Tail tale
Here is the Mosquito tailwheel, which comes apart in a similar way to the mainwheel, and is also made from magnesium.
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I am finding there is a surprising amount of magnesium in the Mosquito design, in all sorts of places, from small brackets to the housing of the windshield wiper mechanism. For the moment we will stick with the undercarriage, because this is made from a class of impact resisting magnesium, cast and heat treated.
With each pour we need to retain samples of the cast material for testing, to make sure the ‘as cast’ material meets spec. So the plan is to make all the patterns necessary for a single casting session of the correct DTD material. In fact, an old pitted original wheel of the correct specification may be melted down in the crucible to be recast as a sound, new wheel, the same wheel with it’s crystals reset, made young and beautiful again.
So the patternmaker does his stuff :
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This particular wheel takes a heavy, rubber Marstrand tyre, named after its inventor. It features two prominent rubber protrustions that are angled towards each other. This creates a self centering action in the castoring tailwheel, addressing a tendency for a plain streamline wheel to set up a ground loop in the Mosquito. Here is a Marstrand tyre on what I think is a deHavilland jet nose wheel :
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What I know see with the Marstrand tyre, referencing the wheel, is that the inner bead is hexagonal, no doubt to stop the tyre from spinning on the rim under the stress of landing. I don’t think Marstarnd tyres or tyres with hexagonal beads are around anymore. Do we use a 70 year old NOS Marstrand tyre or do we adopt a different, modern tailwheel to the Mosquito ? Do we make a pattern to fit a hexagonal bead or do we redesign the wheel casting to take a modern, off the shelf tyre ? In other words to we take the chairlift or start to climb Mt Everest ? Well, I figure this is about the journey so we will have to investigate how Marstrand tyres are made, starting at Everest base camp with a casting pattern for a Marstrand tyre with hexagonal bead. It might make a good door stop.
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