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7 Jan 1914. Wednesday.

07/01/2014

Today Frank started on the chassis (or undercarriage, as we would call it today). The layout was more or less standard for the time, though a lot of designs were still using an arrangement with skids to stop the aircraft nosing over on landing, which was a very common occurrence. (The Avro 504 and the Sopwith Tabloid, for example).

The Sopwith Tabloid preserved at hte RAF Museum, Hendon

The Sopwith Tabloid preserved at hte RAF Museum, Hendon

It was fashionable to have very narrow undercarriages at the time, thought it’s hard to imagine why, since even today the main cause of accidents in aircraft of this vintage is groundloops, and it doesn’t take a degree in physics to see the benefit of setting the wheels as far apart as possible.

Bristol Scout Prototype cowling.

Bristol Scout Prototype cowling.

The stanchions (legs) which Frank drew today are of spruce.

541 Front Chassis Stanchion 7-1-14 542 Rear Chassis Stanchion 7-1-14

The chassis is one of the hardest-working parts of the airframe, and so it has to be designed very carefully to make it as strong as possible without adding unnecessary weight. So the rear stanchions are fitted to the fuselage at the same place as the lower wing front spars. This is pretty much where the centre of gravity is, and so much of the forces are concentrated at one point, which is the best way of keeping things strong and light. The rear stanchions will be taking very high compression loads, and Frank will have had to guess how hard a landing to calculate for in designing them. Today there are standards to work to based on experiments done between the wars but in those days there was a lot more guesswork involved!

The front stanchions are attached to the very front of the fuselage and take far less loads, though unlike the rear legs which are always in compression the front ones take both pulling and pushing loads.

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