SPIT aluminum

Creaking Door, Thanks for that info. ‘Measured’ is good enough, and 9.950″ sounds like it might be the real number anyway. A lot of things on the Merlin seem to be multiples of .025″ !

Chumpy, Thanks too. That clears up a mystery for me.

Cheers,

Speedy.

Surprise

Digby

The 22swg Spitfire skins are made from ‘unobtainium’ or as our US cousins call it – ‘unobtainum’. 😉

Mark

Surprise! Although aluminium is quite correctly “aluminum”, unobtanium is also very “unobtanium” over here in your former colonies. :)-

Does anyone know the exact big end to small end distance of the Merlin conrods? I want to make a rough kinematic model.

Not exact, but it’s approximately 252.75mm (measured) so possibly 9.950” as designed?

Hi Speedy,
The usual rules apply when folding L.163 / DTD390 both much the same material. If you are going to do 2T bends the material will require solution treating. This standard practice within Supermarine and the aircraft industry in general, for most formed sheet metal items regardless of gauge / bend rad.

You might well get away with doing it cold in thin stuff, but 18swg/.050″ and over it will no doubt be very prone to cracking along the fold.

As for the Merlin con-rod bit…I have no idea. I expect Merlin Pete does!

Cheers, Chumpy.

Bend Radii

Does DTD390 ‘tin’ and L163 ‘tin’ allow the same bend radii? Where I work we don’t go tighter than 3T internal on L163, but I note some Spit drawings appear to show DTD390 bent at 2T internal.

Completely unrelated…. Does anyone know the exact big end to small end distance of the Merlin conrods? I want to make a rough kinematic model.

Cheers,

Speedy.

Hi mate,

The tin that you’re referring to, is probably DTD 390, which was a standard ‘Alclad’ Aluminium Clad Aluminium Alloy. The 20 s.w.g. refers to the thickness, which, from memory, is 0.9mm thick.

It has now been superceeded by BS L163, which I believe is Internationally designated ‘2014 Alclad’.

As an aside, L163 is what we are using as a replacement for the obsolete L72 on Vulcan XH558.

Hope this helps

Flipflopman

Good day. I am in the process of doing a repair on an otherwise airworthy Vampire Mrk III. We had an incident in our hangar that caused some hangar rash to the LH Aileron and tab. The manual specs show the material to be D.T.S. 390 and SWG 20. It is identified as Alclad. Can anyone supply me a north american (Canada) equivilant? Cheers 🙂

Alclad (Aluminium Clad) is a sandwich of duraluminium between outer layers of aluminium and I hope that someone with more metallurgical knowledge than myself can help you a lot more. Below is a U.S. link for a supplier which may be of use. Welcome to the Forum and good luck with your project!

http://www.indmetals.com/productslist.asp?material=Aluminum&form=Plate%20Alclad&cmd=reset

Material assistance

Good day. I am in the process of doing a repair on an otherwise airworthy Vampire Mrk III. We had an incident in our hangar that caused some hangar rash to the LH Aileron and tab. The manual specs show the material to be D.T.S. 390 and SWG 20. It is identified as Alclad. Can anyone supply me a north american (Canada) equivilant? Cheers 🙂

I’ve got bloody thousands of the “purple riverts” in my garage, must be close to 150lb of them, all sizes 🙂

All packed in loverley sticky grease in brown paper packets no doubt? 🙂

Fellow frieks..

The term of endearment here in Auss is “Tin Basher”..And damn proud to be one of them…And don,t the other trades hate us so…
“Brrrrrrrrrrrrrrrrrrraaaaaatttttttt”..bit more..”Brrrrrrrrrrrrrrrrrrrrrrrrrrraaaaaaaaaaaaattttttttt”:dev2:

Avdels, by the way, come grouped with their own P/N and not with any kind of solid No.

They are usually ‘snipped’ and then milled down to 0.001″ clearance to finish.
As I am sure you’re aware 😉
Flipflopman

Indeed I was aware 🙂 and many a mess have I seen of that milling job.:(

Maybee you will all get it right eventually

Hi Phixer,
No offence intended by the term freak, just an old 1970s term of endearment! Likewise I also make my living in aircraft sheet metal / fitting and have done for many years, currently with a certain company on the IOW involved in things Supermarine etc.
Alas as the years roll on all those old Brit rivets are becoming an endangered species, with the world taken over by U.S. MS /NAS stuff. Though I have to say those yank radius-tail rivets produce a nicer looking job than SP71 / 80s etc.
And yes those black, double CSK rivets mentioned by Flipflopman do come in real handy when you are having a bad day!
Attached is a shot of some original 1940s Supermarine ‘mixed variety’ rivets, on this occasion the mag ones as good as the day they were put in. Other times they just turn to dust!

