Well I hope you win lotto and get some cash together for the multitude of hollow rivets needed to pin it all in place.:dev2:

Hollow rivets are T26 ! Different Association !
For complete authenticity these structures should be put together by Rosie the Rivetter. So at this stage the project plan calls for ten chicks in bikinis spin rivetting away….
There may be some resource allocation issues, which may result in an alternative reality where I am left by myself in a cold shed late at night, fitting ferrules, muttering and farting…:p

Here is the schedule with Gladiator included in red.

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Because I was eating chocolate cake instead of drinking wine while I was doing the Typhoon schedule I made the error of not doubling the quantities for the fuselage side members. Ie, I only counted one side of the fuselage. This has the affect of increasing the Typhoon values in the latest graph. Thankfully I will not be in charge of calculating oxygen requirements for a Mars mission otherwise the intrepid astronauts will be tapping the bottles half way out….
I must also admit that the Typhoon information I am working from does not also specify whether tubes are T4 (aluminium) or T50 (steel alloy), so the values may have to be revised by a concerned member of the Tiffy Brigade.

In doing the Gladiator work I did not repeat this error, firstly making sure I had opened a bottle of Argentinian Zuccardi Malbec 2012. What stands out is that three different tubes in a tight range constitute 70% of the requirement, with small quantities of outliers.

Then the beautiful thought came : We should not worry about cold drawing the outliers. The smartest thing to do would be to not worry about tooling for these micro quantities. It would be cheaper to use existing tooling that outputted a thicker wall tube then machine/bore out the ID, given the affected outlier members were all short length, approx 3 foot. In other words commission 3% Nickel blooms that run through some cold drawing internal mandrels for the big runs, then use existing tooling for the little runs. Even cheaper, but cover the whole range.

Treasures

Here are two things which raise my pulse these days :

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A piece of rusty steel, not just any common corrosion, but a remnant of Bulldog fuselage vertical strut.:love-struck:
This piece is a mine of information for forensic metallurgy. A small slice can be embedded in clear, solid resin and then polished to reveal the grain structure of the steel alloy, a vital piece of information to assist in understanding its performance. Another small piece can be tested for its chemistry, to provide a confirmation of the alloys used in a known aerostructure, to provide a further dataset to support modern material selection for a modern replica aerostructure. Under the microscope, lost specifications for the type of rivet used to join the section can be confirmed. It is a remarkably useful piece. I would be grateful for anything like this from long lost aeroplanes like the Atlas or Wapiti to help build an understanding of the DNA of these designs. It can look even less spectacular than this piece, as long as it is identifiable to a particular type.

The other thing which excites me is this vintage Avery strip steel fatigue testing machine recently found.

[ATTACH=CONFIG]237351[/ATTACH]

Now we can take modern materials and test them in comparison to each other, to further validate some of the design theory behind strip steel construction. A piece of remnant 3% Nickel T50 tube can be extracted as a flat strip and compared to an identical piece of modern 4130 tube extract. The machine basically grips the test pieces at both ends and applies an cyclical load until the piece breaks.

[ATTACH=CONFIG]237353[/ATTACH]

The longer it lasts, the longer its fatigue life. Particularly good for flying wires and exposing things like the affects of thread cutting on flying wires. All this stuff was bread and butter learning for engineering students a few decades ago. These students then went on to write clever software to simulate this on computers and the pesky old analogue machines were scrapped. Today’s engineering student would probably just laugh at the fatigue tester and ask what it is. But there is nothing quite like watching a piece of metal break in front of your face as a counter clicks the cycles over and you sit rolling in a rocking chair watching it with a cigar and cognac.

Another very useful attribute of this machine is to apply a preload to the test piece, to see how it performs when the actual fitting of the material into a structure creates a pre stress that in some cases may equal service stresses.

