Encore un exploit de notre ami Roy.

Hello.
Le Star a été présenté en Avril 1926 et tout de suite réputé comme un formidable exemple de production moderne en quantité industrielle.
Les tolérances étaient très étroites pour ce type de machine avec des pièces de très petites dimensions qui requéraient de la solidité et de génereuses  surfaces de roulements.
D’un design complètement nouveau, avec ses deux cylindres de 15.87 mm x 15.87 mm , il était constitué de deux fonderies en aluminium: une pour les cylindre et l’arbre manivelle, l’autre pour la base moteur avec ses points d’ancrages.
Les cylindres enfoncés à force dans le carter d’alu étaient en laiton dur et il était livré avec un volant d’inertie de 31.75mm x 16mm.
Ce genre de machine était complètement différente de ce que proposait STUART.

“ Here’s the link for restoration  boiler + engine test  https://youtu.be/egOWA4ujUis  

                    The boiler Stuart 495  dated 1926 – 1938  twin drum  14 cross tubs now serviced :  tested at 100 psi  working pressure is 50/60 psi  -
                     the engine an early Stuart twin Start  , was seized now striped down in a bath , then re-built,  working like new
                     the boat an early isis          1 meter long by a beam of  dated 1926 –1938  very rare few were built.
                    photo’s to follow :  regards Roy

                 

The Star was introduced in April 1926 and was claimed to be “a wonderful achievement of modern methods of production in large quantities.” All tolerances were very tight, for this type of engine, moving parts made to the smallest dimensions consistent with required strength and it had generous bearing surfaces.
This engine was of a completely new design and had two longitudinal cylinders each of 0.6250” bore and 0.6250” stroke. It was constructed of two aluminium castings, one for the combined cylinder block and crankcase and a base plate with four integral mounting lugs. It had pressed in cylinder liners of hard brass. A 1.25” diameter 0.375” thick steel disc wheel was provided as standard.
This engine introduced a number of new features for Stuart engines.
The usual slide valve gear was replaced by a very close tolerance (0.0005”) rustless steel piston valve contained in a gunmetal, single casting, combined valve chest/cylinder head.
The valve gear is driven by two bevel gears enclosed within the cylinder/crankcase casting. The piston valve was driven by a pressed steel eccentric banjo connection which fitted around the valve chest. Both these features went on to become standard on the Sun (Piston and Slide Valve variants) and the Sirius.  
The Star was never made available as castings and materials – it was only available as a complete, ready to run, engine with a displacement lubricator as standard. Although a comprehensive range of interchangeable spare parts were available – and guaranteed to fit.
The design is slightly larger and heavier than the No 1a The Featherweight being 4.75” long, 2.75” wide, 3.75” tall with a weight of 18 oz. It was intended for use in one metre boats such as the Stuart ISIS and was usually combined a Stuart No 495 boiler.
The engine was thoroughly tested by Stuarts who claimed it simply refused to show any signs of wear. Stuarts went into war work in 1939. Sadly, the Star never reappeared in the catalogues after the war.

Thanks Roy!