The Secret Horsepower Race - Special Edition: Merlin: Western Front Fighter Engine Development Hardcover – May 12, 2021

This is a great work - it is comprehensive and academic with footnotes but also has popular appeal with beautiful photos and illustrations nearly all taken from original primary sources. The author did a lot of primary research and writes from a position of authority - being part of design teams of high powered Formula 1 race car piston engines.It deserves the 5 stars.Having noted this, it is not for the casual or general reader. It focuses on the development of aircraft piston engines on the Western Front of WW2 - namely the German, British, American and to a lesser degree (due to their lack of progress) Italian engines. This encompasses not just the engine block but also issues like ball bearings, fuel, turbo and superchargers and boost devices like nitrous oxide. It is superb and rich with technical details.The books is hefty being about 9 x 12 inches (23 cm x 31 cm roughly) and wonderfully illustrated. PLEASE do not be confused by the cover with the painting of the WW2 warbirds. This is NOT a book about aces, or dogfights or the plane designs except where it crosses over to engine issues like where the radiators and air intakes are mounted. The casual WW2 buff or warbird buff may find the details and nuanced discussion about ball bearing design, impeller blades, and intercooling too much but if you really like that sort of discussion, this is the book.It sheds light on an interesting aspect of the technological nature of WW2. Most people are aware that the Allies had superior resources, production and technology but not exactly how and way except in terms of quantity. Less well known are issues like the quality of the aviation fuel - how 100 octane gasoline, for example, was hard for the Germans to synthesize, and how nickel (which is useful in many alloys) hampered their engine work. Finally the whole structure of how industry and research was carried in conjunction with the military showed the greater flexibility in the Allied system - another under appreciated point.Again, a great work, and probably one that will be much sought after in the years to come. If you are interested in the topic or have a friend that is keen on the area and has a technical interest, then this will be a treasured work.

For those interested in military aviation during the Second World War, truly groundbreaking, definitive texts are few and far between: William Green's Warplanes of the Third Reich, Rene Francillion's Japanese Aircraft of the Pacific War, Gunther Sengfelder's German Aircraft Landing Gear come to mind as similar examples of definitive works that were painstakingly researched, and which have stood the test of time. Calum Douglas' work falls into that select category. It is brilliantly researched using original source material. The diagrams, blueprints, graphs, original correspondence, and (perhaps most impressively) photos of individual components are exquisite and plentiful. Want to see the connecting rods of a Jumo 222? This book contains photos of the original design, after it failed, and the later design that tried to cure the problem. Want to see microscopic sections of the plain bearing material used on a DB605 compared to that used in a RR Merlin? It's here. This book provides unprecedented insight into the problems German aircraft engine builders faced due to materiel shortages, such as the lack of sufficient nickel, using minutes kept at their own meetings. It definitively answers questions that have been floating about in the "warbird" community for decades. For instance, there has been widespread speculation that the Daimler Benz engines used different compression rations in their left and right hand cylinder banks because the supercharger was mounted on the left side of the engine, which resulted in lower inlet pressure in the right hand bank. It turns out the inlet pressures were measured at each cylinder during the war, and there was no appreciable variation between any of them. Similarly, the much speculated reasons why the promising Jumo 222 failed to see production are also made clear. Problems with the DB605, its oiling system, and its main bearings are spelled out in detail. When they were first introduced, every aircraft that used them had trouble, and they were de-rated for fighter use for a significant period of time. It was clearly understood to the Germans that aircraft which taxed the engines most also experienced the most problems, and the He-177 was identified in that regard. That puts to rest the ongoing debate about whether it was the engines or the installation that caused so much grief to he Greif. On the allied side, the work Sir Stanley Hooker and his team did on supercharger development and the changes in design that resulted is all here, illustrated, photographed, and performance charted. The American turbochargers are also similarly addressed. Sleeve valves and even disc valves are discussed as well. In addition to those kinds of things, the book provides an amazing insight into just how much technology was being brought to bear on piston engines back then. Looking at a schematic of the nose oiling system used on the Jumo 213 crankshaft, which incorporated a deaerator, or the scroll vanes used around the superchargers of some engines makes you realize just how much brilliant engineering went on and how hard people worked to win the war. Similarly, there is a detailed analysis of carburetors and direct fuel injection. I learned that the advantages of the latter were more than just that the engine did not cut out under negative G loads. Direct injection allowed for greater overlap between inlet and exhaust valves with better scavenging and cooling as a result. I did not know before reading this book that Rolls Royce actually ran a Merlin using a Jumo 211 fuel injection system just to test what could be done with it. This book contains a photo of the lash-up test engine. I could go on and on, but the point is that this is one of those seminal works that will be still be highly regarded fifty plus years from now. It belongs in any enthusiast's library.

