Dennis R. Jenkins' X-15: EXTENDING THE FRONTIERS OF FLIGHT

A book review by Dennis D. McDonald

On paper this book goes for 700+ pages; I read the Kindle edition. Despite the length there’s never a dull moment.

I grew up in the era when the X-15 was active. I remember seeing it in the news and  the records it seemed to break on a regular basis.  I’ve always been keenly interested in post-World War II aeronautical history and this is the best, by far, of all the books I’ve read about the period.

Things that I found especially interesting:

1. The role that wind tunnels played in testing the development of the X-15’s shape.
2. How simulation emerged as a key element in flight planning and pilot training.
3. How much work and expense was involved in planning and preparing flight areas equipped with ample emergency landing sites, tracking systems, and telemetry.
4. The awkward nature of pre-digital computing and reliance on analog computing and recording devices. 
5. Emergence of semi-automated “fly by wire” control systems that integrated traditional aircraft control surfaces with reaction control systems used for control while outside the atmosphere.
6. The amazing extremes of friction-induced surface temperature that had to be managed.
7. The trials and tribulations — and cost overruns — involved in developing the “throttleable” XLR99 rocket engine.
8. The organizational dynamics and politics that regularly cropped up between the U.S. Air Force and NASA.
9. The effort involved in integrating the wildly untested “scramjet” technology with the X-15 program as it approached maturity.
10. How the Edwards flight test facility evolved along with the X-15 program.
11. The challenges in developing effective heat-ablation materials to coat the aircraft.
12. The use of teletypes in support of primitive teleconferencing.
13. Throughout, the key role played by the pilots in the success of every mission.
14. The significant absence of women from this story.

Overall the book doesn’t seem to pull punches when discussing problems and lays out in great detail the engineering challenges and solutions addressed by the X-15 program. In fact, sometimes the footnotes and their links are as interesting as the text itself. 

Frequent mention is made of how useful certain performance data generated by the program were to development of the Space Shuttle program and its orbiter, but I suspect the X-15 program would still be important even if that weren’t true. 

You  have to be interested in engineering and technology to appreciate this book and its detail. So many aircraft books emphasize operational or military applications while skimping on the details that engender an appreciation of the huge number of challenges involved in aircraft development. This one really delivers the goods.

Review copyright (c) 2013 by Dennis D. McDonald