Chumpy….from the land of the 2BA bolt etc!

I’ve got bloody thousands of the “purple riverts” in my garage, must be close to 150lb of them, all sizes 🙂

How long have you owned the Shack? 😀

I’ve got bloody thousands of the “purple riverts” in my garage, must be close to 150lb of them, all sizes 🙂

Hiduminium is (or possibly nowadays – was) a trade name belonging to High Duty Alloys. On it’s own it doesn’t really mean anything, apart from who made or developed it. IIRC, it used to be followed by a number, e.g. Hiduminium 77.

Duralumin is also a trade name. Last I heard it belonged to Alcan but if that’s still true I’ve no idea as I’ve been out of the aluminium business a long time. Again, it doesn’t really mean anything on it’s own but has become a generic term for any reasonably high-strength alloy. I did know at one time which alloy the name was apparently originally used for but it’s another of the many things I’ve forgotten over time.

Avdels, by the way, come grouped with their own P/N and not with any kind of solid No.

They are usually ‘snipped’ and then milled down to 0.001″ clearance to finish.

As I am sure you’re aware 😉

Flipflopman

Hey! I am no freak only a chap trained in aircraft metal working, and a whole lot more, who happens to have used these things, in anger so to speak.;)

Hyduminium rivets were useful for repair, or other, work where salt bath, or other, heat treatment facilities were unavailable.

THey came in standard solid varieties, snap-head or countersunk, or as an Avdel type (a fancy looking pop-type rivet but which left a portion of snapped off mandrel which required trimming down with a special, often pnuematic driven, rotary multi-edged cutter.:)

Phixer,

As far as I am aware, the ‘Purple’ rivets which I jokingly refer to, are Duralumin, rather than “Hyduminium”??

You are correct in that they come in different head sizes, SP40, SP80, SP85 etc…. 60 degree, 90 degree, 120 degree heads etc.

However, the ‘solid types’ are only the Snap, Mush or Countersunk variety.

I too use these rivets on a day to day basis, including the green Mag alloy rivets, and the special “Hush Hush, Double Flush” Black rivets, so have a pretty good day to day ‘Rivet Knowledge’

As far as I am aware, the green Mag rivets would have been replaced by the ‘Purple’ duralumin rivets, and L72/L163 as time went on..

Flipflopman

Hi Rivet freaks!

Hey! I am no freak only a chap trained in aircraft metal working, and a whole lot more, who happens to have used these things, in anger so to speak.;)

Quite common to find both the green mag-alloy and purple rivets alongside each other in bits of structure i.e wing ribs etc. Never quite figured this out, can but presume that Supermarines had boxes of mixed-variety rivets on the shop floor!Cheers, Chumpy.

Hyduminium rivets were useful for repair, or other, work where salt bath, or other, heat treatment facilities were unavailable.

THey came in standard solid varieties, snap-head or countersunk, or as an Avdel type (a fancy looking pop-type rivet but which left a portion of snapped off mandrel which required trimming down with a special, often pnuematic driven, rotary multi-edged cutter.:)

Hi Rivet freaks!
Yes purple rivets (L.86 alloy) are the current order of the day, though these were infact introduced back in the early 1940s. The mag alloy rivets were used mainly due to there lighter weight but they suffered badly from corrosion over time.
Quite common to find both the green mag-alloy and purple rivets alongside each other in bits of structure i.e wing ribs etc. Never quite figured this out, can but presume that Supermarines had boxes of mixed-variety rivets on the shop floor!
The above rivets were used for general structure work, however in high stress areas such as the outer portions of the wing spars, stronger (L.37 alloy) ‘salt-bath’ rivets were used. These supplied in the soft condition and required heat treatment prior to use.
A good source of info relating to the old WW2 material specs can be found in the technical books published by Pitman during the 1930s/40s. A couple to look out for are Materials of Aircraft Construction by F.T. Hill and Metal Aircraft Construction by M.Langley. Much useful data and listings of Air Min DTD / British Standard specs for sheet, bar, tubes etc…a small section attached.

Cheers, Chumpy.