CLERGET 4V ENGINE

The Clerget 4V was a 4-cylinder inline water-cooled aero engine developing 50 horse power at 1,650 normal revolutions per minute. It derived from a car engine.

With a bore of 110mm and a stroke of 120mm, the cylinders were made of cast iron, turned internally and externally, and surrounded by copper water jackets. The cylinders were first prepared with a thick coating of wax to represent the water space, and to form a surface upon which copper could grow in an electrolytic bath. The wax surface was coated with black lead to act as a conductive medium for the electric current which carried the copper, and when the jacket was finished the wax was melted out to leave a hollow space for the water; without using joints or welds.

The special alloy pistons were extremely light. The very light connecting rods were made of treated nickel steel, with a double T profile. The friction of the connecting rod heads was made of anti-friction metal deposited directly onto the steel. Treated nickel steel was also used for the crankshaft, which was hollow with 5 ball bearings wedged on the shaft. The use of these bearings made it possible to reduce the length of the intermediate bearings, resulting in a reduction in the length of the casing which saved considerable weight without altering solidity.

The aluminium casing was strongly ribbed and designed to distribute the forces in the best possible conditions. Large calibre suction and exhaust valves were controlled. Their sections were such that in each cylinder the sum of the diameters of the 2 valves was greater than the bore of the cylinder. Valve control was of the ‘telescopic’ type, that is a tube controlling the exhaust sliding in a tube controlling the intake, all actuated by a single cam per cylinder. 

On the same side of the engine, were located the Zenith Carburettor Co Ltd ABC type carburettor, the centrifugal water circulation pump and the high voltage magneto. – Zenith established laboratories on several mountains in the Alps, at varying heights from 6,000 to 9,000 feet. Their experiments proved that a much weaker air-fuel mixture was required at high altitudes, and they therefore evolved a carburettor having an altitude corrector so that the mixture could be weakened as the aeroplane ascended.   

A small oil pump was placed at the base of the casing, so ensuring forced lubrication of the moving parts by injection. 

The weight of the engine, including all its accessories, was 74kgs. 

Oscar Gnosspelius

By reference to British Aircraft Before the Great War by M Goodall and A Tagg, and to British Aircraft 1809-1914 by P Lewis, in Great Britain there were only 3 Clerget 4V engines. That is, fitted to the Bristol G.E.1 biplane, British Army Beta II airship and Gnosspelius No. 2 hydro-monoplane.

Gnosspelius No. 1 had an Alvaston 20 horse power 2-cylinder air-cooled engine. Whilst  27 mph was reached, there was not enough power to leave the water.

Oscar Gnosspelius was ‘among the earliest pioneers of seaplane construction not only in England but in the world’. – The Aeroplane magazine, 9 May 1923. He was a civil engineer, and a fitter and turner who had served his time at a boatbuilder’s yard.

In July 1910, hydro-aeroplane floats with a ‘step‘ were constructed by Borwick & Sons, boatbuilders of Bowness-on-Windermere, from the designs of Gnosspelius and which he tested at Windermere. These were the first floats with a hydroplane step in the world.

Gnosspelius No. 2 flew on 14 February 1912; Gnosspelius being the only person at Windermere to design and fly his own hydro-aeroplane. Gnosspelius No. 2 was the first British hydro-aeroplane to have wingtip floats. – The History of British Aviation 1908-1914 by D Brett. He was described by Captain Edward Wakefield in the Westmorland Gazette, 6 April 1912 as “the engineer of The Lakes Flying Company, but retains his own machine”.

He also designed The Lakes Flying Company’s Waterhen hydro-aeroplane which first flew on 30 April 1912, and the Gnosspelius-Trotter hydro-aeroplane which first flew on 9 October 1913. In order to improve longevity, he had Borwicks make the underside of the Gnosspelius-Trotter‘s float with an inner skin of ⅛ inch mahogany planks laid diagonally and with an outer skin of  ¹⁄₁₆ veneer, whilst between the brass riveted skins was a membrane of painted fabric. The last known flights of the Gnosspelius-Trotter were on 11 November 1913.

On 12 February 1914, Gnosspelius obtained UK Patent No. 10,801 for a V-shaped construction of float. – Now, all seaplane floats are stepped and V-shaped.

Gnosspelius left Windermere having joined the Royal Naval Air Service on 21 August 1914. He therefore did not see the first flight of the Lakes Monoplane which he designed.

This photo, taken in 1915 at the Cockshott hangar, includes the engine in the foreground. Note that it now has 2 breathers which are angled upwards, in contrast to 1 breather angled downwards as is apparent from the photo link at the first paragraph of this section.

The engine was transferred to a Hydroplane made from the float formerly fitted to the Gnossspelius-Trotter and a Blériot, which was a 2-4 seater ‘kept to give students practice in running fast over water, judging speeds and also as a safety attendant’. – About the Seaplane School booklet, 1915.

He oversaw aircraft production at Brush Electrical Engineering Company Ltd, Loughborough and from 27 December 1916 at Robey & Company Ltd, Lincoln, being attached to the Air Board on 1 April 1917. Following the end of World War 1, Major Gnosspelius joined Short Brothers (Rochester and Bedford) Ltd at Rochester where he was in charge of their experimental department.

Gnosspelius No. 2

On 25 November 1911, Gnosspelius No. 2 made the first take-off from Windermere. ‘But before Mr. Gnosspelius had been going for a minute, the craft was noticed to swerve sharply first to the right and then to the left. Portions of the propeller were then seen to fly high up into the air, and in a moment the aeroplane turned right over from back to front, and the luckless pilot was thrown into the lake. The damage done to the machine consists of the broken propeller and a broken wing. The cause of the mishap was an untoward gust of wind, which at the time was blowing pretty strongly. The hydro-aeroplane is fitted with a fifty horse-power Clerget engine.’ – The Westmorland Gazette, 2 December 1911.

Gnosspelius had received lessons at the Avro Flying School, Brooklands in February 1911, but only so far as flying straight and level. It would appear that when he encountered a strong crosswind at Windermere he reacted with over-correction.

‘On the 14th February 1912 Mr. Oscar Gnosspelius had improved so much with practice that he was able to get nice straight flights out of his rebuilt monoplane, leaving the water cleanly and “landing” quite gently.’ – The Aeroplane magazine, 29 February 1912.

The Aeroplane magazine stated that Gnosspelius No. 2 ‘captures the honour of being the first hydro-monoplane of normal type to fly properly, as well as being the first hydro-aeroplane of any type to leave British waters’. It was therefore attributing the world first by not recognising success to Henri Fabre’s Hydravion, which had flown on 28 March 1910 at Marseilles, because of its unique design.

In April 1912, Gnosspelius No. 2 was flown by Ronald Kemp, who Gnosspelius had met at Brooklands. Gnosspelius recognised his limited flying abilities and invited Kemp to carry out tests which went well. John Trotter, who had asked Gnosspelius to design him a hydro-aeroplane, also flew Gnosspelius No. 2 attaining a record height of 1,000 feet on 4 July 1912 and on 4 November 1912 flew from Hill of Oaks to Ambleside and back.

The last known flights of Gnosspelius No. 2 were on 11 November 1913.