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8. Under the Skin and under the Bonnet

14/01/2012

Having looked through all these drawings, it was time to decide whether we could actually build it, and the answer was that, compared to many later types, there were no serious challenges for a homebuilder.

Fuselage construction, taken from that fantastic parts list

Essentially it’s made the same way pretty much every aircraft of the period was made; a frame made of wood with metal brackets at the corners and wire bracing to hold it all together and keep it straight. There are two large metal frames at the front on which the engine is mounted, the lower wings are attached to the bottom of the ‘N’-shaped part, and the pilot sits just behind them.

Top wing – or ‘plane’, as they called it in those days

The wings are similar – wooden spars (the large bits running the length of the wing) with ribs made from plywood and metal brackets with wire bracing internally to keep it straight.

Most of the wood is spruce, which is still used for aircraft construction today, although the front part of the fuselage and some of the undercarriage was made from ash, because it’s better for the heavy loads imposed by the engine and by the wheels. But although ash isn’t as commonly used for aircraft, it’s still available. There are one or two more unusual pieces of timber – the tailskid, on which the tail rests on the ground, is made of hickory, and semicircular hoops underneath the wingtips (to stop them catching on the ground) are of Malacca cane. But these shouldn’t be too hard to find.

The metal sheet and tube is still available from stock in the original sizes, as are the nuts and bolts. There are no complicated forming processes, forgings or castings to be made; pretty much everything was designed to be made with hand tools on the bench.

The wire bracing consists of cable where the loads are highest and piano wire elsewhere. In every case they have a turnbuckle (a screw adjuster) to adjust the tension in each wire. These are specified on the parts list as coming from a specialist manufacturer – in other words, although the aviation industry was in its infancy (I don’t suppose there were 1000 aircraft in the world by 1915), there were already people going into business to manufacture specialist parts.

Of course, there will be difficulties. The main one is an original engine. Although the RNAS originally specified the Gnome Lambda for its reliability, there are virtually none in existence today; just a couple on static display in museums. But there was one occasion when 1264 was fitted with a le Rhone 80hp, and there are quite a number of those still in existence, and we have hopes of being able to find one.

The story of how it came to be fitted is interesting. Although both engines were nominally 80hp, the le Rhone actually delivered about 90hp, while the Gnome could only manage about 65hp. Because all rotary engines were unreliable and needed lots and lots of maintenance, they could be removed and replaced very quickly. They were also interchangeable.

Granddad got fed up with the fact that he, in the Bristol Scout, couldn’t keep up with the Nieuport 11 which was also there (and which he flew), so one day he switched the Nieuport’s le Rhone engine for his Gnome. He found it handled considerably differently, and (possibly because the le Rhone was significantly heavier than the Gnome) tipped it on its nose on landing!

Bristol Scout 1264 crash landed after fitting a le Rhone engine

The other area that may cause some difficulties is the original instruments. Thankfully, there are very few; airspeed indicator, altimeter and engine tachometer, spirit level and watch in the panel, and a floor-mounted 5/17 compass.

But sufficient unto the day, as they say. The first thing so to get the airframe finished, and no doubt these things will sort themselves out in time.

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From → Research, Technical

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