Outstanding.A fascinating account of the rapid development of piston aero engines in WW2. The author is an engine designer, and brings valuable insight into the design of a variety of WW2 aero engines and the problems encountered in development and in service. Of particular interest is the information he has gleaned from original German sources.He provides extensive information on the advantages and disadvantages faced by both sides. Germany had a head start as a result of the early commitment to develop an advanced aggressive airforce, but on the other hand the designers were hampered by limited access to certain raw materials.The author provides many examples of the remarkable work done by the scientific and engineering intelligence people on both sides, following the recovery and analysis of crashed or captured enemy aircraft. We also see, on the British side, how quickly the findings were disseminated thanks to highly effective liaison between government and industry. As well as revealing useful new ideas, the findings also gave clues to the enemy’s difficulties, for example in fuel supplies or in shortage of alloying elements, and also indicated the potential performance advantages which would need to be counteracted.The key Western Front engines from British, German and US manufacturers are considered, with some limited examination of French and Italian engines.The extent and depth of research by the author is remarkable. The presentation is non-partisan, and very readable.At 2kg, it is perhaps too heavy for bedtime reading! 480 glossy pages, packed with high quality photographs, drawings, and graphs. Some beautiful full page engine drawings, while some other illustrations are quite small, but the resolution is sufficiently high to reward the use of a magnifying glass. The text is set out in two columns, and extracts from source documents stand out clearly by being set in ‘old typewriter’ font.It is a real bargain, even at the full cover price, and I recommend without hesitation to anyone interested in internal combustion engines.

This is a genuinely excellent book. Well written, authoritative without being condescending, detailed and factual without being dry.Gives a well rounded overview of the lead-up to the conflict and then year by year what each of the major players was struggling with and their successes and failures. Doesn’t shy away from the critical technical and engineering stuff but doesn’t get bogged down in it either, and pulls together all the critical background factors in fuels, metallurgy, airframes etc. to give a really well-informed perspective on how aircraft engines in general were developing and the consequences of being ahead or behind the enemy.Unlike other books which focus on one specific thing in mind-numbing detail with limited context (like Vees For Victory) or that cheerlead for one engine or aircraft, this author has focused on how the army of engineers involved struggled against the different challenges each nation faced, and how they were helped or hindered by their national bureaucracies, intelligence agencies and supply situation.It’s not a perfect book, there are of course minor typesetting and editing flaws as one would expect in a book with this much info but I think it is an absolute must-read for anyone with any interest in the technical side of the WW2 air war. Even though it addresses the western front and is particularly well sourced from German materiel, the broad technical aspects it covers are also relevant and informative to anyone interested in the Pacific theatre where the Japanese found themselves in an even deeper hole than the Germans.I wish I’d had a chance to read this book 20 years ago, since it would have helped me understand a lot more from various other books that incidentally touched on these topics but didn’t explain why or how a particular technical detail was important.

Having just finished reading my copy, this is a _great_ book pulling back the veil on the technical aspects of WW2 aero engines.I enjoyed it on two levels; on one level, the specific details are fascinating. What makes a good supercharger, the multiple advantages of fuel injection, how the P-47 was designed around its tail-mount turbocharger, the pros and cons of inverted engines, coolant temps, etc are all really interesting and much of it was new to me, despite having read quite a few books on this area & having a relevant degree.And then at the end, the individual vivid brushstrokes combine to paint an overall picture of how each nation and each company attacked the same fundamental problems, but with different constraints and adopting different technologies along the way.While I could make the odd small criticism of this book, it seems beside the point really. This is an epic tome packed with a wealth of detail, much of it complemented by fascinating first-hand quotes, photos, drawings and charts. I could easily imagine paying £50 or more for this & feeling happy.I'd highly recommend this book to anyone with an interest in the technical details of what makes one engine better or worse than another.

