1933 Napier-Railton Engine

The key to building the model was the Napier Lion XIA engine. It was the most complex part of the vehicle and everything would have to be scratch-built. Since 3D printed parts were going to be essential, the starting point was the generation of a set of 1:8 scale CAD drawings.

A copy of a Napier Lion instruction book issued by Napier provided some good drawings, although not in the XIA configuration. A descriptive handbook issued by the UK Air Ministry provided other details. In addition there were some good photographs on the Internet.


A start has been made on construction, beginning with the bottom end. Although not necessary for a static model, the crankshaft and connected cylinders are designed to rotate. Below are pictures of progress to date and a video of the working bottom end. More details can be found in the Napier Railton Build Story;


Click opposite for a short video of the rotating crankshaft and cylinders:

Here are just a few of the other 3D printed parts:

CAD drawings were the platform for 3D printed parts and the basis for these renderings:


Front 3Q

Rear 3Q

Cylinder head with test assembly of a valve ...


Camshaft drive housing and magneto platform ...


Gear reduction housing ...


Simplex carburetor