Handheld XRF Metallurgical Analysis

Show me a photo of Gilman

p&p

Are current Merlins fitted with Gilman bearings ? Does this explain the engines apparent reliability?

No and yes and ‘don’t know’!

Steel backed shell bearings were a Gilman patent in 1938 but RR went for silver indium as an alternate to copper lead and didn’t have to pay royalties. I figure there was much cross pollination/theft of IP in the 30’s.
It’s hard to ascribe the successful interplay of many components moving at 2500 RPM to one singular design aspect or one single innovator, though the driving force of individuals such as Gilman at Allisons, Fedden at Bristols and the wandering ghost of Royce tended to create a great result.

Gilman is that most unAmerican contributor. This is no self promoter. I cannot find a photo of him anywhere and even the history of the Allison engine coy does not have one and provides a sense that he was a secondary figure. In terms of reliability the Allison of WW2 was very reliable. I figure a designer in California or New York understood an engine failure meant a three week trip on horseback to bring in a replacement for a busted valve spring, so things were sturdy. Things were easier to get to in Europe so a premium was placed on lightweighting and performance. This cannot be proven but you get to wonder when you look at an RR conrod that feels like a bone in a bird’s wing and then an Allison cylinder liner that could probably double as a mortar tube. Probably Russian engines are the same, same three week trip on horseback to change a spring.

I do not think an honest RR development engineer in 1938 would have had much confidence in the developing Merlin. Coolant leakage around cylinder liners was one issue. In the end, of course, a remarkable powerplant.

I have a BBC recording of a Mosquito doing a flypast during WW2 and it doesn’t sound like a Mosquito. I have seen KA 114 fly in NZ and that is a Mosquito ! A loud thing. But the BBC recording sounds like the 1908 Tunguska Meteorite impact meshed with the sound of 15 freight trains running over the foot of Godzilla ! Literally a bunch of 20 something pilots with a smile on their faces and the throttle full forward flogging the chicken crate across the sky. Good chance of punching a conrod out the side. I know I will never see something like that ever in my life. For good reason warbirds are run the way modern children are introduced to swimming, blue faced, anxious parents blowing up inflatable devices to keep them dog paddling in the shallow end. Merlins today have more medical imaging and cosseting than the entire heath budget of sub Saharan Africa in aggregate. The poor things don’t get a chance to be unreliable !

Stop asking questions that get me off topic ! No more questions requiring rambling answers unless you open your wallet and put some top shelf liquor on the table ! 😉

..”bile from other sources…”

I’m ready to donate.

:p I am already self powering the thing ! Thank you for your offer and good humour !

p&p

Are current Merlins fitted with Gilman bearings ? Does this explain the engines apparent reliability?

..”bile from other sources…”

I’m ready to donate.

C’est ne pas possible !

Last post, I promise ! (on this topic 😉 )What I like the most about instant answers are instant new questions. Here is a Gilman bearing from a RR Kestrel that comes up with an astonishing value for Silicon in the steel shell component. I would not believe that so much silicon could be in a steel alloy, surely making it so hard it would snap. After the Lab V XRF test, I have to believe that I am not being taken for an XRF ride. Ferro silicon alloys are used in electrical transformers and are those thin steel wafers you see laminated together and are used for their unique characteristic of absorbing magnetism.

Until the Gilman bearing patent came along RR had lots of trouble making their R and F engines of the thirties to work, the increased HP chewing out the white metal conrod bearings. Then Mr Gilman of the Allison engine company invented a bearing that RR took and paid a royalty for, that made the Kestrel and ultimately the Merlin workable. Chas Lindburgh achieved fame in 1928 for crossing the Atlantic because the engines of the day were certain to fail on such an epic voyage, but he used Gilman bearings and made it.

http://forum.keypublishing.com/showthread.php?128767-RR-Kestrel-Gilman-bearings&highlight=

Now is it possible that the secret behind the Gilman bearing was an ultra hard silicon alloy steel bearing case, connecting to a 5% Nickel conrod shaft ? A metallurgist is as likely to put 13% silicon in a steel as you are to put bourbon on your cornflakes, but perhaps the best discoveries start from an unusual breakfast. Now XRF is my trusty companion on new voyages of re discovery.

