There have been relatively few flight tests conducted over the decades to bring down the costs and risks that hypersonics entails. Managers of each new program try to justify its existence by reaching further than the one before, increasing the risk and cost of failure. Sadly, neither the nation nor the aerospace industry seem willing any longer to countenance failure. And that in itself is a failure of the engineering community, the culture we have created for ourselves and ultimately leadership.
Hypersonics is just the tip of the iceberg. Throughout aerospace, potentially valuable technologies are being held back because of a fear of failure, even at an early stage of R&D. Somehow this industry—essential as it is—has reached a point where there is little or no tolerance for risk. If we are to make progress in hypersonics, then it is time to come to terms with the fact that setbacks will occur. Four X-51s were built for a reason: More flights mean more lessons learned. The last flight failed. So what!
Now it is time to pick ourselves up, resume flight testing and solve the tough problems associated with the development of hypersonics. Fly the remaining X-51, and use it for the purpose for which it was intended: a flying testbed.