SR71, but then i saw that virgin wanted to go at 4x the service ceiling of these two planes. These two planes already had several very hard problems to solve (as related in https://www.goodreads.com/book/show/101438.Skunk_Works https://www.goodreads.com/book/show/101438.Skunk_Works ), i can't begin to imagine the bigger problems to get higher.