WWI Digest 44 Topics covered in this issue include: 1) Re: Engine turned cowlings? by The Flying Wrench 2) Re: Engine turned cowlings by gspring@ix.netcom.com (Greg Springer ) 3) Re: Engine turned cowlings? by modlctzn@pacificrim.net (Mike Franklin) 4) Re: Engine turned cowlings by The Flying Wrench 5) Re: Engine turned cowlings by bshatzer@ednet1.osl.or.gov (Bill Shatzer) 6) Re: Engine turned cowlings by The Flying Wrench ---------------------------------------------------------------------- Date: Sat, 24 Feb 1996 11:23:33 -0900 From: The Flying Wrench To: wwi Cc: Multiple recipients of list Subject: Re: Engine turned cowlings? Message-ID: <199602242023.LAA14772@anchor> >Now I'd always been under the impression that the 'engine turning' >was estentially a cosmetic practice - that the early cowlings were >manufactured by placing a sheet of aluminum over a male mold and >wanging away with a hammer until the sheet of aluminum was in the >shape of a cowl and the 'engine turning' was just a means of covering >up/smoothing out all those hundreds of hammer marks. The Flyin' Wrench remarks: The forming process of which you speak is refered to as "bumping". A component formed in this manner was often referred to as "hand bumped". A bumped cowling or faring is one that is, in essence, hand formed with a hammer. Massed produced components were bumped around a wooden or lead form called a "bumping mould" (Surprise! bet you didn't expect that name). The mould was used to achieve the refined shape and then the part was finished by hand. The finishing process was to bump the component to shape on a sand bag made of leather and then test fit to the airframe. This process was repeated until the desired fit was achieved. Later on in the century, pneumatic and mechanically driven hammers replaced the hand driven hammer. This process was common until other techniques like spinning and moulding replaced it. To this day, the more complex shapes are still bumped. For instance when a cowling is formed for one of those 1930's racing replicas, the cowlings with the rocker cover bumps on it, such components are still hand bumped as the moulds for such a one-off component would be prohibitive. Cost effectiveness is the reason you did/do not find bumped components on modern production aircraft. Bumping techniques resulted in hammer marks on the bumped components. Thes marks on well-formed parts can be smoothed with a coarse "body" file and polished to the point that paint will cover such forming marks. However if you want a bare metal, bumped component, such marks have to be hidden with some other technique. The most renowned example of this was the was found on the cowling of the Spirit of St. Louis. This process was often referred as "jeweling". (There is another term the aircraft industry used for this process that I have now forgotten and cannot seem to find reference to in any publication) Jeweling is simply a swirling process created by a small buffing wheel used in conjunction with a coarse polishing compound. This process creates the swirling effect found on natural metal, bumped, components and resembles that which is found on the inside of the cases of fine watches. There are two points here I am unfamiliar with and are resulting in confusion on my part. (1) The markings I have seen on the Fokker's cowling are definitely not jewled, They have small "S" shapes that give the appearance of a "worms" on the cowling. In no way do they resemble the process used on the "Spirit". However I have achieved a somewhat similar pattern with an electric buffer using a radom buffing pattern (2) The term "engine turned" is totally unfamiliar to me, I would really like to hear a description of what this process entailed. Finally, pure metal does not corrode like alloys. This is the concept behind "cladding". Alclad aluminium is alloyed aluminium metal coated with a thin layer of pure aluminium. The alloyed metal has the desired tensil strength properties and the cladding provides for corrosion resistance. That is why when you scratch Alclad, you have compromised the crossion properities of the Aluminum. Such cladding is easily damaged through mishandling. The Wrench ------------------------------ Date: Sat, 24 Feb 1996 13:18:03 -0800 From: gspring@ix.netcom.com (Greg Springer ) To: wwi Subject: Re: Engine