The only dislike? A misleading statement on page 191, concerning Eric Brown. He was commenting on an early flight in the new De-Havilland Mosquito late in 1941. This book quotes:" RAF test pilot Eric Brown". He may have been testing the new aircraft for the RAF, but Eric "Winkle" Brown was a Lieutenant, Royal Navy, who went on to become the foremost test pilot in Britain. Within a week of Nazi Germany surrendering, he was touring German air force aerodromes and flying various German aircraft with German instrument markings and manuals, prepared for flight by German aviation technicians.Apart from the above, this book is eminently enjoyable for anyone with an interest in WW2 military aviation, its military and civilian leaders of design, development and production of aero engines, and the "potted" biographical details of the main players as they are introduced in this book. The engineering detail is minute and backed with blue-print extracted illustrations. The different relationships between senior military and civilian leaders in the Government organisations directing activities in commercial Aero Engine companies and the Royal Aircraft Establishments, and their foreign counterparts , are described in detail. In many war-time accounts, the necessary logistics to support military action are often overlooked. Not in this book. I was not aware of how unreliable the Luftwaffe's aero engines became as developed power outputs were raised, due principally to the use of synthetic, highly leaded aviation petrol and the lack of important materials such as nickel. The shortages caused major early failures in the exhaust valves of Db and BMW engines. In Britain, Napier struggled for a decade to engineer reliability and power output into the Sabre engine. and Bristol had similar struggles with its Hercules and Centaurus engines. Rolls-Royce lead the field with the 2 stage gear driven supercharger development; the US lead in exhaust driven turbochargers for high altitude operations. Of great interest also is how each Nation, in particular Britain and Germany, went to great lengths to examine power plants from aircraft brought down on the other's territory. Detailed strip, measurement and material analysis examinations and. when possible, test bed running, were carried out urgently. The RAF and the Air Ministry were dismayed when the first Merlin 61 engined P-51 Mustang:"Walked Away" from the new Merlin 61 engined Mk IX Spitfire at 20,00 feet altitude, during comparison trials in Britain. This book is heavy with interesting historical facts. Sometimes the depth of engineering detail on a particular requires much reader concentration and it becomes necessary to put the book aside for a while. It is an absorbing book to spend a couple hours immersed in through a Winter evening after work and enabling a temporary escape from a pandemic world, into the engineering and logistic struggles for air supremacy 75 to 80 years ago.

It might be contended that today we live in an era of technological fog, its products are integral to our lives, but the history of the effort behind it all remains barely known. This is especially true of the internal combustion engine that has become so every day, development of which has seen amazing advances in power and efficiency. Calum Douglas clearly devoted prodigious effort to unravelling a significant part of this evolving story in his substantial book, ‘The Secret Horspower Race’ where the efforts of allies and axis designers and developers in the European theatre sought to extract ever more power from the engines used in fighter aircraft during WW2.This examination finds a natural start during the time of the Schneider Trophy competition, a period when Italy, Britain and others leapfrogged one another as they developed special engines capable of powering aircraft to ever faster speeds. This race certainly helped Britain, whose company, Rolls Royce designed an engine whose successors would play a vital role in the coming conflict. Left out of this stimulus was Germany and latterly the United States, although once the National Socialists gained power in Germany in the early 1930’s this gap was rapidly reduced by German industry, America following its own path that showed its value later.By the time war became a certainty Germany and Britain were on roughly even terms in terms of engine performance, with France and Italy only slightly behind, the situation in Soviet Russia being complicated by the secretive nature of Stalin’s regime. It is however the advent of open conflict that leads us into the real meat of the story, as German ingenuity and rigorous engineering excellence competed with what has traditionally been British individualistic flair, the existential threat posed by Germany’s ambitions exerting shrewd practicality on British efforts.As the war went on the advantages swayed this way and that, over time Germany’s designers grappling with the growing constraints posed by a lack of access to certain metals and eventually limits on fuel quality. Ironically for a nation noted for its industrial prowess, German development was further inhibited by a dis-connect between its various research establishments and the designers, an issue rooted in its politicised government. This contrasted to the way Britain acted, as it shared technologies and lessons with the US which together contributed to a growing Allied dominance in the air over European and North African skies.In delving into all aspects of the story, the challenges faced by all sides in this race is brought out, this goes some way towards supplying the reader with a full appreciation of the complexities behind getting an engine that worked reliably while delivering the performance needed. It is a great contribution to the understanding of piston engine evolution, and some of the truly great minds whose effort contributed to what it has become.This is a superb companion to the efforts of Bill Gunston, Graham White and others who had earlier explored piston engine development. A genuinely great read, perhaps the best technical book I have ever read. Thanks to Calum.