scratch-building engine cowlings

22 May 2004, 07:53 PM

Hello all.

Any suggestions on how to construct a 1/72 engine cowling to go around a Gnome rotary?

I'm looking to build a cowling similar in contour to the early Sopwiths, such as the Tabloid, where the contour is rounded and slightly aerodynamic, rather than cylindrical.

Any thoughts?

Michael · 22 May 2004, 08:45 PM

I'd be tempted to carve it in balsa, then heat plastic card and draw it down over the form. Cut it away and clean up. Staple the plastic sheet to a couple of dowels to avoid burns.

PeterL · 23 May 2004, 09:16 AM

Yup, push moulding (crash moulding if you will) is the answer. Balsa is not the ideal medium though as it is a little soft and sharply defined angles can be a bit tricky, obechi or even scrap pine is better IMO. If you are unfamiliar with the technique there is a full explanation on the Scale Model Aircraft in Plastic Card pages of my WWIModeler site. If you adopt Michaels method of fixing the card to a couple of dowels, or strips of wood, the overcomplicated contraption of frames and bulldog clips shown below will be unnecessary. It's far simpler to place the male part of the mould on the bench, drop the heated and softened plastic over it, then push the female mould over that.

Terry_Crisp · 23 May 2004, 05:14 PM

PJ,
What are you building? I just tried vacuforming some existing cowlings with mixed success ( I melted some I was trying to copy. Bummer,). However, It looks like I will be able to do better on the Revell 1/72 Camel cowlings. I'm gonna put a clerget in there.
Best regards,
Terry

23 May 2004, 06:56 PM

Thanks everyone for your ideas, and to Peter for the links.
I am going to try this.

I have been trying to construct a Royal Aircraft Factory BE-8. It is my first attempt at scratch-building anything.... Two steps forward, one step back, as they say.

sperry · 23 May 2004, 08:40 PM

I did a 1/72 cowl for a Tabloid. Here's the article:

http://wwi-cookup.com/sopwith/tabloid/tabloid_sp.html

HTH
sp

Rob_Owens · 24 May 2004, 07:23 AM

Actually, balsa can be "surface-hardened" by coating it with thin (the "water viscosity") CA. I did this to scratch a Gribeauval gun carriage, and it worked fine. Cut the soft balsa, smear on the CA, and sand. Don't try to do too large an area at once, though, as the heat released as the CA cures is enuf to burn a finger. Hth, Rob

Michael · 24 May 2004, 12:04 PM

Quote:

Originally posted by PeterL@May 23 2004, 12:16 PM
[b] It's far simpler to place the male part of the mould on the bench, drop the heated and softened plastic over it, then push the female mould over that.

I used to do my canopies (and a couple of Oxford cowls for an Anson conversion) without the female mould, but doubtless the results are superior with one.

Michael · 24 May 2004, 12:06 PM

Quote:

Originally posted by Terry_Crisp@May 23 2004, 08:14 PM
[b] PJ,
I just tried vacuforming some existing cowlings with mixed success ( I melted some I was trying to copy. Bummer,).

Depends on the thickness of your original. The old Frog Oxford cowls were solid, as they had the engines moulded in.

StephenLawson · 25 May 2004, 08:52 AM

Here's one of my attempts. The 11 cylinder Siemens Halske rotary found in the Eduard / Flashback SSW D.III kit was used in several other aircraft. In metal the rotary is quite a challenge as it weighs soooo much. The Atlee resin version is ok but to do an early version I had to scratch build the cowling from an old Hawk / Testors Nieuport 17. I quartered it and added about .050 thou. fillers.

There are several aircraft with unique cowlings that are the hallmarks of the company for this engine.