Book Review
Douglas: Light Aero Engines from Kingswood to Cathcart by Brian Thorby
Review By Jean-Pierre Harrison
Douglas: Light Aero Engines from Kingswood to Cathcart is a significant contribution to the aeronautical historical record, and as can be readily deduced when reading the book, is the product of extensive and dedicated effort. Author Brian Thorby sets forth the heretofore largely unknown aeronautical activities of motorcycle manufacturer Douglas Motors, Ltd., of Kingswood, near Bristol, England, and in particular, two of its staff, Cyril G. Pullin and George E. Walker, who went on to make pioneering contributions in rotary-wing aircraft development.
The announcement of the Daily Mail Light Aeroplane Prize Competition in 1923 to encourage the development of small, single-seat aircraft immediately brought attention to Douglas Motors, Ltd., due to the engine power limits stipulated in the rules. In the event, half of the 19 competitors were powered by Douglas flat-twin engines ranging from 17 – 22 bhp output. The design of the flat twin provided inherently smooth operation and a good power to weight ratio, and Douglas engines again predominated in the 1924 Rohn Glider and Light Aircraft Competition. Successive competitions that allowed more powerful engines redirected attention to firms such as Bristol and ABC, though Douglas was scarcely affected due to its increase in production to cater to the fast growing sport and racing motorcycle market, which it came to dominate. Douglas reentered the aero engine market in 1932 when competition from rival manufacturers Rudge and J.A.P. broke Douglas’ supremacy in motorcycle racing circles.
The marine engineering and manufacturing firm of G&J Weir, Ltd., of Cathcart, outside Glasgow, Scotland, in 1932 was developing a single-place Autogiro for which it commissioned a new engine from Douglas Motors, Ltd. Pullin and Walker designed the 40 hp Dryad flat-twin engine which, in addition to driving a propeller at its front, included at its rear an output to power a rotor driveshaft.
Pullin and Walker joined G&J Weir, Ltd., permanently in 1933 as Douglas Motors was undergoing financial difficulty. Soon after arriving at G&J Weir, Ltd., they designed the 45hp Weir Flat Twin for the W-2 Autogiro. They later designed a Weir four-cylinder engine of 45 – 67 hp used on the W-3 and W-4 Autogiros and W-5 helicopter. The engine was licensed in 1938 to Aero Engines, Ltd., successor company to Douglas Motors, Ltd., and received type certification as the Pixie, minus the rotor drive power takeoff, in July of that year.
By this time, Pullin had been appointed Chief Engineer of the Weir Aircraft Department and played a central role in the development of Britain’s first successful helicopters, the W-5 and W-6, later followed by the W-9, W-11 Air Horse, and W-14 Skeeter. During the Second World War, Walker worked on the Hafner Rotochute and Rotobuggy, then joined Bristol Aircraft, Ltd., in the development of the 171 Sycamore and 173 Belvedere helicopters.
Thorby’s emphasis in this book is on engines rather than aircraft, and it is with the former that his expertise lies. He has painstaking researched each powerplant produced by Douglas Motors, Ltd., G&J Weir, Ltd., And Aero Engines, Ltd., and each aircraft type in which they were fitted. He details each engine with technical information, including diagrams and three view sections, many produced by Thorby, and pre-existing illustrations where available. The aircraft descriptions are not so detailed though sufficient information is given for comparison purposes. A few minor errors were found in the text, all limited to matters aeronautical, but these do not detract from the overall quality of the book.
Thorby’s appreciation for the brilliance of the men, particularly Pullin, who designed these engines, is manifest in this book, and the author’s presentation of their work provides appropriate recognition of their accomplishments.
Redcliffe Press, Ltd., Bristol, UK, 2010; http://www.redcliffepress.co.uk
