Bristol Scout C, Gavia 1/48, Upd 19.6.2021 Cowling

[Manni]

Beautiful in every aspect, Frank. I have missed this one up to now. Incredible work on the propeller. I love your selfmade cowling.
Mindblowing as usual.
Bye Manni

[Monty]

Great work happening Frank! Your scratchbuilding skills are amazing! That cowling is just so perfect... hope it fits OK in the end! Regards, Marc

[MichaelStieber]

 Outstanding work as usual.
There is so much that I can learn here 

[lawqbarr]

Frank

Love your work - always a real treat
That engine is a gem - Is it by Small Stuff or did you scratch those rockers yourself ?

That turned cowling is another minor work of art

I hope you will not mind the following ...
 
For those modellers out there who don't have the luxury of having 3-D printer and/ or who are "Unimat challenged" and don't have access to a mini/ micro lathe, you can still produce a revised replacement cowling of the correct internal and external diameter "old school" by either vac-forming, or plunge-molding  The following deals with plunge molding which does not require any special equipment. 

You could attempt a plunge mold of the complete cowl but you may well find yourself very frustrated by a series of failures. You need a cowling that's about 1 cm (6/10ths of an inch ) deep with  a fairly consistent wall thickness and that's hard to do by plunge molding without breaking through the curved section as you push the male part through The other problem is winding up with a part that too thin and flimsy  - Ask any modeller who's experienced with vac kits about this one if you don't believe me !

Plunge molding involves no more than obtaining or creating a tube and then gluing a plunge-molded curved section to one end. You need to bare in mind we are looking at internal and external diameters of the cowling we are trying to create

If you cannot find a pre-made polystyrene tube, don't despair - you can still create a tube by
- forming a tube with the required wall thickness from a single sheet of plastic ( getting a tube that's round and stays that way will be tricky), or 
- finding some round material with an external diameter matching the internal diameter of the cowl, or you could just sand down a piece of wooden dowel in a drill - You use this as a mandrel and then roll thin plastic sheet/ card/ Evergreen around it - Glue it down as you roll it. A set of calipers will help you get the right external diameter. go slightly oversize the external diameter to allow for sanding down

If you use thin liquid glue, be very sparing and make sure you allow the tube to dry for at least 3 days. You have to let the tube stabilise or it may deform when you take it off the mandrel/ core. Alternatively, use CA

Sand the resulting tube to a smooth external surface - you should be able to use a drill on a slow speed to do this

Next step is the curved section of the cowl

Plunge-molding is simple. There are heaps of "how to's" on the net - It's a matter of shaping a piece of basswood or balsa ( You can do this by fixing the wood you are using as the male part of a mold in a drill and sanding it down until you get the right shape You can also shape one end of the mandrel you made if you used a wooden dowel !! ), you then heat some sheet plastic (about 1.5 mm sheet would do ) and and then push/ plunge the male mold through a round "plate" of the correct external diameter. 

After trimming the curved part  (I'd sand it down on a flat surface to ensure a true mating surface that's square with the face of your tube),  glue the new curved section to tube (let it dry properly) and viola !  It sounds a lot harder then it is.

Regards
DavidL   

[Bughunter]

Thank you very much to all of you!

That engine is a gem - Is it by Small Stuff or did you scratch those rockers yourself ?

The engine is build out of the boxbag. Only Small Stuff parts are used.
Here you can see nice pictures of the parts and a link to a detailed description of the recommended build process:
https://www.smallstuffmodels.com/p/products.html#!/1-48-Gnome-7-Lambda-Oberursel-U-0-80-hp-Engine/p/57124350/category=13154092
Most impressive are the rods. I can't measure them without destroying because they are also made of resin. May be 0.15mm thick. Works nicely on the engine, because they are a bit flexible, so you do not destroy parts with a more stable wire.
I still do not understand, how such filigree parts are cast from resin without bubbles in that impressive quality!

I hope you will not mind the following ...

David, thank you for your detailed description!
Since I own a lathe and like to work on it, I try to made parts on it, if possible.
I used aluminum, because I don't have to paint it then. It is may be my way, but I like to display parts on my models by real material. I think for example, that real brass looks much more like brass then any paint called "Brass" that I know.
It may be do not respect a scale effect of the surface, but I like the impression given by real materials.

Sorry, I was not able to work on it, so no update.

Cheers,
Frank

[Fvdm]

Outstanding work Frank, as usual. May I ask what kind of chisel you use to make the outside of the cowling?