S.E. 5a

These issues could have only been resolved by developing a fighter air force to a level higher than that of the enemy, i.e. mainly the German imperial air force’s. It was no easy task. German aircraft technology was highly specialized at the time. The numerous engineers’ offices and factories achieved excellent results in both quality and quantity. Particularly the Fokker company distinguished itself, its engineers Anthony Fokker and Reinhold Platz designing ever more modern and improved constructions. The Albatros company did as well. In 1916 the then best fighter aircraft with the RFC – the Sopwith “Camel” – proved worse than Fokkers and Albatroses in terms of performance and armament. The situation was becoming critical.

Se5a   zdj6

The genesis of the design To change the state of insufficient equipment, the RFC authorities decided to introduce a new fighter to combat. It was to be of simple construction and at the same time durable, heavily armed and easily manufactured in bulk.
A state-owned company, Royal Aircraft Factory at Farnborough, was picked for the manufacturer. Although quite well known, this firm was having financial and structural difficulties, even to the point where its shutdown was considered. But its technical infrastructure was good and with this regard in 1916 the government’s committee issued their opinion, in which the factory was obliged to fulfill the following:
– tests and experiments
– research work
– preparation of design
– overhauls
– production of spare parts


In February 1916 the RFC listed the requirements to be met by the new aircraft. They were as follows:
– climb to 10,000 ft (3,050 m) – 10 minutes
– service ceiling – 18,000 ft (5,508 m)
– top speed at 10,000 ft (3,050 m) – 100 mph (160.9 km/h)
– flight duration – 3-4 hours
– single– or two-men crew
– machine gun ammunition – 500 rounds
These specs, approved by Gen. Sir Trenchard, commander of the RFC, as guidelines for the industry were made before detailed tests on the French Spad VIIC1, which was considered a better aircraft than the British models (it was produced under license at Bleriot & Spad Aircraft Works). However, taking the Spad for the model for copying or improvement was rejected on Sir W. Farren’s opinion, a member of the test team with the Royal Aircraft Factory, although such options were considered. It was decided to develop a home project that would meet the requirements. Engineer Folland, leading the factory’s design office, was the author of several successful aircraft built in the preceding years. These were the S.E. 2 and 2a in 1913 and S.E. 4 and 4a in 1914.
The new team he created engineered the drawings and made the calculations for the new fighter by mid-March 1916 (while the government’s committee still worked at the factory). The aircraft was named S.E. 5 (Scouting Experimental) in connection with the names formerly used by the factory. To a certain degree, its construction was modeled on the earlier designs of the Austin AFB1 and Vickers FB16D.
The S.E. 5 was supposed to be a classic ­biplane with the interplane bay wire-braced. Improvements unusual for that period were assumed: an in-flight adjustable horizontal stabilizer and a steerable tail skid (both items being later on copied from a “competition” project – the FE-10). The landing gear of quite a wide tread had sheathed rubber cords for shock absorption. The basic material for the aircraft construction was spruce and plywood.

Se5a   zdj7

Concurrently, another, alternative fighter project was being developed. It was initially named FE-10. This, too, was a bi-plane, but of an unconventional layout. The power transmission system was housed behind the cockpit, with the tractor airscrew revolving between the cockpit and engine. This, either, was not a novel solution, for similar were used on some older Spads (A-2) and also the British BE-9 and FE-8.
Both alternative aircraft designs shared one common idea: avoiding the issue of synchronization of gun fire with the revolving propeller. In the S.E. 5 project, a Lewis gun was supposed to fire through the reduction gear shaft, while it was ahead of the pilot and engine on the FE-10.
It was seen from the beginning that the FE-10 was a very complex in terms of construction and technology. It portended cooling problems (engine covered by the cockpit). Also, the placement of the armament in front of the pilot was not safe, as was evidenced by experiences with the FE-8 and BE-9, for the possibility of injuring the pilot with the heavy mass of metal that the gun turned out to be in the case of even a “light” overturn. Another threat was the 35-gallon fuel tank positioned under the engine.
For these reasons it was decided not to pursue this project further but stick to the classic design, which offered greater technological flexibility of the assumed large-number production.
The power plant issues The most popular aircraft engines of the time were radial “rotary” ones, in which the bank of cylinders spinned in unison with the prop around a stationary crankshaft that attached the engine to the fuselage.
This construction, designed by the Seguin brothers in 1908, seemed superb in the beginning. The absence of the water installation gave it lightness, i.e. an unusually low power consumption, whereas the rotational movement of the cylinders provided proper cooling. Overheating engines were the nightmare haunting the aviators and automobile drivers of the period – it caused power drops and seizures. Now we know that it was chiefly due to the little knowledge of fuel combustion in an engine and the low octane numbers of the fuels used. These correlations were unknown then.



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