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Lab V XRF

Back to business ! So the ultimate test for XRF is to compare the cuppa soup, 9 seconds to get result, XRF LCD display with conventional spectroscopy via a lab, which took two weeks to arrive, cost a lot of money, needed me to destroy the original piece by cutting off a slice and get a paper cut slipping the test piece into an envelope…

The test piece is Hawker Australian Demon spar, albeit two different locations on the same piece. % Results are :

LAB V XRF :
Mn 0.56 Mn 0.625
Ni 4.56 Ni 4.91
Cr 1.20 Cr 1.04
Mo 0.09 Mo 0.023
V 0.15 V 0.167

So I am pretty happy with XRF to give me PMI as good as the lab in 9 seconds at $5 per result, given that I will hire the unit for one day and do many, many tests. I did not clean the corrosion off the test piece either.

So XRF will lower costs, increase safety and make historic aircraft restoration more effective.
It will not do to leave this on such a positive note, given the zen of the forum, so I must unhappily report that XRF is powered by extracts from the bile ducts of caged baby pandas, though efforts are being made to replace this with bile from other sources, grumpy old goats being a promising line of inquiry.;)

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Beyond all expectations and written with powerfuul imagery. Informative and amusing to boot or, should that be Booquito !

I now stand here bereft of any ammo for Bruce !!

p&p

In your opinion, had it been available in quantity, using Duralumin in the manufacturing process of the Mosquito, would the all round performance of this aircraft been much better than the timber version or, about the same. Setting to one side suspicions about chemical solutions and airframe integrity.

Ahh, you have me ! The Mosquito. The question is like the scientific aphorism of Adam’s navel : If Adam was formed from dust, and did not come from a womb, would he have a navel ? The Ecclesiasticals therefore gave Adam, in image, a fig leaf to cover his belly button, not his modesty, as the question could not be satisfactorily answered. So too this question can never reach a satisfactory conclusion. But we are talking about something more important here than the birth of mankind, the Mosquito, so here goes :

Economically the timber Mosquito WAS better than the Duralumin Mosquito, the Duraquito, let’s call it. I mean in the context of 1940, when metals and metalworking capacity were scarce. Even before it flew it achieved that optimum defined by Von Clauswitz in “On War”, to apply the minimum economic effort for the maximum gain. You cannot argue against turning piano and furniture makers into agents for the delivery of Cookie bombs into the breakfast bowl of Adolf Hitler. I am reminded of the postwar analysis that exposed the Mosquito as the instrument that delivered more munitions into the hide of Nazi Germany at least cost of aircrew than any other weapons platform, so the choice of a timber platform linked to a hot engine design, because it could be built so quickly by an underutilised sector of industry, means that it IS better than the Duraquito.

In respect of the material, the timber ply, monocoque structure was as strong, if not stronger than the Duraquito. As we all know with a cardboard box, the forces it resists are carried in the paper surfaces that are separated by the corrugated centre. Larger corrugations make stronger boxes, separating the planes of stress. You get some corrugated cardboard boxes which are two or three layers thick, which you can park your car on. So the Mosquito had stress bearing birch ply layers separated by a quarter inch of balsa, a remarkably strong materials solution, that carried through to Vampire Jets and is revisited by today’s non aluminium honeycomb structures. Of course the Duraquito could be built to cope with similar stresses, but I go back to point 1, economy in war materials and manufacturing. Of course the Mosquito was designed as an unarmed, reconaissance platform, but was quickly pushed to carry extraordinary weapon combinations. In one recollection of a Navigator in a FB version, the cockpit floor would jump when the FOUR 20mm cannon were in communication mode with Panzers. In this case the modulus of flexibility in a wooden airframe is in demonstration, the whole structure absorbing the kickback, some of course through the chattering knees of the Nav. I do not think that an unarmed, recon Duraquito would have within its original aluminium structure the same ability to take punishment or be adapted to be a weapons platform as widely as the Mosquito, passed from devilish fitter to devilish fitter. I concede that four duralumin beams were installed behind the cannon in the Mosquito to dissipate the recoil force over a larger area of the timber structure, but I think many spanner wielding folk played this game called ‘see how much we can stuff into a Mosquito before it cracks in half,’ and the timber thing proved to be as tough as an old boot. In fact I am surprised that deHavillands DID NOT make a version out of old boots, the Booquito…

