They still have about 10x to go to hit the VTOL rocket record of 3140 meters [1], which they seem to be aiming for, so I assume some more doubling-or-greater is

They still have about 10x to go to hit the VTOL rocket record of 3140 meters [1], which they seem to be aiming for, so I assume some more doubling-or-greater is in the works. [1] http://www.hq.nasa.gov/pao/History/x-33/dc-xa.htm http://www.hq.nasa.gov/pao/History/x-33/dc-xa.htm