P38 Aluminium model help please.

Paul, I’ll take this a bit further.

The Spitfire was also a bit rough in finish, and as I recall, was just ‘not quite right’. I can draw quite well (thank goodness, because that is what I’m paid to do).

I can, like any boy of my era, draw a Spitfire freehand. But it won’t be completely accurate, or depict a particular Mk.

Even though I am bliddy good at CAD, taking that sketch on to 3d would be taxing and even less accurate.

Carving a wooden plug would therefore be a bit rough. Allowing for shrinkage, more or less impossible. I’ve done a bit of wood carving, but all freehand. It would look good, but be totally inaccurate.

Given that my Dad ended up as Chief Engineer on the RR RB211 engine, we can assume that ‘rough’ was not what he would then have accepted. Ceramics and Titanium were his then play things. He was an AFRAES. (post war).

My guess would be that the ‘project’ was to make a plug, mould and then cast. Mirror reflection not required! So maybe it was a test for the entrant at an early age – 16?

When I was 16 I’d have been proud if I had cast something that came out as a monoplane, let alone a Spitfire/Lightning.

A part of my reason for this guess is that he wasn’t even slightly surprised to find that a 18 yo. boguing was casting model yacht keels in Lead in the garage armed with nothing but an A level Chem textbook telling him the melting temperature of Lead.

As a parent, I can say that a ‘yoof’ should not be expected to make a couture product. That can only come with 5,000 hours of practice. But a talented one will have a very good try.

If I had been a tutor to 16yos, I’d be pretty pleased if their models had a wing on each side.

Might we worth a post on pprune – gaining a brevet in mil av, fair few veterans who were not pilots on that.

…flown afterwards!

The very point.

The ‘apprentice piece’ casting is also something that I’ve heard in the past; if that is the way the RAF taught the principals of casting, and it is the best way, why not make something ‘useful’ while teaching.

At my technical school we made model steam engines from scratch. We sand cast the frame and die cast the flywheel though of course we did not make the pattern or die. I wonder if any schools still do this today. My son’s school had a full set of workshops but they were never used to my knowledge. Later whilst at uni had a placement in a model shop of my sponsor (another thing of the past I believe) in the hols and made a machine vice from scratch, still got both of course.

Have to say your point about the availability of bar stock of that size is a good one. The firm I used to work for back in the 70’s used to keep a huge range of stock materials including this sort of size which would probably not be true today. The world was a different place then and if we are talking American and servicemen then probably what seems to us unlikely now was not so then. Need to look at the exhibit in the AAM as I seem to remember it said it was made from metal from aircraft, but maybe wrong. Need to take a picture of it next time I am there.

If, as 43-2195 says, these units had foundries then they could have melted down aircraft parts and it could all fit.

Thanks Creaking Door

And that’s another new skill learnt today, the use of multiple quotes!!!

I am less convinced by the ‘carved from solid’ method of manufacture, for two reasons:

Firstly, the size of this model (8 x 6 x 2 inches); that’s a pretty big slab of aluminium! Assuming this model is made from scrap then where on an aircraft are you going to get a piece of aluminium that size. Even an engine block isn’t going to have a single slab of that size anywhere in it.

Secondly, I know aluminium (or brass) is easy to cut and file but it isn’t that easy; this thing would take a long time to make from solid.

Conversely, casting, once you’ve made a pattern can produce large numbers of semi-finished items quite quickly and the raw-materials, scrap aluminium, especially scrap cast aluminium, would be abundant. Casting is also very suited for a ‘team effort’.

The published unit history of the 27th Air Depot Group'”New Guinea Diary” mentions unit members casting model P-38’s in their spare time whilst at Port Moresby in 1943.

That’s very interesting; I’ve never actually heard any account of anybody actually doing this.

While there are many sand-cast parts on an aircraft most of them would require a great deal of precision machining afterwards. I don’t doubt that it is possible but, echoing the previous post, what parts would be suitable for casting in the field and, more importantly…

…flown afterwards!

The ‘apprentice piece’ casting is also something that I’ve heard in the past; if that is the way the RAF taught the principals of casting, and it is the best way, why not make something ‘useful’ while teaching.

43-2195 That’s interesting. A foundry in the field! I wonder what aircraft parts were consider suitable for casting in the field. This is certainly an interesting possibility. Presumably there were similar units in England such as Burtonwood? Thanks

Thanks for your interest and input.