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An example of a pre stress is a fence wire pulled tight. The fence just sits there but if you apply a ‘service load’ in the form of a prize bull rubbing against it the wire may snap in comparison to a ‘looser wire’.
In strip steel aircraft construction, the steel alloys used are very resistant to forming. So if you have a poorly formed section that is then riveted together the structure can be loaded with a stress that significantly affects actual performance in service. Though on paper the mathematics say the part should survive a service stress, poor forming means it can fail in service. Another indication of this is twisting and buckling in the frame that has to be forced back into shape with jigs. The same problem manifests in welding as weld heat zones expand and distort around cooler zones. Gosh when I flick back through the card files in my mind I remember forcing metal into places it didn’t want to go, when I should have stopped and had a cup of tea and thought it through !

I need this kind of learning because when I was a 17 year old doing up a 1963 Nissan Cedric and I changed the crankshaft bearings over I never thought about checking bearing thickness, just popped them in. Of course somebody had put mixed the bearing shells back in the factory and the crankshaft refused to turn when it was all back together. :confused: So we towed the thing to the top of the hill in neutral then towed it to speed down the hill before I released the clutch and simultaneously my forehead hit the dashboard and the crankshaft loosened up. :p
So now I need to do things with a little more sophistication…

Let then eat cake

Here is the schedule with Quantity for Typhoon entered. I would like to thank Dave and my friend the chocolate cake for repeated support during this phase of data entry.

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The key realization is the fairly even spread of ODs in these monoplane, half monocoque, structures and drift towards larger ODs. I assume that Tempest exhibits a similar pattern. The benefit of a collective approach is to force the production of small volumes on the outer like 5/8″ and 3″ OD within the scale provided by smaller ODs common across designs.

The extra nutrition offered by the chocolate cake has also made me reflect on the fact that up to 30% of aerospace tube may be rejected upon inspection, which is folded into the final price of retailed tube. Thus if you could reduce the reject rate then there is a conceivable reduction in price of up to 30%, which is significant and would help support the production of the smaller volumes on the outer. On top of carefully producing the bloom from which tube is ultimately made another opportunity is to make it a condition of the tender that reject tube is recovered rather than immediately scrapped. Ie – a cold drawn tube may be 30 feet or 10 metres in length in the factory, while final demand requires sections that are 2-3 foot in length only. In the usual production process, a flaw detected by ultrasonics may only occupy a few inches of a 30 foot tube, but the whole tube is rejected by Stacey from QA. In the proposed approach, the flaw area would be marked and the reject portion cut out, with the balance of the tube retained for use. In this case reject may be reduced from 30% to 5%, a very significant saving. Thank you chocolate cake, you cost $3 but the Return on Investment has been handsome.

It will take some time to input the Hurricane and Gladiator tube lengths. I only have the tube schedule and my thumb to roughly scale off. If anybody has a list of tubes and lengths in these aeroplanes or any other types using T50 I would welcome being able to borrow this to speed up the process.

The graph starts to show the boundaries of the tender proposition. I am going to enter some arbitary best guesses as to volume of aeroplanes of a particular type to be restored/maintained over the next decade into the individual schedules to create a total length and mass of T50 required.

Thus I will propose the following :

Hind (Hart family including Demon) – 10 aeroplanes
Gladiator – 3 aeroplanes
Hurricane – 10 aeroplanes
Typhoon/Tempest – 5 aeroplanes

Within the mix for biplanes may be the odd Wapiti or Wallace or Siskin.
This would be as real as whatever you volunteer or argue, publicly or confidentially, may be projects requiring T50 in the next decade or so.
Yes you can use T45/4130, but the initial tube affordability is balanced by serious hurt money incurred in the engineering costs of material substitution and structural analysis.

My gut feel is that a certified T50 production run with a 5% reject rate, well negotiated with a sympathetic aerospace tube mill, with internal mandrels (fit for purpose) and high quality blooms from an aerospace casting plant externally provided by the Association, will be affordable. Whether this intersects with a users capacity to pay or timing of projects on the day the T50 is run will determine whether you can get material at cost price on the day or at additional cost when you are ready later. I would welcome any member willing to enter into any bulk order for profitable sale later on. Anybody willing to risk investment in stock costs, storage and piecemeal sales over time deserves to make whatever profit that market will bear. Once the Association is dissolved and internal mandrels scrapped, “that’s all folks.”

