Engine walkaround vol.26: Hispano-Suiza 8A (type 31)

Subject: Hispano Suiza 8A (Type 31).

Location:Musée d'lair et de l'espace, Le Bourget, Paris, 2015.

Comments: At the beginning of the First World War the production lines of the Barcelona based Hispano-Suiza automobile and engine company were switched to the production of war materiel. Chief engineer Marc Birkigt led work on an aircraft engine based on his successful V8 automobile engine. The resulting engine, called the Hispano-Suiza 8A (HS-31), made its first appearance in February 1915. The first 8A kept the standard configuration of Birkigt's existing design: eight cylinders in 90° Vee configuration, a displacement of 11.76 litres (717.8 cu in) and a power output of 140 hp at 1,900 rpm. In spite of the similarities with the original design, the engine had been substantially refined. The crankshaft was machined from a solid piece of steel. The cylinder blocks were cast aluminium and of. 'mono-block' type that is, in one piece with the SOHC cylinder heads. The inlet and exhaust ports were cast into the blocks, the valve seats were in the top face of the steel cylinder liners, which were screwed into the blocks. Using a rotary driveshaft (tower gear) coming up from the crankcase along the rear end of each cylinder bank, with the final drive for each cylinder bank's camshaft accommodated within a semicircular bulge at the rear end of each valve cover. Aluminium parts were coated in vitreous enamel to reduce leakage. All parts subject to wear, and those critical for engine ignition were duplicated: spark plugs for dual ignition reliability, valve springs, magnetos, etc. Engine reliability and power to weight ratios were major problems in early aviation. The engine and its accessories weighed 185 kg (408 lb), making it 40% lighter than a rotary engine of equivalent power. (Note: This empty weight does not include the radiator and coolant fluid. Generally, air-cooled engines are lighter than their equivalent horsepower water-cooled counterparts. For example, the Bentley BR.2 rotary put out 230 hp (170 kW) and weighed 220 kg (490 lb), Clerget 9B rotary 130 hp (97 kW), 173 kg (381 lb)) The new engine was presented to the French Ministry of War in February 1915, and tested for 15 hours at full power. This was standard procedure for a new engine design to be admitted into military service. However, because of lobbying by French engine manufacturers, the Spanish-made engine was ordered to undergo a bench test that no French-made engine had yet passed: a 50-hour run at full speed. The HS-31 was therefore sent back to Chalais-Meudon on July 21, 1915 and tested for 50 hours, succeeding against all expectations. The design also promised far more development potential than rotary engines which, in spite of being the most common type then in use for aircraft, were getting close to the limits of their development. Rotary engines of increased power generally had increased weight, which in turn increased the already serious gyroscopic torque generated by the engine's rotation. A further increase in torque was considered unacceptable, and the power to weight ratio of the new rotary engines under development did not appeal to aircraft designers. French officials ordered production of the 8A to be started as soon as possible and issued a requirement for a new single-seat high-performance fighter aircraft using the new engine. The Louis Béchereau-designed SPAD VII was the result of this requirement and allowed the Allies to regain air superiority over the Germans.

Aircraft walkaround vol.98: Junkers D1

Subject: Junker D1

Location:Musée d'lair et de l'espace, Le Bourget, Paris, 2015.

Comments: The Junkers D.I (factory designation J 9) was a monoplane fighter aircraft produced in Germany late in World War I, significant for becoming the first all-metal fighter to enter service. The prototype, a private venture by Junkers designated the J 7, first flew on 17 September 1917, going through nearly a half-dozen detail changes in its design during its tests. When it was demonstrated to the Idflieg early the following year it proved impressive enough to result in an order for three additional aircraft for trials. However, the changes made by Junkers were significant enough for the firm to redesignate the next example the J 9, which was supplied to the Idflieg instead of the three J 7s ordered. During tests, the J 9 lacked the maneuverability necessary for a front-line fighter, but was judged fit for a naval fighter, and a batch of 12 was ordered. These were supplied to a naval unit by September 1918, which then redeployed to the Eastern Front after the Armistice

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Experimental aircraft walkaround vol.9: Morane Saulnier Type G

Subject: Morane Saulnier Type G

Location:Musée d'lair et de l'espace, Le Bourget, Paris, 2015.

Comments:The Morane-Saulnier G was a two-seat sport and racing monoplane produced in France before the First World War. It was a development of the racing monoplanes designed by Léon Morane and Raymond Saulnier after leaving Borel and, like its predecessors, was a wire-braced, shoulder-wing monoplane. Construction was of fabric-covered wood throughout, except for the undercarriage struts which were of steel tube. The type was a sporting success. In April 1913, Roland Garros took second place in the inaugural Schneider Cup in a floatplane version, finishing with a time of 40 minutes 40 seconds. On 26 June, Claude Grahame-White flew another float-equipped example from Paris to London via Le Havre, Boulogne-sur-Mer, and Dover, covering some 500 km (310 mi) that day. Between 21 and 28 September the same year, two float-equipped Type Gs competed at the seaplane meeting at San Sebastián, with Lord Carbery winning the short takeoff prize on one, and Edmond Audemars winning the maneuverability prize on the other. The following week, Carbery flew his Type G in the Italian Waterplane Contest from Lake Como to Pavia and back, along with two other Type Gs in the field of fifteen competitors, these flown by Garros and Morane. Garros not only won the Grand Prize in the "general class", but also the prizes for best speed (127.7 km/h, 79.8 mph) and greatest altitude (2,100 m, 6,000 ft).On 28 September 1913 Roland Garros became the first person to cross the Mediterranean Sea by air, flying from Fréjus in the south of France to Bizerte in Tunisia in a Morane-Saulnier G.In 1914, Russian manufacturer Duks arranged to build the type under licence at their Moscow factory for the Russian Army, and the same year, the Turkish military ordered 40 examples. Before these could be delivered, however, war broke out, and the aircraft were impressed into the French Army. To these, the Army soon added an order of 94 aircraft, and the British Royal Flying Corps also acquired a number, these latter machines purchased from Grahame-White, who was manufacturing the type in the UK under licence. At the outbreak of war, the type's military value was found to be wanting, and the French machines were quickly relegated to training duties