Close but no cigar

Matt,

I find that these kind of documents are held on the dusty shelves of old offices in which an old man will sit, quietly oiling a shotgun, muttering about flash pilots and unpaid bills for blade grinding. As they basically constitute the intellectual property of blade grinding they are passed out of the coffin of a departed grinder into the hands of their apprentice. As the art fades and the apprentices go for easier work you may find the information becomes easier to get at if you show genuine interest.

I think I did stumble on what you are wanting but only had the wit to copy a few pages instead of sprinting for the door. Maybe the big rottweiler looking at me had something to do with my timidity. As you can see this 130B looks like a 1960’s edition, but most probably has most of the blades of interest in it. This one is in the USA. No doubt there is another at the bottom of some box. I would recommend contacting your local blade grinder to see what they have.

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The way I saw this worked out on the blade was thus :

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Upon enquiry it was explained that the first 12″ dimension is the distance from the centre of the hub. As the blade is loose on the bench, I assumed that there is a set distance from the shank end, for a particular shank size, that establishes this 12″ position, and the other stations are worked out from there.
Ed

Ian, your project is breaking a lot of ground in transparency and demonstration of old and new technologies. So can we please have a live streaming event with the ability to email questions please! Being one ocean away makes it difficult to attend!

There are a number of threads that touch on this issue and invariably recoil then lapse into silent indecision. Let’s call this one the rectal digital examination of historical aviation that could manage a prostrate issue, but ends up being not done, to be faced ‘another day.’ In simple terms radium emits radiation which excites luminescence from the zinc sulphide in dial paint. Over decades the zinc sulphide breaks down and the dial paint no longer glows. The radium component, however, continues to emit radiation. If you ingest old dial paint or dust by opening a gauge, into your lungs or mouth via your fingers, you ingest a harmful radioactive substance. Never open a gauge or trifle with dial paint. The radium emits in all directions. Therefore, over decades, the aluminium of the gauge face, or the innards of the gauge may become irradiated. So the proper delousing of your gauge needs a thoughtful approach. In the end, a thoughtful approach means proper delousing will cost money. That means a small group of rare gauges might be treated and certified, while a larger group of gauges will not. I know of no service that will do this, given the cost of disposal for radioactive waste and the cost of safe infrastructure to treat gauges without harming personnel exposed to this task for 8 hours per day. These costs intersecting with a large body of collectors without the funds to support such an initiative. Perhaps Museums have funds to do this properly, but not the space in budgets. There is an opportunity for somebody to set up the right service, based on bulk servicing of a number of Museums, in order to create the cashflow to sustain the right type of solution. Ie, get 10 Museums to agree to treat 100 gauges each, 2 per month for 4 years, and use this bulk order to set things up properly. Then individual collectors could piggy back on this with individual gauges, if the economics stack up. In simple terms a certified, treated gauge would have more value, and more future, than one that is not. Until such a solution is available, like Walt Disney in cryogenic storage, do not disturb any gauge.

Aero bearing plate

I went today understanding this is the LARGEST AEROJUMBLE in the southern hemisphere and was pleased to find some juicy bits and this curiosity :

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This is an aero bearing plate, one of the earliest devices for calculating bearing, ground speed and drift. Inscribed on the back was the RAAF serial for a DH9, A6-8, part of the Imperial Gift establishing the RAAF after WW1. A6-8 was converted to components in 1924, and most DH-9s were gone from RAAF service by 1928. This was mixed in with jet age gauges and the usual ephemera of a jumble, a piece of the earliest aircraft in RAAF service with some of the latest. You never, never know what you’ll find if you never, never go.

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I was also very pleased to find a voltage regulator for a wind powered electrical generator used on later Westland Wapitis and Bristol Bulldogs, oil dilution valve for single stage Merlin Mosquito and pilot’s sliding window for Mosquito, all the necessary accessories for the man-about-town.

The Museum was most solicitous of my nutritional needs, putting on a BBQ, and additionally arranged a blue sky day : a well organised event, thank you.:applause:

Good list

Attached is a PDF of the Siskin III & IIIa drawings acquired so far which is, I trust, of interest to some of you. John

John, a great list and a good start.
My take on the Siskin III is ‘materials’ as much as ‘motor’.
The cost of re-engineering an aerostructure will exceed the savings of using available materials, so you may as well use the original materials. The original design has a massive invested cost of computations and also has a history of safe use, so is actually the most conservative path to follow.

But of course the original materials are no longer available.

Siskin III I understand is strip steel construction and pin jointed tube.

I suspect the pinjointed tube is 3% nickel alloy T50 tube.
I suspected the strip steel was DTD 99-100-54a but have seen Bristol Bulldog drawings, completed in 1928, showing BS S40 used, later overwritten with DTD 99-100-54a.

Now I am thinking that the Siskin III being a 1926 (?) design, might be S40 in the fuselage….
Do any of your drawings detail material specifications and gauge of the strip steel or tube materials.

I am looking at these materials and their availability for various strip steel designs. It would be good to know what the material requirements are for a flying Siskin III.

Polyurethane

Guys
I have an actual mould
If someone could identify a good product that is two part , thin enough to pour into the mould and is flexible like rubber once it cures , then I can make
hundreds of these holders.

Polyurethane is a two part elastomer that comes in a wide range of formulations providing a wide range of results. The bushes you might see used in aftermarket car suspension systems are cast polyurethane as is foam cavity filler used to insulate around plumbing entries through walls. The Germans developed polyurethane during the war as a rubber substitute. (I think they were actually trying to make a coffee substitute but the cup kept bouncing off the floor):)

There are many suppliers of polyurethane. Open up the phone directory and they will be there. Take an original holder in or ask them to recommend a black polyurethane formulation of a similar hardness or durometer to natural vulcanised rubber. You will need some release agent to stop the polyurethane sticking to the tooling. Some polyurethanes will set without heat, generating an exothermic heat during the chemical reaction. Some set with external heat.

I will take a few watch holders! How did you end up with this tooling ? Any more tooling ?

Interesting info. Always wondered about how to restore and stabilise old tyres, for display.
British rubber came from Malaya up till 1941, after that I understand South American rubber kept the show on the road. I always wonder where the Germans got their rubber, unless via Vichy France and Indochina. Still you had to ship it, using neutral shipping, but how would a submarine know? The history and struggle of Allied merchant marine is known, but I wonder about the Axis merchant marine.

Lack of access to raw rubber meant the use of more recycled rubber crumb. In grappling with the modern problem of vulcanised tyre recycling, a great body of scientific literature exists on the topic from WW2. But this was more for applications like tank wheel lining or solid rubber tyres for artillery pieces. I doubt whether raw rubber watch holders were used after 1941, as much as the old fob watch was replaced by the wrist watch. The old rubber watch holders would be made from high quality rubber. I understand that aircraft tyres would require high quality rubber : there was a great movement towards standardisation of tyre sizes to make use of rubber more efficient. I understand the development of polyurethanes and nylons was the key way Germany dealt with the rubber tyre question. Dealing with the chemistry of early polyurethanes would be very challenging.

I understand that in any vulcanised natural rubber presentation some material would remain unvulcanised : that a solvent may ‘swell’ some part of a formulation to create some pliability. Rubber science is quite established and accessible, even though most rubber product manufacturing has shifted to China. A good ,practical understanding of rubber chemistry might be got from the local retreader, and they might have some insight into compounds that affect rubber.