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I’m currently looking over an early 1937 DPY Flyer engine that has not been used for donkey’s years. It is ex-Charlie Abbishaw. It has very nicely fitted and carved hardwood (mahogany ?) panels fitted inside the crankcase cheeks, and they are about half an inch thick, so not readily visible. I have never seen anything like it before, and I am pondering WHY….
The only idea I have come up with so far is that it may have been done for sound deadening purposes, to stop or reduce sound resonating from the area.
ANY IDEAS ?
Will it increase crankcase compression?
Not sure if you are joking Carl ? They are not inside the actual crank chambers, and just line the sides of the crankcase cheeks, with a neat cutout to clear the float chamber.
I am not joking, I just misunderstood you – cheeks? – English is such an exotic language. Sound deadening may be a good theory, although using hardwood may not be the best idea. Vincent owners have been known to use lead sheet inside the timing cover to dampen the stone-crushing noise from the valve train with some success – but …
😀 😀 FWITW I had an engine with some sort of crankcase “stuff” inserted in it! From memory it was an engine ex- Gordon Colquhoun. 😀 😀 It went like stink!! Ted
Surely it would insulate the crankcase making it run hotter and thus reducing efficiency?
Squirrels like nuts,
nuts grow on trees,
trees are made of wood,
maybe it was a sort of grafting operation intended to provide a mobile snack?
In other words — as usual — I ‘aint really got a clue!
It’s a long story actually.Too long maybe but I guess you’ll make your own minds up.
Following the design of the long-stroke crank on 1st April 1928, the drawing office realised that they needed to find a way of making sure that you didn’t lose the chunk of crankcase displaced by the rod when the crank let go. Although the crankcase deck was obviously designed to collect the aforementioned piece, occasionally the velocity (and vector) was such that it evaded this designed catchment platform. The timber insert, designed for this application, obviously had to be hard enough to resist complete destruction, whilst not so hard that it caused the dreaded ricochet. African Mahogany was chosen because it had been thought to exhibit the appropriate properties as established using the standard ‘Janka’ test.
The Janka hardness test measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an 11.28mm (.444 in) steel ball into wood to half the ball’s diameter. Although this measurement can be stated in kN or lbf, the normal method is to use the ‘Janka number’.
It was rumored that Harry Shackleton himself spend months testing to find the correct grade for this purpose, eventually settling for the African Mahogany which as you may know has a Janka number of 830. It was so close but a costly mistake. The insert was fractionally too hard and the rider of the test machine, a single downtube frame model with biscuit tin tanks, never sang baritone again.
The drawing office knew they were close to an answer; firstly they decided that they must make sure that they never used biscuit tin tanks again and secondly they must stop at nothing to find the correct hardness of wood.
I won’t go into details, as the travels of Edward Arthur Wickes, the junior draftsman charged with this work, are well documented. His foray into the dark heart of the Congo was reckless but he was convinced that this was where he would find the tree that would bring him recognition back in Saltaire. He was lost for years in that place, losing the heart of Edith who worked in accounts but gaining the experience of the forest, the timber within it and the ingenious construction methods of the people native to that place. All that sustained him throughout that desperate time was the faint hope he held onto that one day he would be able to return to the country of his birth and start his life again with a small chain of builders merchants.
Fortunately for the drawing office, three days after Edward had left on his trip, someone had accidentally dropped a 0.444″ steel ball onto the cafeteria’s doorstop and had realised that it was a perfect indentation. Yes it was mahogany, but Honduran mahogany with a Janka number of 800. Those 30 Jankas were everything and all tests were subsequently performed with repeated perfect capture of the crankcase chunks.
Why don’t you see them any more? It’s very simple. Honduran mahogany was susceptible to common woodworm and all such examples of this fine piece of developmental engineering crumbled away.
Strangely, the original African mahogany prototype was not susceptible but was thought lost after the closure of the factory and the only thing I can think is that this long lost and unique piece of Scott history has somehow found its way to you, Brian.
Life is indeed stranger than fiction.
Let us know how the test ride goes.
One thing is certain…. Charlie Abbishaw isn’t going to tell us…. David Frank has told me tonight that he was killed years ago when riding his Scott Sprint Special somewhere in Yorkshire. (True).
I once bought a 1929 TT Rep that had wooden handlebars, but that is but nothing compared to this engine.
The Common Furniture Beetle, Anobium punctatum, won’t touch mahogany (from any country) that is saturated with Mr. Castrol’s slippery stuff, but the Death Watch Beetle, Xestobium rufovillosum, might be tempted I suspect.
I thought you only got death watch in oak? Or am I thinking of something else completely? 😀
Any hardwood traditionally used in building in the UK, so primarily oak, but also elm and chestnut. They are VERY determined burrowers and in order to make their flight hole to the surface have been known to go through lino, including pvc tiles, and unbelievably sheet lead on church roofs !!! Hence my remark about oil not putting them off…
From 1972 to 2001 I was in the timber preservation business.
The Scott foundry were still looking for that part of the crankcase pattern years later.
How about posting some photos?
I think this is a good one.
Very interesting Mr Moss.
I am reminded of a Mr Rip Van Wyk who, whilst I was living in Rhodesia, had a wooden leg made out of african mahogany mainly for it’s durability and resistance to woodworm etc.
However, he was astounded to find one day, after falling asleep under a mapani tree, that an african woodpecker had drilled a hole into his leg and laid a pair of eggs (evidently african mahogany is not resistant to woodpeckers, african or otherwise – this should be taken into account by anyone in Africa proposing the infill modification previously referred to).
Upon awakening, Mr Van Wyk, a motorcycling man and keen naturalist, not wishing to interfere with natures reproductive course, unstrapped his wooden leg and fixed to to the carrier on his motorcycle.
For some weeks the woodpecker could be seen following Mr Van Wyk’s motorcycle around and, whenever he stopped, it would settle on the nest to hatch the eggs ; with subsequent success I might say. One day a pair of fledgling woodpeckers flew off with their parents, much to the delight of Mr Van Wyk, who was then able to re-attached his leg and, immediately, became a more stable person.
I do not believe that Mr Van Wyk was a Scott man. However, had he been, and had he adopted the african mahogany infill modification, the story might well have been a very different one.