Between 1933 and 1935, John Cobb’s Napier-Railton race car set a number of lap records at the Brooklands race track in the UK. In doing so he established a one lap record of 143 mph. No one beat that record before the Brooklands track was closed during WWII. The car also broke many endurance speed records.
The car was powered by a Napier Lion aero engine. From 1917 through the early 1930s, that engine was at the core of British aircraft developments. It was a twelve cylinder ‘W’ arrangement of three rows of four cylinders which, in its basic form developed over 450 HP. It was the most powerful engine of is day and was used in a number of racing designs, not just for cars, but also for planes and boats.
Why This Vehicle?
First, I thought the Napier-Railton race car would fit in well with my suite of 1930s car models that showcased the transformation of transportation in the 1930s. Second, a chassis-only version of the car would make an interesting contrast to my chassis model of a Rolls-Royce Phantom II. And third, the Napier Lion engine was also used in the Supermarine S.5 seaplane which won the Schneider Trophy in 1927. The Supermarine was a beautiful aircraft so a 1:8 scale model would be a new challenge. However, as it turned out, the version of the engine used in the Supermarine S.5, was quite different from that used in the Napier-Railton. But that's a different story!
Engine & Configuration
The first step would be to build a model of the engine. That's where I started. It was going to be entirely scratch-built and, like all my other models, my goal was for the model to be historically accurate.
Cobb had been able to get an XIA version of the engine. That version featured a large offset gear reducer and housing on the front of the engine and the magnetos and carburetors mounted on the rear. Cobb didn’t use the gear reducer, instead taking the drive directly off the crankshaft.
The sketch of the Napier-Railton racecar chassis shows the distinctive housing for the large gear reducer. Since the engine drives the rear wheels, the engine is mounted backwards with the air intakes and carburetors at the front of the car.