We can go on for a long time, but I have no smoke filled, sticky carpet bar in front of me, no half empty bottle of Penfolds Grange in front of me, so the fuel for my mind to generate more nonsense is lacking. I will however touch on the senses, most neglected in these types of discussions. Briefly, the Mosquito smelt good : it would be a pleasure to be in a woodworking shop, perhaps the whiff of pipe smoke in the air, genial conversation with some humble old furniture maker as the Mosquito was whittled into shape. Compare this with cruel light of a Duraquito plant, the incessant rattle of rivet guns and drills, all those women swapping Oxo soup recipes, a cacophony of smashing pots and pans and sisters staring at you with powerful drills. Then of course there is sound : the doped fabric/timber surface of the Mosquito created an extraordinary sound reflecting surface, in particular between the fuselage and the inboard exhaust stacks of the Merlins. This sound was cupped and reflected from the under surface of the huge wings. So first there would be a subsonic projected pressure wave, then the explosion of Merlin sound as the Mosquito flew over you, unpeeling the paper from the Gauloise in your mouth, as you jackbooted up and down the seawall at Normandy. Nothing like the Duraquito, which sounded like a Beech King Air with fouled spark plugs, only good to send as Lend Lease to Russia.

I trust I have been of assistance.;)

p&p

In your opinion, had it been available in quantity, using Duralumin in the manufacturing process of the Mosquito, would the all round performance of this aircraft been much better than the timber version or, about the same. Setting to one side suspicions about chemical solutions and airframe integrity.

Duralumin, a German invention, was the moment when aluminium alloys came of age, the point when the strength to weight ratio of aluminium finally exceeded wood. Zeppelins bombed London in WW1 courtesy of duralumin, and technology transfer became a matter of scraping up crashed Zeppelins and looking at their metallurgy under the microscope. So you start to see aluminium components replacing timber in the aerostructures of the 1920’s, and I can drink 5 pints of larger and run my tongue over a 1930’s British aluminium remnant and proclaim it as Duralumin and be correct, for entertainment purposes for the up and coming generation. Still, it will pay to XRF the thing beforehand, just in case !

Interestingly the metallurgical library comes up with the US standard 2014 as the nearest equivalent alloy, and this is right ! But you can’t get 2014; you can get 2024 in lots of different gauges. But 2024 has more ‘springback’ than 2014, so some of the press shapes achieved out of duralumin in the 1930’s may not be achievable out of 2024…..

Then you need to go to the wise old happy man in the shed*, and he will give you the answer.

Below is the aileron gearbox surround for the Hawker Australian Demon, BS L3, German Zeppelin.

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*You must travel far pilgrim, but if you thirst and are resolute, you will find !

Tungum Tales

Another thing I like about XRF are instant answers that allow you to progress your thinking. As a child of cuppa soup and TV remote controls, I really don’t have the patience to wait for weeks to progress an inquiry, it becomes all too hard when there are better things to do like finger piano the iPhone and look on this forum !

So I think a Merlin coolant pipe might be Tungum, a copper alloy, but I don’t know, so I put it back on the shelf until it is picked up 15 years later at my estate sale. Instead, I get an instant PMI that let’s me know it is a simple copper alloy that needs to be manipulated differently to Tungum. I don not need to find a Tungum expert, I can wander down to the old blokes at the minature steam railway workshops and ask them about manipulating copper tube, without troubling them about Tungum. No doubt the old bloke I meet worked at Tungum in 1963, but we can steer the conversation forward rather than conclude we need a PMI first…

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Magnesium

Thank you JG.

But wait ! That’s not all !

One thing XRF can’t do are elements to the ‘left’ of Aluminium, which in aerospace is Magnesium. It will, however, pick up other alloying elements to assist in identification of the Magnesium alloy. Below is an ‘Elektron’ Hawker Demon cast magnesium wheel, and the reading shows no magnesium. Elektron is a trade name and in the early days covered a group of magnesium alloys, so this helps to positively identify the alloy.

