If you've ever been interested in the finer points of the air war over Europe in World War II, such as why it was so important to install a Rolls-Royce Merlin engine in the North American Mustang, or why the Germans could not make use of really high-test gasoline, this is the book for you. A lot of these issues are not unknown in the existing literature, but the author brings the experience and knowledge of a one-time race-car power-plant engineer to the conversation, and a bit of the competitive passion of Formula 1 too. This is not to mention that this book is a tribute to modern archival research techniques, as Douglas apparently digitized all the available stenographic minutes from the conferences of the German Air Ministry so that they were in machine-readable form, and turned lose the computer to zero in on more relevant portions. As someone who had a career as an archivist at the U.S. National Archives I'm a little bit in awe at the effort this took. There is very little that I can mark down this book for, apart from some choices in book lay-out that don't contribute to readability; Douglas himself writes well, and makes a very complicated topic pretty comprehensible. ( )

This is a remarkable book for several reasons. First, it's the first coherent account of World War II aircraft piston engine development that I have been able to read. Second, it is one of the few books I have read that was written by an engineer that is actually readable. And third, the author's observations and conclusions reach beyond engineering design and manufacturing practices into the realm of political-military strategy and the functioning of corporate and governmental bureaucracies.

Calum Douglas is a British designer of automotive racing engines who chose to explore the World War II origins of those engines. He was able to turn an engineering job in Germany into a historical research opportunity, gaining access to primary source records about German wartime aero engine development that later grew into similar but smaller efforts in Great Britain, United States, and Italy.

The result was this 479 page book, published in 2020 by Tempest Books. The author begins with a Preface, some notes concerning air intelligence as practiced by the British, Germans, and Americans, a Prologue, ten numbered chapters, a list of archives used by the author in preparing this volume, a brief appendix explaining acronyms and nomenclature, end notes, and an index.

The book is arranged chronologically, with Chapter 1 detailing the racing origins of World War II aircraft engines in the Schneider Cup races and Chapter 2 highlighting the rapidly changing aero engine technologies of the 1930's. Chapters 3 through 9 detail each of the war years, and Chapter 10 provides a good summation of the book. With the exception of Chapter 1, each chapter is subdivided by country, the author detailing engine developments peculiar to Great Britain, German, the United States, and Italy. As the author confesses up front in the Preface, Italy gets short shrift in this work due to a lack of primary source material in that country. Also mentioned in the Preface is the author's decision to leave the details of the U.S. side of the secret horsepower race to the two works on specific U.S. engines: Daniel Whitney's "Vees for Victory" about the Allison V-1710 and Graham White's "R-2800: Pratt and Whitney's Dependable Masaterpiece".

As a consequence of these decisions "The Secret Horsepower Race" is largely a story about Rolls-Royce versus BMW, Daimler-Benz, and Junkers. It is also a story about the British Ministry of Aircraft Production versus the German Reichsluftministerium. Even in the U.S. sections of the various chapters, Douglas largely focuses on Packard's issues in quantity production of their V-1650 version of the Merlin instead of the native V-1710 and R-2800 engines. Rolls-Royce's slow but steady improvement clearly proved a superior process to the German genius but impractical engine innovations that have, ironically, been associated with the modern automotive racing engines with which the author is most familiar. At the government level, the British MAP's "hands off" approach to British manufacturers clear proved superior to the RLM's constant interference with German engine manufacturers to the point that production numbers were adversely affected during the war.

By the end of the book, Douglas convincingly shows the necessity for German blitzkrief--not from a military tactical perspective, but from an economic/logistical strategic one. Germany needed to win every conflict cleanly and quickly as the lack of strategic stockpiles of necessary resources such as nickel and cobalt as well as a complete dependence upon synthetic fuels and lubricants made a lengthy war quite beyond Germany's means. Douglas illustrates the extreme efforts that German engineers made to get around the various roadblocks cause by resource shortages; unfortunately for them, these shortcomings could never be overcome.

Douglas has assembled a unique work that is quite different from the single subject books or encyclopedic-style works which I have read previously. The comparison/contrast effect is most useful. My only complaint is that Douglas should have done a deeper dive on U.S. developments. Although I am not familiar with Graham's work on the R-2800, I am quite familiar with Whitney's V-1710 book. Douglas's brief treatment of the Allison engine is far more balanced than Whitney's paen to Indianapolis--it is a shame we could not see more of the author's informed analysis.

A fabulous read! ( )

A New Benchmark

First of all, any of the glowing reviews you may have read elsewhere are not hyperbole. Second of all as I have gone online to read up on various subjects or personalities mentioned, I have been amazed by the number of specialized technical subject matter blogs that have picked up and are quoting this book since November.

Let’s start with what the book doesn’t cover, you won’t find a large amount of coverage on the R2800, the Griffon, Centaurus, or the V1710. (They are of course mentioned and the coverage they receive is excellent.) Hyper programs, exotic programs like the XIV-22 or the RR two-strokes get some mention in passing. With the exception of the missing Me-109 on the cover pretty much what you see is on the cover is what you get. BMW, Rolls Royce, and Daimler-Benz by far constitute the lions share majority of text. France and Italy receive some attention in passing with some excellent drawings of the Fiat A38 and A40 in the text with Hispano-Suiza getting a few a paragraphs while establishing the pre-war environment.

Are there some nits? Of course. There are large numbers of schematics and keyed drawings that are regrettably missing the key. On page 373, the author mentions a potential shortage of 100 octane fuel and thoughtfully provides a copy of the original message. What variant of “100 octane” was it? Was this shortage for all of Europe? The tactical air forces? Did it include operations by the 8th Air Force? Is it, 100 octane, 100/130, 115/145, or 150?
Also, American readers maybe slightly challenged as the author mixes and matches metric and English units. It will also help to have access to a German to English technical dictionary when for many of the charts. None of these are serious in nature or detract from the book. There is no bibliography as such, but the footnoting runs about sixteen pages of what appears to be a size 6 font. The index is also organized into aircraft, engine systems, engines, events, firms, fuels, groups, materials, organizations, people, places, production, technology and finally weapons. It also is in a small font and runs three pages.

If you’re attracted by the excellent art on the cover and looking for a nice coffee table book or are a modeler looking for modeling details, this is not the book for you. If you’re interested in the technical challenges of getting the engine from the drawing board to the flight line during WWII this is the one book you must have on your shelf, it is a tour de force.

Highly and unequivocally recommended for anyone with a serious interest in piston engine development, WWII aircraft, WWII engine development. Buy this book! ( )