turned cowlings Message-ID: <199602242118.NAA13661@ix4.ix.netcom.com> Hello everyone! I agree with the Wrench's observation on the appearance of the finish on Fokker cowlings. This 'fuzzy S' pattern also appears on the ammunition boxes in Fokker a/c. I wonder if some sort of controlled chemical oxidizing process might have been used similar to the browning or blueing of steel on firearms? Perhaps it is anodized? (I definitely know next to nothing of metalurgy!) Applying a pattern to hide hammer marks makes sense on the compound curves of a cowling but not on the flat sides of a metal box. I reproduced it by making up a 'stencil'. I drilled many holes in a sheet of .015 styrene and then cut little worm-shaped connections between two or three holes at a time. The base coat on the part was flat aluminum. The stencil is set in place over the part with .30 to .40 spacers on either side to hold it slightly away from the surface. Dark grey is then shot through the stencil and the 'fuzzy S' effect is achieved. This method of course only works on flat surfaces. I liked Joey's method of painting them by hand on the cowling and then blurring the outlines with a light mist coat. >From my perusals of antique auto periodicals I believe that the terms 'engine turned' and 'jeweled' are synonymous. Cheers! Greg "I thought the slug balancing act needed a bit of work." -Gen. Sir Ian Hogmanay-Melchitt ------------------------------ Date: Sat, 24 Feb 1996 17:03:52 -0800 From: modlctzn@pacificrim.net (Mike Franklin) To: wwi Subject: Re: Engine turned cowlings? Message-ID: <199602250103.RAA17855@olympic> I believe the process of putting the irregular darker splotches on the aluminum cowls and other parts is called 'riffling'. An old friend of mine who worked on planes many years ago once explained to me that the process was to smooth out the uneven surface, and hide the obviously hand beaten look of the metal panels. This was done by hand with emery paper, a cloth backed wet-or-dry. If you look closely at several photos of Fokker E. type fighters, you will see that there is no regular pattern or shape to the darker spots. The darker spots are not really 'darker' as they are just less smooth and less reflective and as such only look darker in photographs. I have always been curious if this term riffling is related to the tools called riffling files, or rifflers. These are bent files used to smooth out the inside of cupped surfaces. My friend did not know if there was any connection, he said they did not use files to riffle the metal parts on the planes he worked on. I have read of a process used on some allied planes of putting swirles on the aluminum by using a wine cork and sand. This was done by hand as something to do on rainy non flying days. I can't remember where I read this. my 3/4 cents worth (considering inflation) Mike ---------------------------------------------------------------------- | _________________________|__________________________ | | | \ | / | | | "BEWARE THE PUN | ______\_O_O_/______ | | | IN THE SUN!" | / \ | | | annon. | (((((((+))))))) | | | ______|____________\_____/_____________|______ | | / \ | | []/_______\[] | | [] [] | | Mike Franklin is modlctzn@pacificrim.net | ---------------------------------------------------------------------- ------------------------------ Date: Sat, 24 Feb 1996 17:02:18 -0900 From: The Flying Wrench To: wwi Cc: Multiple recipients of list Subject: Re: Engine turned cowlings Message-ID: <199602250202.RAA25853@anchor> At 04:16 PM 2/24/96 -0500, Greg Springer wrote: >Hello everyone! > >I agree with the Wrench's observation on the appearance of the finish >on Fokker cowlings. This 'fuzzy S' pattern also appears on the >ammunition boxes in Fokker a/c. I wonder if some sort of controlled >chemical oxidizing process might have been used similar to the browning >or blueing of steel on firearms? Perhaps it is anodized? The Wrench replies: Defeinitely not anodized as anodizing is a relatively recent process of the last twenty years or so. >Applying a pattern to hide hammer marks makes sense on the compound curves of a cowling but not >on the flat sides of a metal box. This is a new twist and I must agree such masking technique does not add up for flat surfaces. But it does sound like it may have been a protective process. The Wright Brothers