Engines > Your Own Design
1/4 scale Porsche 917 180 degree V12 Build
steamer:
--- Quote from: petertha on September 07, 2021, 03:09:40 am ---Here we go!
Maybe you spoke to this is the design workup but what materials were used in FS engine for the various (I'll loosely call them composite / molded thermoplastic) components. They all have different color amber shades, perhaps heat aging affecting them differently? Or maybe Kevlar used back then? The fan shroud has a hint of fabric so presume its a composite layup vs molded? Will you similarly miniaturize these?
--- End quote ---
Honestly....I haven't gotten that far yet....I have looked at those parts and honestly I think they are Kevlar/polyester resin layups. I think I will probably 3D print some of these parts...
Dave
Vixen:
--- Quote from: steamer on September 09, 2021, 12:55:45 am ---
--- Quote from: petertha on September 07, 2021, 03:09:40 am ---Here we go!
Maybe you spoke to this is the design workup but what materials were used in FS engine for the various (I'll loosely call them composite / molded thermoplastic) components. They all have different color amber shades, perhaps heat aging affecting them differently? Or maybe Kevlar used back then? The fan shroud has a hint of fabric so presume its a composite layup vs molded? Will you similarly miniaturize these?
--- End quote ---
Honestly....I haven't gotten that far yet....I have looked at those parts and honestly I think they are Kevlar/polyester resin layups. I think I will probably 3D print some of these parts...
Dave
--- End quote ---
Hi Dave and perertha,
I think you will find that the fan, the shroud and the injection trumpet decks were dough moulded using the DMC process, rather than a layup. DMC (Dough Moulding Compound) was a popular material for aerospace products in the 1970's 1980's. The DMC is an uncured dough-like thermoset compound, made up from either epoxy or polyester resins with a high proportion of chopped E glass fibre and other fillers.
The DMC process requires expensive heated metal moulds and some form of a mechanical or hydraulic press to close the mould. Similar in some ways to die casting moulds.
A measured amount of uncured dough moulding compound is rolled flat and placed into the heated female mould. The heated male side of the mould is closed, under pressure, forcing the dough molding compound into the mould cavities. Heat from the mould initially softens the dough molding compound so that it flows into every part of the mould very accurately. The heat then cures the compound.
The resulting material is both strong and light with the characteristic translucent amber colouring, you see on the 917 engine. The fibres are usually visible within the resin. The amber coulour seems to darken and become more opaque with age.
Sounds like a 3D print is the way to go. It would be nice to find a translucent amber printing filament to complete the illusion
Mike
steamer:
--- Quote from: Vixen on September 09, 2021, 11:29:26 am ---
--- Quote from: steamer on September 09, 2021, 12:55:45 am ---
--- Quote from: petertha on September 07, 2021, 03:09:40 am ---Here we go!
Maybe you spoke to this is the design workup but what materials were used in FS engine for the various (I'll loosely call them composite / molded thermoplastic) components. They all have different color amber shades, perhaps heat aging affecting them differently? Or maybe Kevlar used back then? The fan shroud has a hint of fabric so presume its a composite layup vs molded? Will you similarly miniaturize these?
--- End quote ---
Honestly....I haven't gotten that far yet....I have looked at those parts and honestly I think they are Kevlar/polyester resin layups. I think I will probably 3D print some of these parts...
Dave
--- End quote ---
Hi Dave and perertha,
I think you will find that the fan, the shroud and the injection trumpet decks were dough moulded using the DMC process, rather than a layup. DMC (Dough Moulding Compound) was a popular material for aerospace products in the 1970's 1980's. The DMC is an uncured dough-like thermoset compound, made up from either epoxy or polyester resins with a high proportion of chopped E glass fibre and other fillers.
The DMC process requires expensive heated metal moulds and some form of a mechanical or hydraulic press to close the mould. Similar in some ways to die casting moulds.
A measured amount of uncured dough moulding compound is rolled flat and placed into the heated female mould. The heated male side of the mould is closed, under pressure, forcing the dough molding compound into the mould cavities. Heat from the mould initially softens the dough molding compound so that it flows into every part of the mould very accurately. The heat then cures the compound.
The resulting material is both strong and light with the characteristic translucent amber colouring, you see on the 917 engine. The fibres are usually visible within the resin. The amber coulour seems to darken and become more opaque with age.
Sounds like a 3D print is the way to go. It would be nice to find a translucent amber printing filament to complete the illusion
Mike
--- End quote ---
Thanks for that Mike....this pesky work thing slows down my response!....That's an interesting note on the DMC process that I did not know about. As far as 3D printing, I'm certainly at the right place to find a substitute material to replicate that. I have a few materials in mind that I could use, but I'm also aware that not everyone has access to those materials, so I may come up with something more readily available......I think I have some time to think that one over. 8)
Dave
Art K:
Mike,
Thanks for the info about DMC. It's above my pay grade I'm sure.
Art
Vixen:
DMC moulding fell out of favor when carbon fibre pre-preg became widely available.
Mike
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