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One useful thing XRF could do is an instant, non destructive,low cost survey of structural components in an historical airframe to identify magnesium. It may surprise you what is made out of maggy. Because of the square crystal structure of magnesium stress corrosion cracking of 70 year old magnesium is highly likely. Expensive old Grand Prix cars from the 50’s with magnesium suspension components, in the hands of caring owners, get the magnesium replaced after a certain number of hours lest a failure occurs at speed. There is one warbird in the most beautiful country in the world that was forced into a wheels up landing due to failure of a magnesium undercarriage component. Expensive.

Great thread ! Full of stuff that I knew nothing about.

A good read, thanks

Thank you

Reads like an infomercial for a product.

Is it?

It wasn’t, but what a great idea ! Most of the information distilled out of all this clumsy experimentation and kite flying I will put here : www.silverbiplanes.com
Have a look, take a biscuit out of the jar, if you want, and put another different one back.

One day I might print tea towels with DTD specs matched to SAE standards !

I will always welcome constructive criticism : I do want to learn something from it. Give me some facts to take me further along my journey and I will send you a tea towel.:eagerness:

Thank you Eddie

I don’t think it is – Mr. “powerandpassion” is a bona fide enthusiast

As to the subject matter; handheld XRF is useful, but its limits have to be understood –
it won’t get you to a specific grade,

I think the pricing is a little off for analytical services, too

cross check the ID with other sources if you’re replacing material.

Thank you Eddie for your back up.
I am just learning about this new tool (for me) and interested in its potential and also downsides.
I agree it will not provide carbon values nor is does it provide an engineering dataset.
I like it as a quick survey tool that, in combination with other immediate datasets like hardness or material knowledge and artifact context can ‘put you in the picture’ and inform subsequent, more detailed (expensive and time consuming analysis).

For basic PMI for new material it’s a great tool.

Much industrial use of XRF for PMI is to check stainless grades in food manufacturing machinery. My XRF trainer, in this application, can now tell from the readout whether the stainless material came from China, Korea, US or Germany, from ‘national signatures’ and even from what mill, via “mill signatures”. Lots of stainless is not what it seems in food and pharma. I do hope, eventually, to be able to know from which mill particular grades of historical aerospace material came from, which I trust will come with exposure to many different samples.

Chips are made from potatoes, but some shops seem to be able to make great chips. There seems to be great variability in aerospace materials too, from what I am starting to understand.

In Australia, getting analyticals done seems to take a long time and cost a lot more than where you are (USA?). Can you provide me with contact details for a good lab or three there, because it makes no cost difference sending a fingernail of material there or here, when I can get fast turnaround and a great price.

Thank you,
Ed

A good read, thanks

I don’t think it is – Mr. “powerandpassion” is a bona fide enthusiast and has posted frequently about metals.

As to the subject matter; handheld XRF is useful, but its limits have to be understood – it’s a positive material ID (PMI) tool, rather than an analytical one. For non-stainless steels in particular, it will usually get you the alloy family, but it won’t get you to a specific grade, because it can’t give you the carbon or sulphur content (so a free machining steel will show the same as a mild steel, or 4130 will show as the same as 4150, if I recall correctly). I think the pricing is a little off for analytical services, too – I think (offhand) that our aerospace accredited lab charges about $50-60 for a full analysis by atomic emissions spectroscopy (which gets the carbon and sulphur content). Certainly not cheap, but it can be done for less than $500! The obvious disadvantage of it is that the material needs to be small enough to be sent to the lab and put on the machine, and it will get damaged in the process.

In short – XRF is useful and can provide a quick ID, but cross check the ID with other sources if you’re replacing material.

Reads like an infomercial for a product.

Is it?

Here is the spindle holding the chain sprocket within the aileron gearbox from a Hawker Australian Demon.
I would assume a modern equivalent would be SAE 4130, but XRF shows 3% Nickel alloy steel, a high strength, highly flexible and fatigue resistant alloy,

The reported analysis matches BS S69, closest SAE equivalent is SAE 2330 – 2340.
BS S69 matches Rolls Royce specification 2063, 3.5% Nickel steel.
SAE 2330 is reported in “Aircraft Materials”, Titterton 1937, as “the standard Nickel steel, possessing good strength and great toughness..used for high grade machined parts such as aircraft bolts,turnbuckle eyes and tie rod terminals”.

Nickel steel was developed in the 1920’s for high stressed automotive applications such as steering columns.
Steels are remarkably varied and there is more than just SAE 4130-4140 out there !