used a metal called "dairy tin", as I remember, and the use of such metal is called for in their plans. Examples of this "dairy tin" metal exist today and it has been found that it does not corrode. However the Smithsonian researchers cannot find out what this metal was or how it was produced, The process has been lost in our modern times and so to perahps the Fokker etching or whatever process has also been lost to us.. >I reproduced it by making up a >'stencil'. I drilled many holes in a sheet of .015 styrene and then >cut little worm-shaped connections between two or three holes at a >time. The base coat on the part was flat aluminum. The stencil is set >in place over the part with .30 to .40 spacers on either side to hold >it slightly away from the surface. Dark grey is then shot through the >stencil and the 'fuzzy S' effect is achieved. This method of course >only works on flat surfaces. I liked Joey's method of painting them by >hand on the cowling and then blurring the outlines with a light mist >coat. I like it, very clever. I can't see why it could not be used on cowlings if .005 sheet styrene was used and curved to fit the cowling contours. >>From my perusals of antique auto periodicals I believe that the terms >'engine turned' and 'jeweled' are synonymous. I can see the "turning" part of the process, but not the "engine" part of the process. >Greg "I thought the slug balancing act needed a bit of work." > > -Gen. Sir Ian Hogmanay-Melchitt Huh? Explanations are in order for us to understand this thought. Perhaps it is a "Proctered" remark? And one final thought - Chat. Does anyone know the orgins of the term "chatting"? Does anyone know what a "chat" is? I have a book about trench warefare and found this term. Can anyone enlighten us as to the meaning of this term? The Flying Wrench ------------------------------ Date: Sat, 24 Feb 1996 18:59:10 -0800 From: bshatzer@ednet1.osl.or.gov (Bill Shatzer) To: wwi Subject: Re: Engine turned cowlings Message-ID: <199602250259.AA29185@ednet1.osl.or.gov> The wrench writes: -snips- >The Wrench replies: -snips- >I can see the "turning" part of the process, but not the "engine" part of >the process. > Just a guess, but I'd speculate that the 'engine' bit derives from the original, early meaning of the term 'engine' as any mechanical device rather than the later use of the term as a motor or a mechanically powered device. As in the military term 'engineers' which refered originally not to folks that sit in a railroad locomotive and pull the whistle cord but rather to folks that built catapults and facines and seige towers and other infernal devices (i.e, 'engines') Some sort of mechanical device, maybe something like a brace and bit, would be used to construct those little swirly marks and, in the original usage of the term, it could be termed an 'engine' >And one final thought - Chat. Does anyone know the orgins of the term >"chatting"? Does anyone know what a "chat" is? I have a book about trench >warefare and found this term. Can anyone enlighten us as to the meaning of >this term? > What was the context in which it was used? I assume we're looking for some meaning other than the usual one of 'banter' or 'converse'. Where are you on this 'un, Mick? Cheers, -- Bill Shatzer - bshatzer@orednet.org -or- aw177@Freenet.Carleton.ca - "The only duty we owe to history is to rewrite it." -Oscar Wilde- ------------------------------ Date: Sat, 24 Feb 1996 19:57:59 -0900 From: The Flying Wrench To: wwi Cc: Multiple recipients of list Subject: Re: Engine turned cowlings Message-ID: <199602250457.TAA01846@anchor> >>And one final thought - Chat. Does anyone know the orgins of the term >>"chatting"? Does anyone know what a "chat" is? I have a book about trench >>warefare and found this term. Can anyone enlighten us as to the meaning of >>this term? >What was the context in which it was used? I assume we're looking for >some meaning other than the usual one of 'banter' or 'converse'. The Wrench elaborates: "For instance soldiers brewed tea, fried bacon, and chatted together. This was a social as well as an individual event, as trench fighters gathered in groups an chatted and gossiped." The soldiers would frequently chat with each other. Any ideas on this? The Wrench ------------------------------ End of WWI Digest 44 ********************