It probably pays to be inter generational though. We need to support the 20 year old today that will take the baton from you in 20 years time and be required to maintain or restore pin jointed tube structures in the future. No doubt 3D printing would have made tube mills obsolete by then ! It would be a good thing to run material and carefully preserve it to be held in trust for somebody eating an ice cream on the flight line today and dreaming of the day when they could work on a Hind or Typhoon. So I would welcome any philanthropic subscription to a volume of production that could be kept wherever the contributor sees fit for later distribution in any way they see fit. I wish somebody :angel: :dev2: had greased up some Merlins and buried them in crates for me decades ago in the same way…:)

Plan A for Adam

Here is a basic Commonality Chart for T50 for Hind, Gladiator, Hurricane, Typhoon. I have not included data for Henley. Apologies to all Henley restorers out there. I have no data at this stage for Tempest. I have no data for Wapiti or Wallace.

The column on the left refers to outside diameter (OD) and then gauge or wall thickness within the OD. These are just fuselage members and do not include T50 in spar liners, aileron spars etc.

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The obvious patterns are smaller diameters for biplanes and larger diameters as monoplanes develop and accommodate greater stresses through the members.

In this chart the relative quantities of various diameters and gauges are not indicated. There will be less 5/8 and more 1 3/8 required, for example. The next step is to add a third axes to the graph that can represent this. This requires a lot more wood chopping to enter the lengths of each individual member within each airframe. Just from looking at this graph and the tube schedules, I get a sense that 60% of the problem for all these T50 thin gauge aeroplane structures is addressed by focusing on 6 tube OD’s.

After understanding the relative quantities required the next step is to enter an estimate of airframe project numbers over future years into the data. There will be less Gladiators and more Hurricanes, perhaps. This data can then be used as the basis for a tender.

In general the following things become apparent within the tube manufacturing task :

Many of the ODs are available in current T45/4130 production, so there is no need to pay for external dies or changes to the processes leading up to cold drawing, except starting with a billet of 3% Nickel alloy steel rather than Chrome Moly.

Much of the demand is within a band of 6 ODs from 1″ to 1 3/4″ with step downs in gauges, meaning a large quantity of a particular OD to the thickest wall section can be made, with portions taken out to be worked down to thinner wall sections.

Total demand can be satisfied be the provision of 23 internal mandrels, basically machined bar. This is not building a space shuttle, but the stuff being whipped out under corrugated iron in India and China. It used to cost $30,000 to machine a helical screw shaft for a plastics extruder a decade ago, but these now float down the Yangtze for $5,000 or less. We are talking about a round bar, not a helical screw shaft. It should not be that expensive in today’s world. Not a lot of material in a 1″ diameter bar. These mandrels, once the needs of the T50 Association are satisfied, may as well be used for caber tossing afterwards. They do not need to be made out of titanium. The 5/8 mandrel may only do three draws, not the thousands that normal mandrels made from expensive alloy are required to do. So maybe the Association commissions the mandrels to fit the chosen plant, and all it is tendering for is plant time. If you leave the mandrels to the plant they might do them to last a hundred years and charge accordingly. Try one caber mandrel and see how it goes.

Where you would have to spend a lot of time is with the bloom, the chunk of 3% Nickel alloy steel that the whole tube making process starts with. Here you would pay a premium to get the most beautiful bloom in the world and your reject rate would go down. For a tube mill, who normally wear the cost of rejects, it becomes easier if the Association carries this risk, and the risk originates in the bloom. So the Association commissions a bloom from the best vacuum furnace aerospace outfit it can find.

