Building a working 3/10 scale model

    of the  BRISTOL  JUPITER  V111  FP

                 radial aero engine

By the autumn of 2000 the 1/4 scale Bentley BR2 was completed. It was made using only a Myford lathe and some of the milling operations had been very slow and laborious, so I planned to buy a Bridgeport for the next project. 

Eric Offen, a friend and model engineer from Guildford, had given a great deal of advice during the two years it took to build the Bentley.

 

  He came with me to the Rolls-Royce Heritage Trust at Filton to help decide on the next project.


  There we met Patrick Hassell, a retired RR designer and now archivist and historian, and also Brian Perkins, a retired RR engineer, who had just decided to build his scale Bristol Hydra.


  With their advice I focused on the Bristol Jupiter in the museum. It was a type V111  FP  from 1928.

  This engine seemed to fit the bill perfectly. It is exceptionally beautiful with its push rods, tie rods and semi-shrouded rockers and it had not been modelled before. There were no dimensioned drawings still existing but a great deal of other reference material was available.


  Patrick Hassel let me have an original maintenance manual on long loan and Brian Perkins made copies of a number of installation and general arrangement diagrams which he found in the archives. 


  This would be enough information. External dimensions could be measured in the museum and some were shown on the diagrams. It would be challenging but not impossible to extrapolate all the internal dimensions step by step.

  The maintenance manual contains many beautiful diagrams, some in perspective section, combined with text explaining the construction and workings of the whole engine. The lubrication diagram above would be particularly useful.


  Back home the next thing was to decide the scale. The largest part that would need to be turned on the Myford was the crank case. At 3/10 scale this would just be possible.  Also at this scale the smaller parts, such as the rocker bearings, oil pumps and carburettors, would be of workable size. The swept volume would be 840cc.


  I settled on 3/10 for the Jupiter and bought a Bridgeport from Terry Braithwaite of Bridlington. He and his team restore these machines to the highest possible standard.    

                         The Bridgeport arrived safely in France

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