The wings in plan on my example look narrower than should be and not like other examples.

Similar thread

http://forum.keypublishing.com/showthread.php?t=32295

Airtanker here is another on Ebay very similar to yours with a selection of pictures. Finish is highly polished which is what I would expect.
http://www.ebay.co.uk/itm/P38-Pilots-Ashtray-Lockheed-Lightning-Australia-South-Pacific-1946-Trench-Art-/160940949294?_trksid=p2047675.l2557&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D4191485787926750409%26pid%3D100011%26prg%3D1005%26rk%3D5%26sd%3D190561033689%26&nma=true&si=F39mGdymr2oJ%252B%252FkwvlsGxr8IlHY%253D&orig_cvip=true&rt=nc

Boguing interesting yes a basic skills engineering apprentice work piece.

Creaking Door many thanks for this. This would explain inaccuracies in model but so would apprentice etc. I do understand that they were made from solid by hand an example is on display in the AAM at Duxford. The finish is something I am wondering about as having gone to the trouble of making the model, in any method a lot of work, then why not finish to a high standard at least a rub down with emery, wet & dry and a buff up to look like the one in the Ebay sale.
Tooling for die cast is expensive so you would need a long run to recover costs so would be aircraft recognition or ash trays. But then you would expect a symmetrical model which this is clearly not. So I agree not die cast.
Foundry workers doing what we used to call a “homer”, but then these were usually not for profit. Are you aware of this sort of thing going on? A lot of people would have to be involved and the volume would have to be worthwhile to warrant the time involved making the pattern.

It seems strange to me that the crude file marks have been left on. I mean really rough on the underside.
Transfers are curious and I wonder if these were applied later although as I say it has been in the family for a long time and I do not remember applying them myself!!

Again thanks all for your interest all comments are appreciated.
Paul

I have a ash-tray assembly,with the tray being a map of Australia,and the P.38 is secured by a curved arm ,with a similar hole in the under side of the P.38 as shown in one of the photo,s.

regards
jack…

My father had to make an Alu model of a Spitfire as a part of his training in the RAF during WWII. It has been lost, but as I recall it had been cast and then hand filed.

I’ve got one of those tho mine does not have any scoops on the booms but the general look of the item is the same with rough surfaces but no decals,i don’t know the origin of mine as my cousin found it at the local tip back in the 80’s (buried p38’s!).

The nacelle profile suggests to me that it is a depiction of a P38E/F rather than a later version. It reminds me of brass examples I have seen which were attached to ashtrays etc. and are typical “trench” art, the screw hole for the support is there. I’d suspect that working aluminium would be no more difficult than working brass so it could be a hand carved example – worked with a file. These were very popular – and off topic a few years back a friend of mine bought an example of early WW1 German trench art which was of all things a little brass Taube.

The published unit history of the 27th Air Depot Group'”New Guinea Diary” mentions unit members casting model P-38’s in their spare time whilst at Port Moresby in 1943.

Air Depot Groups(in the SWPA) were extremely practical and efficient outfits, capable of achieving tasks which are difficult to believe possible in hindsight.

My opinion is that this has been sand-cast and then finished by hand; it certainly hasn’t been die-cast and I doubt very much if anybody would carve it from solid!

Although often described as ‘trench art’ these would be quite difficult to produce (even on a fully equipped airfield). My guess is that these sorts of models were produced in one of the many foundries engaged in other war-work and these were produced by the foundry-workers as a way of raising extra money. It would be easy to make a few with spare (or not so spare) melt.

To sand-cast such a model you’d need a pattern. This pattern would probably have been made from wood and would be crucial to producing an accurate (or even successful) casting; pattern making is a very skilled trade. However not many pattern-makers would have access to a P-38 or detailed plans (which would explain the many errors seen in this type of cast model).

The finish from a sand casting can be pretty rough, especially if the pattern is rough, and there would also be the metal ‘sprue’ from the casting process. This metal sprue (risers, vents and flash) would need to be cut-off and the area finished with a file. All this is pretty time-consuming and not something that the foundry-worker could best use his time for (or ask money for). My guess is that these would have been sold-on semi-finished and the purchaser would be left to file and sand it to his required level of finish.