So most of the work for a tube mill is straightforward and profitable. After running standard T45/4130 of a particular OD a bloom of 3% Ni is slotted in at the tail for heat forming into the raw material subsequently cold drawn. These raws build up at the tail end of standard production of various ODs until the Big Day. Then Al, the best cold drawer in Texas, runs all the ODs and gauges in one 48 hour pizza and coke fueled session followed by Stacey in QA doing the inspect over the next 14 days. Then it all gets divided into who wants what and shipped out. Sounds like a plan.:)

Zombie dawn

The T50 & T2 Tube Association is dead.

For the avoidance of doubt and distress I wish to clarify that from the ruins of the previous initiative the T50 Association, solely focused on T50 tube supply, still exists. Just made the T2 chapter walk the plank and took over their biscuit supply and parking spaces.

The guru says that the original Maintenance AP for Spitfire allows T45 substitution for T50 in the pin jointed engine bearer structure. Anybody got a copy of the Vol II Spitfire Maintenance AP ?

I understand this may mean :

a) Same wall thickness T45, proof tested to T50 values, replacing same wall thickness T50.
or
b) Thicker wall T45 replacing thinner wall T50.

I would be grateful if anybody could clarify this.

Need data.

I think you are overthinking the problem.

If you buy certificated T45, it comes with a test certificate which has all the information you need to make the choice. Some of it will meet the minimum spec for T50, and the work has already been done for you.

Bruce

I overthink that underthinking is more damaging to the human condition !:p I should work for the US State Department…..

I would dearly love a simple answer. I accept that there is one path as you have highlighted, but there can be many ways to skin a cat.

Given this constraint :
T45/4130 cold drawn aerospace tube is widely available in sought after OD sizes, but of greater wall thickness.

I have the following choices :

Option 1. Use it ‘as is’, but incur costs of testing to T50 spec (constraint 2 : many members of various sizes in one airframe) & incur costs of re-engineering structure,

Expressed as : 1lb X 2 (testing cost) X 10 (re-engineering cost)= 20lbs cost equivalent for 1lb tube ACCEPT.

Here is what I am really after, stuff to make the boiling water in my brain go to steam ::)

Option 2. Line bore tube to achieve desired wall thickness.

1lb X 2 (testing cost) X 3 (boring cost) = 6lbs cost with technical problems (?)

(NB Constraint 3 :line boring 11 foot tubes typical in pin joint structures between cockpit and tail is problematical)

Option 3. Cold pilger tube to achieve desired wall thickness.
https://www.youtube.com/watch?v=tkGD7fr_Sos

1lb X 2 (testing cost) X 3 (pilger cost) = 6lbs cost with machinery access problems.

(NB Constraint 4 : cost of internal mandrels and access to plant otherwise employed on large commercial runs)

My thoughts around this option are to adapt a roll forming mill used for strip steel to this task, only because one is available to me, and there is very little chance of getting access to a pilgering process, at this stage.

Option 4. Commission a cold drawing tube mill to make T50 to the original specification

1lb X 5 (being premium for short run and cost of internal mandrels) = 5lbs cost

(NB – Constraint 5 : Scale of aggregate demand for T50 and timing of collective requirements)

So what I am doing in this post is testing Constraint 5.

I am also seeking to test the arbitary factors applied to the reasoning. Is it really a factor of 10 to re-engineer an airframe, solely in respect of the tube component ? If this has already been done, is this re-engineering for Hart family – Hurricane – Tempest commercially available as a fifth potential option ?

Is it really a factor of 5 to commission a run of T50, ie five times as expensive as T45/4130 material? The way to find out is to issue a tender for supply.

I am also seeking to test the concept of collective purchasing, in that items of original manufacture depended on the collective purchasing power and scale demand of governments, funded by collective taxation. It is almost impossible to mimic this process as an individual today. I can’t see any other way of resolving perennial challenges such as LH tractor blade forgings for British radials and other such bits and bobs.

I am now going to eat an ice cream to cool my head down:)